Many of the terms you may encounter when using DMR, D-STAR, System Fusion, P25, NXDN and M17. 549 entries.
If you have a suggestion for terms I may have missed, please email me at chris@n6jet.com.
Plain definition first. A green why it matters note where knowing the term changes what you do. An amber trap where the word means something different from what you would reasonably assume — and in this hobby, a surprising number of them do.
The Pi Zero 2 W and several other small boards have 2.4 GHz Wi-Fi and no 5 GHz radio.
The trapIf your router runs both bands under one name and the hotspot will not join, this is often why. It is not seeing the network you are looking at.
On many DMR systems, the number that disconnects whatever you are currently linked to.
Four-level FSK — four discrete frequencies, so each shift carries two bits. Used by DMR, Fusion, NXDN, P25 Phase 1 and M17.
Why it mattersFive of the six modes use it. What separates them is not the modulation but the vocoder and the network above it.
The usual number for Parrot — the echo service that plays your transmission back to you. Dialled as a private call on most DMR networks.
The set of callsigns or IDs permitted to use a hotspot that is not fully open.
The green activity light on a Pi. During normal running it flickers with SD card access.
Why it mattersOn a headless hotspot it is your only diagnostic before the network comes up. Steady blink patterns at boot signal specific failures — most commonly that the card is unreadable.
The Wires-X listing of which rooms and nodes are currently busy.
The transceiver chip that gives a modem board its own radio. Whether a board carries none, one, or two of them is the whole difference between the three board types.
The password-protected half of the dashboard, holding configuration and the per-mode manager pages. The public half only shows activity.
The rule deciding when a DMR radio is allowed to transmit — always, only if the channel is free, or only if the colour code matches.
The trapSet wrong, the radio simply refuses to key and gives no explanation. It is a genuinely common cause of 'my radio stopped working'.
An amateur DMR network, selectable in most hotspot software.
The height of an antenna above the ground beneath it.
A DMR transmission every radio on the channel hears regardless of its talkgroup settings. Rare on amateur networks.
A worldwide network linking analog FM repeaters, simplex nodes and computers over the internet, so distant machines behave as one system. It runs the app_rpt software, originally by Jim Dixon WB6NIL, on the Asterisk telephone platform. Nodes are identified by number, and you connect and disconnect them much as you would dial a telephone. The current generation is ASL3.
Why it mattersIt matters to digital voice operators because it is what the bridges bridge *to*. When a DMR talkgroup carries an AllStar node, or a hotspot reaches EchoLink, AllStar is usually the analog side of that connection — and USRP is how the audio crosses.
The trapAllStar is not a digital voice mode and does not compete with one. The audio is ordinary analog FM at both ends — only the path between is digital. A radio needs no special capability at all.
The original proprietary vocoder from DVSI, used by D-STAR. Needs a licensed chip or paid software.
A small USB device containing a licensed AMBE chip, used so software can encode or decode AMBE audio legally.
The later DVSI vocoder, shared by DMR, System Fusion and NXDN — and also used by P25 Phase 2.
Why it mattersBecause those modes speak the same vocoder, audio can pass between them in software. Anything crossing to D-STAR, P25 Phase 1 or M17 cannot.
The hardware vocoder chips — one channel and three channels respectively — used inside dongles and transcoders.
Why it mattersWhere software vocoding is not an option, this is the hardware that does the job, and the channel count is what limits how many simultaneous conversations a transcoder can carry.
The transcoding daemon that sits beside an XLX reflector and does the vocoder conversion for it.
Why it mattersA reflector without ambed cannot cross modes, however many protocols it accepts. Multi-protocol and transcoding are different things.
Software that shares an AMBE dongle over a network, so several programs or machines can use one physical chip.
A DMR and Fusion network that unites both in the same rooms, using Yaesu's IMRS repeater linking alongside a DG-ID bridge.
A Fusion radio feature that detects whether an incoming signal is analog or digital and switches to match.
Why it mattersAMS is the single feature that lets a club add digital to a repeater without the FM regulars losing anything — which makes it the strongest argument in any repeater committee meeting.
The DVSwitch component that converts between a digital mode and plain audio, doing the vocoder work.
Saying which talkgroup or reflector you are on when you call.
Why it mattersOn a linked system listeners often cannot see where you are. Saying it removes the commonest reason a call goes unanswered.
Where a hotspot's antenna sits relative to the radio using it.
Why it mattersToo close is a real problem, not a theoretical one. A hotspot on the desk and a handheld in your hand can overload each other.
The password for a Wi-Fi network — the pre-shared key.
A machine-readable interface. Several hotspot dashboards and networks offer one, so activity data can be pulled into a web page or script.
A secret token letting your hotspot dashboard, or an external tool, change settings on a network account on your behalf.
Why it mattersThe key is what allows a dashboard button to add a static talkgroup on the network rather than only on your hotspot. Treat it like a password.
The repeater-control software at the heart of AllStarLink, written originally by Jim Dixon WB6NIL and running on the Asterisk platform.
The Automatic Packet Reporting System, used here for putting a hotspot's position and status on a map.
The internet side of APRS, which is what a hotspot actually reports to.
Debian's package manager, used to install and update system software.
The trapHotspot distributions manage their own software and updating packages by hand can break them.
The usual shorthand for AllStarLink, and what it almost always means in a digital voice or linking conversation.
The trapIt also stands for 'above sea level' in antenna and site discussions. Two entirely different subjects, one abbreviation — context is the only guide.
The current generation of AllStarLink.
Why it mattersInstructions written for earlier versions describe a different installation and different configuration files. Check which generation a guide is written for before following it.
The open-source telephone exchange software that AllStarLink is built on. It is why AllStar talks about nodes and connections the way a phone system does.
How loud you arrive at the far end. On digital voice this is decided entirely inside your radio.
Why it mattersThere is no volume control anywhere in a hotspot, a network or a reflector, because they carry data rather than sound. Every audio complaint traces back to a radio at one end or the other.
When a hotspot cannot join your Wi-Fi it creates its own network instead, so you can connect to it directly and correct the settings.
Why it mattersThis is the way back in when a hotspot is unreachable. It is the rescue mechanism working, not a fault.
A network feature that promotes a talkgroup you use often to permanent status automatically.
An automated routine that measures a hotspot's frequency error and sets the offsets for you.
Why it mattersIt replaces the traditional business of nudging offsets by hand while watching the error rate — worth trying before doing it manually.
The station transmits with no control operator present at any control point. Only certain kinds of station are permitted to operate this way.
Why it mattersThis is the rule that makes 'may I leave my hotspot running while I am out?' a real question rather than an obvious one.
In Part 97, a station transmitting point-to-point within a system of cooperating amateur stations.
The periodic check that removes unreachable reflectors from maintained host lists.
Why it mattersA reflector vanishing from your dropdown usually means it stopped answering, not that your hotspot lost it.
A downloadable archive of the whole configuration, kept off the device. On some systems, placing it on a fresh card restores everything at first boot.
A radio refusing a codeplug because a channel falls outside the frequency range the hardware supports.
Why it mattersNearly always means the radio is a commercial band split that does not reach the amateur allocation.
The agreed division of a band into segments for particular uses. Not law in most places, but the basis on which everything coexists.
Why it mattersSatellite and weak-signal segments are the ones a hotspot can genuinely damage, because it transmits from a fixed spot and never stops.
The frequency range a commercial radio was built for. Surplus equipment is often sold by band split, and a radio outside the amateur allocation is useless to you.
Why it mattersThe single most important thing to check before buying surplus P25 or NXDN gear.
The scheme packing a callsign into a compact number, so M17 can carry it as an address rather than as text.
Why it mattersBase-40 is how M17 manages callsign addressing with no registration server anywhere — the callsign *is* the address, mathematically.
The command language a Linux terminal speaks. Every one-line command in every hotspot troubleshooting guide is bash.
The speed of the serial link between the Pi and the modem, commonly 115,200.
A radio setting preventing transmission while the channel is in use.
Why it mattersClosely related to admit criteria: both stop the radio keying, and both look like a broken radio to somebody who does not know the setting exists.
An automatic periodic transmission. On a hotspot it usually means an identification beacon; in APRS it means a position report; on HF it means a propagation beacon.
The percentage of bits arriving wrong, shown live on hotspot dashboards.
Why it mattersUnder about one per cent is healthy. A rising figure alongside a strong signal points at frequency alignment, not distance.
A list of stations or talkgroups specifically blocked, with everything else permitted. Also applied network-side, where a server refuses particular IDs.
The trapThe two work opposite ways round and both are called access control. Enabling one while thinking of the other produces a radio or a server that admits either nothing or everything.
A desktop and phone application giving access to D-STAR, DMR and Fusion, either with an AMBE dongle or through a network connection.
Debian release names, which appear in hotspot image filenames.
Why it mattersThey matter for one practical reason: instructions written for an older release may describe a dashboard or network configuration that has since moved. Check which your image is built on before following a guide.
The one part of an SD card a Windows or Mac computer can read. Files placed there are picked up at first startup, which is how Wi-Fi details can be set before the hotspot has ever run.
The small program that starts the Pi and hands over to the operating system. On newer models it lives in the board's own memory rather than on the card.
The largest worldwide amateur DMR network. Talkgroups are activated by transmitting on them rather than by asking a server first.
Why it mattersMost hotspot documentation assumes BrandMeister unless it says otherwise, which is why its conventions look like universal rules when they are not.
A link joining two systems that would otherwise be separate — two networks, two modes, or a digital system and an analog one.
Transmissions intended for reception by the general public. Amateur stations are not permitted to broadcast.
The trapA one-way transmission to a reflector with many listeners and no expectation of a reply raises the question of where the line falls, even when everyone involved is licensed.
The hardware address of a particular Wi-Fi access point, as opposed to the network name that may be shared by several.
Why it mattersUseful when a house has more than one access point on the same network name and a hotspot keeps attaching to the far one.
A hole in coverage where the digital signal collapses entirely rather than fading.
The languages the performance-critical parts are written in — MMDVMHost, the gateways, the modem firmware. Compiled to run fast and close to the hardware.
Why it mattersCompilation is why updating those components means installing a new build rather than editing a file, unlike the dashboard.
Controller software that joins repeaters into a network and routes talkgroups between them. Common on older and commercial-derived amateur networks.
Four-level frequency shift keying — the modulation Yaesu System Fusion uses. Strictly it is a modulation scheme, not a mode, but in conversation it is used as a name for Fusion itself.
The trapP25 Phase 1 also uses C4FM. Hearing 'C4FM' does not tell you which mode you are listening to.
A small field woven between DMR bursts carrying slot and channel status.
Why it mattersCACH is how a radio knows which of the two time slots the next burst belongs to. Without it, two conversations on one frequency could not be told apart.
A busy talkgroup used to find people, with the expectation that you move somewhere quieter to talk.
Your licence identifier — and in D-STAR and M17, also your network address.
D-STAR's ability to call a specific station by callsign, wherever it happens to be connected, rather than calling a place.
Why it mattersAlmost nobody uses it now, and it remains the most genuinely original idea in amateur digital voice.
M17's access code, doing the same job as a DMR colour code.
Why it mattersCAN completes the family: colour code on DMR, NAC on P25, RAN on NXDN, DG-ID on Fusion, CAN on M17. Five names, one idea — a number that must match at both ends.
D-STAR's way of routing a call to a person rather than to a place.
The network port used by D-STAR's callsign calling system.
A numbering scheme sharing the same seven-digit space as DMR IDs, used for D-STAR callsign routing on some systems.
A European agreement letting amateurs from participating countries operate in each other's territories without applying for a separate licence, using their own callsign with a prefix.
Why it mattersCEPT is the first thing to check before travelling with a hotspot. The agreement covers operating; it does not settle whether the country permits internet-linked operation or what frequencies a hotspot may use there.
A tiny antenna printed on the modem board itself, instead of an external whip.
Carrier-Grade NAT, where an internet provider shares one public address among many customers.
The trapIt can prevent traffic reaching you, and no hotspot setting fixes it. That conversation is with the provider.
The list of what changed in each software release, reachable from the dashboard.
Why it mattersWorth reading after an update that changed behaviour you relied on. It is usually deliberate and usually explained.
One entry in a radio's memory: a frequency, a mode, and every setting that goes with it. On DMR a channel also carries a talkgroup, time slot and colour code.
Why it mattersOn DMR you often have many channels on one frequency, differing only in which talkgroup they call. That surprises people arriving from analog.
A beep after a received transmission ends, signalling the channel is available.
Why it mattersIt does for digital what a courtesy tone does for an analog repeater — tells you when it is your turn without guessing.
How much spectrum a channel occupies. Most amateur digital voice runs at 12.5 kHz; NXDN also offers 6.25 kHz.
The trapP25 Phase 2 and DMR are often called 6.25 kHz modes. They are not — each uses a 12.5 kHz channel carrying two conversations, which is 6.25 kHz-equivalent per user, not 6.25 kHz occupied.
A published hash you can compare against a downloaded file to prove it arrived complete and unaltered.
Why it mattersA partly-downloaded system image does not announce itself. It fails later, in ways that look like hardware faults.
A hotspot's time being wrong because most single-board computers have no battery-backed clock and learn the time from the internet at startup.
The trapA hotspot that boots with no internet believes it is years ago, and connections then fail for reasons that look nothing like a clock problem.
A free, open vocoder by David Rowe, used by M17. Anyone can read the source, implement it, or improve it.
Why it mattersIt is the one vocoder in amateur digital voice whose source anyone can read.
The single configuration file holding everything a DMR radio knows — your ID, contacts, talkgroups, channels, zones, time slots and access codes.
Why it mattersThe codeplug is the reason DMR feels harder than the other modes. The radio does nothing useful until one exists, and building it is the tuition that actually teaches you the mode.
A configuration file that will no longer load or behave, usually after mixing firmware and programming software versions.
The trapKeep the versions matched, and keep a known-good codeplug saved before every change. Rebuilding from scratch is the usual cure.
The number, usually 1, that a DMR radio and repeater must agree on before anything passes.
The trapA colour code is neither a colour nor a code. It is a gate — and when it is wrong nothing happens at all. No noise, no error, just silence.
Replacement firmware written by amateurs for commercial radios, adding features, fixing faults, or supporting modes the maker never intended.
The trapIt usually voids any warranty and can, if interrupted, leave a radio needing recovery.
On EchoLink, a server holding many stations at once so they all hear each other — the analog equivalent of a reflector or talkgroup.
The trapWritten with asterisks around the name, which is how you tell a conference from an ordinary node in a connection list.
An entry in the radio's list of talkgroups and IDs it can call. On DMR a channel points at a contact to decide where it transmits.
The licensed amateur responsible for a station's transmissions. Every amateur station must have one whenever it is transmitting.
Why it mattersKnowing who that is matters for a hotspot sitting at home transmitting reflector traffic while nobody is in the room.
The place where the control operator performs that function.
The signal from a receiver telling a controller that something is being received.
A card whose label claims more capacity or speed than the chip inside provides.
The trapIt appears to work, then corrupts once you write past the real capacity — which on a hotspot may be weeks later, presenting as a mysterious fault.
The beep an analog repeater sends between overs, signalling that the timer has reset and it is safe to transmit.
Why it mattersMost digital systems have no equivalent, so there is no audible signal that the previous station has finished.
The manufacturer's PC program for editing a codeplug and moving it to and from the radio.
The processor. On a hotspot its speed matters less than its number of cores — dashboard features that read logs continuously need more than one.
How much work the computer has queued, shown on the dashboard as an average.
Why it mattersA hotspot should sit close to idle. A figure persistently near or above the number of processor cores means something is asking more than the board can give.
Shown on most hotspot dashboards. Comfortable is anything well under seventy degrees Celsius; sustained figures in the eighties mean throttling is close.
A phase-modulation scheme used by P25 Phase 1 equipment as an alternative to C4FM. Same information, different waveform.
Software that converts between two modes so they can work each other — a DMR radio reaching a Fusion room, for instance. Named for the direction it runs.
A short control message used for housekeeping such as registration and radio checks, rather than for voice.
A plain text table format, and the usual way talkgroup and contact lists are moved into programming software.
A sub-audible tone on analog FM that must match before a repeater responds. Private Line is Motorola's trade name for it.
Why it mattersWorth knowing because every digital mode has an equivalent — colour code, NAC, RAN, DG-ID. If you have ever set a PL tone, you already understand all of them.
The two older D-STAR reflector protocols, behind REF and XRF reflectors respectively.
Software for text chat, file transfer and forms over D-STAR's low-speed data channel.
Why it mattersGenuinely useful for emergency communications work, and almost unknown outside it.
The oldest of the six, developed in Japan by the JARL and first published around 2001. It routes by callsign rather than by talkgroup.
The trapD-STAR is the only mode that requires a one-time registration before the network side will work at all — and the step is easy to miss, because the radio itself works fine without it.
A one-time process of registering your callsign with a gateway and then activating a terminal against it, before D-STAR's network side will work.
Why it mattersThe radio works on RF without it, which is why people conclude the mode is broken when only the registration is missing.
The Decentralized Amateur Paging Network — the source of the POCSAG messages a hotspot can transmit.
The program that collects pager messages from DAPNET and hands them to the modem for transmission.
The web page you open in a browser to see and control a hotspot. Everything most operators ever need is there.
A modified version of a hotspot dashboard maintained by somebody other than the original author, usually adding features.
Why it mattersForking is how several projects in this hobby began, including at least one full distribution. It also means two people describing 'the dashboard' may be describing different software.
The credential protecting a hotspot's admin area — and on some systems the same credential used for command-line access.
The trapNot the same as your network hotspot security password. Two different secrets, and mixing them up is a common setup failure.
Anything a mode carries that is not voice — text, position, telemetry, paging.
D-STAR reflectors running the Digital Callsign Server protocol.
The trapNothing to do with DCS as the digital squelch code on analog FM. Three letters, two unrelated subjects.
The digital-coded equivalent of CTCSS on analog FM. A continuous low-speed code rather than a tone.
The trapOn D-STAR, DCS means something completely different — a family of reflectors. Same three letters, unrelated subjects.
D-STAR's data mode, carrying around 128 kbit/s on 23 centimetres. The only high-speed data mode among the amateur digital voice systems.
Why it mattersAlmost nobody runs it, and it remains the most ambitious idea in the whole family — an Ethernet-speed amateur link, specified over twenty years ago.
The Linux distribution nearly all hotspot images are built from. Raspberry Pi OS is a version of it.
A receiver being swamped by a nearby strong transmitter, so it hears nothing weaker.
Why it mattersVery relevant to hotspots: a handheld transmitting at five watts a foot away from a milliwatt hotspot can deafen it. Turn the radio's power down.
The device names for serial ports. A HAT-style modem usually appears on one of the first two; a USB stick modem appears as the third.
The trapThe Pi has two serial devices and on Bluetooth-equipped models the better one is claimed by Bluetooth by default. Hotspot images set this for you.
How far the transmitter shifts the carrier. Set too low or too high, a digital signal decodes badly or not at all.
Why it mattersOn a hotspot this is set by the modem's calibration, not by you — which is why a poor link is usually a frequency or offset problem rather than a power problem.
The ratio between how far the transmitter shifts frequency and how fast it is sending symbols.
Why it mattersWrong values cause decode failures that look like weak signal but are not. It is the underlying reason modem calibration exists.
A number set on a Fusion radio that both restricts what you hear and, on a linked system, selects where your transmission goes.
Why it mattersIt does double duty — access control and destination selection — which is why it confuses people who expect it to behave like a colour code.
The alternative Fusion program that routes by DG-ID, so each DG-ID on the radio can point at a different destination rather than one link at a time.
The service in your router that hands out IP addresses automatically.
A router rule that always gives the same device the same address. The supported way to stop a hotspot's address moving around.
Why it mattersEditing the operating system's own network settings to force a fixed address is usually unsupported and tends to be undone by updates.
As a verb, entering a number to select a destination. Digital voice borrowed the telephone word and the idea travels well enough.
A BrandMeister service that lets a radio link a talkgroup by dialling a number, without touching a dashboard.
The point where a digital signal stops working. Analog FM fades gradually into noise; digital stays perfect and then vanishes, with very little warning in between.
Why it mattersWhether this is a disadvantage depends entirely on whether you would rather strain through noise or hear nothing at all.
The downloaded database of DMR IDs that lets a radio show a callsign instead of a number.
The trapLoading the entire worldwide list makes the radio slower and its menus unusable. Curating it is worth the effort; Talker Alias avoids needing it at all.
Anytone's name for listening to all traffic on a time slot rather than only the talkgroups in your receive group list.
Why it mattersThe generic idea is promiscuous mode. Other manufacturers call it other things, and it behaves the same way on all of them — you hear conversations you have no obvious way to answer.
Dropping the current reflector or talkgroup link, usually by dialling a dedicated number or sending an unlink command.
Why it mattersThe unlink command is separate from the link command, and each mode has its own.
The kernel's own message log, recording hardware events — including undervoltage warnings and SD card errors.
Why it mattersWhen a hotspot misbehaves in ways the application logs do not explain, this is where the hardware truth is.
The DMR name for the same idea: radio to radio, no infrastructure.
The trap'Direct mode' in hotspot software means something almost opposite — connecting to exactly one DMR network rather than several. Same words, different subject.
An ETSI commercial land-mobile standard, published in 2005, that amateurs adopted second-hand. Uses talkgroups, colour codes and two time slots.
Link Control data carried inside the voice stream, repeating the source and destination so a radio joining late can still display who is talking and on what.
Why it mattersEmbedded LC is why a radio that turns on mid-transmission can still show the callsign, instead of waiting for the next over.
A number issued to you personally, identifying you on DMR networks. Free, but you must apply and show your licence.
Two devices logged into a network with the same bare ID, so traffic reaches whichever registered last.
Why it mattersThis is the problem ESSIDs solve. Some phone applications use a protocol that does not support ESSIDs at all, which makes them a common cause.
A built-in tool measuring how steadily network packets are arriving from a DMR master.
Why it mattersChoppy audio with a strong signal is nearly always a network problem rather than an RF one. This is how you tell which, instead of guessing.
The dashboard field naming the DMR server your hotspot is currently connected to.
Why it mattersIf it is blank or cycling, the hotspot is not reaching the network — which is a different problem from the modem not working, and looks identical from the radio.
The setting controlling what Talker Alias information your radio transmits — nothing, your callsign, or callsign and name.
Why it mattersSend it and other operators see who you are without needing your ID in their contact list. It is the practical alternative to loading tens of thousands of contacts.
Also written DMR-plus. A worldwide DMR network built on IPSC2 servers, with reflectors as well as talkgroups.
The Motorola Amateur Radio Club network — one of the oldest amateur DMR networks, and the origin of many talkgroup numbers still in use.
The software layer that holds connections to several DMR networks at once and decides which one each talkgroup belongs to.
Why it mattersWithout it a hotspot talks to one DMR network. With it, one radio reaches all of them from the channel knob.
The downloaded database that turns bare DMR ID numbers into callsigns and names on a dashboard or in a radio.
Why it mattersAn old list is why a hotspot that has not updated in months shows numbers instead of callsigns for newer stations. Nothing is broken; the list is simply old.
The everyday Fusion mode, carrying voice and data with error correction. What you use with a hotspot.
The service turning a name such as a reflector's address into the number a connection actually uses.
The trapA hotspot with working internet and broken DNS fails in a way that looks exactly like the reflector being down. Everything by name fails, everything by number works.
In this context, a small USB device carrying a licensed vocoder chip so software can encode or decode proprietary digital voice.
The same audio arriving twice, because one destination is reachable by two active paths at once — typically a bridge plus a direct connection.
Two stations transmitting at once. On analog you hear a heterodyne; on digital, one simply wins and the other is not heard at all.
The Fusion companion to DG-ID, aimed at individual stations rather than groups. Rarely used.
A European narrowband digital standard, closely comparable to NXDN and published by the same standards body that produced DMR.
Why it mattersIt appears on radio spec sheets and in comparisons, and is essentially absent from amateur radio. Knowing that saves you researching a dead end.
D-STAR's position reporting, which feeds positions from D-STAR radios into APRS.
On Icom D-STAR radios, the menu-driven mode that fills in the callsign fields for you from a stored repeater list.
Why it mattersDR mode is the difference between D-STAR being approachable and being an exercise in typing callsigns into four fields correctly.
Yaesu's Fusion repeaters. The DR-2X added IMRS repeater-to-repeater linking and DG-ID control.
Software for phone and desktop that puts you on DMR, D-STAR, Fusion, P25, NXDN and M17 with no radio and no hotspot at all.
Why it mattersThe cheapest possible way to hear a mode before deciding whether to buy into it. It is not radio, and it is not a substitute for a station — but as a way of finding out what a network sounds like, nothing beats it.
Yaesu's older digital squelch code scheme, since superseded by DG-ID.
The trapDocumentation written before DG-ID describes DSQ instead. Both exist in older radios and they are not the same thing.
The older, separate D-STAR engine that predates MMDVMHost handling the mode itself.
The trapDocumentation written when it was current describes a configuration that no longer applies to a modern hotspot. Check the date on any D-STAR guide before following it.
The touch-tones a telephone keypad makes, used on some systems as an alternative way of sending link commands.
One tone sequence that expands into several controller commands.
A radio's duplex offset direction setting.
The trapD-STAR radios generally need duplex enabled even for a simplex hotspot, with the offset set to zero. Leaving it in simplex is a common reason a D-STAR hotspot appears dead.
A modem with two radio chips and two antenna connectors, able to receive and transmit at the same time on a split pair.
The filter that lets a repeater transmit and receive on one antenna at once.
The proportion of time a transmitter is actually transmitting.
Why it mattersA handheld transmits in short bursts. A hotspot relaying a busy talkgroup, or a repeater, can transmit for hours — which is why thermal design, power supplies and antenna ratings matter far more to them than to a radio in your hand.
An early USB dongle providing a personal D-STAR access point, predating multi-mode hotspots.
A modem board family from the Netherlands, made in Pi HAT, Arduino shield and complete-appliance forms. Its Cast and EuroNode products are finished hotspots rather than bare boards.
The trapThere is a similarly named UK product that is not the same thing. Documentation sometimes has to say so explicitly.
In a hotspot's DMR network list, the abbreviation for DVS Phoenix — the UK network.
The trapEverywhere else in digital voice, DVS means DVSwitch, which is unrelated bridging software. Same three letters, two entirely different things, and both turn up in hotspot documentation.
A DMR network in the United Kingdom, appearing in hotspot network lists as DVSPh or Phoenix.
The company behind AMBE, AMBE+2 and IMBE.
The USB dongle carrying an AMBE chip, used where a real vocoder is needed rather than a software one.
The three-channel version of the DVstick, carrying an AMBE3003 chip rather than the single-channel AMBE3000 in the DVstick 30.
Why it mattersThree channels is what a transcoding reflector needs — one dongle can then handle three simultaneous conversations instead of one, which is why this is the one that turns up in XLX and URF transcoder builds rather than on a desk.
A suite of bridging software for joining digital voice systems together, and for reaching them from a phone or computer.
A phone application connecting to DVSwitch, giving digital voice access with no radio at all.
Yaesu's Data Wide mode, giving the fastest data transfer at the cost of voice quality. The third of Fusion's modes alongside DN and VW.
An address issued by the router, which may change.
Why it mattersA changing address is why a hotspot you reached yesterday at one address may not answer there today, and why the .local name or a reservation is worth setting up.
One that switched itself on because somebody transmitted on it, and switches itself off again after a period of quiet.
The trapA dynamic talkgroup switches itself off after its timeout, which looks like a fault and is not.
Another name for the parrot function, particularly on D-STAR.
The number that reaches a mode's echo or parrot test service.
An internet linking system for analog FM, created by Jonathan Taylor K1RFD in 2002. Stations are identified by node number, and — unusually — you can join from a computer or phone with no radio at all. Every user must have their licence validated before the system will admit them.
Why it mattersThe suffix on a node tells you what it is: -L is a simplex link, -R is a repeater, and a bare callsign is somebody at a computer.
The trapEchoLink is the one linking system where the person you are talking to may not be transmitting on radio at all. That is a feature, and it is also why some repeater owners will not carry it.
A relay letting an EchoLink client reach the network from behind a restrictive router or network that would otherwise block it.
Why it mattersThe analog world's answer to the same problem CGNAT creates for digital voice — a reminder that the difficulty is the network, not the mode.
Two separate facts about a service: whether it is running now, and whether it is set to start at boot.
The trapA service started by hand runs perfectly and will not come back after a reboot. On a system with months of uptime, nobody finds out until the day it restarts.
Scrambling transmissions so others cannot decode them. Most commercial digital radios offer it.
The trapDigital does not mean private.
What actually leaves the antenna, accounting for gain and losses, rather than what the transmitter produces.
Two extra digits appended to your DMR ID so several of your own devices can be logged in at once without clashing.
Why it mattersWithout one, a hotspot and a phone app on the same bare ID will fight — traffic goes to whichever connected most recently.
The European standards body that published DMR, and which continues to maintain it.
Why it mattersIt explains why DMR talks about colour codes and talkgroups rather than anything an amateur would have invented: the standard was written for commercial fleets, and amateurs adopted it afterwards.
The first-boot step that grows the system to fill the SD card. It is why the first startup takes noticeably longer than every later one.
Raw text editors in the dashboard for the underlying configuration files.
The trapSaving the ordinary configuration page regenerates those files and replaces what you typed.
Wipes a hotspot's settings back to defaults. Also the way back in when the password is lost.
Speaking the instant you press transmit, before the network path has come up.
Why it mattersYour callsign goes out while the system is still connecting, so what people hear begins halfway through.
A second family of Fusion reflectors, alongside the original YSF ones. Both appear in the same lists; the identifiers simply start differently.
One conversation per channel — the ordinary arrangement. D-STAR, Fusion, NXDN, M17 and P25 Phase 1 all work this way.
Extra data sent alongside the voice so the receiver can rebuild bits that arrived damaged, without asking for them again.
Why it mattersThis is the mechanism behind the digital cliff. While the errors stay within what FEC can repair, the audio is perfect — not merely good, perfect. Once they exceed it, there is nothing to fall back on and the signal vanishes. The abruptness is not a flaw in the design; it is the design working until it cannot.
The housekeeping data inside a Fusion transmission that tells the receiver what kind of frame it is looking at.
How storage is organised into files and directories.
Why it mattersThe filesystem is the thing that corrupts when power is pulled from a running hotspot, and the reason a clean shutdown matters more than it seems to.
Damage to the card's contents, usually from losing power without a clean shutdown.
Why it mattersIt costs thirty seconds and prevents the most common way hotspots die.
A filter deciding which network traffic is allowed. Hotspot software generally runs its own, opening only what the enabled modes require.
Why it mattersIf everything works at home and nothing works at a hotel or on a corporate network, this is usually why — and it is their restriction, not your equipment.
A program stored inside a device rather than on the SD card.
The trapThree separate things get called firmware around a hotspot: the modem's, the radio's, and the host's operating system. 'Update the firmware' is ambiguous until somebody says which.
Writing new software into the modem board itself, as opposed to updating the host.
The trapIt must match both the board model and its crystal frequency. Getting it wrong is one of the few ways to render a modem unusable.
Writing software onto something.
The trapTwo entirely different operations share the verb — writing an image onto an SD card, and writing firmware into the modem. Confusing them at the wrong moment can leave a modem unusable.
The analog mode everything else is measured against, and still the most used mode on VHF and UHF.
Why it mattersWorth stating plainly because every digital comparison assumes you know how FM behaves: it degrades gradually, anyone can hear anyone, and no configuration is required beyond a frequency.
Setting a radio up from its own keypad instead of from a computer.
Why it mattersConvenient for a quick change in the field, and impractical for DMR, where a usable configuration means hundreds of entries. It is why DMR radios ship with programming software and FM radios often do not.
A DMR network built on open-source server software, run as a community project.
A UK-based multi-mode network bridging DMR, D-STAR, Fusion and EchoLink through its own software.
The voluntary process by which repeater frequencies are allocated regionally to avoid interference.
Why it mattersCoordinators in several regions have taken positions on hotspot frequencies where regulators have not. Worth checking what yours says before picking one.
Sending data by shifting the carrier between fixed frequencies.
How much of the channel's capacity is given to the voice itself, as opposed to error correction and data.
Why it mattersThis is the trade behind Fusion's DN and VW modes, and behind why some modes sound better than others on the same equipment. More bits to the voice means better audio and less protection against errors.
The software moving D-STAR traffic between a repeater and the internet.
The newer Icom gateway software, notable for supporting Terminal and Access Point modes — a radio reaching the network with no separate hotspot.
The program handling one mode's internet side — ircDDBGateway for D-STAR, YSFGateway for Fusion, P25Gateway, NXDNGateway, DMRGateway for DMR.
The trapYour router also has a 'default gateway', and D-STAR separately calls its own routing system a gateway. Three unrelated meanings in one setup.
On D-STAR, your callsign with a G in the eighth position, identifying the gateway rather than the module.
FSK with the same smoothing filter applied, for the same reason.
The modulation D-STAR uses. The Gaussian filter smooths the transitions, which keeps the signal narrow.
The double row of pins on a single-board computer that a HAT plugs onto.
Why it mattersDifferent host boards wire those pins differently, which is why hotspot software ships a separate download for each supported board rather than one universal image.
The GNU General Public License, the most common open source licence in this field. It permits use and modification but requires that derived work stays equally open.
Why it mattersThe GPL is the reason the hotspot ecosystem exists at all. One project's work can be built on legally, so it has been, repeatedly, for fifteen years.
The serial port where an attached GPS receiver is connected, for position reporting.
Sending your position from the radio, usually forwarded to APRS by the network or hotspot.
A transmission addressed to a talkgroup, heard by everyone monitoring it. The normal way DMR conversations happen.
A Fusion feature showing the distance and bearing of other stations in your group.
Transmit or receive, but not both at once. What nearly all amateur voice operating is, digital or otherwise.
A smaller amateur DMR network with a compact talkgroup list.
M17's distributed directory, letting one station find where another is without any central server.
Why it mattersIt locates a station without any central server, which is the design goal M17 was built around.
How long a talkgroup stays selected after a transmission ends — counted separately for traffic arriving over the air and from the network.
The trapOn an analog repeater, 'hang time' means the tail after you unkey. Related idea, different measurement.
A board that plugs straight onto a Raspberry Pi's pin header rather than connecting by cable. Most modems are HATs.
Open-source DMR server software, written by N0MJS. Much of the amateur DMR world runs on it, and anyone can stand up a private network with it.
Running a computer with no monitor, keyboard or mouse attached, reaching it over the network instead. The normal state of every hotspot.
Why it mattersHeadless operation is why the dashboard exists, why the Wi-Fi has to be right before first boot, and why a hotspot that cannot join your network appears completely dead when it is working perfectly.
The open protocol repeaters and hotspots use to log into DMR master servers, and the reason amateur equipment can join commercial-derived networks at all.
Why it mattersIt supports ESSIDs, which is why a hotspot can share your ID with other devices. Some phone applications use a different protocol that does not — which is where ID collisions come from.
BrandMeister's live web stream of network traffic, playable in a browser.
Why it mattersThe easiest way to hear your own transmission played back, and the easiest thing to demonstrate to somebody who has never heard DMR.
The small computer that runs the hotspot software — usually a Raspberry Pi.
The trapHotspot software also uses 'host' for a reflector, as in 'startup host', and 'hostfile' for a list of reflectors. The same word means the computer in one chapter and a reflector in the next.
The list mapping a mode's reflectors or servers to addresses and ports.
The trapHotspot software maintains these automatically, so anything typed into one by hand disappears at the next update. There is a separate editor for entries you want kept.
The place to add a reflector or server so it survives the automatic host list updates, rather than being overwritten.
The name a device answers to on the local network, and the first part of a .local dashboard address.
Why it mattersChange it and the address you use to reach the dashboard changes with it.
A one-touch shortcut on a radio, assigned to a channel, a contact, or a function such as calling Parrot.
Why it mattersWorth setting one to your echo test and one to disconnect. Both are things you want without navigating menus while holding the radio.
A modem and a small computer in one box with an antenna, giving a handheld access to worldwide networks from a few tens of milliwatts.
Why it mattersThe RF link is deliberately tiny — a few feet. Everything that makes a hotspot useful happens on the internet side.
The simplex frequency chosen for a hotspot, normally on 70 cm.
The trapSome segments are excluded for this kind of station under Part 97 — including the satellite subbands — and coordinators in several regions publish channels for hotspot use.
A public map plotting hotspots from the coordinates their owners configured.
A secret set in your own network account and entered into the hotspot, proving the connection is yours.
The trapThis is not your dashboard password and not your DMR ID. Getting it wrong is a common reason BrandMeister will not connect.
Yaesu's hardware box connecting a compatible radio to the Wires-X network.
Why it mattersIt is what full Wires-X access requires.
The three parts of a web page: the content, how it looks, and what it does when you interact with it. A hotspot dashboard is all three, served from the hotspot itself.
An AllStarLink node with no radio attached, existing purely to join other nodes together.
The protocol AllStarLink uses to carry audio and control between nodes.
The downloaded list of registered IDs and their callsigns, letting a dashboard or radio show a name instead of a number.
Why it mattersThe database is a snapshot, not a live lookup. A very new operator may not appear until the next refresh, which is why an unknown ID is not necessarily a fault.
An automatic identification transmission sent periodically by a repeater or node.
Sending your callsign as your licence requires. Digital modes carry it in the data stream, but that does not remove the obligation to identify by the rules you operate under.
A rewrite rule that presents a different DMR ID to the network than the one the radio actually sent.
The complete system, downloaded as one file and written to an SD card. You do not install this kind of software onto an existing system — the image is the system.
The trapNothing to do with pictures.
The vocoder in P25 Phase 1. Its core patents have expired, which makes it the one member of the family anyone may implement freely.
The trapExpiry of the IMBE patents did not free AMBE or AMBE+2 — those are separate and later. IMBE also remains a DVSI trademark.
Yaesu's system for linking Fusion repeaters directly to each other over the internet, without Wires-X.
The rule governing what the radio does when you press transmit while a call is already in progress.
Why it mattersTogether with admit criteria it decides when the radio will and will not key. Between them they explain most cases of 'my radio has stopped transmitting'.
A modem calibration setting affecting the inner two levels of a four-level signal, relative to the outer two.
The trapAdjusting it without instrument measurement usually makes things worse.
Spreading the coded bits of each block across time, so a brief fade damages many blocks slightly instead of destroying one completely.
Why it mattersInterleaving is why digital voice survives short interference that would put an audible hole in an analog signal. Combined with error correction, it is most of the reason digital sounds perfect until it does not.
A connection joining matching rooms or modules across two separate reflector servers.
Why it mattersIt explains conversations appearing on a reflector you never linked — the servers are joined behind the scenes.
The number identifying a device on a network. A hotspot needs one to reach the internet, and you need to know it to reach the dashboard.
The server software behind DMR+ and several other networks. IPSC stands for IP Site Connect, a Motorola protocol.
The familiar four-number internet address, such as 192.168.1.50. What nearly all amateur digital voice runs on.
The newer, much longer internet address format.
The trapSome digital voice software supports it poorly or not at all, and a network that is IPv6-only can leave a hotspot unable to reach anything. Worth knowing about before blaming the hotspot.
The network that shares D-STAR callsign and gateway information worldwide, so callsign routing can work across systems.
The program handling D-STAR reflector linking, gateway registration and callsign routing.
Started by David Cameron VE7LTD in 1997. Nodes are identified by number and joined either directly or through numbered reflectors that hold many nodes at once.
The trapRadio-only by design — there is no computer or phone client, and that was a deliberate decision rather than an oversight. It also requires a specific hardware interface board, which is why IRLP nodes are less common than EchoLink ones.
A numbered server holding many IRLP nodes at once, so a conversation reaches all of them.
Variation in the arrival time of network packets. Enough of it produces choppy audio even when nothing is actually lost.
A small deliberate delay that collects arriving packets and releases them evenly, smoothing out uneven internet delivery.
Why it mattersThe buffer is the trade at the heart of every linked system: a larger buffer sounds smoother and adds delay. Everything you hear about digital voice latency comes partly from here.
The common name for widely-cloned inexpensive MMDVM boards, usually sold unbranded. Functionally an MMDVM_HS board.
Why it mattersThey work, and they are how a great many people start.
The trapQuality varies between batches, and firmware is not always matched to the board.
A periodic small message proving a connection is still alive. Miss enough of them and the server drops you.
Why it mattersKeepalives are why a hotspot on a marginal internet connection disconnects during silence rather than during a conversation.
The single callsign authorised to send those commands.
A very short key-up with no speech.
Why it mattersOn several modes a brief key-up is exactly how a link or unlink instruction is sent, so documentation asks you to do it on purpose. Same action, opposite intent.
The trapDistinguish it from the deliberate kind below, which is a real command.
The core of the operating system, sitting between the software and the hardware. Its version is shown on most dashboards.
Why it mattersYou will never set it, but it changes with updates — and a kernel update is one of the few things that genuinely requires a reboot to take effect.
The habit of keying, counting one, then speaking — because a digital path takes a moment to establish through hotspot, network and far-end radio.
Why it mattersWithout it your first word or two is cut off and the other operator hears the end of your callsign instead of the start.
On EchoLink, the marker showing what a node is: -L for a simplex link, -R for a repeater, and no suffix at all for a person at a computer.
Why it mattersA repeater node reaches everyone monitoring that repeater; a bare callsign reaches one person at a computer.
The dashboard list of who has transmitted recently, and for how long.
Why it mattersThe first place to look when checking whether your radio actually reached the network at all.
Repeated identification data sent throughout a transmission, so a radio switched on partway through can still display who is talking and on what talkgroup.
Why it mattersLate entry is why a radio turned on mid-over shows a callsign instead of waiting for the next one.
The delay between speaking and being heard. Digital voice always has some; linking and transcoding add more.
Why it mattersLatency is why the key-up pause matters, and why courteous gaps between overs matter more on linked systems than on a local repeater.
The mechanism by which M17 dribbles fragments of the setup frame through the transmission, so a receiver joining late can still assemble the details.
Why it mattersLICH is M17's answer to the same problem DMR solves with embedded Link Control — how somebody arriving mid-transmission learns who is talking.
The block naming the source, the destination and the call type for the transmission in progress.
Why it mattersLink Control is what lets a receiving radio display who is calling and on what — and why losing it means a call that decodes but shows nothing useful.
Connecting a hotspot or repeater to a reflector, and disconnecting it again. On D-STAR the commands go in the URCALL field; other modes use a dialled number, a dashboard button, or a brief key-up.
Why it mattersWhatever the mode calls it, this is the core operating skill in digital voice.
The trapIn repeater engineering a 'link' is a separate radio joining two sites — a piece of hardware, not an action. Unrelated to this use of the word.
The operating system underneath essentially all amateur digital voice infrastructure — every hotspot, every reflector, every bridge.
Why it mattersYou can run a hotspot for years without a command line. Knowing it is Linux underneath matters the day something breaks and the only instruction available assumes you know.
A link permitted to receive but not to transmit.
A rough measure of how much work the Pi has queued, shown on most dashboards.
Why it mattersOn a hotspot it should sit near idle. A persistently high figure on a small board usually means a dashboard feature is asking more than the hardware can give.
Used three ways: talkgroup 9 is often called 'local', a .local address is how a dashboard is reached, and 'local control' is a licensing term. None are related.
The control operator is physically at the station, operating it directly.
A dashboard page showing the software's running commentary.
Why it mattersIt usually states plainly what is wrong.
Two networks cross-linked in both directions, so traffic circulates endlessly between them.
The trapA bridging mistake rather than a fault, and it can flood a talkgroup across several networks at once. It is the main reason bridges are set up carefully and sparingly.
M17's opening frame, carrying source, destination, type and metadata.
The only amateur-designed digital voice mode, started by Wojciech Kaczmarski (SP5WWP) in 2019. It uses the free Codec 2 vocoder and carries the callsign in the stream with no registration.
Why it mattersIt was started to solve a specific problem: a digital voice mode whose vocoder anyone can read and implement.
The permanent hardware identifier of a network adapter. You need it to set up a DHCP reservation.
A dashboard page for changing links on the fly — pick a reflector from a list and press a button, instead of editing configuration.
Why it mattersEverything the radio-side commands do can be done here, and it is far easier while learning. The radio methods matter when you are away from a browser.
Keying a talkgroup number or ID straight into the radio instead of choosing it from the contact list.
Why it mattersManual dial is how you reach a talkgroup you never programmed — and on many radios, how you reach the control numbers that link and unlink reflectors.
The particular server on a network your hotspot connects to. Networks run several worldwide and you choose a nearby one.
The trapIt reads like 'the main one'. It only means the one you happen to use.
The three-digit prefix at the front of every DMR ID, borrowed wholesale from the mobile phone world.
Why it mattersIt means the first three digits of any DMR ID already tell you the country the operator registered in.
Software that emulates the vocoder chip from a Tytera radio, providing AMBE encoding without a dongle.
Community firmware for TYT radios, adding features the manufacturer never included — promiscuous listening and a full contact database among them.
Why it mattersIt began the whole practice of replacing digital radio firmware, and much of what followed traces back to it.
Zero-configuration name discovery — the trick that lets a name ending in .local resolve without any DNS setup.
The trapNot every network or device supports it. If a .local address does nothing, nothing is broken; you need the IP address instead.
A stored frequency and its settings, recalled by name or number.
A network where nodes relay for each other rather than all reporting to one central point. In amateur radio usually AREDN, built on repurposed wireless hardware.
The seed value sent alongside an encrypted transmission so the receiver can decrypt it.
Why it mattersYou will see it referenced in commercial documentation.
How much the radio amplifies your voice before encoding it.
The trapSet too high and the vocoder is overdriven; set too low and the audio is thin. Nothing downstream can fix either, because past the radio there is no audio left to adjust.
The Pi's only storage, and the component in a hotspot most likely to fail.
Why it mattersUnexplained instability, failed updates and settings that will not stick are more often a worn or counterfeit card than a software problem. Keep a spare and a current backup.
A thousandth of a watt. The usual output of a hotspot board, and enough to cover a house.
Why it mattersPower output is the number that makes hotspots legally and practically different from repeaters, and the reason raising the power changes what the device is.
The open-source hardware and software project nearly every hotspot on the market is built on, whatever name is on the box.
Why it mattersOne project underpins the entire hotspot world. It is why a ZUMspot, a DVMega and an unbranded board all behave alike.
The DVSwitch component that speaks the digital voice network protocols, standing in for a hotspot without any radio hardware.
The open-source firmware that runs inside a hotspot modem board, as distinct from the software on the host computer.
Why it mattersModem firmware is the layer people forget exists. A hotspot has firmware in the modem, an operating system on the Pi, and application software above that — three things that update separately.
The calibration utility for a modem — used to set frequency offset and modulation levels against something that can actually measure them.
The central program in a hotspot. The only one that talks to the modem, and the one handling the on-air side of every mode.
Why it mattersRadio side is MMDVMHost; internet side is a gateway. Knowing which half a fault sits in is most of the diagnosis.
Two dashboard panels answering two different questions. Mode status is about the modem; network status is about the internet.
Why it mattersNoticing which one is unhappy immediately tells you whether to look at hardware or at your connection.
The board that turns your radio's signal into data and back again. The only part of a hotspot that touches radio waves.
The trapNothing to do with an internet modem. MMDVM stands for Multi-Mode Digital Voice Modem.
The serial device the host uses to reach the modem — commonly a hardware serial port for a HAT, or a USB device for a stick.
The trapNot a network port. The firewall's ports are numbered network channels; this is a physical connection.
A letter, A through Z, selecting one conversation on a reflector that hosts several.
The trapD-STAR also calls a repeater's band a module — A, B or C. Same word, different thing, and both appear in D-STAR setup.
The letter after a callsign or reflector number identifying which channel you mean — A, B or C for a D-STAR repeater's bands, A to Z for a reflector's rooms.
To listen without transmitting.
A one-way link that hears another node without passing your traffic back to it. Distinct from a full two-way connection.
Motorola's DMR product line — the XPR, SL and CP families. Common on the surplus market.
Why it mattersThe trade is programming software, cables, and checking the band split covers the amateur allocation before you buy.
Attaching a storage device or partition so its contents can be read.
The reflector software for M17.
The largest packet size a network link will carry in one piece.
The trapSet wrong, some traffic passes and some silently vanishes, which produces faults that look intermittent and mode-specific. Rare, but nearly impossible to guess at.
Controls silencing or blocking particular IDs at a hotspot or repeater.
On D-STAR, the field holding your own callsign.
The code a P25 system carries so a receiver knows the traffic belongs to it. $293 is the default nearly everything ships with, and $F7E is the setting that receives regardless.
Why it mattersIt does the same job for P25 that a CTCSS tone does for FM and a colour code does for DMR — and getting it wrong produces the same symptom, a signal you can see but cannot hear.
A compact hotspot family from BI7JTA, available in simplex and duplex forms.
The regulatory push that forced commercial users onto narrower channels. It is why NXDN exists, and indirectly why so much cheap surplus digital equipment reached amateurs.
How one public address serves many devices on your home network.
A scheduled on-air gathering with someone running it.
Why it mattersThe friendliest place for a first digital contact — somebody is expecting new callsigns and will make room for you, which calling into an unfamiliar talkgroup does not guarantee.
The number saying which part of an IP address identifies the network and which identifies the device.
Means the internet, a named DMR network such as BrandMeister, or a numbered configuration slot inside gateway software — depending entirely on the sentence.
Two sources feeding one talkgroup at the same moment, so one of them is simply dropped.
Why it mattersContention is why you can be transmitting perfectly and still not be heard — somebody keyed a fraction of a second before you, on a repeater you cannot hear.
A string of settings sent to a master when the hotspot connects, carrying things like static talkgroups and relink timers.
One of DMRGateway's fixed positions, each holding one upstream network's address, password and rules.
The trapNothing to do with a DMR time slot, and nothing to do with an SD card slot. Three meanings, one word.
A Wires-X store-and-forward area holding voice messages, text and pictures for later collection.
Why it mattersOne of Fusion's genuinely distinctive features, and almost unknown outside the Yaesu world.
A colour touchscreen display that loads a design file deciding what it shows — typically last heard, mode and network status.
A scheduled overnight restart and housekeeping run on many hotspot systems.
Why it mattersTemporary links do not survive it. Static ones are restored.
In everyday amateur use, almost any internet-linked station.
The trapSome documentation — WPSD's in particular — uses it far more narrowly, for a simplex setup where the modem has no radio of its own and drives a separate external radio.
The five-digit numbers identifying a Wires-X node and a Wires-X room.
The trapNot related to DMR talkgroup numbers, reflector numbers, or anything else. Wires-X has its own numbering entirely.
The number identifying a node on AllStarLink, EchoLink or IRLP, dialled to connect to it.
The trapEvery linking system has its own numbering and none of them interoperate. An AllStar node number means nothing to EchoLink, and neither means anything to DMR.
Whether only your own callsign may key the hotspot, or a listed set of others may too.
No value set. Appears in configuration fields and logs where something is expected but absent.
The trapA field reading null is not necessarily broken — many are optional. It matters only when the thing it configures is not working.
Developed jointly by Icom and JVC Kenwood from 2003, announced in 2005 and sold as IDAS and NEXEDGE. The quietest of the six on the amateur bands.
Why it mattersNXDN is the only one of the six offering true 6.25 kHz FDMA channel spacing. DMR and P25 Phase 2 reach 6.25 kHz-equivalent efficiency instead, by putting two conversations in a 12.5 kHz channel.
The trapOften described as a 6.25 kHz mode. It is dual-bandwidth — 6.25 kHz at 4800 bps and 12.5 kHz at 9600 bps — and the technical specifications were not released publicly until 2012.
A separate number, issued separately, required to operate NXDN. Having a DMR ID does not give you one.
The program handling NXDN reflector and network connections.
A frequency difference — but which one depends entirely on context.
The trapRepeater offset is a transmit-receive split in megahertz. Radio offset is a crystal correction in hertz. Both appear in hotspot setup.
The small monochrome screens, under an inch and a half, that many hotspot cases have a window for.
A transmission not addressed to a particular station and not inviting a reply. Permitted only in specific circumstances set out in the rules.
Software whose source code anyone may read, modify and share.
Why it mattersAlmost the entire amateur digital voice stack is open source, with the exception of the vocoders inside most of the modes.
A protocol for joining two DMR networks together as peers, rather than as a repeater connecting to a master.
Why it mattersOpenBridge is how networks bridge to each other. When a talkgroup appears on two networks at once, this is usually why.
Open replacement firmware for certain Radioddity, TYT and Baofeng handhelds, replacing the manufacturer's own.
Why it mattersAmong other things it can make the radio itself act as a hotspot modem — several watts and a real receiver, instead of a hotspot's milliwatts. It is the cheapest route to a high-power personal node.
Open replacement firmware for a range of digital handhelds, written from scratch rather than derived from a manufacturer's code.
Why it mattersOpenRTX is notable for bringing M17 to radios that never shipped with it — which is currently one of the few practical ways to get on the mode with a handheld.
A family of self-contained commercial hotspots from SharkRF, in Finland. It is not a Pi with a modem on top — it is purpose-built hardware running the maker's own software, configured through its own web interface.
Why it mattersIt is purpose-built hardware running the maker's own software, rather than a Pi with a modem on top.
The trapBecause it does not run MMDVMHost, Pi-Star and WPSD instructions do not apply to it.
One transmission, from key-up to unkey.
Also called APCO-25. The North American public-safety digital standard, begun in 1989. Amateurs run it mostly on retired commercial equipment, and almost always Phase 1.
Why it mattersPhase 1's vocoder is the odd one out — IMBE, whose core patents have expired — which is why bridging Phase 1 does not need the licensed hardware the AMBE modes do.
The trapPhase 1 and Phase 2 are genuinely different underneath — Phase 1 is FDMA with the IMBE vocoder, Phase 2 is two-slot TDMA with AMBE+2. Statements about 'P25' are usually about Phase 1.
The program handling P25 reflector connections.
A network of linked P25 reflectors, organised regionally.
Network data that never arrives at all, as opposed to arriving late or unevenly.
Why it mattersIt sounds different from jitter: jitter gives choppy or stuttering audio, loss gives clean audio with pieces missing. Telling them apart points you at different causes.
A talkgroup number with a prefix and zeros added to reach the length the software expects — which is why TG 321 gets dialled as a seven-digit number.
A service that records what you transmit and plays it straight back. Every mode has one.
Why it mattersThe safest first transmission anyone can make, and it proves the entire path works — radio, modem, hotspot, internet, network, and back.
The United States rules for the amateur service. Other countries have their own equivalents; the concepts usually transfer even when the wording does not.
Blanket rewrite rules passing every talkgroup, or every private call, on a time slot.
The trapOnly one network can hold these, because they claim everything.
Plain uncompressed digital audio — sound as numbers, with no vocoder involved.
Why it mattersPCM is the missing middle step in every transcoding explanation. Crossing modes means decoding all the way down to PCM and re-encoding from it, which is why transcoding costs real processing and adds real delay. There is no shortcut between two vocoders.
The rewrite rule for private calls. It works radio-to-network only, and it is what maps a dialled private call onto a network's own control numbering.
Running a Fusion node from a radio cabled straight to a PC, without a separate interface box.
A phone and computer application giving access to certain digital voice rooms without any radio at all.
The numeric identity a repeater or hotspot presents when registering with a network, as distinct from your personal ID.
The arrangement between two digital voice networks that allows traffic to cross between them.
Why it mattersIt explains why some talkgroups appear on more than one network and others do not. The connection is a decision somebody made, not a technical inevitability.
A link the system re-establishes automatically after any drop, rather than leaving it disconnected.
A half-size HAT board. The usual shape of a hotspot modem, sized to sit on a Pi Zero rather than a full-size Pi.
The language most hotspot dashboards are written in. It runs on the hotspot and produces the page your browser shows.
Two physically identical-looking boards. The original Zero W is single-core; the Zero 2 W is quad-core.
The trapDashboard features that parse logs — resolving callsigns to names, talkgroup numbers to names — are disabled on single-core boards. Their absence is deliberate, not a fault, and no amount of reinstalling brings them back.
The original hotspot software distribution, by Andy Taylor MW0MWZ. A complete system image with every digital voice program installed and configured, controlled from a web dashboard.
Why it mattersIt defined the shape of the whole hotspot world — dashboard, expert editors, modes configured by tick box. Everything since has followed its pattern.
A facility for sending commands to a hotspot from outside its dashboard.
A basic test of whether one device can reach another across a network, and how long the round trip takes.
Why it mattersThe first thing to try when a hotspot cannot reach a network. It separates 'no internet at all' from 'internet works, this particular server does not answer' — two problems with nothing in common.
The Pi-Star command that probes the attached board and reports which modem it believes is fitted.
Two different operations on Pi-Star. Update refreshes host lists and scripts; upgrade replaces the underlying system packages.
The trapThey sound like the same word and are not. Running the wrong one is a common cause of an unexpectedly long or unexpectedly incomplete maintenance session.
The host board the software has detected — which Raspberry Pi or other computer it believes it is running on.
Why it mattersIf it reports something other than the board you actually have, you have written the wrong image, and unexplained faults follow from that alone.
The old radio paging protocol. Not voice at all, but hotspot software can transmit it, so it appears throughout digital voice documentation.
The address identifying one pager, so a message reaches that pager and no other.
A numbered channel on a network connection, used to tell one kind of traffic from another.
The trapA hotspot's 'modem port' is a physical serial connection, nothing to do with these. Same word, unrelated meanings, both in the same setup.
A router rule opening a way in from the internet.
The trapA hotspot does not normally need it — it makes outbound connections and nothing needs to reach in. It is one of the most common wrong answers to a connection problem.
The mains adapter feeding the Pi. Digital voice makes no unusual demands, but the Pi does — brief current spikes that a marginal supply cannot follow.
Why it mattersA phone charger that runs a phone perfectly may not run a Pi reliably.
How far a modem's oscillator sits off its nominal frequency, in parts per million, and the figure calibration corrects.
The trapThe classic symptom is one-way: the hotspot hears your radio perfectly, and your radio hears nothing back. A TCXO-equipped board keeps this small enough not to matter; a cheap board without one drifts as it warms up.
A short burst sent before the voice begins, giving receivers and networks time to notice, synchronise and open the path.
Why it mattersThe preamble is why the key-up pause exists. Speak immediately and your first syllable goes out during the preamble — the other operator hears '…anks for the call' instead of your callsign. Count one before speaking and the problem disappears.
A leading digit that says which of your connected networks a talkgroup number is meant for.
Why it mattersYour radio has one field for a talkgroup number but you may be connected to six networks, and TG 123 exists on several. The prefix is how you say which one you mean.
The one network whose talkgroups you dial bare, with no prefix. Usually BrandMeister.
Used three ways: a private call is a call to one person, a private node restricts who may use it, and privacy usually means encryption — which is not permitted on the amateur bands.
A transmission addressed to a single ID rather than a talkgroup.
Why it mattersA private call is also a control mechanism — on many systems, dialling a particular private call number is how you select a reflector module or ask for status.
A hotspot configured so only your own callsign or ID may transmit through it. The usual default.
A saved snapshot of a complete configuration, stored under a name and switchable in seconds. WPSD and OpenSpot both offer them, under the same name.
Why it mattersIt is the difference between a mistake costing thirty seconds and costing an evening.
The cable joining radio to computer. Many contain a USB-to-serial chip that needs its own driver installed before the software can see the radio.
A radio setting that lets you hear traffic on any talkgroup on the time slot, not only those in your receive group list.
Why it mattersUseful for monitoring, and confusing if you forget it is on — you will hear conversations you have no obvious way to answer.
The UDP ports each mode and network uses to pass traffic. The ones you will meet: D-STAR DPlus 20001, DExtra 30001, DCS 30051 · DMR 62030 for the MMDVM protocol and 8880 for DMO · Fusion 42000 · P25 41000 · NXDN 41400 · M17 17000 · the dashboard itself on 80 and 443. AllStarLink uses 4569 for IAX2.
Why it mattersWorth knowing before you blame the hotspot: if one mode works and another does not, it is very often one port open and another closed.
The trapThis is what actually has to reach the internet, and it is almost never the web port. A hotspot whose dashboard loads perfectly can still be completely unable to pass audio.
The transmit switch.
A hotspot open to any licensed station within range.
Why it mattersWorth thinking about before enabling. You remain responsible for what your station transmits, whoever keyed it.
The red power light. Solid means power is present and adequate; flickering or extinguishing under load points at the supply.
A Python implementation of a Fusion reflector, widely used by people running their own.
A programming language used widely in amateur digital voice — HBlink, pYSFReflector and many bridges are written in it.
Why it mattersPython is readable enough that you can often work out what a tool does by looking, which matters in a hobby built on being able to take things apart.
The DVSwitch client that puts a desktop computer onto a bridged digital voice network.
A contact — a conversation between stations.
A multi-mode network with roots in D-STAR callsign routing, now uniting D-STAR, DMR, Fusion and M17 through what it calls the QuadNet Array.
The warbling, chirping sound a marginal digital signal makes as error correction starts to fail.
Why it mattersR2D2 audio is the digital equivalent of a noisy analog signal — the only audible warning you get before the cliff. If you can hear it, you are close to the edge and about to disappear entirely.
Asking directly for feedback on your audio and signal.
Why it mattersMore likely to get a reply than a bare callsign, and far more useful. On digital the only faults anyone can report are audio ones, so ask about the audio.
On DMR, the number issued to you.
The trapOn Yaesu equipment, 'Radio ID' means a fixed factory serial you cannot change. Identical words, opposite meanings, and both appear while setting up a hotspot.
A correction, in hertz, compensating for a modem's crystal being slightly off frequency. Applied separately for receive and transmit.
The trapRepeater offset is a frequency split measured in megahertz. Radio offset is a crystal correction measured in hertz. Both appear in hotspot setup.
The registry that issues DMR and NXDN IDs to licensed amateurs.
NXDN's version of the same idea.
Why it mattersColour code, NAC and RAN are one concept with three names.
The small computer most hotspots are built around. The Zero 2 W is the usual choice for a compact build; larger models run the dashboard extras more comfortably.
The operating system nearly all hotspot images are built on. It is a version of Debian Linux, renamed.
Some hotspot distributions keep the storage read-only during normal running and switch to writable only when saving.
Why it mattersIt protects the SD card from corruption on power loss — and it is why an edit made at the command line can silently vanish if the system was not switched to writable first.
Restarting the system, versus stopping it cleanly so power can be removed.
Why it mattersA hotspot you intend to unplug wants the second one. Pulling power from a running Pi is the usual cause of a corrupted card.
An arrangement permitting a visiting amateur to operate under their home licence, by agreement between the two administrations.
D-STAR reflectors running the D-Plus protocol. The oldest family, and Icom-adjacent in origin.
A server that joins stations together so everyone connected hears everyone else. The same idea as a talkgroup, arrived at from a different direction.
The trapTo an antenna builder, a reflector is a parasitic element on a Yagi. Entirely unrelated.
Getting a reflector listed in the directories other systems consult, so it can be found and connected to.
The control operator operates the station through a control link from somewhere else.
The trapKeying a handheld into your own hotspot is not remote control — you are originating a transmission, not adjusting the station. Opening its dashboard from work is much closer to it.
Turning code into what you actually see on screen. When a dashboard looks wrong in one browser and right in another, this is the step that differed.
Ordinarily, a station that receives on one frequency and retransmits on another.
The trapHotspot documentation often narrows it to a duplex setup driving external radios — and Part 97 narrows it differently again, to simultaneous retransmission on a different channel. Three usable meanings.
A modem with no radio chip and no antenna connector at all. It is not a radio — it plugs into a real repeater's radios or its controller.
The trapAll three board types look broadly alike in photographs. Buying the wrong one is common and expensive.
A six-digit ID issued to infrastructure — a repeater or hotspot — as opposed to the seven-digit ID issued to a person.
Why it mattersThe digit count tells you what kind of station you are looking at in a last-heard list.
The instruction that turns the number you dialled into the number the network expects, and back again for traffic coming the other way.
Why it mattersYou rarely write these yourself. Knowing they exist explains why the number you dial is not the number the network sees.
A facility letting one nominated callsign restart or reboot a hotspot over the air.
The trapNot the same as link commands and not DTMF. One of them stops the service that would restart things, after which the radio cannot help you.
A DMR feature where the radio automatically moves to the strongest repeater in a defined list as you travel.
What Fusion calls a reflector.
On D-STAR, the fields naming the local repeater module and its gateway.
How strong the incoming signal is, in dBm.
The trapStrong RSSI and high BER at the same time is the classic signature of a frequency or deviation problem. Signal strength alone tells you very little on digital.
A battery-backed clock that keeps time while a device is powered off. Most single-board computers do not have one.
Why it mattersWithout it a hotspot learns the time from the internet at every startup — so one that boots with no connection believes it is years ago, and time-sensitive connections then fail confusingly.
The set of talkgroups a channel will also listen to, beyond the one it transmits on.
Why it mattersThis is why you can hear traffic on talkgroups you did not select. It is also why you sometimes cannot — the list is the filter.
The part of a band reserved by international band plan for satellite uplinks and downlinks.
The trapA hotspot sitting in one transmits from a fixed location and never stops, which is exactly the worst case for a satellite user. This has caused real interference and real complaints.
A complete computer on one small board. The Raspberry Pi is the common example.
On a radio, stepping through channels looking for activity. On a dashboard, 'scan for networks' means looking for Wi-Fi. Unrelated.
A group of channels the radio steps through looking for activity, stopping when it finds some.
The storage a hotspot boots from, and the component most likely to fail in one.
Why it mattersUnexplained instability, stalled updates and corrupted settings are more often a worn card than anything else. Keep a backup and a spare card.
The Wires-X screen for finding a node or room by number or name.
The name of BrandMeister's account page, where you set that password and manage your own settings.
A hotspot that also permits a listed set of other callsigns or IDs.
Why it mattersThe middle ground for a hotspot shared with a club or a neighbour — open to named people, not to everybody.
The friendly label and the actual internet address of a network server, entered together when adding one by hand.
The trapThe name is only a label for your own benefit. The address is the part that has to be right, and a working name with a wrong address fails silently.
A program the system starts automatically and keeps running in the background. Every part of a hotspot's software is one.
Why it mattersThis is why 'restart the service' is a normal instruction, and why a hotspot recovers from most faults on its own without a reboot.
On analog, a description of how a signal sounds — readability and strength.
The trapSignal reports do not transfer to digital. A digital signal either decodes perfectly or fails, so 'five nine' means nothing and neither does anything else on the scale. Useful digital reports describe the audio itself — level, distortion, dropouts — or quote the error rate.
The characteristic way digital modes fail: wrong settings produce no noise, no error and no clue. Nothing happens at all.
Why it mattersWhen nothing happens, work the short list — access code, time slot, is this talkgroup carried here, is my ID right. It is nearly always one of those four.
A modem with one radio chip and one antenna connector, receiving and transmitting on the same frequency. The ordinary personal hotspot.
Two stations working each other directly on one frequency with no infrastructure.
The trapA 'simplex hotspot' is not simplex operating. It means one frequency between you and a box that puts you on the internet — the opposite of working somebody directly.
Some dashboard features need more processing than the smallest boards have, and are disabled there.
Why it mattersTheir absence on the smallest Pi is deliberate. Nothing is broken and there is nothing to fix.
A finished hotspot product from BridgeCom Systems, shipped with its own software image.
Three unrelated things wear this word: a DMR time slot, the SD card slot, and a gateway's numbered network slots.
A low-rate side channel carried underneath D-STAR voice, used for text messages, position and callsign information.
Two small threaded antenna connectors that look identical at a glance. RP-SMA reverses which side carries the pin.
The trapThey will thread together and make no connection. Hotspot boards and antennas come in both, and a mismatched pair produces a hotspot that appears completely deaf with nothing visibly wrong.
Short text messaging, supported on DMR and some other modes between radios and, on some networks, to and from the internet.
A photograph taken with a camera-equipped microphone and sent over C4FM to other Fusion radios.
Why it mattersFusion is the only amateur digital voice mode that routinely carries pictures between handhelds.
On a reflector dashboard, the callsign or ID of the station that originated the transmission you are seeing.
Why it mattersOn a linked or peered system the source tells you where traffic actually came from, which is often not the reflector you are watching.
The circuit that keeps the receiver quiet until there is something to hear.
The trapOn digital modes there is nothing to open a squelch on — you either decode or you do not. The access codes below do the job squelch does on analog.
The originating station of a transmission, as shown in logs and on dashboards — the callsign or ID that keyed up.
Why it mattersOn a linked or peered system the source tells you where traffic actually came from, which is frequently not the reflector or talkgroup you are watching.
A rewrite rule that turns the source ID of incoming network traffic into a talkgroup on the radio side.
An encrypted way of reaching a device's command line from another computer. You can run a hotspot for years without using it.
The name a Wi-Fi network broadcasts.
The trapThree unrelated things share these letters in one setup: the Wi-Fi network name, the DMR ESSID suffix, and the APRS station suffix.
The reflector a mode links to on its own at startup.
The trap'Host' here means a reflector, not the computer. Anything linked later by hand is temporary and reverts to this on the next restart.
Permanently monitored, as opposed to switched on by activity.
The trapTo a ham, static means noise. A static talkgroup has nothing to do with interference.
An address fixed by hand on the device itself, rather than issued by the router.
The trapOn most hotspot distributions this is unsupported and gets undone by updates. A DHCP reservation on the router achieves the same result and survives.
One the hotspot monitors permanently because you configured it to. It is always there.
The trapTo a ham, 'static' means noise. A static talkgroup has nothing to do with interference.
Asking a hotspot what it is currently linked to, usually by dialling a particular number or sending a command, and getting a spoken answer.
Why it mattersThe three-command set worth memorising for any mode: connect, disconnect, and ask where you are.
The microcontroller at the heart of most MMDVM modem boards, and the chip a firmware update is actually written to.
Why it mattersModem firmware and hotspot software are two different things updated two different ways. A great many 'the update did not fix it' reports are one having been done and not the other.
A random number attached to each M17 transmission, letting a receiver tell overlapping streams apart.
A dashboard showing a transmission that never ends, usually caused by a missing end-of-transmission entry in the log rather than by anything actually transmitting.
The Linux command that runs one command with administrator rights. It prefixes almost every hotspot maintenance command you will ever be given.
A repeating block of voice frames grouped together, into which the identification and control data is woven.
Open-source repeater controller and linking software by Tobias Blomberg SM0SVX. It runs a repeater — identification, timers, tones — and links it to others, and it is modular, so one node can carry EchoLink at the same time.
Why it mattersIts newer linking layer, SvxReflector, is organised around talkgroups rather than point-to-point connections — which makes it the analog system that feels most familiar to a DMR operator.
SVXLink's talkgroup-based linking layer, where nodes join a shared server and select talkgroups rather than dialling each other point to point.
Why it mattersSvxReflector is the closest an analog system comes to behaving like DMR, and it is what M17 bridges to when it reaches the SVXLink world.
How many modulation states are sent per second. Fixed by the standard, and not something an operator adjusts.
A strict form of address translation that uses a different outbound port per destination, breaking protocols that expect replies on a predictable one.
A known bit sequence sent at intervals so a receiver can lock onto the timing of the stream and stay aligned with it.
Why it mattersLosing sync is what turns digital audio into silence rather than into noise. There is no partial decode to fall back on.
Running EchoLink attached to a radio, as a link or repeater node, rather than as a single user at a computer.
The scheduler that runs jobs at set times — automatic updates, host list refreshes, the overnight maintenance restart.
Why it mattersCron is the reason a hotspot's links revert overnight and the reason updates appear without you asking. Neither is a fault.
Yaesu's digital voice system, launched in 2013. Sold as Fusion, called YSF by the software, and referred to by its modulation C4FM. All three names mean the same thing.
Why it mattersIts selling point is Automatic Mode Select, which lets a repeater carry analog and digital users side by side without either group losing anything.
FreeSTAR's DMR network. The two names refer to one thing.
Tactical talkgroups — a block set aside for ad-hoc conversations, so people can move off a busy calling talkgroup.
The moment an analog repeater stays keyed after you stop talking.
A private network overlay that lets your devices reach each other directly wherever they are, without opening any router ports.
Why it mattersTailscale is the practical answer to CGNAT. If your provider's address sharing makes a hotspot unreachable from outside, this reaches it anyway — without exposing anything to the internet.
A short beep from the radio confirming the network has accepted your key-up and you may begin speaking.
Why it mattersWaiting for it is the single easiest fix for clipped first words. It is the radio telling you the path is open — speaking before it means talking into a system that is not listening yet.
Transmitting on a repeater's output frequency to work another station directly, bypassing the repeater.
A DMR feature that carries the operator's callsign and name inside the voice stream, so the receiving radio can display who is talking without a contact list entry.
Why it mattersTalker Alias is the practical answer to the enormous contact lists DMR otherwise demands — support varies by radio and by network, so it is worth checking before buying.
A numbered conversation on DMR. Select the number and you hear, and are heard by, everyone else on it.
On several networks, the number that reports back what your device is currently linked to.
Conventionally the local talkgroup — traffic that stays on the machine you are using rather than going out to the network.
The trapOn some systems, slot 2 talkgroup 9 is a network gateway rather than a local channel, so traffic you believe is staying local goes worldwide.
BrandMeister's worldwide talkgroup. Commonly used as a first test because there is nearly always somebody on it.
Why it mattersAnything transmitted there reaches every station monitoring it worldwide.
By convention, a talkgroup used for radio-to-radio simplex digital contacts without any infrastructure.
Moving rapidly between talkgroups.
The trapIt churns network timers and leaves dynamic subscriptions scattered behind you.
A curated set of talkgroups prepared for loading into a radio, usually as a CSV.
Why it mattersLoading a network's entire list makes a radio harder to use, not easier — you scroll past hundreds you will never call to reach the four you actually use.
In Linux service management, a named state the system brings itself to at startup — which services run and in what order.
Why it mattersTargets are the mechanism behind whether a service starts on boot. A service can be running perfectly and still not be attached to a target, in which case it will not come back after a restart.
The temperature-compensated crystal that sets the modem's timing. Its frequency — usually 14.7456 or 12.2880 MHz — identifies which variant of a board you have.
The trapModem firmware is matched to the TCXO. Flashing the wrong variant leaves you with a modem that will not work.
Splitting one channel into alternating time slots so it carries more than one conversation.
Why it mattersThis is DMR's headline advantage: one repeater, one frequency pair, two independent conversations at the same moment.
Any connection made by hand from a dashboard or a radio. It survives until the next restart or the overnight maintenance, then reverts to the configured startup reflector.
The requirement to identify by voice at intervals, regardless of the fact that your callsign is already travelling inside the data stream.
The trapDigital modes carry your identity automatically as data alongside the voice.
Two ways of running a D-STAR radio connected directly to a computer, with no separate hotspot hardware. Terminal mode puts the radio on the network directly; Access Point mode lets it serve other radios over RF.
Why it mattersWorth knowing before buying a hotspot — some Icom radios can already do the job on their own.
The closing frames telling the receiver the transmission has ended.
Why it mattersWhen one goes missing, dashboards can show a transmission that never finishes. It is the usual cause of an apparently stuck transmit.
The usual abbreviation for talkgroup.
A grouped set of talkgroups a system operator can apply to several repeaters at once.
A file of talkgroup numbers and names the dashboard uses to show names instead of bare numbers.
A rewrite rule mapping a block of dynamic talkgroups onto one talkgroup, with dedicated numbers for disconnect and status and spoken confirmation.
An independent DMR network with talkgroups managed through its own website and API. Anyone can create a talkgroup, which gives it a different character from BrandMeister.
The rewrite rule that translates a talkgroup and time slot between radio and network, in both directions, across a block of consecutive numbers.
The Pi deliberately slowing itself when it gets too hot, to avoid damage.
Why it mattersA hotspot sealed in a small case with no ventilation can reach it. Symptoms look like software sluggishness — a dashboard that has gone slow is worth a temperature check before a reinstall.
A message passed on behalf of somebody who is not one of the two control operators.
The trapTwo licensed amateurs talking to each other is not third-party traffic — there is no third party. The rules only engage when somebody else speaks.
Common brand names for AMBE dongles.
The licence-free, low-power part of the DMR standard. Not used in amateur radio.
Conventional DMR — fixed channels, two time slots, no trunking. This is what amateur DMR is.
Trunked DMR, where a controller assigns channels dynamically. Commercial systems use it; amateurs essentially do not.
The internet source a hotspot uses to set its clock, since most single-board computers have no battery-backed clock of their own.
Why it mattersA hotspot that cannot reach one comes up believing it is years ago, and network connections then fail for reasons that look nothing like a clock problem.
One of DMR's two alternating turns on the channel. Written TS1 and TS2.
The trapA simplex hotspot conventionally uses slot 2 — but that is a software convention, not a rule of the DMR standard. It holds in practice because every hotspot does it.
A limit on how long the radio or repeater will transmit before cutting off.
Why it mattersIt exists to stop a stuck microphone holding a system open indefinitely — which on a linked network could mean silencing a lot of people.
Three timers share this word: the radio's transmit time-out, a gateway's network timeouts, and a dynamic talkgroup expiring.
The container format bridging software uses to pass encoded audio between its own components.
A reflector module with a transcoder attached, so users of different modes on it can actually hear each other.
Why it mattersA multi-protocol reflector accepts several modes on the same module. Without transcoding, those users are on the same module and still cannot hear one another.
Converting audio from one vocoder to another — decoding all the way back to plain audio, then re-encoding. It is how a DMR user talks to a D-STAR user.
Why it mattersTranscoding is not a translation you can do on the numbers. The audio genuinely has to be reconstructed, which is why it costs processing power or hardware, and why it adds delay.
The central authority that authorises a callsign onto the D-STAR gateway network.
Why it mattersThe trust server is the piece that makes D-STAR registration a real step rather than a formality — without authorisation the RF works and the network does not.
Another name for admit criteria in some manufacturers' software.
A rewrite rule that converts a group call into a private call on its way out to the network.
The serial connection between the host computer and the modem, whether over GPIO pins or USB. Its device name is what the modem port setting selects.
Another Linux distribution, itself derived from Debian. Common on rented servers, so reflector and bridge instructions are often written for it.
The lightweight network protocol nearly all digital voice traffic uses. It does not retransmit lost packets, which is the right trade for live audio.
Why it mattersUDP is also why restrictive networks break digital voice while ordinary web browsing still works — many block UDP or non-standard ports.
A simple front end to Linux firewall rules, common on self-managed servers.
The number identifying one radio on an NXDN system, in the way a DMR ID identifies a radio on DMR.
The Pi warning that its supply has dipped below what it needs. On a desktop it shows as a lightning bolt; on a headless hotspot it appears in the logs and on some dashboards.
The trapUndervoltage is the single most under-diagnosed hotspot fault. Random reboots, stalled updates, corrupted settings and dead SD cards are far more often a cheap power supply or a thin USB cable than anything wrong with the software.
A radio's complaint that the channel exists but has not been placed in any zone you can select.
Why it mattersAlmost always a codeplug oversight rather than a fault — the channel was created and never added to a zone.
Could mean the hotspot software, the reflector host lists, the ID databases, or the modem firmware. Four different things on four different schedules.
A facility letting software ask a router to open ports automatically.
The trapIt lets any device on your network open a port on your firewall. A hotspot does not normally need it at all.
How long a system has been running without a restart.
The trapLong uptime hides problems rather than proving health — a service started by hand months ago will not come back after the next reboot, and nobody finds out until then.
On D-STAR, the field naming who you are calling. It doubles as a command line — particular letters typed there link, unlink, echo or report status.
A more recent multi-protocol reflector system, developed from XLX. Handles transcoding differently and can run more than one transcoded module.
The long-established American registration network for D-STAR, and the authority most gateways check against.
The plain-audio interface DVSwitch components use to pass audio between each other and to analog systems such as AllStar.
Distributing one plain-audio stream to several destinations at once, so a single source feeds multiple systems.
EchoLink's requirement that you prove you hold a licence before the system will admit you, since it can be used without a radio.
Why it mattersValidation is the mechanism keeping a system anyone could reach from a laptop inside the amateur service.
In practice, operating on a frequency you have typed in rather than on a programmed channel.
The trapOn DMR a bare frequency is rarely enough — the talkgroup, time slot and colour code have to come from somewhere too, which is why many DMR radios restrict or omit VFO operation entirely.
The part that turns speech into a very low data rate and back again. It is what makes digital voice possible on a narrow channel, and it is why digital voice sounds the way it does.
Why it mattersWhich vocoder a mode uses decides whether it can be bridged to another mode in software, or whether it needs hardware. Nothing else about the mode matters as much.
The opening frames of a digital transmission, carrying who is calling, who they are calling, and the settings needed to decode what follows.
The trapIf the header is lost — the receiver was not yet listening, or the first fraction of a second was clipped — the rest of the transmission may not decode at all. You are on the air and nobody hears you.
The spoken confirmation a hotspot sends back when it accepts a command, so you know it worked without looking at a screen.
Voice-operated transmit, keying automatically when you speak.
The trapOn a linked system it keys on any sound in the room, not only on speech directed at the radio.
An encrypted tunnel joining a device to a distant network as though it were local.
Why it mattersOne way to reach a hotspot from outside without opening router ports — and worth knowing that a VPN active on the same network can send digital voice traffic somewhere unhelpful.
A rented computer in a data centre. Where most reflectors and many bridges actually live.
Why it mattersA reflector is not a piece of radio equipment. It is software on a server with no transmitter, no antenna and no licence — the amateur stations are the endpoints.
A Fusion mode using the full channel for voice, giving better audio and no data.
The trapReflectors and hotspots generally expect DN. Leaving a radio in VW is a common reason a Fusion setup appears not to work.
A background monitor that restarts hotspot programs if one crashes or hangs.
Why it mattersThe watchdog is why a hotspot usually recovers on its own overnight. It also means stopping something by hand often does not stick — the watchdog quietly puts it back.
A list of the only stations or talkgroups permitted. Everything not named is refused. Used both in a radio and, on the network side, by a server deciding which IDs may connect.
The regulatory region setting telling the Pi which channels and power levels are permitted where you are.
Why it mattersStill worth setting for regulatory correctness, and the hotspot Wi-Fi builders ask for it.
The trapWidely repeated as a blanket requirement. Raspberry Pi OS blocks Wi-Fi until it is set only on DUAL-BAND models — Pi 3B+ onward, Compute Module 4 onward, and the keyboard machines. The Pi Zero W and Zero 2 W, which host most hotspots, are 2.4 GHz single-band and are not blocked.
One carried on a great many repeaters at once.
Why it mattersThe convention is to make contact and move to a tactical talkgroup.
Yaesu's own internet linking system for Fusion, using Yaesu hardware and Yaesu's servers.
The trapWires-X and YSF reflectors both carry Fusion. Wires-X uses Yaesu hardware and Yaesu's servers; YSF reflectors are the open reflector world hotspots use.
A radio feature that raises an alarm if the operator does not respond to a periodic prompt.
Why it mattersA commercial safety feature — it exists for lone workers, not for amateurs — which is why it puzzles hams reading a DMR radio's menu.
Anytone's setting for whether the radio operates from programmed channels or from a directly entered frequency — what other radios call channel mode versus VFO.
A hotspot software distribution by Chip W0CHP. It began in late 2020 as W0CHP-PiStar-Dash, a fork of Pi-Star, and has since diverged into a separate distribution with its own update model, dashboard and features. The name is a recursive joke: WPSD Plausibly Signifies Divergence.
The trapWPSD is no longer a version of Pi-Star, and each project runs its own support channels — but the fork origin is why the two look alike.
A multi-protocol reflector system. One XLX reflector can accept D-STAR, DMR, Fusion and M17 connections, with lettered modules.
The trapMulti-protocol is not the same as transcoding. An XLX reflector accepts several protocols; whether those users can hear each other depends on whether a transcoder is attached.
A link joining one XLX reflector to another as an equal, so their modules carry the same traffic.
Why it mattersIt explains why a conversation on one reflector appears on another you never connected to — the reflectors are peered behind the scenes.
The reflector server software, and the transcoder that lets one reflector carry several modes at once.
Why it mattersThe transcoder is the hard part and the expensive part — it needs hardware vocoder chips, which is why multi-mode reflectors are far less common than single-mode ones.
D-STAR reflectors running the DExtra protocol.
A Fusion reflector system organised around DG-ID, so one connection can carry many separate rooms selected from the radio.
As the hotspot software names it. You will see YSF in menus and Fusion on the box.
A Fusion reflector in the open, non-Yaesu world. Identified by number and name in hotspot host lists.
The program handling Fusion links to YSF and FCS reflectors.
A named group of channels the radio selects between, usually as much as fits on one knob.
The trapThe hotspot configuration page also asks for a time zone. Unrelated, and both come up during setup.
A well-regarded MMDVM modem board family from ZUM Radio, sold as a Pi HAT, a USB stick and a duplex version. Widely treated as the reference against which other boards are judged.
Why it mattersIts firmware variants are named separately in flashing tools, so knowing you have a ZUMspot rather than a generic board matters when updating.