Interactive ยท Simplex
Everyone knows digital reaches further than FM. The datasheets do not agree. DMR does beat its own analog by a couple of dB. P25 is a dead heat. And D‑STAR, on Icom's own published figures, is nearly six decibels worse than the FM in the same radio. Pick a radio and see what it really does.
| Radio | Mode | Analog FM | Digital | Digital gains | Spec'd at |
|---|
Every figure below is a published manufacturer specification. Motorola XPR6550 (DMR): 12 dB SINAD at −118.4 dBm, 5% BER at −121.3 dBm. Motorola XTS5000 (P25, 700/800 MHz): −120.8 and −121.1 dBm. Both reported by a commercial radio engineer who bench-tested them on a service monitor. ZTE PH790 (DMR): datasheet lists 0.3 µV analog (12 dB SINAD) and 0.25 µV digital (5% BER). Icom IC‑9700 (D‑STAR): Icom's own published specification — FM 12 dB SINAD at 0.18 µV, DV at 1% BER at 0.35 µV. Into 50 Ω that is −121.9 and −116.1 dBm. Yaesu FTM‑400 / FT1DR (Fusion): 0.19 µV digital at 1% BER. Yaesu do not publish a comparable analog FM figure for the same radio, so the Fusion row has no delta — I have left the gap rather than invent one. The threshold problem, stated plainly: Motorola spec at 5% BER; Icom and Yaesu at 1% BER. Using the digital-cliff model on this site, the raw error rate climbs from 1% to 5% over roughly 2–3 dB of signal. Even crediting D‑STAR the full 3 dB, the IC‑9700 lands near −119 dBm in DV against −121.9 dBm in FM — still worse than its own analog. The gap survives the correction; it is not an artefact of how it was measured. And from the other side: Yaesu's own product literature for the FTM‑400 states that analog FM is effective when weak signal causes audio drop‑out in the digital mode, and enables communication up to the borderline of the noise level. That is a digital radio manufacturer telling you analog works where their own digital quits. Coverage scales as range = 10^(Δ dB / 10n); at n = 4 the XPR6550's 2.9 dB is worth about 40% more area, matching the ~39% reported from field testing. Flat earth, no terrain, no fading — and fading hurts digital more than FM. 73 de N6JET