Calibration

BER (Bit Error Rate) — the percentage of erroneous bits in a DMR stream. We break down: what counts as normal, why it climbs, and how to lower it by calibrating your hotspot.

Why the radio is right next to the hotspot but there's no link: frequency drift in cheap MMDVM modems, how to set RXOffset/TXOffset, find the BER minimum with a frequency sweep, and verify that…

Step-by-step calibration of an MMDVM hotspot with MMDVMCal: BER test, frequency tuning (RXOffset/TXOffset), TX/RX levels. Minimum BER means reliable data reception…

How to set up RSSIMappingFile in MMDVMHost: file format, calibration from reference points via MMDVMCal S-mode, interpolation, and display in the portal's last-heard.

A breakdown of MMDVM.ini: the [General], [Modem], [DMR] and [DMR Network] sections, the Duplex, ColorCode, offset and level parameters, common mistakes and a cheat sheet of dangerous values.

Hotspot can't hear the radio and BER is climbing? We break down frequency drift on ADF7021 boards: why a cheap crystal wanders with temperature, what a TCXO gives you, and how to fix drift with RXOffset/TXOffset calibration.

What TXLevel and RXLevel in MMDVM.ini are, how they affect deviation and BER, how to set them via MMDVMCal, and why it matters for data on the DMRhub network.