UV-5RM-Radio-Mod

This project provides custom firmware and companion tools for a specific hardware revision of the Baofeng UV-5RM, based on the open-source bf-5rh firmware. Its main feature is TEXT, which sends messages of up to 50 characters directly between radios, retries until delivery is confirmed, and saves messages. Both radios must have the app open and use the same simplex frequency; reception stops when TEXT is closed. Messages are neither encrypted nor secure, and automatic replies can collide when more than two radios are involved. Other additions include preset and custom scan modes, band sweeps, repeater-frequency and tone finding, signal searching, and a rough transmitter-distance estimate, plus a custom interface and startup sounds.

Installation is high risk and limited to radios that display the exact hardware identifier 5RHNRFB-YP07; visually identical models may use incompatible chips. The instructions call for backing up radio memory, entering bootloader mode, flashing firmware, and installing the logo and apps with Python tools. The change cannot be reversed because no factory firmware is known, a failed flash could brick the radio, and CHIRP will no longer work; included browser-based tools replace it for channel programming. Testing has covered only two radios, with messaging tested mainly at short range. Transmit is disabled initially, and users must enable it themselves. The project also emphasizes licensing and operating restrictions: messages transmit automatically in response to received texts, ham operators must identify by voice, and the radio should be treated as receive-only on FRS, GMRS, and MURS channels.