HamMap

Plug your phone into your radio, turn the squelch off, and drive. Everyone's readings go on one map.

Session code Frequency (MHz) Only nodes on the same frequency are combined. Retuning? Change it here too. Radio Audio input Pick your USB adapter, not the built-in microphone.

Your name or callsign Antenna

Before you start

Turn the squelch off (monitor mode) and leave it off. With it on there is no noise to measure, and a muted radio reports maximum signal at all times. You won't have to listen to the hiss — this app squelches its own playback.
Set the volume once and leave it. Turning the knob mid-hunt invalidates this radio's calibration.
Mount the phone and plug it in. The screen has to stay on — iOS stops GPS and audio the moment it sleeps.
Spread out. Five people in one parking lot produce nothing useful.