You could try to use ARTEMIS Offline Signal Identification to identify it. Download at ARTEMIS Download . Set a filter to 462MHz to listen to signal samples known (76 at the moment) to be available in the band, click through them and listen to the audio sample and hopefully you will find a match. Listen in particular to the samples of the obvious choices first - NXDN, DMR, P25, Motorola. Ignore obvious ones that are not relevant in the US like NMT, PAL, RTS-9TS, etc. Here's a Techminds video of how to use ARTEMIS: https://www.youtube.com/watch?v=W_8Y_4FvoHI