P25 Invalid Frames at End of Transmission

[tadsmith]

I've noticed that at the trail of some transmissions, the LDUs will contain a repeated number of packets with invalid fundamental frequencies. The source of these tend to always be dispatch consoles. Any idea what they might be, if anything?

03/14/23 20:35:46.823878 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.824420 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.824948 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.825467 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.826263 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.827073 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753

 

[boatbod]

I've noticed that at the trail of some transmissions, the LDUs will contain a repeated number of packets with invalid fundamental frequencies. The source of these tend to always be dispatch consoles. Any idea what they might be, if anything?

03/14/23 20:35:46.823878 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.824420 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.824948 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.825467 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.826263 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753
03/14/23 20:35:46.827073 [0] IMBE fc 00 00 00 00 00 00 00 00 00 00 errs 15 SRC: 126753

Seeing "errs 15" is an indication that FEC failed and nothing in that frame should be relied upon.