Mixed System?

[ilgrant]

So I'm observing an APCO 25 system using an older version of Unitrunker. This is my display under the channel column...

772.9375
773.1875
773.4875
774.1875
#03-3578
#03-3579
#03-3674
#03-3675

The frequencies have LCNs that start with 01 and have associated frequencies with them. What are the 03's?

I tried this with the graphical unitrunker with the same results.

Thanks.

 

[SCPD]

What are the 03's?

The 03's are a different set of channels. In P25 - the channel is identified by a pair of numbers. The first number selects one of 16 possible band plans. In this case - plan 3. Plan 0 is usually 851 Mhz and plan 1 is usually 762 Mhz. The other number is the channel number within that plan. For whatever reason, the system isn't announcing bandplan #3 so the program can only display the number, and not the frequency for those channels. Do you see any calls on these channels? Are the hit counts for those channels zero?

 

[ilgrant]

LCN 03-3578 and 03-3579 both have 560 hits on it.

My theory is that these are narrow bandwidth channels spaced every 3.125 khz (1/2 of 6.25 khz) . By accident, I was searching the 773 to 775 range on the BC 396. 773.1875 (LCN 01-1789) was very active on the BC 396 while two LCN's mentioned were switching back and forth on Unitrunker. The decoded digital could not be heard...only the digital sound as it appears the BC 396 can't decode what may be a very narrow band signal.

I played around with the Main-> Insert -> Band in Unitrunker and it seems to confirm my theory.

And how about this...3578 is double 1789.

 

[SCPD]

Interesting stuff. I'd like to see a decode log from this system.