UniTrunker and P25 systems

[troymail]

Now that I've become engrossed in UniTrunker and a local P25 system, I've noticed some differences between TGs and radio IDs (as well as TG IDs) for P25... For example, UniTrunker is showing a TG of 65536 on a the highesy frequency in the system every half hour and it is used to broadcast a morse call sign for the system. Are TGs higher than 16 bits valid for P25 systems? I'm pretty sure for the older Motorola systems TGs are limited to 16 bits. Also, the radio IDs are entirely different - for example, "2110484" vs. the other non-P25 TRS's in my area where the radio IDs are 7xxxxx. In reference to the latter, I heard some cross-system testing the other day on a system where the radios are 7xxxxx but when the user appeared on the new P25 system for the testing, the radio IDs were more like 1040001 -- are the "older system" radios capable of switching to the new system or am I seeing completely different radios?

Just some observations...

If someone can point me to a good location that describes P25 formats, etc. and/or the differences between the two, I'd appreciate it.
EDIT: found one -> http://www.p25.com/resources/P25TrainingGuide.pdf

 

[SCPD]

Now that I've become engrossed in UniTrunker and a local P25 system, I've noticed some differences between TGs and radio IDs (as well as TG IDs) for P25... For example, UniTrunker is showing a TG of 65536 on a the highesy frequency in the system every half hour and it is used to broadcast a morse call sign for the system.

Right - that's the BSI (base station identifier).

Are TGs higher than 16 bits valid for P25 systems?

Yes - that's why I use 65536 - it's a seventeen bit number - so no conflict with any real group ids.

I'm pretty sure for the older Motorola systems TGs are limited to 16 bits.

Right. Actually, they're 12 bits - the lower 4 bits aren't really part of the group id on a Type I or Type II system.

Also, the radio IDs are entirely different - for example, "2110484" vs. the other non-P25 TRS's in my area where the radio IDs are 7xxxxx. In reference to the latter, I heard some cross-system testing the other day on a system where the radios are 7xxxxx but when the user appeared on the new P25 system for the testing, the radio IDs were more like 1040001 -- are the "older system" radios capable of switching to the new system or am I seeing completely different radios?

The radios are highly configurable. At a push of a button or turn of a knob - the radio can change it's (a) group id (b) system id (c) radio id (d) any combination of the above. In the case of an inter-system call ... it depends greatly on the configuration and capabilities of the interconnect used to tie the two systems together. This may be the same radio, different radio, or the interconnect system is substituting a placeholder radio id for the real analog id.

-rick