OKlahoma City APCO P25 PI & PII TDMA Alternating

[air-scan]

Well I just noticed the new system isn't always Phase 2 TDMA voice. Sometimes It's Phase 1 or Phase 2 TDMA. See the blue box in my image. I thought everything would be Phase 2 TDMA full time

 

[pb_lonny]

They can have a mix of the two.

 

[air-scan]

They can have a mix of the two.

It's still a brand new system. I am learning new things about it. I was used to the old EDACS Provoice they are soon dismantling after they get the rest of the city services and suburbs to finish migrating. Thanks for replying!

 

[hiegtx]

In the RadioReference database, if control channel data indicates that the system can use P25 Phase II, it's tagged as Phase II.

However, many Phase II capable systems are set up to allow P25 Phase I transmissions as well. If someone with an older radio (portable, mobile, whatever), that can only use Phase I, is affiliated with the system on that talkgroup, the talkgroup transmissions will be handled as Phase I. However, if there are no "Phase I only" radios affialted, then the talkgroup conversations will be strictly Phase II.

 

[air-scan]

In the RadioReference database, if control channel data indicates that the system can use P25 Phase II, it's tagged as Phase II.

However, many Phase II capable systems are set up to allow P25 Phase I transmissions as well. If someone with an older radio (portable, mobile, whatever), that can only use Phase I, is affiliated with the system on that talkgroup, the talkgroup transmissions will be handled as Phase I. However, if there are no "Phase I only" radios affialted, then the talkgroup conversations will be strictly Phase II.

Exactly what is happening. Thanks!

 

[plaws]

P25 is P25. An old P25 "subscriber unit" will work on a modern P25 system. Likewise, a modern P25 "subscriber unit" will work on a P25 system that is not up-to-date. It's a standard. That's why they made it.

Whether your scanner can keep up is a different issue.

My understanding is that if a single radio on a talkgroup is incapable of TDMA, all radios on that TG just drop back to non-TDMA and life moves on. Eventually, those radios will go away. This isn't like the 1970s or 80s where you could have the same radio for 20 years - this is capitalism.

 

[air-scan]

P25 is P25. An old P25 "subscriber unit" will work on a modern P25 system. Likewise, a modern P25 "subscriber unit" will work on a P25 system that is not up-to-date. It's a standard. That's why they made it.

Whether your scanner can keep up is a different issue.

My understanding is that if a single radio on a talkgroup is incapable of TDMA, all radios on that TG just drop back to non-TDMA and life moves on. Eventually, those radios will go away. This isn't like the 1970s or 80s where you could have the same radio for 20 years - this is capitalism.

thanks

SDRTrunk handles it well. DSDPlus FL has troubles. those troubles might be the fact it FMP24 is struggling with having throttled data rate from a xHCI 3.1 USB controller. Already been established and only cure is to run RTL-SDR on a actualy USB 2.0 controller which my laptop has none.

 

[plaws]

I can't imagine that USB bandwidth is a bottleneck. Even in USB 1.1 days, "Full Speed" was 12 MBit/s!