Phase-2 TDMA question.

[ButchGone]

Tennessee is building out a Motorola dual band P25 phase2 two slot TDMA system. FCC data base shows the VHF hi and 700mhz sites each will have 3 frequencies. Does this mean there will be one freq used for control channel, with the other two freqs able to handle two conversations each for a total of four conversations going on at once? Or can the freq used for control channel also handle a voice path, for a total of five conversations sharing three freqs at once? Thank you.
BG..

 

[GTR8000]

The control channel is 12.5 kHz FDMA for all P25 systems, so it takes up the entire bandwidth of the frequency. It's not possible to have a voice path on the control channel.

One frequency dedicated for the control channel, the other frequencies used as two-slot TDMA voice channels, yielding two voice paths per frequency. Three frequencies = 1 CC, 4 voice slots (4 simultaneous conversations)

 

[spunwobbly]

Tennessee is building out a Motorola dual band P25 phase2 two slot TDMA system. FCC data base shows the VHF hi and 700mhz sites each will have 3 frequencies. Does this mean there will be one freq used for control channel, with the other two freqs able to handle two conversations each for a total of four conversations going on at once? Or can the freq used for control channel also handle a voice path, for a total of five conversations sharing three freqs at once? Thank you.
BG..

In TDMA systems like this the control channel will only take up one time slot of one freq leaving the second timeslot on that freq available for a voice path. These sites should have 5 voice paths available. Unless they are doing something special like dedicating one time slot for some data application. 5 voice paths would be the basic config though...

 

[mikey60]

The Phase 2 P25 control channel is backward compatible with Phase 1 systems. There is no difference, and no TDMA is used on the control channel frequency. 3 Freqs would yield 4 talkpaths and 1 FDMA control channel.

Mike