Channel Hierarchy

[Volfirefighter]

After logging a Motorola P25 system control channel for 24 hours, I have come to the following conclusion; please tell me if I am wrong. The voice channels are arranged in a hierarchy. The first voice channel in the list is always assigned the transmission unless busy and then it is assigned to channel 2 unless busy and then channel 3 and so forth. The alternate control channels can be used for voice but are very last in the hierarchy.

 

[GTR8000]

Not exactly. Default configuration for ASTRO 25 systems is to rotate through the traffic channels to balance the load on the repeaters. The BSI channel is normally the most protected, followed by the alternate control channels, which are used for traffic only if the normal non-protected traffic channels are already in use. There are always going to be exceptions to the rule, and some of it depends on how many channels are at the site, if data is provisioned, whether FDMA, TDMA, or DDM is in use, how each channel is provisioned as far as being data and/or voice capable, etc.

So yes, there is a hierarchy, but that primarily applies to channels with a specific purpose such as control-capable and the BSI channel on most run of the mill ASTRO 25 systems. It is possible to have some fairly complicated setups when you start getting into systems with DDM and data enabled, where you'd want to steer certain traffic to particular channels at the site.

 

[mtindor]

After logging a Motorola P25 system control channel for 24 hours, I have come to the following conclusion; please tell me if I am wrong. The voice channels are arranged in a hierarchy. The first voice channel in the list is always assigned the transmission unless busy and then it is assigned to channel 2 unless busy and then channel 3 and so forth. The alternate control channels can be used for voice but are very last in the hierarchy.

Which system? Stark Co Simulcast? I haven't monitored it for a while now, but I can tell you that the 800 mhz freqs are some of the last to be used. I've seen days where there was never a hit on the 800 mhz freqs because the 700 mhz frequencies hadn't all been in use simulctaneously, thus not requiring the need for the 800 mhz freqs.

Mike

 

[Volfirefighter]

Which system? Stark Co Simulcast? I haven't monitored it for a while now, but I can tell you that the 800 mhz freqs are some of the last to be used. I've seen days where there was never a hit on the 800 mhz freqs because the 700 mhz frequencies hadn't all been in use simulctaneously, thus not requiring the need for the 800 mhz freqs.

Mike

Yes it is the Stark Simulcast and this is exactly what I have observed. The 800 freqs are last in my "hiearchy". Do 700 freqs somehow perform better on the system and are thus preferred? The 800 freqs are leftovers from the old Stark County System and there are still 7 of them left to be used if needed. A while back, they stated that more repeaters were being added to increase capacity.

 

[GTR8000]

And that's exactly what I meant about exceptions to the rule. It's very possible that the 800 MHz channels were flagged as protected back in the day when the cell was transitioning from SmartZone to MARCS-IP, and the 700 MHz channels would've been unprotected as they were newly added. If no one ever unprotected the 800 MHz channels, they would be the last to be used to this day, with 700 MHz taking preference.