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Cambridge P 25 system.

Posted: 06 Feb 2013 15:24
by garys
As an experiment I took all of the Cambridge analog Talk Groups, well, the public safety ones, divided by 16 and came up with the P25 equivalents. Then I put them into ARC-XT and loaded them on to my 996XT. Today I went to Microcenter and held on the P25 trunk. I heard a lot of Pro Ambulance traffic, including a notification to Cambridge Hospital. I also heard a lot of what I think is public works type traffic. I think that this is simulcast from the analog side, not users with P25 radios. The Pro and Cambridge talk groups I calculated were correct, so the formula works.

Coverage wasn't too bad, I heard the P25 system as far south as Neponset Circle.

Posted: 06 Feb 2013 15:59
by N1BHH (Silent Key)
The P-25 system is easier for me to copy than the analog system for some reason. Still trying to figure that one out. There may be some active P-25 users, this is a similar situation to when Boston was switching to Zone 1. Some agencies had a mix of radios with some on the Boston system and others on Zone 1. I heard the plan was non public safety to go P-25 first to work the bugs out, so when Fire and Police are ready they'll have everything worked out.

Cambridge P 25 system.

Posted: 06 Feb 2013 16:13
by jrm3607
garys wrote:As an experiment I took all of the Cambridge analog Talk Groups, well, the public safety ones, divided by 16 and came up with the P25 equivalents. Then I put them into ARC-XT and loaded them on to my 996XT. Today I went to Microcenter and held on the P25 trunk. I heard a lot of Pro Ambulance traffic, including a notification to Cambridge Hospital. I also heard a lot of what I think is public works type traffic. I think that this is simulcast from the analog side, not users with P25 radios. The Pro and Cambridge talk groups I calculated were correct, so the formula works.

Coverage wasn't too bad, I heard the P25 system as far south as Neponset Circle.
Pro EMS mobile radios seem to be operating on the P25 system and the portables on the Analog system. I'm guessing they will go full time P25 at the same time as the CFD.

I also notice in Medford the P25 comes in 5 bars and the analog only with 3 bars. They may have added more antennas for the new system?

Posted: 06 Feb 2013 17:17
by garys
It's likely that they moved non public safety users over first, as you note. I don't know what model radios they are using, so I don't know if what they have are P25 capable or if they have to buy all new radios. They might have more transmitter sites for the P25 system. If so, we might have a chance to find out if the Uniden firmware upgrade for the HP-1, and XT digital scanners worked.

Posted: 06 Feb 2013 17:19
by garys
jrm3607 wrote:
I also notice in Medford the P25 comes in 5 bars and the analog only with 3 bars. They may have added more antennas for the new system?
Medford? Have they gone to P25?

Cambridge P 25 system.

Posted: 06 Feb 2013 17:26
by jrm3607
garys wrote:Medford? Have they gone to P25?
No, I mean I pick up the Cambridge P25 control channel in Medford better then the Motorola control channel. Medford is still conventional analog

Posted: 06 Feb 2013 18:08
by garys
jrm3607 wrote:No, I mean I pick up the Cambridge P25 control channel in Medford better then the Motorola control channel. Medford is still conventional analog
Oh. I was just a little confused by the wording you used. That makes sense.

Posted: 08 Feb 2013 08:44
by CW115
My understanding is that the P25 system is a multi-site simulcast which would explain the better signal compared to the analog system. When the P25 first came on the air it was noticeably weaker than the analog. Right around the first of this year there were a couple of days when the MSP techs were testing on the Cambridge P25 system from various locations around Boston and all were reporting better signal strength, I suspect that the upgrade to multi site may have occurred then.

Gordon