P25 USAD programming

[JAFO]

JAFO - as my previous posts point out - the bandplan might be totally useless and not even configured if the system is explicit.

I'll take your word for it Matt, I don't have all those you-bout trunk decoding programs to know what you guys are seeing and talking about, so I'll take your word for it.

[citabria]

When I nut out whats going I'll post up some more information with examples and screenshots from those programs. I'm not saying "this is how things are" I'm just explaining that theres two different ways these things work, and it could be either at this stage - I don't know yet.

Having a full copy of the P25 specs is very handy, all this info is detailed in and it explains how things work better than any Motorola user manual can.

[citabria]

Heres some reading material for people that are interested:-

http://www.aeroflex.com/ats/products/pr ... /p25cc.pdf
http://www.p25.com/resources/manuals/29 ... unking.pdf
http://www.jcair.com/ats/products/prodf ... ctions.pdf

These explain the concepts in detail. Of course we are at the mercy of the scanner manufactures - since scanners aren't P25 compliant, who knows how they have implemented the specs

[Longreach]

thanks for editing my post, nice

[citabria]

Yeah - that was a mistake - I hit the edit button instead of the quote one and ended up typing my reply in there by mistake - I think the second line got deleted when I fixed it up.. but anyway... no harm, no foul...

[Longreach]

no worries

[soupbones]

Well I loaded up JAFO's file and it loaded fine. He gave me two, both which are slightly different to the one I made up. The digital GRN is very quiet at the moment, so I can't confirm myself that its tracking correctly, ut it appears to be.
The difference in the file is this. The first one has all the control channels piles into one site list, and has older TGs in the listing.
The second one is set up for site trunking, but each site has a GPS reference programmed into it. I deleted the original one I made up, and will see if I can replicate the same file from scratch.

[soupbones]

Just created a new digital GRN system file from scratch, but changed one thing in it. I added a band plan figure. Going from what people are seeing in Pro96Com for the band plan for this system, I chucked in 412.4750 with a spacing of 6.250. File loaded fine. I put in only two sites this time as a test, and only 10 TGs from the list of known ones.
Seems to be tracking fine, but can't be sure if the band plan settings are correct for this system. Going by what people have discovered, it seems to me to be the only one that was probably correct. I might make one up with the known 3 base and offsets of the analogue GRN but change the stepping to 6.250 to suit P25 channel spacing.

What do you think?

[citabria]

Sounds like some good troubleshooting, I like it - only one thingI can suggest - they're using phase one P25 which is 12.5k channel width.

The biggest problem I've had is that lack of traffic too. Makes it really hard to test things and sniff out whats going on!

[Mike Alpha]

What gets me with all this is that when I first tuned to a P25 CC in the 996 custom search and set it for CC only and P25, it tracked the talkgroups fine - no bandplans needed.

Why all the difficulty when trying to program a P25 system?

Mike