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| Problem with P25 reception http://interceptradio.com/bbs/viewtopic.php?f=1&t=8078 |
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| Author: | MTM [ Wed May 06, 2015 11:42 am ] |
| Post subject: | Problem with P25 reception |
New Pro-651 and Pro-652 units. The newer Pro-651 is the same unit as the older Pro-106 portable. I am able to hear stations using P25 and indicates the NAC, but both units are not "Decoding" the voice - on certain frequencies/stations. Just getting the under water garbage. Am I hearing P25 phase 2 ? Some P25 stations work and others I just get the under water garbage -- but I do get the NAC Code. |
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| Author: | Vizwar [ Thu May 07, 2015 3:04 pm ] |
| Post subject: | Re: Problem with P25 reception |
The NAC is repeated fairly often in the data stream, so if you decode anything at all it'd probably be that. Sounds like you're experiencing high bit error rate. Signal quality can obviously cause that, but multi-path will as well. Digital hates multi-path. Are the stations you're not able to fully decode in a different band than the ones you can? |
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| Author: | MTM [ Thu May 07, 2015 3:50 pm ] |
| Post subject: | Re: Problem with P25 reception |
Having problems with a few VHF and UHF stations. Lots of local P25 stations are fine. (Both VHF + UHF). Just a few Federal systems that I am having problems with. Yet I do hear alot of other USFS / NPS and BLM P25 traffic. Could it be: 1.) Station signal level -- low signal level , or multi-path or 2.) P25 phase II ?? If it's a P25 phase II station -- should I be able to decode the NAC -- or not -- without decoding voice ?? |
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| Author: | Wilrobnson [ Thu May 07, 2015 4:29 pm ] |
| Post subject: | Re: Problem with P25 reception |
As I understand, those models are the same as both the PSR500 -- and the PSR600 -- neither of which even do Phase-2 P25. I have both, and neither even register that there's Phase-2 traffic occurring. Also -- unless I'm badly mistaken -- and I often am -- you can't get Phase-2 on a VHF or UHF conventional system -- trunked only. |
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| Author: | MTM [ Thu May 07, 2015 6:26 pm ] |
| Post subject: | Re: Problem with P25 reception |
Thanks guys. I think it's just a poor signal (Low or multi-parh) that prevents decoding the voice. I get a good NAC indication. The few channels I have problems with - are federal and are not trunked. Thanks MTM |
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| Author: | cparris2 [ Fri May 08, 2015 4:49 am ] |
| Post subject: | Re: Problem with P25 reception |
If you are just hearing the under water garbage, most likely its's encrypted. NACs will still decode with encrypted traffic... - Chris |
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| Author: | MTM [ Fri May 08, 2015 5:06 am ] |
| Post subject: | Re: Problem with P25 reception |
BOOM. Ton of Bricks just hit me on the head. Thanks Chris. All of the frequencies that I am having problems with are Federal. All of the local PD stuff work fine. |
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