p25p2 Using NXDN ?

[telescopedepth]

So I have a New Scanner and I have this garbled noise on certain talkgroups Oregon State Radio Project is the system. 9010 9021 9031 etc anyway it always is interfering with my abiltiy to search for talkgroups because it goes off alot and i done extensive tinkering trying to figure out what the problem is i have the bcd996p2 scanner and it says that when it comes across encrypted traffic that its programmed to not listen so i started using a SDR dongle and DSD+ (It told me +NXDN ) to try and figure out what the issue is because i noticed that these particular talk groups are using multiple frequencies at the same time is it possible they are just splitting the signal like NXDN or whatever it is and if so Could You Join them Either with scanner settings or SDR any thoughts would be apreciated I know I Cant do NXDN on my scanner but i never imagined they would use p25p2 and nxdn

 

[ka3jjz]

According to our database (link is in blue)

https://www.radioreference.com/apps/db/?sid=8010

There are some talkgroups that are encrypted. You can't ever receive anything on these with any scanner

Mike

 

[clbsquared]

There's no NXDN on that system. It's mostly a Phase 2 system, with alot of encryption. There are a handful of Phase 1 users (which would explain why you're seeing multiple frequencies) left on the system that are encrypted. It's possible that you are hearing the Phase 1 encrypted user.

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[telescopedepth]

thanks

 

[telescopedepth]

Theory

I know what the database says. I believe its wrong. I also know my scanner has decoded those talkgroups when im too close to the source of the transmission so the database is made by men Men are fallible. They hear garbled transmissions on those talkgroups and assume they are encrypted what if they are split into two seperate channels and your only recieving half of the audio stream would that cause it to sound like its underwater as oppose to because only on those talkgroups transmissions are there two frequencys being used simultaniously other talkgroups are random a line pops up here there but when this one goes of its in pairs of 2 so just asking and im probably in the wrong place but im new to all this and im smart but also prone to being very creative but faulty in my thinking . My scanner has come accross Encrypted traffic and it shows ENC it doesnt with that talkgroup it just garbles unless like i say your really close to the source and the two frequencys are not far from each other so well i was just wondering if im crazy or someone with experience in this stuff knows.

 

[ka3jjz]

This is a more likely spot to get your questions answered...

https://forums.radioreference.com/o...-forum/281575-oregon-state-radio-project.html

Mike

 

[clbsquared]

I know what the database says. I believe its wrong. I also know my scanner has decoded those talkgroups when im too close to the source of the transmission so the database is made by men Men are fallible. They hear garbled transmissions on those talkgroups and assume they are encrypted what if they are split into two seperate channels and your only recieving half of the audio stream would that cause it to sound like its underwater as oppose to because only on those talkgroups transmissions are there two frequencys being used simultaniously other talkgroups are random a line pops up here there but when this one goes of its in pairs of 2 so just asking and im probably in the wrong place but im new to all this and im smart but also prone to being very creative but faulty in my thinking . My scanner has come accross Encrypted traffic and it shows ENC it doesnt with that talkgroup it just garbles unless like i say your really close to the source and the two frequencys are not far from each other so well i was just wondering if im crazy or someone with experience in this stuff knows.

Even if you could, why would you combine P25 Phase 2 and NXDN on a statewide system. They're two entirely different types of system.

On another note. Phase 2 is TDMA. Which takes one frequency and splits it into two time slots. Phase 1 is FDMA which uses multiple frequencies and assigns them to a talkgroup as they are available. As I said before, this could be why you're seeing multiple frequencies on one talk group. It's a little more complex than that, but I think you get the point. Now, it is quite common for phase 1 systems to have simulcast distortion on the majority of scanners. It's also quite possible that you could be hearing a Phase 1 radio being patched to a Phase 2 talk group. There are lots of different scenarios that could be causing your issue. But I can guarantee you it's not because it's a mixed P25 Phase 2 / NXDN system.

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[hiegtx]

Even if you could, why would you combine P25 Phase 2 and NXDN on a statewide system. They're two entirely different types of system.

On another note. Phase 2 is TDMA. Which takes one frequency and splits it into two time slots. Phase 1 is FDMA which uses multiple frequencies and assigns them to a talkgroup as they are available. As I said before, this could be why you're seeing multiple frequencies on one talk group. It's a little more complex than that, but I think you get the point. Now, it is quite common for phase 1 systems to have simulcast distortion on the majority of scanners. It's also quite possible that you could be hearing a Phase 1 radio being patched to a Phase 2 talk group. There are lots of different scenarios that could be causing your issue. But I can guarantee you it's not because it's a mixed P25 Phase 2 / NXDN system.

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Exactly. The 996P2 cannot be upgraded for NXDN anyway. If the OP is seeing some indication of NXDN when using the SDR, then likely interference is causing a false indication.

If the NXDN presumption is being made because of garbled traffic not flagged as encrypted, that would not be conclusive at all. I have a wide mix of systems in use in my metro area (Dallas/Fort Worth). Some analog, some P25 Phase I, some Phase II, and others that have both Phase I & Phase II traffic. The 'ignore' for encrypted P25 Phase II transmissions is not as accurate as the one used for Phase I. Whether that is because the scanner is not recognizing it, due to a weak signal, or the encryption not set up correctly (at least not set to normal specs), occasionally I will get a dose of jumbled voice.

 

[telescopedepth]

Thank you for the explained version i like to understand ..its informative.. i will learn all this eventually i was just hoping it was something beatable and not illegal. OH WELL back to my project of trying to get my sdr to decode phase 2 systems