Audio with DSDPLUS and Without in SDRTRUNK

[edcomnrocha]

Hello everyone.

I'm new to all this, and I've been experimenting with various configurations with dsdplus and sdr++ and I've been able to listen to some transmissions in DMR, and P25 Phase I.

Also using sdrtrunk with 2 RTL-SDR V4 dongles I can hear some things in DMR.

However, there is a frequency (P25 Phase I) that with DSDPLUS and SDR++ I can hear, but it is not a control channel, and unfortunately I cannot find the control channel.
But when I try to listen to the same frequency with sdrtrunk and when transmitting on it, sdrtrunk tells me that it is encrypted and remains silent, but in dsdplus I can hear it.

Am I doing something wrong in sdrtrunk?
OR to listen to it do I have to have the control channel configured in sdrtrunk?

And is there a way to find the control channel without searching frequency by frequency that I see has P25?


Thanks everyone, and sorry if I'm being too noob but I didn't find anything like what I have for help before asking.

 

[boatbod]

Hello everyone.

I'm new to all this, and I've been experimenting with various configurations with dsdplus and sdr++ and I've been able to listen to some transmissions in DMR, and P25 Phase I.

Also using sdrtrunk with 2 RTL-SDR V4 dongles I can hear some things in DMR.

However, there is a frequency (P25 Phase I) that with DSDPLUS and SDR++ I can hear, but it is not a control channel, and unfortunately I cannot find the control channel.
But when I try to listen to the same frequency with sdrtrunk and when transmitting on it, sdrtrunk tells me that it is encrypted and remains silent, but in dsdplus I can hear it.

Am I doing something wrong in sdrtrunk?
OR to listen to it do I have to have the control channel configured in sdrtrunk?

And is there a way to find the control channel without searching frequency by frequency that I see has P25?


Thanks everyone, and sorry if I'm being too noob but I didn't find anything like what I have for help before asking.

P25 Phase 1 can be either Conventional (non-trunked) or Trunked. You might be able to learn something by looking up the NAC in your regional RR database. You may also learn something by examining the signaling (contents of LCW) to see if other simultaneous group voice grants are being announced on the channel you are decoding. Obviously a P25 Conventional system does not utilize the concept of a voice grant, so the presence of one would definitely imply you are monitoring one channel of a trunked system, whereas absence would reinforce the assumption of a stand-alone conventional freq.

 

[Whiskey3JMC]

However, there is a frequency (P25 Phase I) that with DSDPLUS and SDR++ I can hear, but it is not a control channel, and unfortunately I cannot find the control channel. But when I try to listen to the same frequency with sdrtrunk and when transmitting on it, sdrtrunk tells me that it is encrypted and remains silent, but in dsdplus I can hear it.

OR to listen to it do I have to have the control channel configured in sdrtrunk?

And is there a way to find the control channel without searching frequency by frequency that I see has P25?

Please provide specific agency & frequency so we can look it up in the database to see if it's P25 conventional or part of a trunked system to be able to give you the correct course of action. If traffic is encrypted full time (mode DE, TE or P25E in the database) you will not be able to hear voice comms regardless of what app you use to decode

 

[edcomnrocha]

P25 Phase 1 can be either Conventional (non-trunked) or Trunked. You might be able to learn something by looking up the NAC in your regional RR database. You may also learn something by examining the signaling (contents of LCW) to see if other simultaneous group voice grants are being announced on the channel you are decoding. Obviously a P25 Conventional system does not utilize the concept of a voice grant, so the presence of one would definitely imply you are monitoring one channel of a trunked system, whereas absence would reinforce the assumption of a stand-alone conventional freq.

Hello, thank you for your answer!!

Ok, I looked in the RR database, something from Brazil (my region) and also my state São Paulo.
However, there is little data and the frequencies that exist there are outdated, some even work, but without coding.

However, there is no frequency with P25, at least from what I saw.

Where can I learn about NAC and LCW, maybe I can build a list and even send it to RR, but it might take a while lol.

Hello, thank you for your answer!!

Ok, I looked in the RR database, something from Brazil (my region) and also my state São Paulo.
However, there is little data and the frequencies that exist there are outdated, some even work, but without coding.

However, there is no frequency with P25, at least from what I saw.

Where can I learn about NAC and LCW, maybe I can build a list and even send it to RR, but it might take a while lol.

Please provide specific agency & frequency so we can look it up in the database to see if it's P25 conventional or part of a trunked system to be able to give you the correct course of action. If traffic is encrypted full time (mode DE, TE or P25E in the database) you will not be able to hear voice comms regardless of what app you use to decode

Hi, thanks for your reply too

Ok, the agency apparently belongs to the municipal guard in my region or some other police agency, which I find strange, because from what I know here they are all encrypted (but I'm not sure).
Frequency is 173.106Mhz.

DSDPLUS + SDRPP traffic is audible and uncut, it does not appear to be encrypted.
But the same frequency in SDRTRUNK says it is and remains silent.

So either DSDPLUS is crazy because I can hear it, or SDRTRUNK is crazy because it shows as encrypted.

I don't want to listen encrypted, as I know I can't do it without the network key.
But I was confused because one application listened and the other said it was encrypted

As I said in the other answer above, I'm from Brazil, São Paulo.

And I didn't find much information on RR here, just a little information that I think is out of date

 

[dave3825]

Where can I learn about NAC

Channel Operation and Numbering | Tait Radio Academy

An in depth analysis and comparison of units & groups numbering, identifying a P25 trunked network, and how radio channels are addressed on a trunked P25 system.

www.taitradioacademy.com

So either DSDPLUS is crazy because I can hear it, or SDRTRUNK is crazy because it shows as encrypted.

an you post a screenshot of each program receiving on the said freq?

 

[edcomnrocha]

an you post a screenshot of each program receiving on the said freq?

Hello.

It's really me who's going crazy lol.

I was selecting different frequencies in both applications.

Today I actually managed to listen to both DSD and SDR-TRUNK lol

I now receive this information.

At the weekend I will read the information on the page you sent.

And start looking to see if there is a control frequency, this channel has little voice traffic.