OP25 No audio.

[maus92]

P25 has both Conventional and single channel trunking flavors with talk groups and NAC access control. Some of the OP's images show no signal on the tuned channel which suggests a Conventional system or a misconfigured SDR. I'm not sure if a P25 Conventional channel would show tgids; his data shows (only) one talk group: TG=1 and multiple users. All ENC btw.

 

[veceme]

Making some good progress now. Still appears to be Conventional P25 but the incoming signal level is overloading your SDR.
Lower the LNA setting to maybe something like 20. The signal spike optimally should be approximately 30-35 dB above the
noise floor in the FFT plot.

Getting the LNA gain set will reduce decoding errors and this is always an important first step in getting op25 operating
properly. Once you've got the LNA adjusted per the above then please capture a Mixer plot and post that. It looks like
the PPM is probably very close but would like to verify as next steps.

Hello everything is fine? I did what you asked as requested, and put LNA 20. Is it good or do I have to decrease more. Thanks for the help.

 

[veceme]

Nice constellation, but unfortunately the DSD logs are indeed showing AES encrypted communications. OP25 isn't going to be able to decode it.

Hi, no kidding, seriously. So how should I listen to this communication?

 

[veceme]

P25 has both Conventional and single channel trunking flavors with talk groups and NAC access control. Some of the OP's images show no signal on the tuned channel which suggests a Conventional system or a misconfigured SDR. I'm not sure if a P25 Conventional channel would show tgids; his data shows (only) one talk group: TG=1 and multiple users. All ENC btw.

I fully agree. How should I configure SDR to get this data. I'm new to this system and I don't know how to do it. Would you mind letting me know? Thank you very much for the help!

 

[a417]

Hi, no kidding, seriously. So how should I listen to this communication?

No kidding. You will need an authorized subscriber unit with the correctly provisioned encryption system on it to decode the encrypted transmissions. Your best bet is to become a member of that agency in an official capacity, and they will likely issue you a radio with said provisions.

 

[veceme]

No kidding. You will need an authorized subscriber unit with the correctly provisioned encryption system on it to decode the encrypted transmissions. Your best bet is to become a member of that agency in an official capacity, and they will likely issue you a radio with said provisions.

Got it, I suppose I have to buy a radio because they won't give it to me, and get the key.
Or.
If I only get the key. It would be possible to put it in the OP25 in some specific file.

 

[a417]

Got it, I suppose I have to buy a radio because they won't give it to me, and get the key.
Or.
If I only get the key. It would be possible to put it in the OP25 in some specific file.

They will likely not put a key in a radio you buy. They have encryption to keep you out.

 

[boatbod]

They will likely not put a key in a radio you buy. They have encryption to keep you out.

Agencies are naturally very cautious about handing out encryption keys. Unless you have a legitimate need to access those communications - in which case you're going to be issued a properly programmed radio - you are likely straight outta luck.

 

[veceme]

I understand, I'll keep studying about this subject and if I discover something, I'll post it here.
But thank you all for your help.

 

[veceme]

I've been researching, actually listening to an AES 256 signal is a bit complicated if it's brute force.
But if I have the key!
How do I do?
Where do I place?
How to put?
How to configure?

 

[MTL_Emergencies]

You legally and realistically can't brute force AES 256... There are over 10^77 possibilities (which is also why it's considered secure).
OP25 can only decrypt ADP (ARC4 encryption) IF you have the key.
If you legally obtain the key (for AES), you can use a subscriber radio or Unication pager for decryption.
Case closed.