P25 Audio Framing

[aka_ramon]

In a conventional (non-trunked) system that has mixed P25 and analog audio, how is the P25 audio framed and at what bit rate is it transmitted?

Is it framed as per the P25 standard (48 bit frame sync of hex 5575F5FF77FF) and followed by the HDU, then LDUs containing the IMBE audio until the terminator is seen? And status symbols inserted every 70 bits?

Or, is the IMBE digital audio data just sent out with some sort of unique framing arrangement?

This seems like such a fundamental question to me, but I haven't seen any docs that explicitly discuss this. Perhaps I'm just missing it somewhere,

R

 

[SCPD]

In a conventional (non-trunked) system that has mixed P25 and analog audio, how is the P25 audio framed and at what bit rate is it transmitted?

Is it framed as per the P25 standard (48 bit frame sync of hex 5575F5FF77FF) and followed by the HDU, then LDUs containing the IMBE audio until the terminator is seen? And status symbols inserted every 70 bits?

Yep.

-rick

 

[aka_ramon]

RFMobile: I wish I knew *half* of what you did about this stuff.

Thanks much (again) for taking the time to answer,

R

 

[SCPD]

RFMobile: I wish I knew *half* of what you did about this stuff.

Questions (especially those that include the answer) are always welcome!

-rick

 

[N_Jay]

In a conventional (non-trunked) system that has mixed P25 and analog audio, how is the P25 audio framed and at what bit rate is it transmitted?

IOf iots P25, then it is framerd and formatted at P25.

Why would it not be?

The P25 CAI includes conventional mode.