So is there a standalone Apco-25 "decoder"

[Harbinger]

Like, plugging the speaker output of the scannerinto a "black box" and voila out comes real audio?

[scancapecod]

AOR makes the ARD25 decoder, but it requires a 10.7 MHz IF output. There have apparently been some modifications that allow it to work with a discriminator tap.

http://aorusa.com/ard25.html

I've owned a few of them, and they work well, but they are very pricey. I think if AOR halved the price they'd sell a lot more of them. It is nice to have P25 decoding capability in a quality receiver such as the AOR AR5000 or Icom IC-R8500. This device allows for that to happen...but at a hefty price of about $400.00 shipped.

[N_Jay]

The issue is with the discriminator and filtering.
The four level FSK like signal is not well demodulated with some discriminator circuits and severely distorted by any audio processing.

Picking it up at the IF eliminates these issues.

However, that said, I am sure a REALLY GOOD DSP engineer could characterise a specific radio and get reliable decode.

[DaveNF2G]

If such a device existed, it would cost almost as much as a digital scanner because of the licensing fees. Might as well just plunk down the bucks for the scanner.