[Scan-DC] Uniden Digital Scanners Pricing/Availability

[Justin D Osborn]

On Wed, 11 Dec 2002, John Antonelli wrote:

> Folks, unless you are in an area that is digital, I say wait
> a bit and let em work the bugs out and perhaps get away from
> this add on card feature
> 
What I don't understand, is why somebody hasn't written software to do the
digital decoding, or hacked a digital radio apart and come up with some
sort of software solution.

The new digital systems have the same control scheme as the analog
trunking systems, the radios just digitally encode the audio stream
before they send it.  This means that any of us with a semi-recent
trunktracking scanners can track a digital system, we'll just hear the
audio as digital noise.

So there are two options:

1) Hook up the audio output of the scanner to a computer and write
software to decode it.  This is probably the least expensive
option.  That's the way people used to scan trunking systems before
trunktracking scanners.  Get a regular scanner, have it scan the control
channel and have the audio hooked up to a computer.  Have the computer
decode the control channel, and then have the computer tune a computer
controlled scanner to the proper channel.

Main problem:  The APCO-25 standard isn't proprietary, but they want $600
for the design papers.  So we'd need a group of people that have some
digital audio programming experience, and maybe we could all pitch in to
pay for the specs.

2) I'm guessing that since the control scheme hasn't changed, the radios
really haven't changed much either.  What I'm guessing is:  whatever the
analog radios are like now, the digital radios are exactly the same, with
the addition of two chips.  They've gotta have one chip that takes the
analog audio stream and converts it to the actual digital data.  Then
there's a chip that takes the digital data, decodes it, and turns it into
the analog stream.  So if somebody has a digital radio, we could take it
apart and see what the chip design is like.

Main problem:  I don't know enough about EE yet.  Also, it's possible they
could've completely redone the radios and all the processing is on one
chip.  But if you go to the hardware route, you could make a small
attachment for the scanner, and you could still have them be portable.

There's a third option that a friend of mine suggested, which would be to
reprogram one of the new radios on the fly.  Apparently they have some
sort of computer programming port so that they can be programmed with
frequencies and talkgroups.  He figured it'd be easier to reverse engineer
the programming protocol than the digital encoding.  The problem is that
you'd need to get a digital radio, which are probably more expensive than
the Uniden scanner/card combination combined.

I'd be in favor of the software solution, that way anybody with a computer
could listen, and the software might even be ported to a Palm/Pocket PC
device, allowing for portability again.

Does anybody know why people aren't working on decoder software or
hardware projects?  I think for most of us, paying $600 for a new scanner
isn't really an option...and I don't feel like waiting for years for
prices to go down.

Justin

--
Justin Osborn                         "Empty are the musings 	
University of Maryland                   And wasted are the days
Class of '05                               You said you were only waiting
jdosborn@wam.umd.edu                         Famous last words"
lunokhod.student.umd.edu	                   -- Jars of Clay