[aprssig] BPSK decoding

[Dave Baxter]

Hi Scot.

Texas Instruments used to (may still do) a DSP evaluation kit for
affordable monnies, that there was code avalable for to use as a PSK31
modem (both BPSK and QPSK).  It talked to the host PC (in DOS mode) with
plain old RS232.  I forget the exact details, but I have one at home,
and it worked very well the last time I used it.

That's as near a hardware decoder as you can get I think.  No doubt
something like the dsPIC could do the same, and as a tracker at the same
time.

Nowerdays, for shack use, PC's and soundcards get used of course.

Dave G0WBX.
 

> -----Original Message-----
> From: scott at opentrac.org [mailto:scott at opentrac.org] 
> Sent: Monday, May 08, 2006 10:23 PM
> To: 'TAPR APRS Mailing List'
> Subject: [aprssig] BPSK decoding
> 
> I've had PSK31 code working on the OpenTracker for some time 
> now, but as far as I know, there's no inexpensive 
> hardware-based demodulator for the mode.
> Your options seem to be either a soundcard or an expensive 
> multimode TNC.
> 
> Is there a simple circuit somewhere for single-channel BPSK 
> demodulation?
> Specifically, can it be done with an XR2211?  Seems like you 
> ought to be able to have it track the carrier frequency and 
> use the phase detect output to detect the 180-degree phase 
> reversals.  Or does that cause the '2211 to lose lock for too long?
> 
> I think it'd be cool to have a PSK31 QRP rig for backpacking 
> that'd do APRS and hook up to a PDA for text messaging.
> 
> Scott
> N1VG
> 
> 
> 
> 
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>