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[aprssig] MFJ working on a new SMT version 1270

Scott Miller scott at opentrac.org
Sat Aug 25 23:08:05 UTC 2007


> And just out of curiosity, what were the tweaks for the
> Tracker2/TCM3105 combo?

I'm trying to remember now.  The stock code doesn't do quite as well 
with the TCM3105 in the current revision, but it still does a little 
better than your average MX614.

Most of the things I was tweaking involved PLL error thresholds and 
details of the clock recovery code.  That's where the T2 really gains an 
advantage over TNC2 clones - its clock recovery is a lot smarter.

For the OT1+, I've duplicated the DSP code on a PC so I can run 20 
minutes of captured audio in about 1.5 seconds.  Makes it a lot easier 
to test revisions.  It still scores lower than the hardware-based 
demodulators, though.  But not bad for an 8-bit chip at 7.3 MHz.

Scott
N1VG





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