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[aprssig] D7 and ITEM

Bob Bruninga bruninga at usna.edu
Mon Oct 9 14:52:41 UTC 2006


> but does the D7's decoder just stink?
> I "hear" what seem to be nice solid packets but the
> majority don't decode at all... some do.

The D7 conects its TNC directly to the discriminator and so it has a FLAT response, where many digipaters just connect the TNC to the MIC and Speaker so the audio is pre-emphasizd and demphisied.

It is an excellent decoder, and works all the way down to -122 dBm which is extremely good.  It can decode with only two little LCD segments lit.  But does not receive very well the often slapped-together-and-stick-it-up digi. 

Amateur Packet Radio is DEPLORABLE with more than 90% of the signals on the air being just slapped together with no attempt to properly set up the audio.  I am not saying here that everyone has to connect to their discriminator.  I am saying that far-far too many digis are just set with th audio levevl from the TNC being too high so that causes distortion and SKEW to the tones.  The HIGHER level tone causes the MIC LIMITER to clip or cut back the gain and then the lower tone is suppressed.

But people just plug a TNC in, send a strong packet and say "see, it works" and never do anything else...

Good luck.
Bob, WB4APR




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