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[aprssig] Soundcard Packet Analyzer

Steve Noskowicz noskosteve at yahoo.com
Sun Oct 23 02:12:06 UTC 2011

Nice idea.

  And if it can decode the packet, it should display it so you know who to contact.  I haven't listened lately,but a while back there was a signal around NE Illinois with a squeal before the pasket and it wouldn't decode on the D7 ot D700.
The variation in the sound of the various packets is quite striking. 
  Being from the "old school" (whatever that is) it always fried me when the younger Engineers (@ Motorola) wouldn't have a speaker on while measuring receivers, but just reading the digital readouts of the HP test equipment.
  Hey! it's HP, it has to be reading correctly.  Sure, but just WHAT is it reading??

Whlne, Whine, "but I, or someone else in the lab, dislikes the 1 kc tone while measuring SINAD..."

Last time I checked a Doppler worked quite well on an APRS squwak.

 73, Steve, K9DCI   USN (Vet) MOT (Ret) Ham (Yet)

--- On Sat, 10/22/11, Bob Bruninga <bruninga at usna.edu> wrote:

> From: Bob Bruninga <bruninga at usna.edu>
> Subject: [aprssig] Soundcard Packet Analyzer
> To: aprssig at tapr.org
> Cc: aprs at yahoogroups.com
> Date: Saturday, October 22, 2011, 6:20 PM
> What we really need is a PACKET
> ANALYZER software!
> Something to start pointing fingers at all the bad apples
> on the air.  Every packet expert I know will admit that
> Most if not 90% of signals on the air are poorly
> adjusted.  Levels, Skew, TXD, distortion, pre-emphasis,
> etc.
> Performance could be SO much better!
> Trying to get everyone to look at a scope is hard to
> do.  Or ven interpreting what they see.  But if
> they could just download a sound-card PACKET ANALYZER then
> at least we would have a baseline.  Here is what it
> would do on EVERY packet:
> 1) note the modulation level
> 2) Note distortion content
> 3) Note skew
> 4) Note pre-emphasis
> 5) Note the TXD
> 6) Note SNR
> 7) Measure length
> 8) Comment on PATH
> etc...  Of course, most of the above analysis depend
> completely on  the receiver used to receive the
> signals, so this has always been a difficult and subjective
> process.
> HOWEVER, a large number of signals on the air are from
> three rather popular factory-aligned packet radios, the D7,
> D700 and D710.  They might not be perfect, they might
> not be best, they might not be perfectly set, but having
> come from a factory, they should be consistent.
> SO, my suggested calibration of this PACKET ANALYZER would
> be to monitor the channel for D7's, D700's and D710's and
> benchmark their performance.  Then compare that to what
> ever we think PERFECT is, and then from that, we can
> benchmark what the ideal parameters should be.  Of
> course just listening to empty channel nooise can also tell
> lots about the receiver used.
> Then this program measures all signals against that
> benchmark.
> Then we can immediatleyl point out the bad apples.
> Not that we are going after individual stations.  But
> we can go after the DIGIPEATERS because they represent the
> 95% of all packets on the air.  If we can get those
> digipeatetrs adjusted, then we can really clean up the
> network!
> Mike Chesena, KA2ZEV suggested something like this.
> I think it is a GREAT idea!
> Do we have any DSP jockies that can write this code? 
> Or probably most of it alreayd exists somewhere.  But
> the self-calibration will be important so we are all
> comparing to the same orange.
> Bob, WB4APR
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