[Skimmertalk] Possible Concerns for Multi-Op Stations and Skimmer

Pete Smith n4zr at contesting.com
Tue Sep 23 06:07:45 EDT 2008

There *may be a couple of issues affecting potential use of Skimmer by a 
multi-transmitter station.  I emphasize the "may" because I don't have the 
means to test these scenarios.

The first is decoder upsets from strong local signals on the band the 
Skimmer is listening on - it seems to take a second or so between the time 
strong signals stop blocking the receiver front-end and the time that the 
decoder resumes decoding properly.  If a station has antennas for in-band 
S&P listening, my original thought had been that those could be used for 
the Skimmer, with a simple multi-coupler or passive splitter.  However, a 
friend recently suggested that a lot probably
depended on the use of narrow CW filters by the S&P radios, and that the 
inherently wideband SDR front ends might still be clobbered by transmitted 
signals.  If that's true, I'm thinking that multis may not get the Skimmer 
payoff they'd hope for - with 3 seconds or so between CQs on the run radio, 
a 1+ second decoder recovery time would cut substantially into Skimmer's 
listening time.

The second issue has to do with computer loading from the flow of 
spots.  Because Skimmer re-spots each station that it is still hearing 
every ten minutes, the volume of spots from each Skimmer could be very 
high.  As an example, during the SAC this past weekend I was receiving well 
over 100 spots on 20 per 10 minute period.  Now multiply that by several 
bands open at once during the night, and there is some question how well 
the logging software can manage the load of receiving the spots and 
populating the various bandmaps.  Filtering to allow only spots on the 
desired band to populate the bandmap on each computer may be the solution 
to this.

I may be worrying unduly, but we won't really know till someone tries it.

73, Pete N4ZR

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