[CQ-Contest] Skimmer had finally arrived

Dick Green WC1M wc1m73 at gmail.com
Mon Feb 20 13:05:31 PST 2012

As W9RE pointed out, one of the problems with Skimmer is that more stations
are zero-beat in your pileup, making it more difficult to separate the
signals. It's generally worse when a lot of lower-power stations from the
same part of the world are calling you, and may be worse on radios with
all-digital signal processing.

I think the zero-beat problem is worse with Skimmer than packet. When a
human spots, the reported frequency might be off by a few tens of Hz or
more, depending on where the op landed and his pitch preferences (or not
wanting to take the time to zero beat or not knowing how.) Skimmer always
spots zero-beat, as long as the radio is properly calibrated. I suspect the
SDRs people are using for Skimmer are better calibrated than the rigs they
use for QSOs.

73, Dick WC1M

> -----Original Message-----
> From: Edward Sawyer [mailto:SawyerEd at earthlink.net]
> Sent: Monday, February 20, 2012 7:09 AM
> To: cq-contest at contesting.com
> Subject: [CQ-Contest] Skimmer had finally arrived
> For the first time, I can say, that skimmer is finally making a
> noticeable impact out there.  As likely the most active Vermont station
> out there this weekend, I was a needed "mult" for most.  I noticed that
> when I started CQing on 80M or even 160 the first night.  Within 1
> minute I would often get called by a handful of stations, many M/M
> usually all at the same time.  I checked this morning, and as I
> suspected, I wasn't spotted on the cluster that quickly.  Interestingly,
> this was not 100 stations it was no more than half a dozen from a region
> (15M to JA had the same affect).  I noticed a couple of SA and EU
> stations were always in the first group on 3 different bands where it
> occurred.
> Clearly skimmer is having an impact.  I found it interesting that it was
> quick and efficient but not overwhelmingly numerous, yet.  If there are
> hundreds of skimmer enabled "quick find and hit" stations out there,
> most are not doing too well with it yet.  I ran a few times on 80M.  The
> quick hit group was gone in less than 2 mins usually.  Then you would
> settle in to a "normal run".  Periodically a spot might happen and you
> get the uptick.
> But if hundreds were employing this technique, you would know it.  They
> aren't.  Not from what I see.  At least not in Europe, where the VT mult
> on 80M was a wanted commodity.  And it isn't not being heard, because I
> would then knock off 50 or more stations from around the region with no
> problem.
> I am sure there are A LOT more people using skimmer populating the band
> map than what I am describing above.  But the "quick hit" group appears
> small yet.  Next year I expect it will increase significantly.
> Ed  N1UR

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