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CW Skimmer Errors and RBN spots

After several contests, monitoring of the softrock skimmers has turned up a bit of a problem with using softrocks as the skimmer platform. Â Very strong signals are producing a mirror image that is often reported as a spot to the RBN. Â Certain to be annoying for the S&P packet crowd during a contest. Â Annoying enough that a few flame mails have arrived.

The volume of the bad spots is relatively low on the lower bands, and more common on the higher bands. Â 40m is somewhere in the middle, with most of the bad spots being sent for domestic USA stations.

The problem is a combination of the hardware and software, both contributing to the problem. Â A software fix could potentially be made to CW skimmer or to the RBN aggregator to correct for the problem. Â Will inquire to the authors…..

In the meantime the best solution available is to throttle the RBN aggregator to allow only spots below the center frequency to be reported. Â For example, the 15m skimmer is based on a softrock with a center frequency at approximately 21044.5Mc. Â So for the duration of the ARRL DX CW contest, an entry in the “Notched Frequencies” will be active to not report 21044.5-21100 to the RBN.

That solution does nothing to correct for half of the possible bad spots(i.e., a strong signal above the center frequency whose mirror image is being spotted below the softrock center frequency). Â But it should […]

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