After several contests, monitoring of the softrock skimmers has turned up a bit of a problem with using softrocks as the skimmer platform. \u00c2\u00a0Very strong signals are producing a mirror image that is often reported as a spot to the RBN. \u00c2\u00a0Certain to be annoying for the S&P packet crowd during a contest. \u00c2\u00a0Annoying enough that a few flame mails have arrived.<\/p>\n
The volume of the bad spots is relatively low on the lower bands, and more common on the higher bands. \u00c2\u00a040m is somewhere in the middle, with most of the bad spots being sent for domestic USA stations.<\/p>\n
The problem is a combination of the hardware and software, both contributing to the problem. \u00c2\u00a0A software fix could potentially be made to CW skimmer or to the RBN aggregator to correct for the problem. \u00c2\u00a0Will inquire to the authors…..<\/p>\n
In the meantime the best solution available is to throttle the RBN aggregator to allow only spots below the center frequency to be reported. \u00c2\u00a0For example, the 15m skimmer is based on a softrock with a center frequency at approximately 21044.5Mc. \u00c2\u00a0So 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.<\/p>\n
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). \u00c2\u00a0But it should alleviate many\/most of the actual bad spots, since most run stations prefer to operate as low in the band as they are able.<\/p>\n
Open to other suggestions short of replacing the softrocks with better (yet unaffordable) hardware.<\/p>\n
Update 20130217, 2140Z:<\/em><\/span> \u00c2\u00a0There are new versions of both skimmer and aggregator. \u00c2\u00a0Perhaps upgrade will help.<\/p>\n","protected":false},"excerpt":{"rendered":" After several contests, monitoring of the softrock skimmers has turned up a bit of a problem with using softrocks as the skimmer platform. \u00c2 Very strong signals are producing a mirror image that is often reported as a spot to the RBN. \u00c2 Certain to be annoying for the S&P packet crowd during a contest. \u00c2 Annoying enough that a few flame mails have arrived.<\/p>\n The volume of the bad spots is relatively low on the lower bands, and more common on the higher bands. \u00c2 40m is somewhere in the middle, with most of the bad spots being sent for domestic USA stations.<\/p>\n The problem is a combination of the hardware and software, both contributing to the problem. \u00c2 A software fix could potentially be made to CW skimmer or to the RBN aggregator to correct for the problem. \u00c2 Will inquire to the authors…..<\/p>\n In the meantime the best solution available is to throttle the RBN aggregator to allow only spots below the center frequency to be reported. \u00c2 For example, the 15m skimmer is based on a softrock with a center frequency at approximately 21044.5Mc. \u00c2 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.<\/p>\n 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). \u00c2 But it should […]<\/p>\n