As many of you may be aware, the RBN uses CW Skimmer, and CW Skimmer
uses what's called a pattern file to distinguish between legitimate
callsigns and scraps of other CW communications. The files identify
patterns consisting of up to 3-character explicit prefixes and 1-3
character numeric and alphabetic wildcards. Here's a tiny sample:
+ CE6@
CE6@@
+ CE6@@@
CE7#@@
CE7@@
+ CE7@@@
So for example, CE6A (or any other CE6 plus one letter) is judged to be
reasonably common, and Skimmer would only need to "hear" it twice before
deciding to spot it. This doesn't mean in a single transmission -
Skimmer "listens" to a 50-hz wide decoder, using a 256-character FIFO
buffer, so as long as a station doesn't QSY more than that, it's treated
as one transmission. CE7AA does not have a "+", and would need to be
heard three times. CE7@ (that is, CE7A or any other single letter) does
not appear on the list at all, and would have to be heard 4 times before
it would be spotted.
My impression is that the rash of odd callsign prefixes of the last 10
years or so has abated considerably, but it's always possible that there
are still new calls out there that would require a revision to the
pattern file. For example, if a BY4AA (random example), were to acquire
BY4A, they would go from being spotted after two repetitions to
requiring four.
If this is your situation for the upcoming contest season, please e-mail
me by September 25, and I will put out a new pattern file on October 1.
Thereafter, each time any RBN node-op who starts the Aggregator to
connect to our server and hasn't yet done so will be prompted to
download the new pattern file, and take a few seconds to be fully
up-to-date.
--
73, Pete N4ZR
Check out the new Reverse Beacon Network
web server at<https://reversebeacon.net>.
For spots, please use your favorite
"retail" DX cluster.
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