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KH6LC Reverse Beacon Network (RBN) Receiver
“CW Skimmer” is the name
of clever software from Alex VE3NEA that automatically decodes CW signals from a
broadband sampled data stream from, in the simplest instance, a sound card
attached to your radio's audio output. Radios are available that will digitize
much more bandwidth than is available from a sound card, and a special version
of the Skimmer software (Skimmer Server) is capable of extracting thousands of
CW streams simultaneously from the data provided by these broadband software
defined radios. The Skimmer software can be instructed to extract the frequency,
signal strength, and call sign of stations calling CQ anywhere in the analyzed
bandwidth, and to forward the information to the Reverse Beacon Network (RBN).
The result of dozens of skimmers operating worldwide is available from the RBN
through its web site
www.reversebeacon.net , and in standard packet spot format through
telnet connection to any of several providers, for example, ve7cc.net, port 23.
The RBN is a very useful tool, enabling the CW
operator to determine who is on the air, what frequency they are on, and how
strong they are at a number of locations. It also can be used to make a direct
comparison of your own signal strength with the signal strength of other
stations as seen at remote locations, and to measure antenna patterns.
Until July 30th 2011, there was no provider of
spots to the RBN in the central Pacific. Now, Lloyd KH6LC, assisted by Curt
AH6RE, Rob NH6V, Fred KH7Y and Wes WZ7I, has assembled the equipment to provide
spots from Hawai'i. The skimmer receiver is located far enough away from active
HF stations that the skimmer receiver there won't be overloaded by extremely
strong local signals.
The equipment is pretty simple. A Hy-Gain
AV-18Hy-Tower Jr. vertical antenna feeds a Clifton Laboratories low-noise
preamplifier which in turn feeds an SRL Quicksilver QS1R wideband programmable
sampling receiver. The receiver cooperates with the Skimmer Server software, and
the combination is capable of simultaneously analyzing up to 192 kHz from each
of seven user selectable bands up through 6 meters in its standard
configuration. Additional software routes the results to the RBN by means of an
Internet connection.
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