CW Skimmer receiving station
I run a QS1R SDR receiver with Skimmer Server, software from Alex Shovkoplyas, VE3NEA, that detects CQ calls on 7 bands at once. You can use DX cluster software to have these CQ calls pop up on your computer, often before your friend finishes his call.
Here is some information on my receiver:
A HyGain HyTower Jr. vertical antenna obtains a signal which is amplified by the Clifton Labs Norton amplifier and then fed to the QS1R SDR receiver. The Skimmer Server software runs both in the FPGA chip in the receiver and on a PC. The CQ calls are identified and are made available by telnet. You can access them via the internet from many DX Cluster sites such as ve7cc.net, port 23. These servers should give you quite complete coverage of CW on the bands. If for some reason you prefer to connect directly to my Skimmer computer, telnet to cw.wz7i.com, port 7300. but a direct connection has the disadvantage of no filtering capability.
You will undoubtedly want to do some filtering at the cluster server to reduce the number of spots to something manageable. Having forgotten the telnet commands to set up filters, I downloaded VE7CC's "CC User" software and got the sever filters set up exactly as I wanted.
On my shack computer I run SpotCollector, an excellent DX Cluster telnet program, and receive these spots just as any other ham with an internet connection can do. SpotCollector makes it very easy to connect to as many as four telnet spot sources at once. .
But what if you are interested in Rag Chewing?
A feature of SpotCollector which I appreciate is the ability to "Tag" a call sign. After a good QSO I can put the call in SpotCollector with a Tag like "interesting fellow", or "great fist" and when that ham next calls CQ, up pops his call with my comment. This makes it easy for me to identify CQ's that I know will result in an enjoyable QSO. ( Or I might insert a tag that I wasn't able to copy the ham's fist... chuckle.)
Much of the same information is also available through a web page without using telnet software. There may be a few seconds delay and the spots won't be fed into your logging software, but you will find all of the pages at the www.reversebeacon.net to be thoroughly entertaining if you are interested in propagation. This site offers valuable tools for analyzing your signal.
If you do not live near my QTH, look at this list of Skimmer receiving stations and find one closer to you. Many of these telnet sources are using SDR receivers that work on one band at a time. They may sit on a favorite band or they may monitor each band for a few minutes before moving to another, a method that is surprisingly effective in finding DX stations calling CQ. You will be able to figure out what they are receiving from the web site.
Using skimmers in contesting
Here is an excellent presentation from the Contesting University at Dayton, 2013, by Bob Wilson, N6TV.
What are these signal/noise ratios?
Each spot also contains a S/N ratio determined by the Skimmer software. The absolute numbers seem to depend on the RF gain and other parameters for each receiving station but the relative numbers are very useful. With the reversebeacon web site you can compare the signals of any two stations at each of the receiving sites. Or you can measure the difference in performance of two antennas by logging on to the site, calling CQ a few times, determining the S/N ratio at various receivers, then switch antennas, move a khz or two and call CQ again. It is fascinating to see what happens to S/N at the receiving stations when you lower your transmit power. And just how much advantage does the big pistol station in the next county have over your more modest station? Answer all these questions with the www.reversebeacon.net web site or at Reversebeacon.blogspot.com.