SDR & Numbers Stations

An interest of mine that’s off the beaten path is “Numbers Stations”. Coupled with SDRs from within other areas, the two can be worlds of fun for those of us that love to operate radios. You may have heard about either of these, or you may have tried it out and forgotten how much fun it can be.

First is the online and public accessible Software Defined Radios (SDRs). These radios are controlled by an individual to RECEIVE signals, depending on their own capabilities, from Long Wave LW through Gigahertz and are completely tunable by you, the user. CW/AM/FM/SSB are covered and there’s a plethora of different filters you can play with. An online SDR radio is PERFECT for operators to practice tuning in signals on specific bands. For those of you that “accidentally” switch from USB to LSB on different bands (above 40m) and from LSB to USB on other bands (40m and below), this is a toy that can be used to increase your operative effectiveness.

SDR Links:

http://websdr.ewi.utwente.nl:8901/ (europe)
radman.no-ip.ca:8901 (Canada I think)

Second, combined with the above, is something I find extremely fascinating, and that would be “Numbers Stations”. Numbers stations are broadcast stations that simply broadcast a series of numbers. Those not familiar, numbers, groups of numbers, groups of letters, etc. are how old HF encrypted communications were accomplished. For example, through a simple substitution method, whereas A=E, T=W, then “at” would = “EW” or more to the point, A=EGHTN and T=WDFGT then AT=”EGHTN WDFGT”. What is theorized about these “Numbers Stations” is that covert operatives for independent countries listen to the appropriate frequency at the appropriate time, hear the numbers being read and take them down, then decrypt them with the “one time pad” cypher previously entrusted to them by their handlers. While the message may be non-sense, the location of these stations are very interesting indeed. Triangulation is used to isolate the location. This triangulation is accomplished by multiple participating listening stations accumulating the data and working together to find the locations. There are many different websites dealing with “Numbers Stations”, including an email list that participants send notifications to. I am on one such list and I see when stations are active.

Some links for more info on “Numbers Stations”:

http://priyom.org/
http://lifehacker.com/5961035/how-to-listen-to-real-spy-broadcasts-right-now/all
https://www.hfunderground.com/board/index.php

You can combine the two above and use the SDR to listen for Numbers Stations.

For those interested, here’s a movie dedicated to “Numbers Stations”: www.imdb.com/title/tt1659338/?ref_=nv_sr_1