Propagation Beacon Tracking: By Way of SDR - Part 4

This is the 4th part (actually the 6th Blog) on the subject of Beacon Tracking.  Another approach to beacon tracking recently occurred to me - namely, the use of internet accessible Software Defined Receivers (SDR's).  While I don't normally like being dependent on the internet, having access to different listening vantage points can in fact be quite useful.

Another approach to beacon tracking is to use a TRIO of SDR receivers, allowing a triangulation
of a specific beacon frequency.  This provides three ways of determining:

• If a given TX is on or off the air.
• If the TX can be heard from some geographical "angles" (azimuth).
• With 3+ SDR listening-points, we can determine/better-predict the actual "atmospheric ducts" to the beacon location(s) - there are 3 Russian beacons in East Asia, alone.

With occasional exceptions most (if not all) NCDXF beacons are on-air, all the time - somewhere
in their 3:00 minute cycle.  Using SDR receivers we can triangulate in much the same way as with
the Russian beacons, except that any given NCDXF beacon frequency is heard for only ~5 seconds, every 3 minutes.  Writing our own "decoder" for SDR data streams, we could probably sort it all out.

With the Russian military beacons, unless they are having serious operational problems, the "ID" letter is sent every 1 - 2 seconds.  Then again (as has been noted in my previous blogs on this subject), occasionally (albeit rarely) a given Russian beacon alters the style with which the
ID is sent.  There has been considerable speculation on why the change in "ID" is made
(when they are made); there seems to be no real pattern to those changes.

To aid in tracking the Russian beacons, I've added a specific screen to the WQ6X Beacon Tracking software.  At the very least, this screen is a reminder that there is a considerable amount of on-going Russian beacon activity all over Europe and Asia, all of the time.

In recent weeks, the "F" beacon has been AWOL and the "M" beacon has been on and off. 
For a couple of weeks, the "K" beacon shifted from sending the ID-letter every 1.5 seconds to
sending "K K K K" and then pausing for 2 seconds.  Then, it was back to ID'ing every 1.5 seconds.  

I have been wondering what effect the Ukrainian conflict conflict would have on beacon operations.  Listening around the bands on the Dutch utwente.nl recently found the "P", "S" and "C" beacons operating as I would expect, however the "D" and "A" beacons seem to not be active.  I will check back later this week to see if that was just a fluke-day.  A couple of evenings back, listening to 7038.8, the "K" beacon has again become AWOL, while the "M" beacon (Magadan) is now back, just as if it
had never left.

 

I do not understand what all of this means, however it DOES seem to be a fascinating mystery, looking to be deciphered.

What about YOU?

Have you ever tracked propagation beacons via SDR.

What DiD YOU Discover?