The first weekend of May each year hosts a Europe-wide VHF/UHF contest. It’s one I always look forward to: there’s a decent chance of tropo on some of my favourite bands (unfortunately not this year); a slim chance of Es (definitely not this year!); and, most reliably, it’s around the peak of the Eta Aquariids meteor shower.

Eta Aquariids meteors are quite unusual because they are relatively swift (at 66.9km/s) compared with many other shower meteors. When seen visually, they leave long and persistent trains in the night sky. In a similar fashion, from a radio perspective they often result in long and intensely strong “bursts”. Combined with a decent peak hourly rate of 40 and a lot of QRO, well-sited stations all over Europe, this can make for some interesting listening! This year did not disappoint with many bursts heard on 144MHz, some lasting tens of seconds.

A step up from simply tuning around searching for meteor-scatter bursts is to use a Software Defined Radio (SDR), with appropriate software, to record a portion of spectrum to hard disk for a period of time. This data can then be viewed after the event, tuning across the recorded spectrum as if it was in real-time. As an example, I used Simon Brown’s excellent SDR-Radio suite (Version 2.3 in my case) to do just that at various points through the weekend, capturing several very good meteor bursts.

Included below is a video of me using SDR-Radio’s data file analyser to play back signals captured during one good burst on 144 MHz, which I’ve annotated with information about each station received, wherever possible.  Enjoy!

This data was captured in IO51vw using an 11el F9FT antenna at 6m a.g.l., azimuth 095 degrees, a mast-head preamp into an active 0dB loss splitter, feeding an RTL SDR dongle on one port. The recorded spectrum was originally 1MHz wide, centred at 144.280MHz, but I’ve used the data file analyser to zoom in such that the spectrum now covers from approximately 144.150 MHz to 144.410 MHz.

I’m happy with my Perseids results this year, with sixteen new locators (easy to come by with my low total) and three new DXCC (OH0/DM2ECM, YL2AO, HV0A), but it didn’t seem like a great shower – certainly not one of the all-time greats. There was also a somewhat negative impact at this QTH from the Meteorscatter-Sprint Contest but more of that in another blog, coming soon…

According to the International Meteor Organisation, the Perseids peaked this year at around 17:00z on August 12th, two or three hours earlier than originally expected. Radio observations here would tend to indicate some sort of peak at that time but it seemed weaker than the diurnal effect, when local 6am is generally best due to the fact that the Earth is revolving into the path of oncoming meteors at that time (the Earth’s rotational speed is added to the direction of travel around the Sun at dawn, and subtracted at dusk), so the relative speed is highest. In fact, the Sodankylä Geophysical Observatory’s real-time meteor radar (note: link is to current data, not from Perseids peak) showed a much higher radio rate at around 9z on each day from 11th to 13th August, than at 17z on the 12th.

The best way to describe the shower this year was “clumpy”, or “like trying to start an old car on a damp morning”, i.e. it never really got going. Every now and then there would be a series of good reflections, maybe of several seconds each, but often there would follow a period of silence for a considerable time, maybe tens of minutes. It would have been easy to describe these silent periods as “worse than random”, if that actually meant anything! If one was lucky enough to get the timing right a QSO could be completed quickly, otherwise patience was required. Unfortunately, the reflections never became sustained enough for a significant amount of SSB activity, which used to be one of the trademarks of the Perseids, but I did manage a couple of SSB QSOs for “old time’s sake”…

Looking at the log, a quick summary of QSOs measured by distance shows three over 2100km (ES3RF/KO29if/2194km, IC8TEM/JN70cn/2123km, SK2AT/KP03bu/2105km), six over 2000km and eleven over 1900km – not bad!

A blog from me wouldn’t be complete without at least a couple of audio clips 😀 Here are a few nice bursts from OH0/DM2ECM (JP90wg/1951km) sending me R26, including one that lasted an entire 30s period:

(.wav files for direct decode in WSJT: DM2ECM_130812_172200.wav, DM2ECM_130812_173000.wav, DM2ECM_130812_173100.wav – right click and “save as”)

… and this is a nice burst from UA2FT (KO04lt/1946km) who only runs 50 Watts, sending me 26:

(.wav file for direct decode in WSJT: UA2FT_130812_181400.wav – right click and “save as”)

Finally, below is a map of contacts made from this QTH around the 12th August, plus or minus a day or two:

Contacts made by EI3KD around the peak of the 2013 Perseids

I monitored a meteor scatter schedule between Gordon, GW6TEO (IO71lp) and Peo, SM5EPO (JP80mc/1802km) this morning and conditions seemed quite reasonable. Their QSO was more-or-less completed when I received an unusual reflection from Peo: It lasted about seven seconds, but changed frequency by almost 1kHz in a fairly linear fashion over that time. I’ve heard bursts with lots of doppler quite often, although 1kHz is pretty large, but the normal burst characteristic is a very short period of doppler followed by a significantly longer period with none.

I checked with Peo that he hadn’t tuned his VFO at all (and neither did I). I also eliminated the possibility of a reflection from the International Space Station (ISS) because it was over the Middle East at that time. So, the reflection must have been from some other large space object crossing the path at a relatively (by meteor standards) low speed?

Here is the WSJT display of the burst, which appears at the start of the period, fades a little, then reappears stronger at about T+6 (note: the time displayed in the decoded messages in this image is accurate, other times are incorrect):

SM5EPO unusual doppler

And here is the SpecJT display, which shows it in more detail (note: the times displayed in this image are incorrect, because it was generated after the event):

SM5EPO unusual doppler

And here is a zoomed image of the burst:

The .wav file saved by WSJT can be downloaded from here (right click and “save link as”). This file can be opened directly in WSJT, or simply played as an audio file. I found I had to left-click on the burst to get a decent decode.