An observatory dedicated to radio reflection phenomena
By Andy Smith, G7IZU

Andy continuously monitors remote Band 1 TV stations to observe radio reflection phenomena with live results available on his website. These include aurorae, meteors and Sporadic-E events. The characteristics of meteor reflections will be of particular interest to amateur radio astronomers who plan to do meteor detection work.

Most of the first page of the website is reproduced below, courtesy of Andy. All links point to the website itself. Visit the website for the latest information.

The main website can be found here.

Meteor Shower, Aurora, Sporadic E Detection using Radio Signal Reflection
by Andy Smith G7IZU

Also as featured in Short Wave Magazine May 2004 (p55).
Some of the site has changed or evolved since the article was published.
Above: 24 hour FFT plot of the Quadrantids shower Jan 2004.

The LIVE Spectrum analysis pages are active! Click here
  Clcik for Latest Spectrogram
< Current latest plot. Click for full size.

NB: Other links to internal and external sites are at the bottom of this page.


The radio detection of aurora and meteors is made possible at my QTH in Plymouth, UK by listening to the carriers of distant  Band 1 TV stations. The frequencies I've chosen are 48.250MHz (European TV channel "E2") and 59.258 MHz (channel R2-6p). 

I use DL4YHF's excellent and dead cool Spectrum Laboratory v2.5b6 fed from the audio output of two Icom PCR-1000s in USB mode, which are tuned to zero-beat frequencies of 48.249485 and 59.258330 MHz. The antenna is a dipole, in the loft, tuned to approx 50MHz, with a 9dB wideband dual-output amplifier. Any other frequencies that gives good returns at your location will also do just as well. See the links below for various TV  frequency lists. More detail about the setup can be found here [ How-to setup a Radio Meteor Obs. Station]

Several European TV stations are present on this frequency that cannot be received by ground wave propagation. Any other mode of propagation that bounces the signal in my direction is detectable, such as sporadic E, meteor reflection, auroral reflection and (maybe possibly?) reflection from high-flying aircraft or even spacecraft. I've seen signals that appear to be the later, though proving that theory is difficult! Doppler shifts of a few tens of hertz, as caused by aircraft, have been well observed by others and myself by monitoring HF broadcast carriers, but I'm not sure about the satellites. There may be other reasons for fast changing carriers sweeping through the detection range...

Radio Aurora

The image above is a very good example of an auroral signal. It was recorded on 31st Oct 2003 between 0010 and 0110 GMT, during the second night of big aurora over the UK in 2 days. Visible in the sky over Plymouth were various red glows and an arc of white stretching overhead. The signal is spread out due to the rapid Doppler shift caused by the charged particles in the auroral curtain rapidly moving. Also, several TV carriers which are a few hundred hertz apart are being reflected simultaneously, making the Doppler effect appear bigger than it really is. 

Above is shown a typical busy meteor period. The upper part of the trace is monitoring the Eastern European channel R2, on 59.258 MHz. The spots are caused by "underdense" meteors. The lower part of the trace has a few "underdense" meteors, but also one quite heafty "overdense" trail lasting a few minutes. This might have been classed as a "fireball" had it been visually sighted.

This is an example of how a Sporadic E (Es) opening looks. Signal levels can be extremely high, and the receivers' AGC levels are often compressed. Here, two carriers only 6 Hz apart are visible on Channel R2. Also visible in the lower trace are the typical 50Hz harmonic lines from the analogue TV transmitter in Sweden. 

Another Sporadic E Opening, showing how the signals can stop coming from one direction or location, and turn to another. Here TVE Spain gives way to RTP Portugal. The wobbling Portugese signal is caused by the transmitter frequency drifting in a 10 minute cycle, due to poor TX frequency control or local mains frequency instabilities at the TX site.
For daily update announcements about this site, click the weblog link on the live page. Any other announcements of significance will be made in the and uk.sci.astronomy newsgroups, and in the Meteorobs mail list.