18 November 2008

Listening On The Leonids

Every year on November 17 a meteor shower called Leonids hits the Earth. These small meteors cause ionized trails in the upper atmosphere. Radio signals are reflected on these trails. It is easy to hear these reflected signals from a distant transmitter with a radio receiver. In the video above you can hear radio signals popping up out of the noise. The receiver is tuned to 49.739 MHz, a distant TV transmitter stations frequency somewhere in eastern Europe. My antenna is a 50 m long wire and the receiver is a Yaesu FT-857D transceiver.

In the video above you can hear a very strong reflection with long duration caused by a larger meteor trail. It was recorded 07:34 UTC and in the sound spectrogram below you can see this reflected signal. The spectrogram is provided by G7IZU in the U.K.. The x-axis shows the time and the y-axis the sound frequency of the receivers audio output.

In the spectrogram above from G7IZU a big event, called a fireball, is recorded some hours later.

In the diagram above from Make More miles On VHF you can see that the meteor activity is accentuated on November 17. Detailed info about this type of reflections is provided by the International Meteor Organization.