Sporadic E propagation, which is caused by the ionization of the ionosphere at around 90-120 km altitude, is most common between the summer months of May and September in the northern hemisphere, and October to March in the southern hemisphere, during daylight. Openings can also occur at other times, day or night. It's also possible for the muf* to rise high enough for F-layer propagation at these frequencies, but this is much more rare. Fuller explanations for the reasons behind these forms of propagation can be found elsewhere on the net.

Below are various, and sometimes unusual examples, as seen by my spectrum analysis of the 48.250 and 55.250 MHz TV channels in Europe.

*muf = maximum useable frequency

[Es Gallery page 2] [Back to live spectrum page] See bottom of page for more internal links.

 July 07 2005 0700-0800 utc

A full-blown sporadic-E opening in progress. Seven or eight transmitters can be seen, 
along with all their associated 50Hz hum bars!

 Jan 17 2004 1300-1855 utc

Portugese transmitter on 48.250450 MHz, drifting.
Oscillation period approx 45 minutes.
 

 
Ten minute plot of the same opening, including the signal
from the Liege, Belgium transmitter on 55.250044 MHz at the top.

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