In the illustration above the general principle of meteor
observations by forward scattering of RF energy off ionized
layers caused by meteor trails can easily be understood.
Having looked at the general principal we now have to evaluate
the requirements of the transmitter/receiver frequency, the
distance of the path and its direction.
The frequency range most suited to meteor scatter lies between
40 and 110 MHz , above and below these frequencies other problems
are encountered in the form of propagation and frequency limiting.
So the meteor receiving station must be equipped with a VHF
radio receiver capable of covering this range and, depending
on the software to be used and the transmitters modulation,
the ability to switch between different modes i.e. WFM, NFM,
AM, USB and LSB. It should be noted that the mode of operation
also governs the receiver sensitivity (bandwidth consideration)
and hence the number of meteor counts.
Typically for a scanning receiver:
|10 dB S/N
||-121 dBm USB/LSB
-97 dBm AM
|12 dB SINAD
||-118 dBm NFM
-107 dBm WFM
Using the forward scatter principle the transmitter and receiver
are at different locations and below the horizon due to the
Earths curvature, so direct radio contact is impossible. This
means that large distances are involved, typically 800 to
1600 km, and as with frequency above and below these distances
other problems are encountered. If possible when selecting
the path between receiver and transmitter a North - South
path (or close to) is preferable.
Having decided on a frequency to use by selecting a transmitter
in the right band and at a suitable distance the meteor counts
have to be recorded.
Several methods are available:
1. Manual observations by listening to the receiver.
2. Recording with a pen/chart recorder thus giving a permanent
3. Probably the most common form is using a computer and software
I have tried to keep all of the above information as concise
as possible, more in depth reading material is available from
the sites listed under Links, the
IMO site in particular is a very good primer.