One of the biggest problem with forward scatter data is that each recording station is different from the others. One station might be using a highly directional yagi type antenna with it’s associated forward gain, while others might be using a simple vertical antenna. Others stations use a one wavelength closed loop, discones, or even quadafilar antennas. Each type of antenna places a certain bias on how many echoes are heard per hour.
In addition to the various antennas in use, radio observers also employ many different types of receivers. Some are state of the art while others are less sensitive and less selective than the more capable receivers. This again will influence the station’s daily data.
Yet an other variable among the stations it their frequency and transmitter choice. A few Japanese station listen to beacons on 28 MHz while several Europeans listen to the French satellite radar at 143. Frequency choice and the transmitter’s output power can greatly affect a station’s data.
Recognizing this inter-station variability a few of us decided to attempt a numerical model to ‘level the playing field’ by using the concept of Observability Function. There will be follow ups to improve this initial modeling. It has been field tested and provides some hope on equalizing the data from such diverse stations.
The complete paper (WGN 34:3 p87-97) can be downloaded here.