Analysis of Gibraltar-United Kingdom ionospheric scatter signal recordings

The recordings of ionospheric scatter signals received at East Hanningfield, Essex, from the experimental transmitter at Gibraltar have been analysed, but, because of some disturbing factors, great care had to be exercised in accepting certain data. In general, the mean signal levels are a maximum between 0400 and 1200 G.M.T., while a fairly well-defined minimum occurs at about 1800 G.M.T. Signal bursts of duration greater than 1 min appear to have a diurnal variation similar to that of the observed mean signal levels. The time relationship between the first appearance of an identifiable burst at two receiving stations separated by a distance of 70 miles has been investigated. On an east-west route the mean lag at the west station is just over 2 min, the range being from +11 to ¿6 min; the latter represents a lag at the east station. A pronounced seasonal variation in mean signal levels has been disclosed by the analysis. Two sharply defined minima occur, one centred on March, the other on October; of the two maxima, that which occurs in December is the higher. The variation of transmission loss with frequency derived from the analysis confirms the American data obtained at a similar mean latitude. Compared with 37 Mc/s, the mean signal levels for corresponding months show a reduction of 10 dB for 48 Mc/s and 19 dB for 70 Mc/s.