Satgen 402 Operating on RS15 by GM4IHJ (BID SGEN402) 7 Dec 96 RS15 is an excellent mode A 2m up 10m down low earth orbit satellite. Indeed it is the highest altitude satellite in the RS family and as such gives maximum DX coverage. But it is not always easy to use. The following study of orbits over several weeks using equipmemt capable of continuous measurement of performance ( rather than individual operators ears ), outlines some of the difficulties in respect of where and when they were encountered, and, their possible causes,( Figures quoted are doppler shifts ). Orbit pass Type 1st quarter 2nd quarter 3rd quarter 4th quarter SW thru N to E Strong +500hz Weaker +200 Weaker -200 Strong -500 close pass little qsb Bad qsb Bad qsb little qsb W thru N to E Strong +500hz Weaker +200 Weaker -200 Strong -500 close pass little qsb Bad qsb Bad qsb little qsb W thru S to SW +550 Moderate signals Moderate signals -550 close pass Bad qsb Some moderate qsb W thru SW to S +440 Moderate signals Strong signals -440 far pass Bad qsb Some moderate qsb NW to W +160hz Poor signals Poor signals -160hz At horizon Bad qsb Bad qsb Records were obtained using FFTDSP 4.2m audio spectrum analysis software. It is noteworthy that when RS15 proceeds away from the station at a small angle on its stern , fading (qsb) is minimal. At other satellite aspects fading is often quite serious and seems to be cyclic. One clear point coming from the records , is that the fading is not in the pattern one would expect from Faraday rotation of signal polarisation. Comparisons wth results of similar tests on RS10 show marked differences , whereby RS10 fading is generally what would be expected from Faraday effect. It would be interesting to know , how if at all, the antenna types and antenna sites differ on the two satellites, It is appreciated that, RS15 passes at 65 degrees inclination seen at a station located at latitude 56 degrees , are quite different in aspect from passes by RS10 inclination 83 degrees . Whether this affects the fading pattern would perhaps be revealed if stations nearer the equator could report ,when and if they experience severe fading on some orbits of RS15.