Satgen386 Mode A/K Sat Experiments by GM4IHJ 17th Aug 96 At this point in the Solar cycle , with almost no obvious ionospheric propagation at frequencies above 20Mhz, this might seem an odd time to discuss satellite observation of HF propagation anomalies. But lack of propagation is a myth. Opportunities are limited, but surveillance by satellites makes them easy to spot. Opportunities which VHFers would welcome if they occured in their bands, are being revealed by our Mode K 21 Mhz up 29Mhz down, and Mode A 145 Mhz up and 29 Mhz down satellites. The experiments are there for the taking for anyone who has computer prediction of satellite tracks and an HF receiver. RS15 beacon 29.353 Mhz, RS10 beacon 29.358 Mhz, and RS12 beacon 29.408 Mhz are all available via their transponders across the 40 Khz above the beacon ( for qsos ), or for experiments via the beacons themselves . Recent studies at GM4IHJ , have included :- 1. Pre Auroral Enhancement of HF over high latitude paths. Indicating that perhaps we should abandon the "Pre Auroral" part of the name we give to these events. Because it is becoming clear that the precursor is a Solar Coronal Mass Emission (Satgen297 refers), and this may or may not be followed every time by Aurora, but is usually followed at an interval by a Polar HF enhancement event. 2. Looking ( via FFTDSP Spectrum Analysis AF9Y software ) at HF signals from satellites over Polar areas , to see if there is any evidence of signal bandwidth spreading due to Auroral doppler. The regular October auroral season will be with us soon. Without fail most years, we seem to get big Auroras end September or in October. So perhaps this is a good time to get ready for observation of distant satellites, noting that from their great height , they often "see" aurora and illuminate it with their signals , long before earth rotation turns our station around to the point where the Aurora comes above our station horizon. 3. Last but not least , there is no time like the present - even at the bottom of the Sunspot cycle , to look and listen for sub horizon signals from satellites. In previous Solar cycles , both local enhanced propagation from satellites up to 4000 kms below the horizon, and, antipodeal signals from the opposite side of the Earth have been heard, It has to be admitted that the higher the sunspot count the greater the likelyhood of these events, but they have been reported at solar minimum. So, as over the next few years the Solar activity begins to climb up to a new maximum, there are ,many things we can do . The fact is , we actually know very little about this star on our doorstep. Yes we know about Sunspot cycles on stars, but not the why and wherefore of what causes them , and even less about the effects the Sun has on Radio propagation. Just try asking an "expert" why we recently had a major Solar Coronal Mass Emission at Solar cycle minimum , and you will find that we actually know very little. So perhaps radio amateurs with their very useful satellites have something to contribute.