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Updated: 01/03/2025
FM Satellite Quick Reference Guide SSB Satellite Quick Reference Guide
AMSAT-NA
Satellite
N2YO.com Amateur Amateur Radio Satellite Tracking and Info Satellite Terms Modes U/v - UHF Uplink or transmit and VHF Downlink or receive. Was known as Mode B. V/u - VHF Uplink or transmit and UHF Downlink or receive. Was known as Mode J. V/a
- UHF Uplink or transmit and 10 meter Downlink or receive. Tracking AOS - Acquisition of Signal. Start of the satellite pass and when the satellite comes above the horizon. TCA - Time of Closes Approach. Middle of the pass at the highest elevation. LOS - Loss of Signal. End of the pass and when the satellite goes below the horizon. Azimuth - Measured in degrees around your QTH. Picture a 360 degree circle with 0 degrees being due north, 270 west, 180 south and 90 east. Elevation - Measured in degrees above the horizon a satellite is from your QTH. 0 degrees would be at the horizon and 90 is directly overhead. Tracking programs will show the Azimuth and Elevation of the satellite through out the pass so you know where to point your antenna. When working portable this is approximate and helps to track via signal strength rather than precise azimuth and elevation. Keplerian Keplerian Elements or Keps as they are called are a set of numbers that indicate the orbit of the satellites. These must be updated on a regular basis for our tracking programs to be correct. Elements should be updated weekly at a minimum. Update methods very between tracking programs. Frequency Doppler Shift - The change in frequency of due to the speed of the satellite. VHF usually does not need adjusted if using the FM satellites but on SSB the shift is more apparent on VHF. UHF on average is 10 khz higher at AOS than the satellites transmit frequency, on the transmit frequency at TCA and 10 khz lower at LOS.
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