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T8B12

SIGNALS AND EMISSIONS · Amateur satellite operation: Doppler shift, basic orbits, operating protocols, modulation mode selection, transmitter power considerations, telemetry, satellite tracking programs, beacons, uplink and downlink mode definitions, spin fading, definition of "LEO", setting uplink power

T8B12T8B →

Which of the following is a way to determine whether your satellite uplink power into a linear transponder satellite is neither too low nor too high?

  1. ACheck your signal strength report in the telemetry data
  2. BListen for distortion on your downlink signal
  3. CYour signal strength on the downlink should be about the same as the beacon
  4. DCompare your signal to others on the downlink using an internet SDR receiver
Why A linear transponder is a shared amplifier: its limited output power is divided among everyone using the passband, so one loud station robs power from all the others. The satellite's beacon is transmitted at a known, fixed level, which makes it a built-in reference. If you listen to your own downlink and it comes back about as strong as the beacon, your uplink power is in the right range - weaker means you need more power, noticeably stronger means you are hogging the transponder and should back off.
Watch out Listening for distortion only catches gross overdrive, and it gives you no way to tell when you are too weak; the telemetry stream reports satellite housekeeping data, not a signal report for your individual station.
Beacon = your yardstick. Match the beacon, don't beat it.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
← T8B11 All of T8B

The rest of T8B

  1. T8B01 What telemetry information is typically transmitted by satellite beacons?
  2. T8B02 What is the impact of using excessive effective radiated power on a satellite uplink?
  3. T8B03 Which of the following are provided by satellite tracking programs?
  4. T8B04 What mode of transmission is commonly used by amateur radio satellites?
  5. T8B05 What is a satellite beacon?
  6. T8B06 Which of the following are inputs to a satellite tracking program?
  7. T8B07 What is Doppler shift in reference to satellite communications?
  8. T8B08 What does it mean if a satellite is operating in U/V mode?
  9. T8B09 What causes spin fading of satellite signals?
  10. T8B10 What does the term LEO mean in reference to communication satellites?
  11. T8B11 Who is permitted to receive telemetry from an amateur radio satellite?
  12. T8B12 Which of the following is a way to determine whether your satellite uplink power into a linear transponder sa…
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