SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/ham-satellite-doppler

What is Doppler shift in satellite communications?

A change in signal frequency caused by relative motion.

  1. A change in the satellite orbit
  2. A frequency change caused by relative motion ✔
  3. Receiving on one band and transmitting on another

Why: As a satellite races toward you, its signal appears higher in frequency, and lower as it moves away. Operators retune during a pass to follow it.

Huh, didn't know that: The same effect makes a passing train horn sound higher, then lower.

The dad joke
Why did the satellite change its tune? It was moving too fast to stay on key.
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Sources

  1. NCVEC 2026-2030 Technician Question Pool (Feb 19, 2026 release) https://www.ncvec.org/downloads/2026-2030%20Technician%20Pool%20and%20Syllabus%20Public%20Release%20Feb%2019%202026.pdf

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