Question E1D01:
[97.3] What is the definition of telemetry?  

Choices:  
A: One-way transmission of measurements at a distance from the measuring instrument  
B: Two-way transmissions in excess of 1000 feet  
C: Two-way transmissions of data  
D: One-way transmission that initiates, modifies, or terminates the functions of a device at a distance    

Correct Answer is  A: One-way transmission of measurements at a distance from the measuring instrument  

To calculate what “telemetry” means, use the FCC Part 97 definition.

Why the correct answer is correct:
- Telemetry is defined in 47 CFR §97.3 as a one-way transmission of measurements at a distance from the measuring instrument.
- Think “tele” = distance, “metry” = measurement. It’s measurement data sent one-way (e.g., satellite health data, remote weather station sensors).

Why the other choices are incorrect:
- B: Two-way transmissions in excess of 1000 feet — Distance thresholds are irrelevant, and telemetry is one-way, not two-way.
- C: Two-way transmissions of data — That’s just data communications; telemetry is specifically one-way measurements.
- D: One-way transmission that initiates, modifies, or terminates the functions of a device — That is telecommand, not telemetry.

Rules of thumb:
- Telemetry: one-way measurements out.
- Telecommand: one-way control in.