Question E1D04:
[97.119(a)] Which of the following is required in the identification transmissions from a balloon-borne telemetry station?  

Choices:  
A: Call sign  
B: The output power of the balloon transmitter  
C: The station's six-character Maidenhead grid locator  
D: All these choices are correct    

Correct Answer is  A: Call sign  

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Explanation:

1) Why A is correct:
- Part 97.119(a) requires every amateur station (including a balloon-borne telemetry station) to transmit its assigned call sign for identification at least every 10 minutes during a communication and at the end of the transmission.

2) Why the others are incorrect:
- B (Output power): Part 97 does not require announcing transmitter power as part of station identification.
- C (Maidenhead grid): Grid locator is not required for legal ID; it’s optional/useful for operating or contesting but not a regulatory requirement.
- D (All these choices): False, because only the call sign is required.

3) Useful rules of thumb:
- ID timing: transmit your call sign at least every 10 minutes and at the end of the communication.
- ID method: you may ID by CW, by phone (in English), or via data/RTTY as part of the telemetry frame, as long as the call sign content is clear and decodable per §97.119(b).
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