Question E2A05:
What do the letters in a satellite’s mode designator specify?  

Choices:  
A: Power limits for uplink and downlink transmissions  
B: The location of the ground control station  
C: The polarization of uplink and downlink signals  
D: The uplink and downlink frequency ranges    

Correct Answer is  D: The uplink and downlink frequency ranges  

Correct answer: D — The uplink and downlink frequency ranges

1) Why D is correct
- A satellite “mode” like U/V, V/U, L/S, or S/X tells you which band you transmit to the satellite on (uplink) and which band it transmits back on (downlink).
- Rule of thumb: first letter = uplink band, second letter = downlink band.
  - Example: U/V means uplink on 70 cm (UHF, ~435 MHz) and downlink on 2 m (VHF, ~145 MHz).

2) Why the other choices are incorrect
- A: Power limits are not encoded in the mode designator; they are specified in operating guidelines or by coordination notes.
- B: Ground control station location is not part of the mode designator.
- C: Polarization (e.g., RHCP, LHCP, linear) is specified separately, not by the mode letters.

3) Useful rules of thumb
- Mode format: uplink/downlink, e.g., U/V, V/U, L/S, S/X.
- Common band letters:
  - V = 2 m (~144–148 MHz)
  - U = 70 cm (~420–450 MHz)
  - L = 23 cm (~1240–1300 MHz)
  - S = 13 cm (~2400–2450 MHz)
  - C = 5 cm (~5.8 GHz)
  - X = 3 cm (~10 GHz)
- Legacy names you may see:
  - Mode J = V/U (2 m up, 70 cm down)
  - Mode B = U/V (70 cm up, 2 m down)
  - Mode A = 2 m up, 10 m down

Memorize: first letter = uplink band, second letter = downlink band.