Which modulation type is Morse code transmitted using on the PRC-160?

Which modulation type is Morse code transmitted using on the PRC-160?

• A. CW
• B. USB
• C. FM
• D. AME

Answer: (A)

Morse code is sent by turning the RF carrier on and off to create a sequence of short and long pulses. That simple on/off keying keeps the carrier essentially constant in frequency and amplitude while the signal is present or absent, which is exactly what the CW mode provides. In CW, the listener decodes the dots and dashes from the timing of the carrier’s presence, not from changes in frequency or amplitude. The other modes involve altering the carrier in ways Morse code isn’t meant to rely on. Upper/lower sideband modes (USB/LSB) and frequencies-modulated or amplitude-modulated signals introduce changes to the carrier that aren’t needed for Morse timing and would complicate reception and decoding. Morse on a radio is most efficiently and reliably transmitted as continuous wave, hence the correct choice.

Morse code is sent by turning the RF carrier on and off to create a sequence of short and long pulses. That simple on/off keying keeps the carrier essentially constant in frequency and amplitude while the signal is present or absent, which is exactly what the CW mode provides. In CW, the listener decodes the dots and dashes from the timing of the carrier’s presence, not from changes in frequency or amplitude.

The other modes involve altering the carrier in ways Morse code isn’t meant to rely on. Upper/lower sideband modes (USB/LSB) and frequencies-modulated or amplitude-modulated signals introduce changes to the carrier that aren’t needed for Morse timing and would complicate reception and decoding. Morse on a radio is most efficiently and reliably transmitted as continuous wave, hence the correct choice.