*Question G2E01:
Which mode is normally used when sending RTTY signals via AFSK with an SSB transmitter?*  

*Correct Answer is  D: LSB*  

### AI Response: (may contain errors)  

When sending RTTY (Radio Teletype) signals via AFSK (Audio Frequency Shift Keying) with an SSB (Single Sideband) transmitter, the mode normally used is LSB (Lower Sideband). Here's why:

1. **Why the correct answer is LSB:**
   - RTTY signals are traditionally transmitted using LSB on HF bands. This is a convention that has been established to maintain consistency and compatibility among operators.
   - When using AFSK with an SSB transmitter, the audio tones generated by the AFSK are modulated onto the RF carrier. Using LSB ensures that the frequency shift of the tones is correctly represented in the transmitted signal.

2. **Why the other choices are incorrect:**
   - **A: USB (Upper Sideband):** While USB is commonly used for voice communications on frequencies above 10 MHz, RTTY on HF bands typically uses LSB. Using USB could result in the tones being inverted, which would make the signal unreadable by standard RTTY decoders.
   - **B: DSB (Double Sideband):** DSB is not typically used for RTTY because it transmits both sidebands, which is inefficient and unnecessary for digital modes like RTTY.
   - **C: CW (Continuous Wave):** CW is a mode used for Morse code transmission, not for RTTY. RTTY requires a method to shift between two tones, which CW does not provide.

3. **Useful rules of thumb:**
   - On HF bands, digital modes like RTTY typically use LSB below 10 MHz and USB above 10 MHz, but RTTY is an exception that uses LSB regardless of the band.
   - Always check band plans and mode conventions for specific frequencies to ensure proper operation and compatibility with other operators.