Why is it not legal to transmit a 3 kHz bandwidth USB signal with a carrier frequency of 14.348 MHz?
USB is not used on 20-meter phone
The lower 1 kHz of the signal is outside the 20-meter band
14.348 MHz is outside the 20-meter band
The upper 1 kHz of the signal is outside the 20-meter band✓Respuesta correcta
Explicación
An upper-sideband signal occupies roughly the 3 kHz above its carrier frequency, so a carrier at 14.348 MHz puts energy up to about 14.351 MHz while the 20-meter band ends at 14.350 MHz. The carrier frequency itself is inside the band, which rules out the choice calling 14.348 MHz out of band, and USB places nothing below the carrier, so the lower edge is not involved.