Answer 5.10
The carrier recovery circuit uses the squaring
device to double the frequency of the incoming signal hence forcing the 0o and
180o phase modulation to modulo 360o. The squared output is thus at
twice the input carrier frequency including any frequency error in the system such as
Doppler shift. For this case, the output frequency would thus be 2 x (1 MHz + 70 Hz) or
2000140 Hz