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Communication Systems - Engineering

Q1:

If in a radio receiver, RF signal has a frequency of 800 kHz and local oscillator that of 1000 kHz, then at the output of the mixer, the frequencies found would be __________ kHz.

A 800 to 1000

B 200, 800, 1000, 1800

C only 200

D only 1800

ANS:C - only 200

Mixed produces a frequency equal to the difference between local oscillator and radio wave frequency.

So, If = Oscillator frequency - Radio Frequency,
= 1000 Khz-800 Khz,
=200 Khz.