8-20C: Mixers Flashcards
Receiving Systems (2 cards)
8-20C1
The diagram in Fig.8C9 shows a simplified RADAR mixer circuit using a crystal diode as the first detector. What is the output of the circuit when no echoes are being received?
A. 60 MHz CW.
B. 4095 MHz CW.
C. 4155 MHz CW.
D. No output is developed.
ANSWER D
When no echoes are received, the output from the circuit is zero because there is no output from the first detector.
8-20C3
An RF mixer has what purpose in a RADAR system?
A. Mixes the CW transmitter output to form pulsed waves.
B. Converts a low-level signal to a different frequency.
C. Prevents microwave oscillations from reaching the antenna.
D. Combines audio tones with RF to produce the RADAR signal.
ANSWER B
To obtain the required gain and bandwidth of a signal, a crystal mixer is empolyed to lower the frequency of the received signal to the 30-60 MHz band.
