6. The IF stage in a radio receiver performs some important functions.
One
purpose of this stage is to
a. amplify the fixed-tuned signal before demodulation.
b. remove audio modulation and filter out the RF carrier.
c. combine the input signal with the output of the local oscillator.
d. convert
electrical
audio-frequency
variations
into
corresponding
sound
waves.
7. Tuned LC circuits are commonly used in radio receivers to provide signal
a. amplification
c. detection.
b. modulation.
d. selection.
8. What characteristic of a radio receiver gives the receiver the ability to
reject all frequencies except the desired frequency?
a. Fidelity
c. Sensitivity
b. Stability
d. Selectivity
9. Assume that the carrier frequency of a transmitter is 970 kHz and the highest
modulating frequency is 5 kHz.
What band of frequencies must be passed by the
tuned circuits in the RF amplifiers in the receiver?
a. 970 to 975 kHz
c. 965 to 975 kHz
b. 960 to 980 kHz
d. 967.5 to 972.5 kHz
10. The receiver characteristic which is measured by the minimum signal input
voltage that will provide a standard signal output power is the
a. fidelity.
c. sensitivity.
b. stability.
d. selectivity.
11. Static noise in a radio receiver is commonly caused by
a. electric motors.
b. diathermy machines.
c. atmospheric disturbances.
d. spark plugs in auto engines.
12. Most noises introduced into a receiver from an external source have the form
of transient disturbances. These disturbances are called
a. hum.
c. shot effects.
b. impulses.
d. thermal agitation.
322 L1
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