13. The signal-to-noise ratio limits the maximum sensitivity of a radio receiver.
The signal-to-noise ratio is a number that represents the ratio of the input signal
to the
a. external noise created by atmospherics.
b. shot-effect noise created by electron tubes.
c. internal noise caused by thermal agitation of components.
d. total noise that appears with the signal in the useful frequency band.
14. On the front panel of most communication radio receivers are found controls
for tuning, output volume, sensitivity, and bandwidth.
The control that is most
effective in improving the signal-to-noise ratio is the control that adjusts
a. tuning.
c. sensitivity.
b. bandwidth.
d. output volume.
15. Interference between receivers located in the same area becomes a possibility
if the local oscillator signals of the receivers are radiated by the antennas.
This interference can best be suppressed by
a. using RF amplifier stages.
b. neutralizing the RF amplifier circuits.
c. shielding the oscillator circuits and leads.
d. using an efficient antenna-coupling device to reduce signal loss.
CHECK YOUR ANSWERS WITH LESSON SOLUTIONS ON PAGE 49.
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