2.
If the intensities of the various noises are recorded at a strategic microwave terminal for a period of 1
year, there will be seasonal variations in noise intensities. The most significant intensity changes will be
in the solar noise and the
a.
thermal noise.
c.
terrestrial noise.
b.
manmade noise.
d.
atmospheric noise.
3.
Fluctuations in the strength of the incoming signal make reception of the desired signal difficult. These
fluctuations can be caused by
a.
solar radiation.
b.
atmospheric noises.
c.
disturbances in the propagating medium.
d.
electrons giving up energy as they revert to a power energy state.
4.
Reception of weak signals becomes difficult when propagation conditions cause fading of the incoming
signal. The effect of fading is a function of the ratio
a.
C
c.
C+N
N
N
b.
S
d.
S+N
N
N
5.
All electronic receivers have some degree of internal interference.
One of the causes of internal
interference is the
a.
inconsistencies of the magnetic field strength surrounding the equipment.
b.
small voltages generated by electrons moving within the components of the receiver.
c.
dust or smoke particles which reduce the amount of energy that can be picked up by the antenna.
d.
bombardment of the antenna by particles created by the thermonuclear reactions on the sun.
6.
The noise power developed across a resistive device establishes a noise threshold level. Incoming signals
must exceed this noise threshold, or the resistive device cannot produce a useful output. The noise power
developed across the resistive device is caused by
a.
variations in the system's bandwidth.
b.
amount of opposition offered by the device.
344 L4
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