3. Store-and-forward system.
a. The satellite employed in this system may be operated as either a real-time repeater or a store-and-
forward repeater by shunting the recorder.
b. The satellite can receive and send at high speeds when it is in the most advantageous position-with
respect to the ground stations.
c. The satellite holds its messages until a suitable code signal from a ground station causes the tape
recorder to "unload" or play back.
d. This system can handle more information in less time than real-time repeaters or passive reflectors
because of the high speed of record and playback of the tape recorder in the satellite.
e. The equipment must be capable of very broadband operation because of the high speed at which the tape
recorder must record and play back.
f. This type of satellite requires highly sophisticated circuitry, and therefore is susceptible to equipment
failure more often than satellites using simpler circuitry.
4. Synchronous system.
a. The Doppler shift has been minimized because the satellite hovers above a selected point on the Earth's
surface.
b. The ground-based receiving and transmitting antennas can be maintained in a more or less fixed
position, greatly simplifying the tracking antenna mechanisms.
c. Since the satellite will be in sunlight 99 percent of the time, solar cells can provide a nearly constant
source of power.
d. Temperature control equipment is not required because the satellite spends almost all its time in
sunlight.
e. The satellite is always within range of the ground stations. This permits constant and uninterrupted
communications as long as the satellite and ground equipment are functioning.
f. A potential enemy can interfere with transmission from the satellite because he can determine its
position at all times.
g. The frequency of transmission is a fixed value and cannot be varied.
h. The number of communications channels is limited by the bandwidth characteristics of the equipment
installed in the satellite.
SS0031
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