Figure 2-10.—Basic microwave relay system.
and a receiving terminal. Figure 2-10A shows you such
a system. A duplex relay system (figure 2-10B)
provides two-way communications by using two
simplex systems, one transmitting in one direction
and the other transmitting in the opposite direction.
The duplex system is further refined by using a
single antenna for transmitting and receiving. This is
done by using different transmitting and receiving
frequencies and by using a duplexer in the
transmission line.
The rf equipment in terminal and repeater stations
are basically the same. Terminal equipment can be
converted to repeater equipment and vise versa. Let’s
take a look at a typical microwave transmitter and
receiver.
MICROWAVE TRANSMITTER
A typical microwave transmitters shown in figure
2-11. In operation, the output of a telephone multiplex
terminal, which consists of a frequency multiplexed
AM carrier signal, is applied to the terminal
transmitter. This input signal (baseband signal) also
could be a television signal or any other form of signal
to be transmitted. A pre-emphasis network accentuates
the high frequencies, relative to the low, to improve the
2-10
