MICROWAVE TRANSMITTER
The block diagram shows the equipment of a microwave transmitter station on earth.
The signal to be transmitter must be at uplink frequency. The converter multiply the signal frequency to uplink frequency after it is encoded and modulated properly.
After upconverting the frequency, it is applied to power dividers. The output of power divider goes to high power amplifier. Normally travelling wave tube amplifiers or multicavity klystron amplifiers are used. These tubes require good amount of cooling.
Here the modulation is performed at 70 MHz intermediate frequency and is then upconverted to a uplink frequency of 6 GHz. The output of several high power amplifiers are combined in a power combining amplifier and the output then passes through band pass filter and circulators. Frequency stability and power control are necessary to avoid interferences. The manufacturing is high and it increases as transmitted power increases.
MICROWAVE RECEIVER
The first stage of the terminal station receiver is the front end converter which is usually a double converter to convert the down link frequency signal of the order of GHz into an intermediate frequency of 70 MHz.
Now this intermediate frequency signal is first passed through a chain of bandpass filters and amplifier combinations to improve signal strength. Thus the IF signal is demodulated to get the original baseband signal. The FM used here is a phase-locked loop (PLL) type of FM demodulator.
Now the signal is amplified after it is given to de-emphasis network. A 5.5 MHz sound trap is provided in the circuit to get the sound IF. Now this sound IF is given to FM detector to get the original audio signal.
The block diagram shows the equipment of a microwave transmitter station on earth.
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| Block Diagram of Microwave Transmitter |
After upconverting the frequency, it is applied to power dividers. The output of power divider goes to high power amplifier. Normally travelling wave tube amplifiers or multicavity klystron amplifiers are used. These tubes require good amount of cooling.
Here the modulation is performed at 70 MHz intermediate frequency and is then upconverted to a uplink frequency of 6 GHz. The output of several high power amplifiers are combined in a power combining amplifier and the output then passes through band pass filter and circulators. Frequency stability and power control are necessary to avoid interferences. The manufacturing is high and it increases as transmitted power increases.
MICROWAVE RECEIVER
 |
| Block Diagram of Microwave Receiver |
Now this intermediate frequency signal is first passed through a chain of bandpass filters and amplifier combinations to improve signal strength. Thus the IF signal is demodulated to get the original baseband signal. The FM used here is a phase-locked loop (PLL) type of FM demodulator.
Now the signal is amplified after it is given to de-emphasis network. A 5.5 MHz sound trap is provided in the circuit to get the sound IF. Now this sound IF is given to FM detector to get the original audio signal.