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Radar System Engineering

Radar System Engineering

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SEC. 17.14] MZCROWA VE SYSTEM FOR POINT-TO-POINT SERVICE 725<br />

in the frequency-control circuits so that they will not stabilize against the<br />

signal frequencies.<br />

Not shown in the transmitter diagram is a monitor, consisting of a<br />

crystal mixer and a video amplifier, which draws power from the main<br />

waveguide. In combination with a synchroscope, this provides a very<br />

effective means of checking and aligning the transmitter.<br />

R~fll~<br />

wltage<br />

D-c<br />

amplifier<br />

+(<br />

Microwatie<br />

discriminator<br />

Reference<br />

cavity<br />

E<br />

Transmitter<br />

lMb<br />

directional<br />

coupler<br />

(<br />

Antenna<br />

)<br />

Mixer<br />

l-f amplifier<br />

I<br />

Automtic<br />

gain control<br />

Video<br />

amplifier<br />

FXQ. 17. 19.—Microwave<br />

Receiver<br />

equipment.<br />

Manual<br />

77gain mntrol<br />

Signals<br />

The local oscillator of the receiver is also frequency-stabilized against<br />

a cavity. The circuits and layout of the i-f amplifier and the automatic<br />

gain control are similar to those of the receiver described in Sec. 12.11,<br />

the bandwidth being 11 Me/see. A tw~stage limiter is used ahead of the<br />

i-f discriminator, care being exercised to provide sufficiently rapid limiting<br />

action to reduce impulse noise. The discriminator is similar to that used<br />

in radar AFC circuits and has a bandwidth of about 17 Me/see between<br />

peaks.

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