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Radar System Engineering

Radar System Engineering

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SEL 57] ttANGE-JfEAS[’RING DOPPLER SYSTE.%f 141<br />

taken this beat will completely<br />

dominate the target signals.<br />

Since the sense of this inequality<br />

is an important factor in<br />

all the systems to be described<br />

from here on, this section closes<br />

with a few further remarks concerning<br />

it.<br />

The doppler frequency is, by<br />

Eq. (l), dependent only on tho<br />

wavelength and the radial velocit].<br />

Values as a function of wavelength<br />

and for various speeds are given<br />

in the curves of Fig. 5.9.<br />

The modulation frequency is<br />

ordinarily made as large as pos-<br />

distance to a single target, only one additional sideband is needed.<br />

,Second, the presence of the doppler shift, applying as it does to both sidebands,<br />

does not interfere Nihh distance measurement. Third, the two<br />

receivers are separate and their bandwidths are determined by the<br />

doppler frequency, not by the modulation or repetition frequency.<br />

Fourth, we now have two design frequencies, f~ and j,, and it is a matter<br />

of great importance which is the greater. If .f~

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