Trackingorclosein interception x

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Unformatted text preview: he higher the probability of detection x Low power means smaller and more compact radar units and less power required to operate Beamwidth Beamwidth x Target search vs. tracking or close­in interception x Early warning radar used to search wide area, wide beam pattern—accuracy is sacrificed for max detection probability x Tracking/guidance requires extreme accuracy, so radar beam has a narrow width propagated at higher frequencies x Narrowness of beam determines accuracy with which radar can measure bearing/elevation Beamwidth Vs. Accuracy Beamwidth Vs. Accuracy Beamwidth vs Accuracy Ship A Ship B Beamwidths determine the angular accuracy of the radar! Signal Reception Signal Reception Only a tiny amount of RF energy is reflected off target x Even less of that energy makes it back to receiver x x The weaker the signal that the receiver can process, the greater the effective range Signal­to­Noise Ratio Signal­to­Noise Ratio x Ability to recognize target in random noise x Noise is always present x At some range, noise is greater that target’s return Noise sets the absolute lower limit of the unit’s sensitivity x Atmospheric disturbances, stray signals x Signal­to­Noise Ratio Signal­to­Noise Ratio To cope with this problem, the operator To can set a threshold level can x If signals are below this threshold level, If they will not be displayed they x x If threshold level is set too low - you get many false detentions x If set to high - could mask out the real contact x Must compromise Receiver Bandwidth Receiver Bandwidth x x Is the frequency range the receiver can process Receiver must process many frequencies x x x Pulses are generated by summation of sine waves of various frequencies Frequency shifts occur from Doppler Effects Reducing the bandwidth x x Incr...
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This document was uploaded on 03/28/2014.

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