From Radar Techniques Using Array Antennas
Overview
The fundamental problems and different aspects of the detection of moving radar targets have long been treated by many authors. We will discuss here those aspects which are especially relevant for a phased-array system.
A series of pulses is generally applied in one beam position. The reason is to provide the possibility for Doppler filtering, clutter suppression, Doppler frequency estimation of targets and eventually for target separation with different Doppler frequencies. Further, the possibility for energy management by adapting the number of pulses to the anticipated target range and cross section is also provided. The first possibility for energy management is in the choice of the pulse length with corresponding modulation, as discussed in chapter 7. Both measures may of course be combined. A special test procedure for phased arrays with a variable number of pulses for each individual test, sequential detection, will be presented and discussed in chapter 9.
For processing all received signals are stored in a memory. Then the signals are read out of this memory according to the individual range cells. For each range cell the period of the signals corresponds to the radar's pulse period T. All Doppler frequency effects of the echoes are considered generally for these signal series corresponding to individual range cells.
A major task for signal processing is the suppression of clutter echoes. We may observe different clutter types:
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Clutter echoes from large fixed targets as buildings and other man made structures. The echoes will be fairly stable in...
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