Principles of Modern Radar - Volume 2 1891121537

11.2 Colored Space-Time Exploration 503θθθθθθ(a) (b) (c)θθθFIGURE 11-3Successivediagrams(a) Frequency coding(b) Fast angularscanning (c) Pseudorandom orthogonaldiagrams.P channelsreceptionMatchedfilterFor each transmitter,P receiving channelsFor each illuminateddirection, P receivingchannelsFor each illuminateddirection, Pdirections on receiveDelay DelayDelayFIGURE 11-41 subpulse 1 subpulse1 subpulseW (Separation of individual transmitters)y 1 y 2 y 3 y N-1 y NA (Beamforming on Transmit)z 1z 2z 3z N-1z NT Sub-pulsex 1x 2 x 3 x MDBFReceiveDBFReceiveDBFReceiveDBFReceiveDBFReceiveT/R Imaging(P Channels Reception, N Channels Transmission)Optimum receptionof colored signals.The optimum processing then basically consists in the operations described in Figure 11-4(essentially a coherent summation of the received samples, for each angle – Doppler –range hypothesis):• Transverse filtering, for separating the signals received from the different transmitters;For instance, if the transmitted signals are different frequencies, this is just a bank offilters separating the different frequencies; the y n signals correspond to each transmittern, for all the P receiving channels;• Digital Beamforming on transmit (basically Fourier transform), coherently summingthe transmitted signals, for each receiving antenna (i.e. each receiving channel); the z nsignals correspond to each direction n, for all the P receiving channels;• Digital Beamforming on receive, for each direction on transmit (again basically Fouriertransform);Basically, there are then two beamforming algorithms which are used, 3 one on transmitand one on receive – but not all the directions have to be examined, since for eachtransmitting direction only one receiving direction should be examined, in general.3 Excepted for intra-pulse scanning, as shown in the example below