Compression of polyphase codes with Doppler shift

Future electronic steerable multifunction radars will be realized with active array antennas applying individual transmit/receive modules for each antenna element. These modules will be finally realized cost effectively with MMIC devices. The peak power of transistor amplifiers is at maximum twice the mean power. Therefore to utilize the available mean power the transmit pulses have to be as long as possible, dependent on the specific radar task, e.g. search for sew targets, acquisition or tracking detected targets at various ranges. For special radar concepts even a CW signal is transmitted. For these applications modulation with a phase code has to be applied to achieve the necessary range resolution in combination with pulse compression on the receiving side. The length of the subpulse determines the range resolution. Within the experimental phased array radar system ELRA an active array antenna is operated. The length of the subpulse may be 2 or 10 μs. With a selectable codelength of 1, 16, 64, 128 or 256 a high variability for signal modulation results