A high-performance digital if receiver and application in ISAR imaging

In order to obtain high range resolution and long effective detection range simultaneously, high resolution radars usually transmit super wide-band frequency-modulated signals for pulse compression. The pulse compression methods of frequency-modulated signal can be matched filter and strecth. The principle and performance of the two methods is contrasted, and the matched filter method is adopted based on software defined radio theory. General requirements for wideband digital radar receiver are analysed and a universal receiver module is designed and implemented. The receiver module mainly consists of two ADCs with 2 Gsps sampling rate and 1 Obits resolution and two Vertex5 FPGAs. These two ADCs may work as two separate channels or in interleaved mode. A common DDC structure based on poly-phase decimation filter is introduced. The requirements for digital intermediate frequency receiver of the ISAR are analysed. And the implementation parameters and design details of the DDC based on poly-phase decimation filter for super wideband LFM waveform are introduced. The simulation result proves the effectiveness of the high-performance digital receiver.