Research On Digital Techniques Of Wideband IF Receiver

Wide-band digital receiver is an important part of the new generation radar. This system has three features: firstly, the high-speed A/D converter is placed as near the RF end as possible to cover a wide range of frequency band; secondly the data rate converter is used to reduce the data rate in the following processing of the data received and keep the information of the target signals and thirdly, programmable devices, such as Digital Signal Processor (DSP), Field Programmable Gates Array (FPGA) and so on, are utilized to process the low rate signals intercepted. Its advantanges lie in its capability of processing different signals via different methods by changing the softwares on the programmable devices.The input signals can be processed real-timely by utilizing the techniques of multirate digital signal processing and partition of frequency spectrum. Under the condition of prefect reconstruction of filterbanks, a novel method of designing filterbanks is presented, which is based on the criteria of minimum variance in spectrum domain. A specific filterbank with flat passband and narrow transition band and deep stopband attenuation is designed. The influence of the channel dropping filters is discussed in detiail and the pulse compression method is derived by the multi-channel pulse compression technology.