Short Data Fast Frequency Measurement And Downconversion

The continuous developments of modern radar technology and the consequent more complicated electromagnetic environment have made it crucial to design wideband, digital, multifunctional software electronic reconnaissance equipment. The digital signal processing has drawn wide attentions in the engineering area and provides an idea development mode for electronic reconnaissance system, which is different form the communication system in its wide-band processing. At present, the mismatch between the high-speed data flow of the wideband A/D converter and processing capability of the general DSP hinders the digitization of the electronic reconnaissance system most. On the other hand, the fast developments of micro-electronic technology and the wide applications of FPGA made digital circuit design more effective and afford an available method to resolve the mismatch between high-speed A/D converters and DSP chips. The emulation cuicut of full-probability digital receicer is designed with FPGA in the paper. And a fast frequency estimation method is put forward in the paper. As a result, the method has very little quantity of operation and high operation speed. I t will be helpful to the design of frequency measurement devices of digital receivers and on both suspects of theory and practice.Parallel mixer is applied in the high-efficiency DDC structure, and it solves the bottleneck in mixing. The partition of the tuning channel according to the digital mixing sequence, and the digital down-conversion by means of decimating first, the low-pass filtering and mixing realize efficiently the down-conversion of the variable carrier frequency band-pass signal.An emulation board of full-probability digital receiver is developed to realize the verification cuicut for the implementations of DDC and frequency estimation algorism with FPGA. The COM port is used to change data between the board and the PC. And this emulation board can be easily used to do verification for the implementations of digital processing.