Broadband Digital T / R Modules In Digital Conversion And Digital Delay The Realization Of The Study

The Wideband Digital Array Radar (WDAR) is a fully digitized array antenna radar where the wideband signal waveform is transmitted and the digital beamforming (DBF) technology is used in receiving and transmitting , which is the tendency of the development of phased array radar.With the development of high-speedy sampling technology and the rapid digital signal processor, it is possible that wideband radar signal can be treated in fully-digital. The wideband digital T / R components of wideband digital array radar is a very important element.Compared with the conventional narrowband phased array radar, the true time delay is applied in the wideband digital array to replace the phase shift. Because traditional beamforming approach will lead to inaccurate beam direction and the main lobe broadening.First of all, the dissertation introduces the bandpass sampling theorem, multi-rate sampling, polyphase filtering and the principle of digital IF technology model, then introduced two special ways of filter realization.After researching the digtal T/R module technology over the world, the dissertation present a solution of wideband digital T/R module, and its work principle are introduced. Then, the selection of the main devices are introduced.Then, this dissertation discussed Matlab simulation and FPGA implementation of the wideband digital down conversion and the narrowband digital down-conversion. Narrowband digital down-conversion architecture uses the traditional NCO, mixing, extraction. Wideband Digital Down Conversion Based on Polyhase Filtering is of high performance and great saving of resources. And proven, digital down-conversion structure is correct. Then introduces the theory of digital delay, three digital delay design methos are described, finally choose the fractional delay filter to accomplish digital delay compared three different methods to achieve fractional delay filters, Completing system debugging and the test in the existing hardware platform of the digital T/R module, the test result indicated these modules can work and satisfies needs the technical specification request.