Design Of Radar Intermediate Frequency Signal Generator

In the past, simulation method was used in the most of the radar while signal waveform generating, too many equipment needed and the accuracy is lower, only a few simple waveforms produced. Now, the technology of direct digital frequency synthesis (DDS) is used when generateing radar wave, the technique is valued day by day. Using the DDS digital method can generate various radar waveforms, and it can quickly change the radar signal waveform flexibility. This paper describes the key technology of DDS, the system of radar signal by USB and the FPGA controling the DDS chip.dual-produce a variety of radar signal. A radar signal system was designed and realized, by a DDS chip AD9858 produced by the ADI to simulate variety of radar signals.The system can simulated a variety of radar signal commonly used and arbitrary and length coding two-phase, four phase, eight phase, it can meet the requirements of high linearity, high stability, high signal to noise ratio(S/N) and low spurious.In this paper, the system design, DDS design and software design works are carried out,, including the development of firmware program, drivers program and PC control program. The final purpose of the design is to generate frequency for about 300 MHZ radar IF signal, to establish a library with multi-radar signals while the user can can easily control the radar signal parameters by computer, to provide a common simulation platform achieve which can realize diverse forms, controlable strongly, parameter variable, and arbitrary code and coding length of radar IF signal.This design is realized USB device plug and play characteristics and also solved the problem of USB cannot real-time transmission AD9858 registers parameters very well by USB and FPGA controling chip AD9858, so that means if USB transmiting the registers' parameters to AD9858 directly, the USB pin may not realize real-time transmission and then the radar signal affected.This is the innovation of this paper.