Research On The Double Channel Broadband Waveform Generator

In modern electronic warfare environment, radar is faced with many threats, therefore, radar is required for anti-interference and strong survival ability. Radar waveform generator should have the ability to produce the waveform that is highly stable, wide band, frequency agility, and has the output capacity of arbitrary waveform. And in some case, the double channel even multi-channel output signal is needed, it requires that these output signals can adjust their parameters and has the channel consistency. With the rapid development of modern digital technology, direct digital synthesis(DDS) technology has been widely used. Digitally generated waveform has the advantages of strict coherence, high stability, high frequency resolution, and programmable, etc. Therefore, the research on the double channel broadband waveform generator which is based on digital technology has an important significance.Based on the further study of the working principle of DDS and intermediate frequency chirp signal generation method, a scheme of multichannel parallel waveform generation is designed in this thesis, on the basis of DDWS structure of digital baseband and digital orthogonal modulation. According to this scheme, FPGA implementation of the double channel broadband waveform generator is completed. Finally, the system level simulation of output signal waveform is completed.The main work of this thesis includes:(1) Some basic theoretical knowledge of radar signal processing are introduced, including the signal detection theory, the matched filtering theory and the theory of pulse compression(2) The working principle of DDS is analyzed. The generation methods of intermediate frequency chirp signal based on the structure of DDWS is respectively introduced.(3) The polyphase structure design of interpolation filter and the control method of numerical control oscillator(NCO) are analyzed. A scheme of multichannel parallel waveform generation which is based on DDWS structure of digital baseband and digital orthogonal modulation is proposed.(4) According to the waveform scheme, FPGA implementation of the double channel broadband waveform generator is completed. The key internal modules in FPGA are analyzed and designed, and the system level simulation has been completed.