The Software Design And Implementation Of Arbitrary Waveform Based On FPGA

With the continuous development of the times, arbitrary waveform signal generator is widely used in electronic measurement, communications, industry,agriculture, biomedicine fields, and with the continuous promotion of large-scale virtual instrument technology, arbitrary waveform generator towards to virtualization, miniaturization, intelligence, complete test function. This paper uses the technology of PCI-e and direct frequency synthesis technology(DDS) in FPGA.A system of arbitrary waveform signal based on FPGA is implemented. The system of virtual instrument is based on PCI-e bus technology and uses DDS technology to realize the arbitrary waveform. Based on traditional arbitrary waveform generator, a new method of amplitude offset adjustment is proposed and the spurious spectrum of the output waveform is analyzed. It also puts forward the method of using the same size of memory to realize the different way of waveform storage. This method improves the spurious performance of sine. The whole system can generate 7 kinds of non-modulation waveform(including the arbitrary waveform) and 5 modulation waveform. And also the system has the feature of virtualization, miniaturization,intelligence, complete test function. The main research contents as follows:Firstly, the paper analyzes the key technique of the arbitrary waveform signal system and uses DDS technology to implement the waveform generation and applies the technology of PCI-e to implement serial communication for realizing virtual instrument system. Then the paper further analyzes the advantages and disadvantages of DDS technology. According to the functional requirements of the system, the paper determines the technical proposal of the system including what kind of scheme to realize PCI-e bus communication and DDS technology.Then the design of waveform logic of the system is described in detail which includes the realization principle and structure design of various waveforms. It clarifies how to control the waveform frequency, phase, amplitude, offset, how to control the realization of modulation wave amplitude modulation index of AM,how to achieve the maximum frequency bias of FM, how to control the modulation wave and carrier of 2FSK/2PSK, and how to control the scanning time of SWEEP. A new method is proposed in the amplitude control block and it also puts forward the method of using the same size of memory to realize the different ways of waveform storage. Then it analyzes the inherent spur of the DDS and makes the MATLAB simulation on the source of stray. Eliminate the spurious method from the simulation results, and put forward the method of eliminating spurious used in this system. In the end, analyzes the causes of the waveform burr phenomenon in the part of thewaveform logic part and proposes solutions.A detailed description of the logic of PCI-e communication interface in the system is given including the PCI-e core and user logic. The structure of Rx engine,Tx engine, DMA controller, read request unit and data buffer unit is described in detail. Then testes the logic of PCI-e communication interface designed in the system and insures that the accuracy of data transmission and the requirement of PCI-e data transmission rate designed in the system. In the end, analyze the commonly encountered PCI-e transaction layer TLP packet transmission in the TLP sequence and presents the solution.Finally set up a testing platform for the whole system. The waveform,amplitude, frequency, type, the modulated wave and stability of the system are tested. The test shows that the system is stable and has practical value in engineering.