Scheme I: clock counting methodThe

Scheme I: clock counting methodThe signal generator involves the adjustment of the frequency, amplitude, duty cycle, phase and other parameters of the signal. In this way, different parameters of the signal can be formed by counting the system clock. After the sampling point of each signal is determined, the data is stored, and the system clock is counted. When the count value arrives, the data of the corresponding waveform is read, the waveform data is refreshed, and the count value is cleared. Such continuous cycle counting and refreshing will form the required signal.Scheme 2: DDSThe principle of direct digital frequency synthesis (DDS) is the technology of frequency synthesis based on the concept of "phase". DDS frequency synthesizer consists of five parts. These five parts are digital to analog converter, frequency register, waveform ROM, phase accumulator and filter. At the time of design, the system clock is fixed. The frequency word in the frequency register determines the output frequency. The resolution of the signal is determined by the word length of the phase accumulator [1].Scheme demonstration:In the case of the same clock frequency, the accuracy of the signal generated by the clock counting method is low and the frequency range is small, while the direct digital frequency synthesis technology has no requirements for the clock frequency, and the generated signal has a wide range, high accuracy, flexible control, high frequency resolution, many output frequency points, and continuous phase during frequency switching. Direct digital frequency synthesis DDS technology is selected according to the needs.