Full-period sampling circuit and full-period sampling method in harmonic analysis

Abstract

The invention discloses a full-period sampling circuit and a full-period sampling method in harmonic analysis. The sampling method is characterized in that the sampling circuit comprises a first timer, a second timer, a first waveform shaping module, an edge detection module, a control processing module provided with a waveform lookup table, a digital-to-analog converter, a low-pass filter, a second waveform shaping module and an analog-to-digital converter module; the sampling method has the advantages that the waveform lookup table is matched with the digital-to-analog converter, an analog synthesis waveform after integer frequency multiplication is output, then a full-period sampling pulse is obtained through the simple low-pass filter and the second waveform shaping module, the analog-to-digital converter performs full-period sampling on a measured waveform according to a sampling trigger pulse to obtain a full-period sampling waveform, and the whole-period sampling process is completed; and the whole-period sampling function is accurate, and within the permissible range of the performance of the processor, the frequency of the tested analog periodic signal is changed at will, and the frequency of the synthesized waveform and the waveform of the tested analog periodic signal are still kept in a stable integral multiple relation.

Description

technical field [0001] The invention relates to a full-cycle sampling circuit and a full-cycle sampling method of an analog periodic signal, in particular to a full-cycle sampling circuit and a full-cycle sampling method in harmonic analysis. Background technique [0002] In the field of harmonic analysis technology, one of the main technical means is to perform ADC sampling on the measured waveform, convert it into a series of digital quantities, and then perform fast Fourier transform in the control processing module to obtain the measured analog periodic signal However, when fast Fourier transform technology is used for analysis, if the relationship between the number of sampling points and the frequency of the measured analog periodic signal cannot be guaranteed to be an integer multiple, spectrum leakage will occur, resulting in analysis errors. [0003] For this reason, a large number of documents and patents have introduced the whole-period sampling technology in harm...

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Problems solved by technology

[0002] In the field of harmonic analysis technology, one of the main technical means is to perform ADC sampling on the measured waveform, convert it into a series of digital quantities, and then perform fast Fourier transform in the control processing module to obtain the measured analog periodic signal However, when fast Fourier transform technology is used for analysis, if the relationship between the number of sampling points and the frequency of the measured analog periodic signal cannot be guaranteed to be an integer multiple, spectrum leakage will occur, resulting in analysis errors

[0003] For this reason, a large number of documents and patents have introduced the whole-period sampling technology in harmonic analysis. Most of them use digital phase-locked frequency multiplication technology. The signal of the measured analog periodic signal is sampled for the entire period; these documents and patents have achieved the purpose of sampling the entire period by their own means, but some of these technologies are relatively complicated to implement and require more complex implementation circuits. When performing digital frequency multiplication, the finite word length is basically used for calculation, and there is a large truncation error, resulting in insufficient frequency multiplication accuracy, and it is impossible to achieve a complete integer frequency multiplication within the entire analog signal cycle.

[0004] In order to realize the sampling of the whole cycle of the measured analog periodic signal, there is another technology, by measuring the frequency of the measured analog periodic signal or the time of one cycle, using a direct digital frequency synthesis chip to generate an integer multiple frequency signal to generate the measured analog cycle Sampling pulses with integer multiples of the signal frequency, this method requires an external dedicated direct digital frequency synthesis chip, and it is inconvenient to control the phase of the generated sampling pulses

[0005] Because synchronous sampling is relatively difficult to achieve, there are also a large number of articles that use asynchronous sampling technology to obtain sampling sequences through high-speed ADCs, and use various data processing algorithms to complete harmonic analysis in post-processing. Obviously, this type of technology requires high-speed ADC sampling, and the algorithm is complex, the requirements for the control processing module are high, and it is not easy to realize real-time analysis

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