Digital measurement method for alternating-current frequency
A measurement method and alternating current technology, applied in frequency measurement devices and other directions, can solve the problems of inaccurate measurement accuracy of AC signal frequency and large amount of calculation, and achieve the effect of clear physical concept, small amount of calculation, and improved anti-interference ability.
Inactive Publication Date: 2012-12-05
NANJING UNIV OF POSTS & TELECOMM
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[0005] The technical problem to be solved by the present invention is to propose a digital measurement method for AC frequency, which can also be used for fixed Frequency measurement of low-frequency sinusoidal signals with little or no frequency variation
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[0027] Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:
[0028] The essence of the present invention is to select a sampling point P1 after the signal crosses the positive and negative peak values for continuous digital sampling signals, and select two consecutive points P2 and P3 in the subsequent sampling points. The selection conditions of P2 and P3 are: P1 The negative value of the sampled value is in the interval [P2 sampled value, P3 sampled value]. Then, a point P4 can be calculated on the line segment composed of P2 and P3 by interpolation method, so that the value of P4 is equal to the negative value of the sampling value of P1, and the virtual occurrence time of point P4 can be obtained at the same time. The zero point of the electrical signal is calculated from the sampling occurrence time of P1 and the virtual occurrence time of point P4, and the frequency or period of the electrical signal...
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The invention discloses a digital measurement method for an alternating-current frequency. According to the digital measurement method, aiming at continuous digital sampling signals, a sampling point P1 is selected after the signals passing through a positive peak and a negative peak; two continuous points P2 and P3 are selected from subsequent sampling points; the selection condition of the P2 and P3 is that the negative value of the sampling value P1 is within the interval [sampling value P2, sampling value P3]; a point P4 is solved on a line segment formed by the P2 and P3 by an interpolation method, so that the numerical value of the P4 is equal to the negative value of the sampling value P1; simultaneously, the virtual occurrence time of the P4 can be acquired; the zero point of an electric signal is calculated by the sampling occurrence time P1 and the virtual occurrence time of the P4; and the frequency or the period of the electric signal is calculated by zero-crossing points of a series of electric signals. A low-frequency signal is not required to be converted into square wave, so that the method is particularly suitable for the frequency measurement of low-frequency sinusoidal signals, the system detection is convenient, the hardware overhead is low, the anti-interference capacity of the system is high, the method is implemented easily and reasonably, and the data are accurate and reliable.
Description
technical field [0001] The invention relates to a digital measurement method for alternating current frequency, which can also be used for frequency measurement of low-frequency sinusoidal signals, triangular wave signals, etc. with fixed frequency or little frequency change. Background technique [0002] In daily life and production process, it is often necessary to monitor the frequency of the signal. The more accurate the measured frequency, the better the application effect. In the existing frequency measurement methods for low-frequency signals, the low-frequency signal is first formed into a square wave by a shaping circuit, and the time interval T between two adjacent rising or falling edges of the square wave is detected, and the frequency is obtained by calculating the reciprocal. In addition, there are some methods for measuring frequency by software, such as: zero-crossing method, analytical method, error minimization principle algorithm, DFT algorithm, quadrature...
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Inventor 戴尔晗
Owner NANJING UNIV OF POSTS & TELECOMM