Phase test device and control method thereof

Abstract

The invention discloses a phase test device and a control method thereof, and relates to the technical field of digital signal processing. The phase test device comprises a conditioning circuit, an A / D converter, a digital signal processor, an output driver and a display circuit of the output driver, wherein an analog signal is accessed to the conditioning circuit, the conditioning circuit adjusts the amplitude of the analog signal according to a first threshold to obtain a first analog signal, the first analog signal is sampled by the A / D converter to obtain a sample sequence, the sample sequence is accessed into the digital signal processor through a parallel digital input manner, an estimated phase value of the sample sequence is obtained through processing of the digital signal processor, and the estimated phase value of the sample sequence is output and displayed by the output driver and the display circuit of the output driver. The phase test device can realize accurate estimation of instantaneous phase of the center sample point by using shorter sample data; the phase test device can realize phase estimation without frequency estimation; without frequency estimation, error of frequency estimation is avoided, the cost of hardware and the requirement on complexity are reduced, and the requirements in actual application are met.

Description

technical field [0001] The invention relates to the technical field of digital signal processing, in particular to a phase measuring device and a control method thereof. Background technique [0002] In engineering fields such as communications, instrumentation, electric power, optical applications, and fault diagnosis, there are a large number of high-precision, efficient, and fast estimation problems for the phase of signals. For example, in a communication system using QAM and PSK modulation, only by quickly estimating the initial phase of the carrier in each symbol period at the receiving end can the constellation diagram be correctly restored and correct decoding be realized [1] ; Among all kinds of instruments, the phase meter is a common one. The basic function of the phase meter is to accurately measure and calculate the phase of the signal at each moment [2] ; and in the case of grid-connected closing of the power system, it is required to accurately measure the ph...

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Problems solved by technology

It can be seen that the disadvantages of this method are: (a) a reference sine wave needs to be generated, and the frequency of the reference signal is required to be exactly the same as that of the measured sine signal. If there is a slight deviation, it will bring serious deviations to the measurement results ; (b) The pulse counting signal needs to be specially generated, and the measurement accuracy largely depends on the basic pulse width T 0 , only by reducing T 0 In order to improve the measurement accuracy, this requires high hardware equipment

[0019] However, through experiments and theory, it can be proved that various phase estimation methods based on DFT spectrum correction have the following defects: when these DFT spectrum correction methods estimate the phase, they all follow the steps of first estimating the frequency, obtaining the frequency deviation value, and then performing phase estimation. is carried out, so this will directly bring the error of the frequency estimation into the phase estimation

However, literature [21, 22] pointed out that an N-order all-phase FFT needs to consume 2N-1 input samples to obtain the instantaneous phase estimation of the center sample.

Therefore, although the all-phase FFT has high precision, it consumes a little more samples, and it is not suitable for phase measurement of short-sample low-frequency signals.

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