Method for calibrating local clock through utilization of short wave time service signal

Abstract

The invention discloses a method for calibrating a local clock through utilization of a short wave time service signal and mainly solves the problem that in the prior art, the hardware complexity is high and the anti-noise performance is low. The method comprises the realization steps of 1), sampling received signals, then transmitting the signals to a DSP chip and multiplying the signals by corresponding points of a local sequence; 2), carrying out Fourier transform on the processed signals, thereby obtaining quasi-signal-to-noise ratios; 3), superposing quasi-signal-to-noise ratios of corresponding positions; 4), calculating a starting point position of the signals through the position of the maximum superposed quasi-signal-to-noise ratio; 5), getting the point from the starting point position of the signals, carrying out segmentation related Fourier transform, thereby determining the length of the received signals; and 6), determining specific time according to the length of the signals and a broadcast time table of the signals and calibrating the local clock. According to the method, a Fourier transform algorithm is utilized, complex filtering does not need to be carried out on the signals, the hardware complexity is greatly reduced, the relatively high anti-noise performance is achieved, and the method can be applied to time synchronization of various radio stations when links are synchronously established among short wave radio stations.

Description

technical field [0001] The invention belongs to the technical field of short-wave communication, and particularly relates to a method for calibrating a local clock by using short-wave time service, which can be used for time synchronization of various stations when short-wave stations are synchronously establishing links. Background technique [0002] Shortwave timing is a method of time calibration using shortwave radio signals with an accuracy of 1ms. The time signal broadcast by the radio station is reflected one or more times by the ionosphere and transmitted to the user; the user then uses the radio receiver to receive the time signal, and then performs local time correction. Users must also consider factors such as location, frequency and season when receiving signals. The short-wave time signal mainly relies on the sky-wave signal reflected by the ionosphere to serve the majority of users. The advantages of short-wave timing service are wide coverage, relatively sim...

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Problems solved by technology

[0012] At present, special shortwave timing signal receivers are used for time correction. For example, Chen Yongqi, Xing Yan, and Chen Yingming proposed "Design and Implementation of BPM Shortwave Timing Receiver" in "Journal of Time and Frequency" in February 2016. This method uses When it comes to various devices such as band-pass filter, synchronous controller, 5MHz isolation amplifier, phase-shift control register and 1PPS isolation amplifier, the structure of the short-wave timing receiver realized by it is complex, and the equipment cost is relatively high

Another example is "A Method for Extracting Time Information from BPM Signals" proposed by Li Yueqiao, Tan Diqian, and Yang Qixun in "Modern Electric Power" in January 1995. This method mainly uses cross-correlation algorithm to extract time signals, and its anti-noise performance is poor , when the noise is large, the signal is submerged and accurate time information cannot be extracted

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