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Square wave vector lock-in and amplification method for increasing signal-to-noise ratios of atomic frequency scale query signals

A technology of query signal and lock-in amplification is applied in the field of cesium atomic frequency standard, which can solve the problems of inability to stabilize the cesium atomic frequency standard, low signal-to-noise ratio, and large amplitude value error, so as to avoid complicated hardware devices and improve signal-to-noise. Compared with the effect of improving the accuracy

Active Publication Date: 2015-02-18
LANZHOU INST OF PHYSICS CHINESE ACADEMY OF SPACE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The query signal is superimposed with the shot noise of the cesium ion beam, the dark current noise of the electron multiplier and the noise caused by the circuit amplification. The output amplitude error is used to regulate the voltage-controlled crystal oscillator, and when the query signal is small and the signal-to-noise ratio is not high, the amplitude value obtained by the single-chip microcomputer has a large error, which cannot stabilize the cesium atomic frequency standard well.

Method used

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  • Square wave vector lock-in and amplification method for increasing signal-to-noise ratios of atomic frequency scale query signals
  • Square wave vector lock-in and amplification method for increasing signal-to-noise ratios of atomic frequency scale query signals
  • Square wave vector lock-in and amplification method for increasing signal-to-noise ratios of atomic frequency scale query signals

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Embodiment 1: Inquiry signal quadrature vector digital lock-in amplification with square wave modulation at 2 frequency points

[0035] (1) The Ramsey transition pattern of the 2-point frequency modulated cesium atomic clock is as follows image 3 shown. Take the resonant frequency of the cesium beam tube, that is, the frequency corresponding to the central peak is f 0 , when using 2-point frequency modulation, the 2 frequency points are respectively f 0 -F p1 and f 0 +F p1 , the corresponding signal amplitude is i 1 and i 2 . Among them, F p1 is a specified frequency offset, which is determined according to the specific parameters of the cesium atomic clock, where half of the frequency width of the central peak is taken.

[0036] (2) The modulated square wave signal input to the cesium beam tube is as follows: Figure 4 As shown, the frequency at f 0 -F p1 and f 0 +F p1 switch between. Here, each frequency point is 12.9ms, each cycle is 25.8ms, and lasts...

Embodiment 2

[0043] Embodiment 2: Inquiry signal quadrature vector digital lock-in amplification with square wave modulation at 4 frequency points

[0044] (1) The Ramsey transition pattern of the 4-point frequency modulated cesium atomic clock is as follows Image 6 shown. Take the frequency corresponding to the central peak as f 0 , when the 4-point frequency modulation method is adopted, the 4 frequency points are respectively f 0 -F p2 , f 0 -F p1 , f 0 +F p1 and f 0 +F p2 , the corresponding signal amplitude is i 3 i 1 i 2 and i 4 . Among them, F p1 , F p2 is the specified frequency offset, determined according to the specific cesium atomic clock parameters, here, F p1 Take half the frequency width of the central peak, F p2 Take the central peak frequency width.

[0045] (2) The modulated square wave signal input to the cesium beam tube is as follows: Figure 7 As shown, the frequency is first at f 0 -F p2 and f 0 +F p2 Switch between, each frequency point 12.9m...

Embodiment 3

[0051] Embodiment 3: Query Signal Orthogonal Vector Digital Lock-in Amplification with Square Wave Modulation at 3 Frequency Points

[0052] (1) Use the 3-point square wave at the central peak frequency point to modulate the Ramsey transition pattern of the cesium atomic clock as follows Figure 9 shown. Take the frequency corresponding to the central peak as f 0 , then the three frequency points are f 0 -F p1 , f 0 , f 0 +F p1 , the corresponding signal amplitude is i 1 i 3 and i 2 . Among them, F p1 Take half the frequency width of the central peak.

[0053] (2) The modulated square wave signal input to the cesium beam tube is as follows: Figure 10 As shown, the frequency is first at f 0 -F p1 and f 0 Switch between, each frequency point 12.9ms, each cycle 25.8ms, last 4 cycles; then f 0 +F p1 and f 0 Switch between, each frequency point 12.9ms, each cycle 25.8ms, last 4 cycles.

[0054] (3) The corresponding cesium beam tube output query signal is as fol...

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Abstract

The invention discloses a square wave vector lock-in and amplification method for increasing signal-to-noise ratios of atomic frequency scale query signals. The square wave vector lock-in and amplification method has the advantages that frequency modulation flicker noise can be lowered, equivalent noise bandwidths can be reduced, the signal-to-noise ratios of the atomic frequency scale query signals can be increased, and accordingly the stability of cesium atomic frequency scales can be improved; the query signals are extracted from background noise by the aid of low-pass filtering links in a lock-in amplifier, so that the signal-to-noise ratios of the query signals can be increased; the amplitude of the orthogonal vector lock-in amplifier is computed, so that amplitude errors can be accurately acquired during multi-point frequency modulation, the computation precision can be improved, and the square wave vector lock-in and amplification method is favorable for improving the accuracy of output frequencies of cesium atomic clocks; the square wave vector lock-in and amplification method is implemented by the aid of a pre-amplification circuit, accordingly, current signals of the query signals can be converted into voltage signals which are favorable for the lock-in amplifier to carry out computation, and shortcomings of complicated hardware devices and inconvenience in use of pre-amplifiers in the prior art can be overcome.

Description

technical field [0001] The invention relates to the technical field of cesium atomic frequency standards, in particular to a square wave vector lock-in amplification method for improving the signal-to-noise ratio of atomic frequency standard query signals. Background technique [0002] The stability of the commercial cesium atomic frequency standard is one of its key indicators, and the stability depends on the signal-to-noise ratio of the query signal output by its physical part, that is, the cesium beam tube. Including double-beam magnetically-separated state cesium atomic frequency standard, single-beam magnetically-separated state cesium atomic frequency standard and laser cloud extraction cesium atomic frequency standard) is a very concerned issue. Foreign commercial cesium atomic frequency standards with magnetic separation are usually 1000-3000 (1Hz bandwidth). To improve the stability of commercial cesium atomic frequency standards, it is necessary to increase the am...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03L7/26
Inventor 王骥陈江成大鹏马寅光朱宏伟袁征难黄良育郑宁高玮张涤新李得天刘志栋
Owner LANZHOU INST OF PHYSICS CHINESE ACADEMY OF SPACE TECH
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