Improved phase generated carrier (PGC) demodulation method

A demodulation method and carrier phase technology, applied in the direction of using optical devices to transmit sensing components, etc., can solve the problems that the dynamic range and phase resolution cannot be expanded at the same time, the two algorithms cannot be run at the same time, and the phase resolution is degraded. Increase the phase resolution and dynamic range, eliminate the effect of associated amplitude modulation, and increase the dynamic range

Active Publication Date: 2015-12-16
HARBIN ENG UNIV
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Problems solved by technology

However, neither of them gave detailed instructions on how to improve the dynamic range of the demodulated signal of the PGC algorithm and the suppression of associated amplitude modulation harmonics.
The advantage of the 3×3 coupler fixed phase shift algorithm is that it makes full use of the sampling bandwidth, and all the signals within the sampling frequency are involved in the calculation, so that signals with larger amplitudes and higher frequencies can be demodulated, but what follows is coupling in More noise, degrading the phase resolution of the system
Moreover, the 3×3 coupler fixed phase shift algorithm requires the coupler to be perfectly symmetrical, and the three outputs have the same splitting ratio and a fixed phase difference of 120°. When the splitting ratio and phase difference change, the demodulation results will deteriorate.
Xie Yong et al. proposed a portable multi-functional optical fiber hydrophone signal demodulation method (CN200910100835.3), which combines the PGC demodulation method and the 3×3 fixed phase shift demodulation method into one device, but The device cannot run two algorithms at the same time, and cannot expand the dynamic range and phase resolution at the same time, and complete the suppression of harmonics

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Embodiment 1

[0073] Embodiment 1——Dynamic range extension of phase demodulation system

[0074] Interferometer devices such as figure 2 As shown, the device selection and parameters of the interferometer measurement device are as follows:

[0075] (1) The central wavelength of the light source 201 is 1550nm, the half-spectrum width is greater than 45nm, and the fiber output power is 1mW-10mW;

[0076] (2) The working wavelength of the fiber optic isolator 222 is 1550nm±5nm, the insertion loss is ≤1.0dB (at 23°C working temperature), and the return loss is ≥55dB;

[0077] (3) The first 1×2 coupler 211, the second 1×2 coupler 223, and the third 1×2 coupler 224, the operating wavelength is 1550nm&1310nm, the splitting ratio is 50.5% / 49.5%, and the insertion loss of the two channels is 3.03dB respectively , 3.12dB;

[0078] (4) The piezoelectric ceramic used to load the calibration signal has a size of 24mm, a capacitance of 22nF, and a withstand voltage range of 0-120V;

[0079] (5) The ...

Embodiment 2

[0098] Example 2 - Suppression of amplitude modulation effect associated with PGC algorithm

[0099] The device selection and parameters of the PGC algorithm-associated amplitude modulation effect suppression measurement device are as follows:

[0100] (1) The central wavelength of the light source 201 is 1550nm, the half-spectrum width is greater than 45nm, and the fiber output power is 1mW-10mW;

[0101] (2) The working wavelength of the fiber optic isolator 222 is 1550nm±5nm, the insertion loss is ≤1.0dB (at 23°C working temperature), and the return loss is ≥55dB;

[0102](3) The first 1×2 coupler 211, the second 1×2 coupler 223, and the third 1×2 coupler 224, the operating wavelength is 1550nm&1310nm, the splitting ratio is 50.5% / 49.5%, and the insertion loss of the two channels is 3.03dB respectively , 3.12dB;

[0103] (4) The piezoelectric ceramic used to load the calibration signal has a size of 24mm, a capacitance of 22nF, and a withstand voltage range of 0-120V;

...

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Abstract

The invention belongs to the field of fiber-optic interferometer measurement, and more particularly relates to an improved phase generated carrier (PGC) demodulation method. The improved phase generated carrier (PGC) demodulation method comprises the steps of using a first path of fixed phase FPS signals and a second path of FPS signals that are outputted by a 3x3 coupler at the rear end of an interferometer for FPS algorithm phase demodulation; and using a phase generated carrier algorithm for demodulating a first path of PGC signals and finally performing reasonable integration of the demodulation results of the two algorithms. The invention combines the fixed phase method based on the 3x3 coupler with the PGC algorithm, and uses the PGC algorithm for demodulating low-frequency small signals and the FPS algorithm for outputting high-frequency large signals, so as to improve the phase resolution of the system and enlarge the dynamic range while an original sampling rate is maintained, thereby finally increasing the phase resolution and dynamic range and eliminating associated amplitude modulation influence under a constant sampling rate.

Description

technical field [0001] The design of the invention belongs to the field of optical fiber interferometer measurement, and in particular relates to an improved PGC demodulation method for generating carrier phase. Background technique [0002] The interferometric optical fiber sensor uses the phase change in the optical path to measure physical quantities, including vibration, stress, displacement, speed, etc. This method has the characteristics of high sensitivity, high linearity, small size, and large dynamic range. Typical fiber optic sensor applications include fiber optic hydrophones, fiber optic seismometers, fiber optic strain gauges, etc. Optical fiber seismometers can monitor large-scale signals such as earthquakes and nuclear explosions. Zumberge et al. pointed out that its dynamic range is about 180dB1kHz; optical fiber hydrophones are mainly used to monitor underwater invisible targets and blind areas that cannot be detected by radar. Compared with the traditional...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01D5/26
Inventor 杨军侯璐彭峰苑勇贵吴冰苑立波
Owner HARBIN ENG UNIV
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