CN-116840930-B - High-speed acquisition system and acquisition method applied to laser interference fringe signals of optical absolute gravimeter

CN116840930BCN 116840930 BCN116840930 BCN 116840930BCN-116840930-B

Abstract

The invention discloses a high-speed acquisition system and a high-speed acquisition method applied to laser interference fringe signals of an optical absolute gravimeter, the system comprises an analog signal conditioning unit, an analog-digital conversion unit, a system core control unit, a data caching unit, a data transmission unit and a measurement and control terminal processing display unit. Aiming at the characteristics of high frequency, low voltage amplitude, high acquisition rate, high signal integrity required by absolute gravity precision measurement, high measurement precision and the like of laser interference fringe signals, the invention designs an optical free falling absolute gravimeter laser interference fringe signal high-speed acquisition system realized based on an FPGA, fully utilizes the advantages of FPGA parallel computing processing, and greatly shortens the processing time of the acquisition system in the aspects of interference fringe signal acquisition, storage, transmission and the like by combining a serial bus transmission technology (USB) and a FIFO buffer technology. The invention effectively improves the acquisition speed of absolute gravity and provides a basic guarantee for realizing dynamic measurement and monitoring of absolute gravity.

Inventors

HU RUO
WANG QIYU
FENG JINYANG
LI CHUNJIAN
WU SHUQING
ZHANG HUASHUAI
YAO JIAMIN

Assignees

中国计量科学研究院

Dates

Publication Date: 20260505
Application Date: 20230705

Claims (7)

1. The high-speed acquisition method applied to the laser interference fringe signals of the optical absolute gravimeter is realized by a high-speed acquisition system, and is characterized in that the high-speed acquisition system comprises the following components: the analog signal conditioning unit converts an optical signal generated by laser interference into an electric signal, performs filtering treatment, removes linear drift and suppresses part of high-frequency interference noise, and amplifies an original small signal to be within the range of the analog-digital converter; An analog-to-digital conversion unit converting the continuous analog signal into a discrete digital signal; An external clock unit outputting a sine wave signal, providing a stable external clock and a time reference; The system core control unit is used for collecting, storing and transmitting the laser interference fringe signals and controlling the laser interference fringe signals; The power supply conversion power supply unit maintains the normal operation of the acquisition system; The data transmission unit is used for transmitting the data which is calculated and processed by the microprocessor to the measurement and control terminal for display; The measurement and control terminal processes the display unit, the discretized interference fringe information processed by the front-end data acquisition is continuous and presented on the display; the high-speed acquisition method comprises the following steps: s1, setting the number of buffer memory packets and the byte number of single buffer memory packets, and setting a receiving threshold value; s2, judging whether the USB3.0 acquisition equipment is accessed to the measurement and control terminal, if so, executing S3, and if not, popping up a dialog box to remind that no equipment is accessed; s3, the USB3.0 acquisition equipment which is successfully connected is prepared for communication, if the connection is successful, S4 is executed, if the connection is unsuccessful, a popup dialog box prompts reconnection and reports related errors; S4, starting a receiving thread, creating byte arrays with the same number as the number of the buffer memory packets set in S1, wherein the array length is the same as the number of the single buffer memory packets set in S1, and storing all the byte arrays in a List < byte [ ] > array; S5, reading the acquisition information of the USB3.0 acquisition equipment through infinite loop, and sequentially receiving the acquisition information according to the sequence of byte arrays in the List < byte [ ]; S6, circularly traversing the List < byte [ ] > array, detecting whether all pre-received data in S5 have a start symbol or not through a Indexof () method of the array, executing S7 if a certain byte array exists, and repeatedly executing S5 if the byte array does not exist; S7, receiving the byte array of which the beginning symbol is detected in S6 and all arrays after the byte array, detecting whether an ending symbol exists in the currently received array through a Indexof () method of the array, executing S10 if the ending symbol exists, and repeatedly executing S8 if the ending symbol does not exist; S8, resetting the byte array received in the S7, and resubmitting the reset byte array to the List < byte [ ] > array in the S5 for receiving data; S9, finishing the reading of the acquired information, and storing all the read data into a local text document; S10, finishing the reading of the acquired information, storing the acquired information into a task queue of a local text document task, deleting invalid data before a start symbol and after an end symbol of the acquired data in a multithreading mode, storing the invalid data into the local text document, and removing the task queue; s11, generating a signal diagram for the data processed in the S10, resetting all arrays for storing the received data, and then starting to execute the S4 until the acquisition is manually finished.
2. The method of claim 1, wherein the analog signal conditioning unit comprises a THS3091 operational amplifier.
3. The method of claim 1, wherein the analog-to-digital conversion unit comprises an AD9248 analog-to-digital conversion chip and peripheral circuits thereof.
4. The high-speed acquisition method as set forth in claim 1, wherein the system core control unit is an XC7K160T series FPGA micro-control processor supporting USB3.0 transmission protocol with built-in FIFO logic.
5. The high-speed acquisition method of claim 1, wherein the data transmission unit comprises an FT601 chip for bridging between USB3.0 and the FIFO, and the USB3.0 micro-B interface is used for connecting and communicating with the measurement and control terminal.
6. The method of claim 1, wherein the measurement and control terminal processing display unit reads USB3.0 acquisition equipment information, stores data in a local document, and adopts a multithread cooperation mode to respectively process valid and invalid data and generate interference fringe signal waveforms on a measurement and control terminal display interface.
7. The method of claim 1, wherein in step S7, if the received data amount reaches the threshold set in S1 and no end symbol is detected, S9 is performed.

Description

High-speed acquisition system and acquisition method applied to laser interference fringe signals of optical absolute gravimeter Technical Field The invention belongs to the technical field of absolute gravity rapid measurement research, and particularly relates to a high-speed acquisition system and a high-speed acquisition method applied to an optical absolute gravimeter laser interference fringe signal. Background The gravity acceleration value is a variable parameter, and the gravity acceleration on the earth surface is continuously changed along with the altitude, longitude and latitude, tide, polar motion, air pressure and other factors. The gravity acceleration has important significance in the fields of metering, aerospace, geophysics, auxiliary navigation, resource exploration and the like. The optical absolute gravimeter is characterized by that it adopts classical free falling mode and uses laser wavelength as reference of measuring length, and the top of vacuum cavity is equipped with a falling body of pyramid prism, so that it can be freely fallen in the cavity, after the light beam emitted by laser device is reached to light splitting environment, one path of reference light can be passed through spectroscope, and another path of reference light can be used as measuring light, and can be vertically upwards formed into interference. The interference signal is converted into an electrical signal by a photodetector. And combining rubidium atomic clock signals with high-precision time frequency through a data acquisition system to obtain interference fringe signals falling freely, and performing secondary fitting on a time-displacement sequence pair with the interference signal amplitude of zero by adopting a double-sample zero-crossing sampling method to obtain the gravity acceleration value of the measured point. With the objective demands of technological advancement and scientific experiments, the demands of the field of gravity application for the field of mobile gravity observation and the deep sea ocean absolute gravity rapid dynamic measurement are increasing, and the demands of the field mobile gravity observation are not met by the static measurement of absolute gravity under the static base state of a laboratory. Compared with the absolute gravity measurement under the static base state of a laboratory, the system has the advantages that under the working conditions of field flow and deep sea ocean dynamic absolute gravity measurement, higher requirements and standards are provided for a data acquisition system, so that the acquisition system is required to be small enough in mass and volume, the system is beneficial to carrying, the signal acquisition and processing speed is high, meanwhile, adverse environmental factors of field complex changes are overcome, the requirement of long-term field rapid dynamic measurement is met, and the problems that the traditional static measurement absolute gravity data acquisition system is difficult to carry due to data packet loss, measurement and control terminal jamming, large volume mass and the like under the rapid measurement condition can be solved. Disclosure of Invention Aiming at the problems, the invention aims to provide a high-speed acquisition system and a high-speed acquisition method for laser interference fringe signals of an optical absolute gravimeter, which are based on an FPGA micro-processing controller, so that the advantages of parallel processing calculation are fully exerted, the overall running speed of the system and the integrity and accuracy of signal acquisition are improved, and the effects of high-speed signal acquisition and stable data transmission are achieved. In order to achieve the purpose, the technical scheme adopted by the invention is as follows, and the high-speed acquisition system applied to the laser interference fringe signal of the optical absolute gravimeter is characterized by comprising the following components: The analog signal conditioning unit comprises a THS3091 operational amplifier, converts an optical signal generated by laser interference into an electric signal, performs filtering treatment, removes linear drift and suppresses part of high-frequency interference noise, and amplifies an original small signal to be within the range of the analog-digital converter; The analog-digital conversion unit comprises an AD9248 analog-digital conversion chip and a peripheral circuit thereof, and converts continuous analog signals into discrete digital signals; An external clock unit outputting a sine wave signal, providing a stable external clock and a time reference; The system core control unit comprises an XC7K160T series FPGA micro-control processor, supports a USB3.0 transmission protocol, embeds FIFO logic, and performs processing and control of acquisition, storage and transmission of laser interference fringe signals; The power supply conversion power supply unit maintains the normal operatio