CN-117311128-B - GNSS and TDC-GPX 2-based high-precision time interval measuring instrument

CN117311128BCN 117311128 BCN117311128 BCN 117311128BCN-117311128-B

Abstract

The invention discloses a high-precision time interval measuring instrument based on GNSS and TDC-GPX2, which comprises a constant-temperature crystal oscillator, a level conversion module, a clock buffer module, a GNSS receiver module, a time interval measuring module, a main control module and a digital-to-analog conversion module. According to the invention, a taman variance-based outlier algorithm module is designed to improve stability in the taming process by combining a taman constant temperature crystal oscillator taming technology by adopting a 1PPS signal output by a GNSS receiver, reasonable filtering parameters can be obtained according to a Kalman filtering state equation of the established constant temperature crystal oscillator output frequency, so that the Kalman filtering algorithm module can effectively reduce measurement errors caused by 1PPS signal jitter, the constant temperature crystal oscillator can output a high-precision clock signal under long-term taming, and a time interval measuring module takes the high-precision frequency signal output by the constant temperature crystal oscillator as a reference clock signal, thereby improving measurement precision.

Inventors

YANG YEQUAN
ZHANG HAO
FENG WENJIE

Assignees

三峡大学

Dates

Publication Date: 20260512
Application Date: 20231018

Claims (7)

1. High-precision time interval measuring instrument based on GNSS and TDC-GPX2, characterized in that it comprises: The constant-temperature crystal oscillator is used for outputting a 10MHz square wave CMOS level signal; The level conversion module is used for receiving the 10MHz square wave CMOS level signal and converting the 10MHz square wave CMOS level signal into a 10MHz square wave LVCMOS level signal; The clock buffer module is used for buffering the 10MHz signal output by the level conversion module and dividing the 10MHz signal into multiple paths of outputs; the GNSS receiver module is used for outputting 1PPS signals and NMEA-0183 data format message information; The time interval measuring module is used for measuring 1PPS output by the GNSS receiver module and a physical event to be measured by taking the 10MHz signal output by the clock buffer module as a reference clock; The main control module is used for receiving and extracting message information of the GNSS receiver module, processing peripheral interrupt signals of the time interval measurement module, receiving and processing measurement result data of the time interval measurement module, and outputting a constant-temperature crystal oscillator regulation signal; The digital-to-analog conversion module is used for converting the regulation and control signal output by the main control module into voltage and outputting the voltage to the constant-temperature crystal oscillator voltage control end.
2. The high-precision time interval measuring instrument based on GNSS and TDC-GPX2 according to claim 1, wherein the clock buffer module is CDCLVC clock buffer, 4 paths of 10MHz signal output are split, pins Y0 and Y1 are electrically connected with an SMA interface for external output, and pin Y2 is electrically connected with the time interval measuring module for providing a reference clock.
3. The GNSS and TDC-GPX2 based high precision time interval measurement instrument according to claim 1, wherein the time interval measurement module is a TDC-GPX2 time digital chip, comprising 4 channels: the measurement channel 1 is electrically connected with the GNSS receiver module and used for inputting 1PPS signal measurement; the measuring channels 2 to 4 are electrically connected to SMA2, SMA3, SMA4 interfaces, respectively, for user measurements.
4. The high-precision time interval measuring instrument based on GNSS and TDC-GPX2 as set forth in claim 3, wherein the TDC-GPX2 time digital chip buffers the measured coarse count and fine count result data into an internal FIFO each time the measurement is completed, and then generates an interrupt signal, wherein the interrupt signal is electrically connected with the main control module to prompt the main control module to receive the data.
5. The high-precision time interval measuring instrument based on GNSS and TDC-GPX2 according to claim 1, wherein the main control module is an STM32F407ZGT6 single chip, and 4 modules of calculation time, outlier rejection, kalman filtering and PID control are integrated.
6. The high-precision time interval measuring instrument based on GNSS and TDC-GPX2 according to claim 5, wherein the STM32F407ZGT6 single chip is further integrated with USART, I2C and SPI hardware peripherals, and an LCD12864 liquid crystal screen is externally connected.
7. The high precision time interval measurement instrument based on GNSS and TDC-GPX2 according to claim 1, wherein its operating modes include two modes, a discipline mode and a hold mode: 1) The method comprises the steps of obtaining the number of satellites currently received by analyzing message information output by a GNSS receiver module, enabling 1PPS output by the GNSS receiver module to be high and stable when the number of satellites received reaches the requirement, and entering a discipline mode, wherein the software process in the discipline mode is that a main control module receives a measurement result of a time interval measurement module, calculates time data, eliminates a time data wild value and carries out Kalman filtering treatment, calculates the time data into frequency data, obtains the nominal frequency deviation value of the current frequency and a constant-temperature crystal oscillator, and finally calculates the current control value by a PID controller; 2) When the number of the received satellites does not meet the requirement, the 1PPS signal at the moment has low precision and large error, a holding mode is started, and in the holding mode, the central voltage of the constant-temperature crystal oscillator is output to control the constant-temperature crystal oscillator.

Description

GNSS and TDC-GPX 2-based high-precision time interval measuring instrument Technical Field The invention belongs to the technical field of time-frequency measurement, and particularly relates to a high-precision time interval measuring instrument based on GNSS and TDC-GPX 2. Background Time is one of the most basic physical quantities, which supports the operation of the whole economy and society. The time interval measurement is widely applied to the fields of space science, laser ranging, time-frequency transmission, medical treatment and the like. The time interval measuring instruments commonly used in the market at present are SR620, 53230A, YN5636 and the like, which have high precision but high price, and can achieve high-precision measurement by matching with additional frequency references. The TDC-GPX2 is a special time-to-digital chip, and has low cost and high precision. At present, in the case of a time interval measuring instrument designed based on TDC-GPX2, most of the time interval measuring instrument uses a common crystal oscillator as a reference clock, so that the clock jitter is large, the measuring precision is influenced, the common crystal oscillator is easy to age, and the precision is continuously reduced along with long-time use. Based on the current situation, in order to optimize the prior art, the invention combines the tame constant temperature crystal oscillator technology, and designs a multichannel, simple, low-cost and high-precision time interval measuring instrument integrated with a high-precision reference clock source. Disclosure of Invention Aiming at the problems that the existing high-precision time interval measuring instrument is high in price and needs to be matched with an additional frequency reference for use, and the measurement precision cannot be guaranteed due to the fact that a TDC-GPX2 design scheme based on a common crystal oscillator is selected as a reference clock, the invention provides the high-precision time interval measuring instrument based on GNSS and TDC-GPX2, and the 1PPS output by a GNSS receiver is utilized to discipline a local constant-temperature crystal oscillator, so that the output frequency of the constant-temperature crystal oscillator is locked, the accuracy and the stability of the output frequency of the constant-temperature crystal oscillator are improved, and therefore a high-precision reference signal can be provided for a time interval measuring module, and the measurement precision is improved. In order to solve the technical problems, the present invention provides a high-precision time interval measuring instrument based on GNSS and TDC-GPX2, comprising: The constant-temperature crystal oscillator is used for outputting a 10MHz square wave CMOS level signal; The level conversion module is used for receiving the 10MHz square wave CMOS level signal and converting the 10MHz square wave CMOS level signal into a 10MHz square wave LVCMOS level signal; The clock buffer module is used for buffering the 10MHz signal output by the level conversion module and dividing the 10MHz signal into multiple paths of outputs; the GNSS receiver module is used for outputting 1PPS signals and NMEA-0183 data format message information; The time interval measuring module is used for measuring 1PPS output by the GNSS receiver module and a physical event to be measured by taking the 10MHz signal output by the clock buffer module as a reference clock; The main control module is used for receiving and extracting message information of the GNSS receiver module, processing peripheral interrupt signals of the time interval measurement module, receiving and processing measurement result data of the time interval measurement module, and outputting a constant-temperature crystal oscillator regulation signal; The digital-to-analog conversion module is used for converting the regulation and control signal output by the main control module into voltage and outputting the voltage to the constant-temperature crystal oscillator voltage control end. Further, the clock buffer module is CDCLVC clock buffer, 4 paths of 10MHz signal output are split, pins Y0 and Y1 are electrically connected with the SMA interface to be externally output, and pin Y2 is electrically connected with the time interval measuring module to provide a reference clock. Further, the time interval measurement module is a TDC-GPX2 time digital chip, and comprises 4 channels: the measurement channel 1 is electrically connected with the GNSS receiver module and used for inputting 1PPS signal measurement; the measuring channels 2 to 4 are electrically connected to SMA2, SMA3, SMA4 interfaces, respectively, for user measurements. Further, when the TDC-GPX2 time digital chip finishes each measurement, the measured coarse count and fine count result data are cached in an internal FIFO, and then an interrupt signal is generated, and the interrupt signal is electrically connected with the main control