CN117856786A - spaceVPX specification-based satellite-borne high-precision time-frequency reference equipment - Google Patents

Abstract

The invention provides spaceVPX specification-based satellite-borne high-precision time-frequency reference equipment, which comprises: an internal frequency reference source, an external frequency reference receiving circuit, a time-frequency processing unit, a time-frequency output circuit, a remote measuring and controlling circuit and a secondary power supply circuit; the chip-level atomic clock and the quartz crystal oscillator main backup redundancy are adopted as internal frequency reference sources, 10MHz pulse signals generated by the atomic clock and the crystal oscillator are subjected to phase calibration by navigation second pulse, and local time counts generated by the atomic clock and the crystal oscillator are subjected to time calibration by navigation second pulse and navigation time code; the time-frequency reference device outputs a reference time code, a reference second pulse, and a digital synchronous clock signal. The invention configures a chip-level atomic clock and a quartz crystal oscillator to mutually serve as a main clock and a standby clock to realize high-reliability stable operation, provides rich time information and pulse information to the outside, and supports complete time-frequency generation, propagation, monitoring and service system construction of a satellite-borne time-frequency unified system.

Description

spaceVPX specification-based satellite-borne high-precision time-frequency reference equipment

Technical Field

The invention relates to the technical field of satellite-borne electronic equipment, in particular to a satellite-borne high-precision time-frequency reference device based on the SpaceVPX specification.

Background

The satellite-borne time-frequency unified system is used for meeting the time-frequency consistency and local time self-holding requirements among different satellites, among satellites and among systems in the satellite, autonomously generating high-accuracy and high-stability frequency signals and time information on the satellite and issuing the high-accuracy and high-stability frequency signals and the time information to the outside in real time, so that all time users in the satellite share satellite data information based on the unified time-frequency reference under the unified time-frequency reference, and the inside of the satellite, the ground and the inter-satellite are cooperated to normally operate.

In order to meet the requirement of high-precision time synchronization during the satellite in-orbit flight, most remote sensing satellites adopt a mode of combining navigation time with quartz crystal oscillator timing. The quartz crystal oscillator has small volume, light weight, low power consumption and higher precision, but has poorer long-term stability and accumulated time errors. The navigation time stability is high, no time error accumulation exists, but the continuous navigation positioning cannot be ensured, the navigation time precision index is reduced under the condition of short-time non-positioning, the navigation function is invalid under the condition of long-time non-positioning, and the time information cannot be output.

With the gradual severity of space environment and the rapid development of low-orbit constellations, the demands for long-term high-precision self-conservation under navigation failure or service refusal are increasingly stringent. The quartz crystal has higher reliability as a frequency reference source, but the accuracy and stability indexes gradually cannot meet the application requirements. Atomic clocks are currently the most accurate time and frequency standard devices. The chip-level rubidium atomic clock can be directly applied to high-precision observation remote sensing satellites, formation cooperative flying satellites and constellation networking satellites, replaces a high-stability crystal oscillator used in the traditional satellites, and provides high-performance, high-reliability and light-weight frequency standards for the satellites.

The invention patent with the application number of CN106154822, namely a time synchronization method for locking a rubidium atomic clock by a satellite and a positioning station, discloses a method for comparing and correcting a local clock signal according to a normal reference time signal sent by the satellite and the local clock signal generated by the rubidium atomic clock. The invention patent with the application number of CN112147874, namely a time-frequency reference generating device and a time-frequency reference generating method based on satellite time service and CPT atomic clock time service, discloses that a satellite time service component acquires time service signals of a navigation satellite to form time service time information and time service second pulse signal output, and an atomic clock time service component adjusts atomic clock reference frequency to form time service pulse signals and time service time information output. The invention patent application numbers CN108199712 'a CPT atomic clock frequency tame control circuit' and CN108183709 'a CPT atomic clock frequency tame control method and equipment' disclose a method for determining the frequency offset of the CPT atomic clock local oscillation frequency in a set time interval based on a local oscillation frequency generation frequency division to obtain a first pulse signal and a second pulse signal input by an external port, and tame adjustment is carried out on the CPT atomic clock local oscillation frequency according to the frequency offset.

Searching and analyzing the prior art can find that the following problems exist:

1) The chip-level atomic clock is not subjected to enough examination in a severe space environment to prove that the chip-level atomic clock has long service life and high reliability and stable operation capacity, and if the chip-level atomic clock is only used as a satellite internal frequency reference source, the system reliability may not meet the application requirements;

2) In the application environment with limited space-borne resource expense, a chip-level atomic clock, a quartz crystal oscillator and a navigation system are required to be comprehensively utilized, rich time information and pulse information are provided for the outside, and a complete space-borne time-frequency unified system time-frequency generation, propagation, monitoring and service system construction is supported.

Based on the above-mentioned considerations, the present invention proposes a technical solution to improve the above-mentioned technical problems.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide spaceVPX specification-based satellite-borne high-precision time-frequency reference equipment.

The spaceVPX specification-based satellite-borne high-precision time-frequency reference device provided by the invention comprises: an internal frequency reference source, an external frequency reference receiving circuit, a time-frequency processing unit, a time-frequency output circuit, a remote measuring and controlling circuit and a secondary power supply circuit;

the internal frequency reference source adopts a chip-level atomic clock and a quartz crystal oscillator main backup redundant form to respectively generate 10MHz frequency signals to be input into the time-frequency processing unit, the chip-level atomic clock is the main part of the frequency reference source, and the quartz crystal oscillator is the frequency reference source backup;

the external frequency reference receiving circuit adopts an RS422 interface circuit to receive a navigation time code and a navigation second pulse output by the navigation receiver through an external connector and a backboard connector respectively, and inputs the navigation time code and the navigation second pulse into the time-frequency processing unit;

the time-frequency processing unit receives the navigation time code and the navigation second pulse, and utilizes the navigation second pulse to tame the 10MHz frequency signals input by the chip-level atomic clock and the quartz crystal oscillator, and correct clock error and phase difference; the self-selection of the atomic clock and crystal oscillator frequency source after the tame correction is carried out, and the internal frequency reference source appointed by the selection of the external remote control instruction is also received; performing time counting according to the frequency source 10MHz frequency signal after the domestication correction and the navigation time code, and outputting a reference time code, a reference second pulse and a digital synchronous clock signal; receiving and processing external remote control instructions according to a space data packet format, and sending telemetry data of time-frequency reference equipment;

the time-frequency output circuit outputs the reference time code, the reference second pulse, the digital synchronous clock signal and the 10MHz pulse signal output by the time-frequency processing unit to a time-frequency user through an external connector and a backboard connector;

the remote measuring and controlling circuit adopts an RS422 interface circuit to receive a remote control instruction data packet and send a remote measuring data packet through the backboard connector;

the secondary power supply circuit receives external power supply input through the backboard connector and performs voltage conversion to generate power supply voltage required by the time-frequency reference equipment.

Preferably, the navigation time code and the reference time code are in a space data packet format, and the time code, the time code valid indication and the time code reference source indication data are placed in a packet data field part of the packet format.

Preferably, the time-frequency output circuit outputs a reference time code and a reference second pulse by adopting an RS422 interface circuit through an external connector, outputs 64KHz and 2048KHz digital synchronous clock signals by adopting an RS422 interface circuit, outputs a 10MHz pulse signal by adopting an SMA interface, and outputs the reference time code by adopting an Ethernet interface circuit; through the backboard connector, the RS422 interface circuit is adopted to output a reference time code and a reference second pulse, the RS422 interface circuit is adopted to output 64KHz and 2048KHz digital synchronous clock signals, the RS422 interface circuit is adopted to output a 10MHz pulse signal, and the Ethernet interface circuit is adopted to output the reference time code.

Preferably, the SpaceVPX standard specification is adopted, the mechanical size of 6U is adopted, the power supply required by the module is taken from the back board through the back board connector P0, a 10MHz pulse signal is output, an RS422 interface reference time code and a reference second pulse are output through the back board connector P4, a digital synchronous clock signal is output, an Ethernet interface reference time code is output, an RS422 interface telemetry data packet is output, and an RS422 interface remote control instruction data packet is input.

Preferably, the time-frequency calibration and output process comprises:

firstly, the system is initially electrified, the frequency of a 10MHz frequency signal of a chip-level atomic clock is doubled to 100MHz, the frequency of a 10MHz frequency signal of a quartz crystal oscillator is doubled to 100MHz, and the phase difference between the 10MHz signal and the 100MHz signal is equal;

step two, according to the cycle count of the 100MHz frequency multiplication signal of the atomic clock, after the count of the 100MHz frequency multiplication signal is full of 10, carrying the local time counter of the atomic clock, and generating the local time counter of the atomic clock with the resolution of 10 MHz; according to the cycle count of the 100MHz frequency multiplication signal of the crystal oscillator, after the count of the 100MHz frequency multiplication signal is full of 10, carrying the local time counter of the crystal oscillator to generate the local time counter of the crystal oscillator with the resolution of 10 MHz;

step three, receiving a navigation second pulse and a navigation time code, if the navigation time code is valid, entering step four, and if the navigation time code is invalid, ending;

step four, directly assigning the received navigation time code with an atomic clock local time counter and a crystal oscillator local time counter;

step five, initial synchronization of navigation second pulse, namely comparing difference values according to an atomic clock local time counter locked by the navigation second pulse, a crystal oscillator local time counter and a navigation time code corresponding to the navigation second pulse, and respectively correcting the atomic clock local time counter and the crystal oscillator local time counter by utilizing the difference values;

step six, navigation second pulse Kalman filtering processing;

step seven, counting and measuring navigation second pulses according to a chip-level atomic clock 10MHz frequency signal to obtain NA1, and counting and measuring navigation second pulses according to a quartz crystal oscillator 10MHz frequency signal to obtain NJ1;

step eight, counting and measuring the difference value between a navigation second pulse starting edge and a 10MHz frequency signal counting starting edge according to a 100MHz frequency multiplication signal of a chip-level atomic clock to obtain NA2, and counting and measuring the difference value between a navigation second pulse stopping edge and a 10MHz frequency signal counting stopping edge to obtain NA3; counting and measuring the difference value between the navigation second pulse starting edge and the 10MHz frequency signal counting starting edge according to the quartz crystal oscillator 100MHz frequency multiplication signal to obtain NJ2, and counting and measuring the difference value between the navigation second pulse stopping edge and the 10MHz frequency signal counting stopping edge to obtain NJ3;

step nine, the theoretical count value of the navigation second pulse 10MHz frequency signal is N, and the chip-level atomic clock count measurement isQuartz crystal oscillator count measurement is->Calculating atomic clock count measurement deviationCrystal oscillator count measurement deviation->

Step ten, if delta A is more than or equal to 0, subtracting 1 when the cycle count of 100MHz frequency multiplication signals of the atomic clock is full of 10 counts; if delta A is less than 0, adding 1 when the cycle count of 100MHz frequency doubling signals of the atomic clock is full of 10 counts; if delta J is more than or equal to 0, reducing 1 when the cycle count of the 100MHz frequency doubling signal of the crystal oscillator is full of 10 counts; if delta J is less than 0, adding 1 when the cycle count of the crystal oscillator 100MHz frequency doubling signal is full of 10 counts;

step eleven, when the atomic clock local time counter counts to the whole second, generating atomic clock reference second pulse, wherein the time is atomic clock reference time code TA; when the local time counter of the crystal oscillator counts to a whole second, generating a reference second pulse of the crystal oscillator, wherein the time is a reference time code TJ of the crystal oscillator; the navigation time code corresponding to the navigation second pulse starting edge is TGNSS;

step twelve, counting and measuring the difference value between the navigation second pulse starting edge and the atomic clock reference second pulse starting edge according to the atomic clock 100MHz frequency multiplication signal to obtain delta NA; counting and measuring the difference value between the navigation second pulse starting edge and the reference second pulse starting edge of the crystal oscillator according to the 100MHz frequency multiplication signal of the crystal oscillator to obtain delta NJ;

thirteenth, if delta NA is less than or equal to 100, if TGNSS is more than TA, the 100MHz frequency multiplication signal count of the atomic clock local time counter is increased by 1, and if TGNSS is less than TA, the 100MHz frequency multiplication signal count of the atomic clock local time counter is decreased by 1; if delta NA is more than or equal to 99999900, if TGNSS+1 seconds is more than TA, the 100MHz frequency multiplication signal count of the atomic clock local time counter is increased by 1 more, and if TGNSS+1 seconds is less than TA, the 100MHz frequency multiplication signal count of the atomic clock local time counter is decreased by 1 more; if delta NJ is less than or equal to 100, if TGNSS is more than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is increased by 1, and if TGNSS is less than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is decreased by 1; if delta NJ is more than or equal to 99999900, if TGNSS+1 seconds is more than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is increased by 1, and if TGNSS+1 seconds is less than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is decreased by 1;

fourteen, outputting a reference second pulse and a reference time code serving as time-frequency reference equipment by using the atomic clock reference second pulse and the atomic clock reference time code if the frequency reference source is a chip-level atomic clock; if the frequency reference source is quartz crystal oscillator, the crystal oscillator reference second pulse and the crystal oscillator reference time code are output as the reference second pulse and the reference time code of the time-frequency reference equipment.

Preferably, according to the 10MHz frequency signal of the chip-level atomic clock and the 10MHz frequency signal of the quartz crystal oscillator after the calibration in the step ten, 64KHz digital synchronous clock signals and 2048KHz digital synchronous clock signals are respectively generated through frequency division, and according to the frequency reference source selected in the step fourteen, the atomic clock or the digital synchronous clock signal of the crystal oscillator is selected for output.

Preferably, the navigation second pulse and the navigation time code simultaneously calibrate the phase of a 10MHz pulse signal generated by a chip-level atomic clock and a quartz crystal oscillator and calibrate the time of a local time counter, so that the smoothness of the pulse signal and time information when the atomic clock and the crystal oscillator frequency reference source are switched is improved.

Preferably, the time-frequency user selects to receive the time-frequency information output by the time-frequency reference equipment according to the need;

for time-frequency users with higher precision time requirements, selecting an RS422 interface to receive a reference time code and a reference second pulse, or selecting an Ethernet interface to receive the reference time code and the RS422 interface to receive the reference second pulse;

for time-frequency users without high-precision time requirements, the RS422 interface is selected to receive the reference time code, or the Ethernet interface is selected to receive the reference time code.

Preferably, for time-frequency users with frequency counting requirements, the RS422 interface is selected to receive 10MHz pulse signals, or the SMA interface is selected to receive 10MHz pulse signals.

Preferably, for users with higher synchronous operation requirements, the RS422 interface is selected to receive 64KHz, 2048KHz digital synchronous clock signals and reference second pulses, and high synchronism of operation between different time-frequency users is realized through the clock signals which are output in a homologous mode.

Compared with the prior art, the invention has the following beneficial effects:

(1) The invention provides spaceVPX specification-based satellite-borne high-precision time-frequency reference equipment, which is provided with a dual-redundancy hot backup with a chip-level atomic clock and a quartz crystal oscillator as main and standby clocks, so that the requirements of high reliability and continuous stability are met;

(2) The invention calibrates the frequency and time of the chip-level atomic clock and the quartz crystal oscillator through the navigation second pulse and the navigation time code output by the navigation system, and outputs the time code, the second pulse, the frequency signal and the digital synchronous clock signal through the RS422, the SMA and the Ethernet interface so as to meet the use requirements of various time-frequency users.

Drawings

Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:

FIG. 1 is a functional schematic diagram of a spaceVPX specification-based on-board high-precision time-frequency reference device design and apparatus of the present invention;

FIG. 2 is an interface schematic diagram of a satellite-borne high precision time-frequency reference device;

FIG. 3 is a diagram of a navigation seconds pulse frequency count;

FIG. 4 is a frequency count diagram I of pilot pulses and internal frequency reference source pulses;

FIG. 5 is a second diagram of frequency counts of pilot pulses and internal frequency reference source pulses.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.

Examples

The invention provides spaceVPX specification-based satellite-borne high-precision time-frequency reference equipment, which comprises an internal frequency reference source, an external frequency reference receiving circuit, a time-frequency processing unit, a time-frequency output circuit, a telemetry and remote control circuit and a secondary power supply circuit, wherein the figure 1 is shown.

The internal frequency reference source adopts a chip-level atomic clock and quartz crystal oscillator main backup redundant form, the chip-level atomic clock and the quartz crystal oscillator respectively generate 10MHz frequency signals and input the signals into the time-frequency processing unit, the chip-level atomic clock is the frequency reference source main part, and the quartz crystal oscillator is the frequency reference source backup.

The external frequency reference receiving circuit adopts an RS422 interface circuit, receives the navigation time code and the navigation second pulse output by the navigation receiver through an external connector and a backboard connector respectively, and inputs the navigation time code and the navigation second pulse into the time-frequency processing unit. When the navigation receiver is a stand-alone device, the navigation time code and the navigation seconds pulse are input through an external connector. When the navigation receiver is a modularized product based on the SpaceVPX specification, a single machine where the time-frequency reference equipment is can be inserted, the navigation time code and the navigation second pulse are transmitted through the single machine backboard, and the time-frequency reference equipment is received from the backboard connector. The navigation time code is the time corresponding to the navigation second pulse jump edge.

The time-frequency processing unit is mainly constructed by taking a processing device as a core, and in the satellite-borne application environment, an antifuse FPGA is preferentially adopted in order to ensure the reliability of a satellite-borne time-frequency unified system. The time-frequency processing unit mainly completes the receiving, the calibrating, the generating and the outputting of the time-frequency signal, and comprises the following steps:

1) Receiving a navigation time code and a navigation second pulse, and performing taming on a 10MHz frequency signal input by a chip-level atomic clock and a quartz crystal oscillator by using the navigation second pulse, and correcting clock errors and phase differences;

2) The self-selection of the atomic clock and crystal oscillator frequency source after the tame correction is carried out, and the internal frequency reference source appointed by the selection of the external remote control instruction is also received;

3) Performing time counting according to the frequency source 10MHz frequency signal after the domestication correction and the navigation time code, and outputting a reference time code, a reference second pulse and a digital synchronous clock signal;

4) And receiving and processing external remote control instructions according to the space data packet format, and sending telemetry data of the time-frequency reference equipment.

The time-frequency output circuit outputs the reference time code, the reference second pulse, the digital synchronous clock signal and the 10MHz pulse signal output by the time-frequency processing unit to the time-frequency user through the external connector and the backboard connector, as shown in figure 2. When the time-frequency user is a stand-alone device, the external connector outputs a reference time code, a reference second pulse, a digital synchronous clock signal and a 10MHz pulse signal. When the time-frequency user is other modules of the single machine where the time-frequency reference equipment is located, the reference time code, the reference second pulse, the digital synchronous clock signal and the 10MHz pulse signal are output through the backboard connector, and the time-frequency user receives through the single machine backboard.

In specific implementation, the time-frequency output circuit outputs a reference time code and a reference second pulse through an external connector by adopting an RS422 interface circuit, outputs 64KHz and 2048KHz digital synchronous clock signals by adopting an RS422 interface circuit, outputs a 10MHz pulse signal by adopting an SMA interface, and outputs the reference time code by adopting an Ethernet interface circuit; through the backboard connector, the RS422 interface circuit is adopted to output a reference time code and a reference second pulse, the RS422 interface circuit is adopted to output 64KHz and 2048KHz digital synchronous clock signals, the RS422 interface circuit is adopted to output a 10MHz pulse signal, and the Ethernet interface circuit is adopted to output the reference time code. The time-frequency user can receive corresponding signals according to the requirements of time and frequency, including:

1) For users with higher precision time requirements, the RS422 interface can be selected to receive the reference time code and the reference second pulse, and the Ethernet interface can also be selected to receive the reference time code and the RS422 interface can be selected to receive the reference second pulse;

2) For users without high-precision time requirements, the RS422 interface can be selected to receive the reference time code, and the Ethernet interface can also be selected to receive the reference time code;

3) For users with frequency counting requirements, the RS422 interface can be selected to receive 10MHz pulse signals, and the SMA interface can also be selected to receive 10MHz pulse signals;

4) For users with higher synchronous operation requirements, the RS422 interface can be selected to receive the digital synchronous clock signals of 64KHz and 2048KHz and reference second pulse, and the synchronous operation between different single machines can be performed through the digital synchronous clock signals which are output in a homologous way.

The remote-measuring and remote-controlling circuit adopts an RS422 interface circuit to receive the remote-controlling instruction data packet and send the remote-measuring data packet through the backboard connector.

The secondary power supply circuit receives external power supply input through the backboard connector and performs voltage conversion to generate power supply voltage required by the time-frequency reference equipment.

The navigation time code, the reference time code, the remote control instruction data packet and the remote measurement data packet all adopt a space data packet format. In order to ensure that the time-frequency data receiving end knows the state of the sending end, the corresponding time code valid indication and time code reference source indication are needed in addition to the time code. The time code valid indication may indicate whether the time code and corresponding pulse-per-second in the data packet are valid or not, and the time code reference source indication indicates that the time code and corresponding pulse-per-second in the data packet originate from a chip-scale atomic clock or quartz crystal oscillator.

The time-frequency reference equipment adopts the SpaceVPX standard specification, has the mechanical size of 6U, takes a secondary power supply required by a module from a back board through a back board connector P0, outputs a 10MHz pulse signal, outputs an RS422 interface reference time code and a reference second pulse through a back board connector P4, outputs a digital synchronous clock signal, outputs an Ethernet interface reference time code, outputs an RS422 interface telemetry data packet and inputs an RS422 interface remote control instruction data packet.

The time-frequency calibration and output steps of the satellite-borne high-precision time-frequency reference equipment comprise:

firstly, the system is initially electrified, the frequency of a 10MHz frequency signal of a chip-level atomic clock is doubled to 100MHz, the frequency of a 10MHz frequency signal of a quartz crystal oscillator is doubled to 100MHz, and the phase difference between the 10MHz signal and the 100MHz signal is equal;

step two, according to the cycle count of the 100MHz frequency multiplication signal of the atomic clock, after the count of the 100MHz frequency multiplication signal is full of 10, carrying the local time counter of the atomic clock, and generating the local time counter of the atomic clock with the resolution of 10 MHz; according to the cycle count of the 100MHz frequency multiplication signal of the crystal oscillator, after the count of the 100MHz frequency multiplication signal is full of 10, carrying the local time counter of the crystal oscillator to generate the local time counter of the crystal oscillator with the resolution of 10 MHz;

step three, receiving navigation second pulse and navigation time code, judging the validity of navigation signals, if the navigation time code is valid, entering step four, and if the navigation time code is invalid, ending;

step four, directly assigning the received navigation time code with an atomic clock local time counter and a crystal oscillator local time counter to realize the 'coarse synchronization' of time information of the time frequency reference equipment and the navigation time;

step five, the initial synchronization of the navigation second pulse is carried out, difference comparison is carried out according to an atomic clock local time counter locked by the navigation second pulse, a crystal oscillator local time counter and a navigation time code corresponding to the navigation second pulse, and the atomic clock local time counter and the crystal oscillator local time counter are respectively corrected by utilizing the difference values, so that the time information 'accurate synchronization' of the time frequency reference equipment and the navigation time is realized;

step six, the navigation receiver has high long-term stability, but has poor short-term stability, and the navigation second pulse has jitter, so the navigation second pulse is subjected to Kalman filtering processing to improve the short-term stability of the navigation second pulse, and the influence of the navigation second pulse jitter on frequency is avoided;

step seven, counting and measuring navigation second pulses according to a 10MHz frequency signal of a chip-level atomic clock to obtain NA1, wherein the navigation second pulses are counted at the moment of a navigation time code corresponding to the falling edge of the navigation second pulses as shown in FIG. 3, and the rising edge of the 10MHz frequency signal starts counting; similarly, counting and measuring navigation second pulses according to a quartz crystal oscillator 10MHz frequency signal to obtain NJ1;

step eight, counting and measuring the difference value between a navigation second pulse starting edge and a 10MHz frequency signal counting starting edge according to a 100MHz frequency multiplication signal of a chip-level atomic clock to obtain NA2, counting and measuring the difference value between a navigation second pulse stopping edge and a 10MHz frequency signal counting stopping edge to obtain NA3, counting the rising edge of a 100MHz frequency signal, and enabling the 100MHz frequency signal to be in phase with the 10MHz frequency signal, wherein the figure 3 shows that; similarly, according to a quartz crystal oscillator 100MHz frequency multiplication signal, counting and measuring the difference value between a navigation second pulse starting edge and a 10MHz frequency signal counting starting edge to obtain NJ2, and counting and measuring the difference value between a navigation second pulse stopping edge and a 10MHz frequency signal counting stopping edge to obtain NJ3;

step nine, the theoretical count value of the navigation second pulse 10MHz frequency signal is N, the 10MHz frequency signal is taken as a pulse count unit, and the chip-level atomic clock count measurement is as followsQuartz crystal oscillator count measurement is->Calculating the count measurement deviation of an atomic clock>Crystal oscillator count measurement deviation->

Step ten, if delta A is more than or equal to 0, the actual 10MHz frequency signal of the atomic clock is faster than the standard frequency, 1 is reduced when the 100MHz frequency doubling signal of the atomic clock is counted fully 10 counts to slow down the frequency count, and if delta A is less than 0, the actual 10MHz frequency signal of the atomic clock is slower than the standard frequency, 1 is added when the 100MHz frequency doubling signal of the atomic clock is counted fully 10 counts to speed up the frequency count; similarly, if DeltaJ is more than or equal to 0, the cycle count of the 100MHz frequency doubling signal of the crystal oscillator is reduced by 1 when the cycle count is full of 10 counts, and if DeltaJ is less than 0, the cycle count of the 100MHz frequency doubling signal of the crystal oscillator is increased by 1 when the cycle count is full of 10 counts; the influence of frequency variation is reduced through the frequency adjustment of the 100MHz frequency multiplication signal;

step eleven, when the atomic clock local time counter counts to the whole second, generating atomic clock reference second pulse, wherein the time is atomic clock reference time code; when the local time counter of the crystal oscillator counts to a whole second, generating a reference second pulse of the crystal oscillator, wherein the time is a reference time code of the crystal oscillator;

step twelve, counting and measuring the difference value between the navigation second pulse starting edge and the atomic clock reference second pulse starting edge according to the atomic clock 100MHz frequency multiplication signal to obtain delta NA; counting and measuring the difference value between the navigation second pulse starting edge and the reference second pulse starting edge of the crystal oscillator according to the 100MHz frequency multiplication signal of the crystal oscillator to obtain delta NJ;

step thirteen, if Δna is less than or equal to 100, as shown in fig. 4, if TGNSS > TA, which indicates that the local time count is delayed, the 100MHz frequency multiplication signal count of the atomic clock local time counter is increased by 1 more, and the local time count is corrected in a gradual fine tuning mode; if TGNSS is less than TA, the local time count is advanced, and the 100MHz frequency multiplication signal count of the atomic clock local time counter is reduced by 1; if ΔNA is equal to or greater than 99999900, as shown in FIG. 5, it is indicated that there is a whole second deviation between the navigation second pulse and the reference second pulse, so if TGNSS+1 seconds > TA, the 100MHz doubling signal count of the atomic clock local time counter is increased by 1 more, and if TGNSS+1 seconds < TA, the 100MHz doubling signal count of the atomic clock local time counter is decreased by 1 more; similarly, if ΔNJ is less than or equal to 100, if TGNSS is more than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is increased by 1, and if TGNSS is less than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is decreased by 1; if delta NJ is more than or equal to 99999900, if TGNSS+1 seconds is more than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is increased by 1, and if TGNSS+1 seconds is less than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is decreased by 1;

fourteen, if the frequency reference source is selected as a chip-level atomic clock, outputting atomic clock reference second pulse and atomic clock reference time code as reference second pulse and reference time code of time-frequency reference equipment; if the frequency reference source is selected as a quartz crystal oscillator, outputting reference second pulse and reference time code of the crystal oscillator as reference second pulse and reference time code of time-frequency reference equipment; the selection of the frequency reference source may be made by an external remote control command.

In the step, according to the chip-level atomic clock 10MHz frequency signal and the quartz crystal oscillator 10MHz frequency signal calibrated in the step ten, digital synchronous clock signals of 64KHz and 2048KHz are respectively generated through frequency division, and according to the frequency reference source selected in the step fourteen, the atomic clock or the crystal oscillator digital synchronous clock signal is selected to be output.

In the above steps, the navigation second pulse and the navigation time code simultaneously calibrate the phase of the 10MHz pulse signal generated by the chip-level atomic clock and the quartz crystal oscillator and calibrate the time of the local time counter. Because the calibration is performed based on the same external frequency reference, namely navigation second pulse and navigation time code, when the atomic clock and crystal oscillator frequency reference source are switched, the output reference time code, the reference second pulse, the digital synchronous clock signal and the 10MHz pulse signal jump are smaller, and the smoothness of the pulse signal and the time information is improved.

Those skilled in the art will appreciate that the systems, apparatus, and their respective modules provided herein may be implemented entirely by logic programming of method steps such that the systems, apparatus, and their respective modules are implemented as logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc., in addition to the systems, apparatus, and their respective modules being implemented as pure computer readable program code. Therefore, the system, the apparatus, and the respective modules thereof provided by the present invention may be regarded as one hardware component, and the modules included therein for implementing various programs may also be regarded as structures within the hardware component; modules for implementing various functions may also be regarded as being either software programs for implementing the methods or structures within hardware components.

The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily without conflict.

Claims (10)

1. spaceVPX specification-based satellite-borne high-precision time-frequency reference equipment is characterized by comprising: an internal frequency reference source, an external frequency reference receiving circuit, a time-frequency processing unit, a time-frequency output circuit, a remote measuring and controlling circuit and a secondary power supply circuit;

the internal frequency reference source adopts a chip-level atomic clock and a quartz crystal oscillator main backup redundant form to respectively generate 10MHz frequency signals to be input into the time-frequency processing unit, the chip-level atomic clock is the main part of the frequency reference source, and the quartz crystal oscillator is the frequency reference source backup;

the external frequency reference receiving circuit adopts an RS422 interface circuit to receive a navigation time code and a navigation second pulse output by the navigation receiver through an external connector and a backboard connector respectively, and inputs the navigation time code and the navigation second pulse into the time-frequency processing unit;

the time-frequency processing unit receives the navigation time code and the navigation second pulse, and utilizes the navigation second pulse to tame the 10MHz frequency signals input by the chip-level atomic clock and the quartz crystal oscillator, and correct clock error and phase difference; the self-selection of the atomic clock and crystal oscillator frequency source after the tame correction is carried out, and the internal frequency reference source appointed by the selection of the external remote control instruction is also received; performing time counting according to the frequency source 10MHz frequency signal after the domestication correction and the navigation time code, and outputting a reference time code, a reference second pulse and a digital synchronous clock signal; receiving and processing external remote control instructions according to a space data packet format, and sending telemetry data of time-frequency reference equipment;

the time-frequency output circuit outputs the reference time code, the reference second pulse, the digital synchronous clock signal and the 10MHz pulse signal output by the time-frequency processing unit to a time-frequency user through an external connector and a backboard connector;

the remote measuring and controlling circuit adopts an RS422 interface circuit to receive a remote control instruction data packet and send a remote measuring data packet through the backboard connector;

the secondary power supply circuit receives external power supply input through the backboard connector and performs voltage conversion to generate power supply voltage required by the time-frequency reference equipment.

2. The spaceVPX specification-based on-board high-precision time-frequency reference device according to claim 1, wherein the navigation time code and the reference time code are in a space data packet format, and the time code, the time code valid indication and the time code reference source indication data are placed in a packet format packet data domain part.

3. The spaceVPX specification-based satellite-borne high-precision time-frequency reference device according to claim 1, wherein the time-frequency output circuit outputs a reference time code and a reference second pulse by adopting an RS422 interface circuit, outputs 64KHz and 2048KHz digital synchronous clock signals by adopting an RS422 interface circuit, outputs a 10MHz pulse signal by adopting an SMA interface, and outputs the reference time code by adopting an Ethernet interface circuit; through the backboard connector, the RS422 interface circuit is adopted to output a reference time code and a reference second pulse, the RS422 interface circuit is adopted to output 64KHz and 2048KHz digital synchronous clock signals, the RS422 interface circuit is adopted to output a 10MHz pulse signal, and the Ethernet interface circuit is adopted to output the reference time code.

4. The spaceVPX specification-based satellite-borne high-precision time-frequency reference device according to claim 1, wherein the spaceVPX specification is adopted, the mechanical size of 6U is 6U, a power supply required by a module is taken from a back board through a back board connector P0, a 10MHz pulse signal is output, an RS422 interface reference time code and a reference second pulse are output through a back board connector P4, a digital synchronous clock signal is output, an Ethernet interface reference time code is output, an RS422 interface telemetry data packet is output, and an RS422 interface remote control command data packet is input.

5. The SpaceVPX specification-based on-board high precision time-frequency reference device of claim 1, wherein the time-frequency calibration and output process comprises:

firstly, the system is initially electrified, the frequency of a 10MHz frequency signal of a chip-level atomic clock is doubled to 100MHz, the frequency of a 10MHz frequency signal of a quartz crystal oscillator is doubled to 100MHz, and the phase difference between the 10MHz signal and the 100MHz signal is equal;

step two, according to the cycle count of the 100MHz frequency multiplication signal of the atomic clock, after the count of the 100MHz frequency multiplication signal is full of 10, carrying the local time counter of the atomic clock, and generating the local time counter of the atomic clock with the resolution of 10 MHz; according to the cycle count of the 100MHz frequency multiplication signal of the crystal oscillator, after the count of the 100MHz frequency multiplication signal is full of 10, carrying the local time counter of the crystal oscillator to generate the local time counter of the crystal oscillator with the resolution of 10 MHz;

step three, receiving a navigation second pulse and a navigation time code, if the navigation time code is valid, entering step four, and if the navigation time code is invalid, ending;

step four, directly assigning the received navigation time code with an atomic clock local time counter and a crystal oscillator local time counter;

step five, initial synchronization of navigation second pulse, namely comparing difference values according to an atomic clock local time counter locked by the navigation second pulse, a crystal oscillator local time counter and a navigation time code corresponding to the navigation second pulse, and respectively correcting the atomic clock local time counter and the crystal oscillator local time counter by utilizing the difference values;

step six, navigation second pulse Kalman filtering processing;

step seven, counting and measuring navigation second pulses according to a chip-level atomic clock 10MHz frequency signal to obtain NA1, and counting and measuring navigation second pulses according to a quartz crystal oscillator 10MHz frequency signal to obtain NJ1;

step eight, counting and measuring the difference value between a navigation second pulse starting edge and a 10MHz frequency signal counting starting edge according to a 100MHz frequency multiplication signal of a chip-level atomic clock to obtain NA2, and counting and measuring the difference value between a navigation second pulse stopping edge and a 10MHz frequency signal counting stopping edge to obtain NA3; counting and measuring the difference value between the navigation second pulse starting edge and the 10MHz frequency signal counting starting edge according to the quartz crystal oscillator 100MHz frequency multiplication signal to obtain NJ2, and counting and measuring the difference value between the navigation second pulse stopping edge and the 10MHz frequency signal counting stopping edge to obtain NJ3;

step nine, the theoretical count value of the navigation second pulse 10MHz frequency signal is N, and the chip-level atomic clock count measurement isQuartz crystal oscillator count measurement is->Calculating atomic clock count measurement deviationCrystal oscillator count measurement deviation->

Step ten, if delta A is more than or equal to 0, subtracting 1 when the cycle count of 100MHz frequency multiplication signals of the atomic clock is full of 10 counts; if delta A is less than 0, adding 1 when the cycle count of 100MHz frequency doubling signals of the atomic clock is full of 10 counts; if delta J is more than or equal to 0, reducing 1 when the cycle count of the 100MHz frequency doubling signal of the crystal oscillator is full of 10 counts; if delta J is less than 0, adding 1 when the cycle count of the 100MHz frequency doubling signal of the crystal oscillator is full of 10 counts;

step eleven, when the atomic clock local time counter counts to the whole second, generating atomic clock reference second pulse, wherein the time is atomic clock reference time code TA; when the local time counter of the crystal oscillator counts to a whole second, generating a reference second pulse of the crystal oscillator, wherein the time is a reference time code TJ of the crystal oscillator; the navigation time code corresponding to the navigation second pulse starting edge is TGNSS;

step twelve, counting and measuring the difference value between the navigation second pulse starting edge and the atomic clock reference second pulse starting edge according to the atomic clock 100MHz frequency multiplication signal to obtain delta NA; counting and measuring the difference value between the navigation second pulse starting edge and the reference second pulse starting edge of the crystal oscillator according to the 100MHz frequency multiplication signal of the crystal oscillator to obtain delta NJ;

thirteenth, if delta NA is less than or equal to 100, if TGNSS is more than TA, the 100MHz frequency multiplication signal count of the atomic clock local time counter is increased by 1, and if TGNSS is less than TA, the 100MHz frequency multiplication signal count of the atomic clock local time counter is decreased by 1; if delta NA is more than or equal to 99999900, if TGNSS+1 seconds is more than TA, the 100MHz frequency multiplication signal count of the atomic clock local time counter is increased by 1 more, and if TGNSS+1 seconds is less than TA, the 100MHz frequency multiplication signal count of the atomic clock local time counter is decreased by 1 more; if delta NJ is less than or equal to 100, if TGNSS is more than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is increased by 1, and if TGNSS is less than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is decreased by 1; if delta NJ is more than or equal to 99999900, if TGNSS+1 seconds is more than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is increased by 1, and if TGNSS+1 seconds is less than TJ, the 100MHz frequency multiplication signal count of the local time counter of the crystal oscillator is decreased by 1;

fourteen, outputting a reference second pulse and a reference time code serving as time-frequency reference equipment by using the atomic clock reference second pulse and the atomic clock reference time code if the frequency reference source is a chip-level atomic clock; if the frequency reference source is quartz crystal oscillator, the crystal oscillator reference second pulse and the crystal oscillator reference time code are output as the reference second pulse and the reference time code of the time-frequency reference equipment.

6. The spaceVPX specification-based satellite-borne high-precision time-frequency reference device according to claim 5, wherein the 10MHz frequency signal of the chip-level atomic clock and the 10MHz frequency signal of the quartz crystal oscillator after the calibration in the step ten are respectively generated into 64KHz and 2048KHz digital synchronous clock signals through frequency division, and the atomic clock or the crystal oscillator digital synchronous clock signal is selected to be output according to the frequency reference source selected in the step fourteen.

7. The spaceVPX specification-based satellite-borne high-precision time-frequency reference device according to claim 5, wherein navigation second pulse and navigation time code simultaneously calibrate the phase of a 10MHz pulse signal generated by a chip-level atomic clock and a quartz crystal oscillator and time calibrate a local time counter, so that the smoothness of the pulse signal and time information during the switching of the atomic clock and the crystal oscillator frequency reference source is improved.

8. The spaceVPX specification-based satellite-borne high-precision time-frequency reference device according to claim 5, wherein a time-frequency user selects to receive time-frequency information output by the time-frequency reference device according to requirements;

for time-frequency users with higher precision time requirements, selecting an RS422 interface to receive a reference time code and a reference second pulse, or selecting an Ethernet interface to receive the reference time code and the RS422 interface to receive the reference second pulse;

for time-frequency users without high-precision time requirements, the RS422 interface is selected to receive the reference time code, or the Ethernet interface is selected to receive the reference time code.

9. The SpaceVPX specification-based on-board high-precision time-frequency reference device of claim 8, wherein for time-frequency users with frequency counting requirements, the RS422 interface is selected to receive 10MHz pulse signals, or the SMA interface is selected to receive 10MHz pulse signals.

10. The spaceVPX specification-based on-board high-precision time-frequency reference device according to claim 8, wherein for users with higher synchronous operation requirements, the RS422 interface is selected to receive 64KHz, 2048KHz digital synchronous clock signals and reference second pulses, and high synchronism of operation between different time-frequency users is achieved by the clock signals outputted by the same source.