CN103197535B - Method for satellite-ground timing with oscilloscope - Google Patents
Method for satellite-ground timing with oscilloscope Download PDFInfo
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- CN103197535B CN103197535B CN201310127507.9A CN201310127507A CN103197535B CN 103197535 B CN103197535 B CN 103197535B CN 201310127507 A CN201310127507 A CN 201310127507A CN 103197535 B CN103197535 B CN 103197535B
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Abstract
The invention provides a method for satellite-ground timing with an oscilloscope. According to the method, the oscilloscope is used for carrying out a ground experiment to obtain satellite-ground time delay delta T satellite-ground time delay, accurate satellite-ground time difference is then calculated, and satellite timing is then carried out according to the measured satellite-ground time difference to enable an on-satellite data management clock to be synchronous with a ground clock.
Description
Technical field
The present invention relates to space exploration technical field, particularly relate to a kind of utilize oscillograph with carrying out star school time method.
Background technology
China Satecom's engineering, from the starting of development sounding rocket, then concentrates strength on developing artificial satellite, emphasis development types of applications satellite; During the ninth five-year plan, China's development and engineering management work have had large increase, develop and transmit 11 dissimilar artificial satellites altogether and first Shenzhou (Divine Vessel) tests airship; After this, China transmits again goddess in the moon's series of satellites, makes the aerospace industry of China be a a progressive step;
But in reality, on star, number pipe clock cannot keep synchronous with terrestrial clock, therefore needs to be calibrated satellite; When calibration method generally adopts concentrated school, concentrate and to refer to during school and in particular moment, time on star to be adjusted, consistent when making it the ground with current time.Concrete operation method is, T when first recording on star
starwith T during ground
groundbetween difference DELTA T
the star ground time difference=T
ground-T
star, injected by upstream data afterwards and adjust Δ T by during star
star ground the time difference, make adjust after star time be T'
star=T
star+ Δ T
the star ground time difference=T
ground, process when completing school; In practical operation, due to the existence of systematic error, cause Δ T
the star ground time differencedata inaccurate, and then object when not reaching accurate school; Below in conjunction with Fig. 1, systematic error is made a concrete analysis of:
Several pipe computing machines on star, when generating downlink telemetry frame synchronization head EB90 (H) the 1st bit forward position, obtain time t on star
star, this time encoding (namely star is beaten markers) in current telemetry frame, and is sent to ground by observing and controlling downlink; Ground observing and controlling baseband equipment, after demodulating telemetry frame synchronous head, records current ground elapsed time t in synchronous head the 1st bit forward position
ground(namely markers is beaten on ground), and this time is mail to ground master control with the telemetry demodulated.Master control parses the t in every frame telemetry
starand t
ground, calculate Δ t=t
ground-t
star, after data processing, obtain star ground time difference Δ T
the star ground time difference, finally by the up upper note star of observing and controlling.
Measured value Δ t consists of the following components: star ground time difference Δ T
the star ground time difference, on-board equipment time delay Δ T
star, uphole equipment time delay Δ T
ground, observing and controlling downlink transmission time delay Δ T
transmission, namely
Δ t=Δ T
the star ground time difference+ Δ T
star+ Δ T
ground+ Δ T
transmission
Δ T
starcaused by processes such as number pipe framing, chnnel coding, PSK modulation on star.Δ T
groundseparated the processes such as mediation channel-decoding to cause by the baseband equipment PSK in ground receiving equipment.Δ T
transmissioncaused by the descending long cable of the observing and controlling connecting satellite and ground in the general assembly electrical measurement stage, can be calculated by cable length, uphole equipment also can be utilized to carry out Measurement accuracy, satellite can be calculated by distance and the light velocity after heaven.Above factor is systematic error when measuring the star ground time difference, after raw measurement results Δ t is deducted said system error by master control, just can obtain the star ground time difference accurately.
In said system error, Δ T
transmissioncan measure by theory calculate or directly.Δ T
starwith Δ T
groundindependent measurement is had any problem, and generally measures when number pipe and integration test joint-trial, obtains sum of the two Δ T
star ground time delay=Δ T
star+ Δ T
ground, be referred to as star ground time delay.Can find out, star ground time delay is the important parameter of satellite when concentrating school, directly affects accuracy during concentrated school; Therefore the invention provides a kind of utilize oscillograph with carrying out star school time method;
Summary of the invention
The invention provides a kind of utilize oscillograph with carrying out star school time method, utilize oscillograph to carry out ground experiment and obtain star ground time delay Δ T
star ground time delay, then calculate the accurate star ground time difference, according to measure the star ground time difference obtained carry out satellite school time, to make on star number pipe clock keep synchronous with terrestrial clock.
The object of the invention is to be achieved through the following technical solutions:
Step one: the several pipe computing machines on star, when generating downlink telemetry frame synchronization head EB90 (H) the 1st bit forward position, obtain time t on star at that time
star, by this time encoding in current telemetry frame;
Step 2: the telemetry frame containing time encoding in step one is carried out pulse code, is modulated into pcm stream, converts described pcm stream to psk signal through sub-carrier modulation further;
Step 3: psk signal step 2 obtained sends to observing and controlling baseband equipment by video cable telemetering channel;
Step 4: observing and controlling baseband equipment carries out subcarrier demodulation to the psk signal received and obtains PCM signal, after demodulating telemetry frame synchronous head, records current ground elapsed time t in telemetry frame synchronous head the 1st bit forward position
ground, and by this ground elapsed time t
groundmaster control computer is mail to the telemetry demodulated;
Step 5: first master control computer parses time t on the star at that time in every frame telemetry
starwith current ground elapsed time t
ground, obtain the difference DELTA t of time and ground elapsed time on star, Δ t=t
ground-t
star; Then according to formula Δ T
the star ground time difference=Δ t-Δ T
star ground time delay-Δ T
transmissioncalculate star ground time difference Δ T
the star ground time difference;
Wherein Δ T
transmissionlearnt by theory calculate or direct measurement; Δ T
star ground time delaydrawn by ground experiment, the on-board equipment adopted, uphole equipment are real equipment, and on-board equipment is connected by cable with uphole equipment, and cable length used in experiment is all within 3 meters, the measuring error caused by cable time delay, at nanosecond order, is ignored; Ground experiment comprises step one to step 4, and the step of increase is:
1) telemetry frame after step one time encoding is exported a number pipe frame-synchronizing impulse to oscillograph through pulse producer, telemetry frame synchronous head EB90 (H) the 1st bit forward position in the forward position alignment procedures one of this number pipe frame-synchronizing impulse;
2) the PCM signal that step 4 demodulation obtains is sent to oscillograph, this PCM signal is with telemetry frame synchronous head EB90 (H);
3) oscillograph receives several pipe frame-synchronizing impulse and the step 2 of step 1)) demodulation after PCM signal contrast: the mistiming obtaining telemetry frame synchronous head EB90 (H) the 1st bit forward position of the PCM signal after several pipe frame-synchronizing impulse forward position and demodulation, this mistiming is star ground time delay Δ T
star ground time delay; By star ground time delay Δ T
star ground time delaysend to master control computer;
Step 6: by star ground time difference Δ T
the star ground time differencesend on star by observing and controlling up-link, for the time on clock adjustment star on star.
Ground elapsed time t current in step 4
groundtime reference is provided by source of uniting during GPS.
Current ground elapsed time t
groundwhen mailing to master control computer with the telemetry demodulated, adopt the mode of remote measurement true add ground elapsed time mark.
Beneficial effect of the present invention:
This measuring method overcomes systematic error, and then accurately obtains the star ground time difference, when the star ground time difference then obtained according to measurement carries out satellite school, makes number pipe clock on star keep synchronous with terrestrial clock.
Accompanying drawing explanation
Fig. 1 is prior art schematic diagram;
Fig. 2 is instrumentation plan of the present invention;
Fig. 3 is uphole equipment time system principle schematic;
Fig. 4 is star ground latency measurement principle schematic;
Fig. 5 is star ground latency measurement block diagram;
Embodiment
In order to understand technical scheme of the present invention better, below in conjunction with drawings and the specific embodiments, the present invention is described in further detail.
The invention provides a kind of utilize oscillograph with carrying out star school time method, systematic error can be overcome according to this measuring method, and then accurately obtain the star ground time difference, when the star ground time difference then obtained according to measurement carries out satellite school, make number pipe clock on star keep synchronous with terrestrial clock.
First make a concrete analysis of according to Fig. 2 below:
Concrete steps of the present invention are:
Step one: the several pipe computing machines on star, when generating downlink telemetry frame synchronization head EB90 (H) the 1st bit forward position, obtain time t on star at that time
star, by this time encoding in current telemetry frame;
Step 2: the telemetry frame containing time encoding in step one is carried out pulse code, is modulated into pcm stream, converts described pcm stream to psk signal through sub-carrier modulation further;
Step 3: psk signal step 2 obtained sends to observing and controlling baseband equipment by video cable telemetering channel;
Step 4: observing and controlling baseband equipment carries out subcarrier demodulation to the psk signal received and obtains PCM signal, after demodulating telemetry frame synchronous head, records current ground elapsed time t in telemetry frame synchronous head the 1st bit forward position
ground, and by this ground elapsed time t
groundmaster control computer is mail to the telemetry demodulated;
Wherein time t
groundwhen mailing to master control computer with the telemetry demodulated, adopt the mode of remote measurement true add ground elapsed time mark; Ground elapsed time t is provided
groundterrestrial clock by during GPS unite source calibrate, as shown in Figure 3, during GPS unite source receive gps satellite signal by gps antenna, through parsing after export time signal.Source of uniting during GPS provides two kinds of time service interfaces, and wherein hardware time service interface is observing and controlling baseband equipment CORTEX time service specially, is that the telemetry frame received beats markers for CORTEX.Hardware interface comprises 3 road signals: IRIG-B coded signal, 10MHz frequency reference, 1-PPS pulse signal.Having under 1-PPS pulse situation, CORTEX markers precision is ± 10us; Under not having pulse per second (PPS) situation, markers precision is ± 50us.Software interface provides NTP time service to serve by network interface, and master control and each subsystem uphole equipment can obtain temporal information by NTP Client, and time service precision is in millisecond magnitude.
Step 5: first master control computer parses time t on the star at that time in every frame telemetry
starwith current ground elapsed time t
ground, obtain the difference DELTA t of time and ground elapsed time on star, Δ t=t
ground-t
star; Then according to formula Δ T
the star ground time difference=Δ t-Δ T
star ground time delay-Δ T
transmissioncalculate star ground time difference Δ T
the star ground time difference;
Wherein Δ T
transmissionlearnt by theory calculate or direct measurement; Δ T
star ground time delaydrawn by ground experiment, the on-board equipment adopted, uphole equipment are real equipment, and on-board equipment is connected by cable with uphole equipment, and cable length used in experiment is all within 3 meters, the measuring error caused by cable time delay, at nanosecond order, is ignored; Ground experiment comprises step one to step 4, and the step of increase is:
1) telemetry frame after step one time encoding is exported a number pipe frame-synchronizing impulse to oscillograph through pulse producer, telemetry frame synchronous head EB90 (H) the 1st bit forward position in the forward position alignment procedures one of this number pipe frame-synchronizing impulse;
2) the PCM signal that step 4 demodulation obtains is sent to oscillograph, this PCM signal is with telemetry frame synchronous head EB90 (H);
3) oscillograph receives several pipe frame-synchronizing impulse and the step 2 of step 1)) demodulation after PCM signal contrast: the mistiming obtaining telemetry frame synchronous head EB90 (H) the 1st bit forward position of the PCM signal after several pipe frame-synchronizing impulse forward position and demodulation, this mistiming is star ground time delay Δ T
star ground time delay; By star ground time delay Δ T
star ground time delaysend to master control computer;
As Fig. 4, number pipe computing machine, while delta frame synchronous head EB90 (H), exports a negative pulse, and EB90 (H) the 1st bit forward position is aimed in its forward position.The psk signal using uphole equipment logarithm pipe to export carries out demodulation, and CORTEX, after completing PSK solution mediation channel-decoding, can externally export PCM signal waveform.By the PCM signal waveform of oscillograph observed number pipe frame-synchronizing impulse and ground demodulation, mistiming relatively between two paths of signals forward position, star ground time delay can be obtained, as Fig. 3, desktop joint-trial is belonged in experiment, cable length used in experiment is all within 3 meters, and the measuring error caused by cable time delay, at nanosecond order, can be ignored.
The problem that star ground latency measurement runs into and solution, because CORTEX equipment (CORTEX2 in Fig. 5) the telemetry demodulation module used at present does not possess the function exporting PCM signal, therefore directly cannot carry out star ground latency measurement.For solving this problem, use a CORTEX1 that can export in CORTEX(Fig. 4 of remote measurement PCM waveform of model use in the past).During experiment, first use during GPS and unite source by the time synchronized of two CORTEX, the remote measurement psk signal of two CORTEX receiving demodulation number pipe outputs simultaneously afterwards, measure the star ground time delay Δ T of CORTEX1 according to the method described above
1 star ground time delay, when comparing the same frame remote measurement of two CORTEX demodulation afterwards beat the difference Δ T of markers
12 markers, calculate Δ T
1 star ground time delay-Δ T
12 markersbe exactly star ground time delay Δ T when using CORTEX2
2 star ground time delays.
This experiment actual measured results is as follows:
Step 6: by star ground time difference Δ T
the star ground time differencesend on star by observing and controlling up-link, for the time on clock adjustment star on star.
In sum, these are only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (3)
1. utilize oscillograph with carrying out star school time a method, it is characterized in that,
Step one: the several pipe computing machines on star, when generating downlink telemetry frame synchronization head EB90H the 1st bit forward position, obtain time t on star at that time
star, by this time encoding in current telemetry frame;
Step 2: the telemetry frame containing time encoding in step one is carried out pulse code, is modulated into pcm stream, converts described pcm stream to psk signal through sub-carrier modulation further;
Step 3: psk signal step 2 obtained sends to observing and controlling baseband equipment by video cable telemetering channel;
Step 4: observing and controlling baseband equipment carries out subcarrier demodulation to the psk signal received and obtains PCM signal, after demodulating telemetry frame synchronous head, records current ground elapsed time t in telemetry frame synchronous head the 1st bit forward position
ground,and by this ground elapsed time t
groundmaster control computer is mail to the telemetry demodulated;
Step 5: first master control computer parses time t on the star at that time in every frame telemetry
starwith current ground elapsed time t
ground, obtain the difference DELTA t of time and ground elapsed time on star, Δ t=t
ground-t
star; Then according to formula Δ T
the star ground time difference=Δ t-Δ T
star ground time delay-Δ T
transmissioncalculate star ground time difference Δ T
the star ground time difference;
Wherein Δ T
transmissionlearnt by theory calculate or direct measurement; Δ T
star ground time delaydrawn by ground experiment, the on-board equipment adopted, uphole equipment are real equipment, and on-board equipment is connected by cable with uphole equipment, and cable length used in experiment is all within 3 meters, the measuring error caused by cable time delay, at nanosecond order, is ignored; Ground experiment comprises step one to step 4, and the step of increase is:
1) telemetry frame after step one time encoding is exported a number pipe frame-synchronizing impulse to oscillograph through pulse producer, telemetry frame synchronous head EB90H the 1st bit forward position in the forward position alignment procedures one of this number pipe frame-synchronizing impulse;
2) the PCM signal that step 4 demodulation obtains is sent to oscillograph, this PCM signal is with telemetry frame synchronous head EB90H;
3) oscillograph receives step 1) several pipe frame-synchronizing impulse and step 2) demodulation after PCM signal contrast: the mistiming obtaining telemetry frame synchronous head EB90H the 1st bit forward position of the PCM signal after several pipe frame-synchronizing impulse forward position and demodulation, this mistiming is star ground time delay Δ T
star ground time delay; By star ground time delay Δ T
star ground time delaysend to master control computer;
Step 6: by star ground time difference Δ T
the star ground time differencesend on star by observing and controlling up-link, for the time on clock adjustment star on star.
2. as claimed in claim 1 a kind of utilize oscillograph with carrying out star school time method, it is characterized in that, ground elapsed time t current in step 4
groundtime reference is provided by source of uniting during GPS.
3. as claimed in claim 1 a kind of utilize oscillograph with carrying out star school time method, it is characterized in that, wherein current ground elapsed time t
groundwhen mailing to master control computer with the telemetry demodulated, adopt the mode of remote measurement true add ground elapsed time mark.
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| CN201310127507.9A CN103197535B (en) | 2013-04-12 | 2013-04-12 | Method for satellite-ground timing with oscilloscope |
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| CN201310127507.9A CN103197535B (en) | 2013-04-12 | 2013-04-12 | Method for satellite-ground timing with oscilloscope |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109085609A (en) * | 2018-06-28 | 2018-12-25 | 上海卫星工程研究所 | Xing Shang mechanism closed-loop control latency measurement system and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103777517A (en) * | 2013-12-27 | 2014-05-07 | 航天科工深圳（集团）有限公司 | System and method for checking GPS time setting precision |
| CN105068415B (en) * | 2014-12-31 | 2017-11-03 | 中国人民解放军63921部队 | Method during with testing survey station star school is docked without star |
| CN105182733A (en) * | 2015-08-07 | 2015-12-23 | 北京利和顺达电子有限公司 | Precision improvement method and system for Beidou time service synchronization |
| CN107329394B (en) * | 2017-05-16 | 2019-06-28 | 上海卫星工程研究所 | High precision star ground time difference measurement method |
| CN111812966B (en) * | 2020-07-02 | 2022-01-28 | 北京航天飞行控制中心 | Multi-spacecraft-based time difference between heaven and earth determining method, determining device and processor |
| CN114943061B (en) * | 2022-06-28 | 2022-10-25 | 北京航天驭星科技有限公司 | Satellite time difference data processing method and system, electronic device and medium |
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