CN104702401B - A kind of synchronous method of ground base navigation system time - Google Patents
A kind of synchronous method of ground base navigation system time Download PDFInfo
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- CN104702401B CN104702401B CN201510137785.1A CN201510137785A CN104702401B CN 104702401 B CN104702401 B CN 104702401B CN 201510137785 A CN201510137785 A CN 201510137785A CN 104702401 B CN104702401 B CN 104702401B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
- H04J3/0658—Clock or time synchronisation among packet nodes
- H04J3/0661—Clock or time synchronisation among packet nodes using timestamps
- H04J3/0667—Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays
Abstract
The invention discloses a kind of ground base navigation method, system time synchronization, its flow process is：S1：The timing signal of slave station tracking lock main website；S2：After tenacious tracking, slave station clock frequency and main website are consistent, and carry out two-way Time transfer receiver；S3：During two-way Time transfer receiver, measuring apparatus transmission channel is propagated with the signal of receiving channel and is combined time delay；S4：Collect main website measurement result；S5：Calculate clock error between stations △ t ', slave station adjusts clock as side-play amount；That is, according to two-way Time transfer receiver result and propagation combination time-delay calculation clock error between stations, adjust local clock using this clock error between stations.The present invention can overcome the impact timing tracking accuracy for the tropospheric delay, realize precise synchronization between low cost station.
Description
Technical field
The invention mainly relates to ground base navigation system regions, refer in particular to a kind of synchronization side being applied to ground base navigation system time
Method.
Background technology
Applied satellite navigation system positioning, generally existing signal blocks problem in the environment such as mountain area, city, interior.Especially
It, in some large size cities, causes a large amount of urban canyons because high building stands in great numbers, and leads to visible star to reduce so that satellite navigation positions
Precision substantially reduces.In this case, ground base navigation system base-station, transmitting are arranged on several known or measurable coordinate points
Ground based system navigation signal, can strengthen and improve integrity, the positioning precision of alignment system；Even in satellite-signal quilt completely
In the case of blocking, ground base navigation system can be from becoming " constellation ", and the region for demand provides high-precision location navigation service.
Such as, ground base navigation system can be used as the supplement of Beidou satellite navigation system, backup, enhancing, and it is mainly characterized by can either
With satellite navigation system collaborative work it is also possible to satellite navigation system disturbed, being blocked etc. cannot be under use condition, one
High accuracy, highly reliable positioning and time service service is separately provided in individual finite region.
Locata system is a zone location navigation system based on continental rise of Australian GPS production firm exploitation,
Not only can be suitably used for the area navigation location requirement that under some extreme terrains, gps signal cannot cover, also can be in strong electromagnetic
Under environment, GPS location functional realiey is strengthened.Locata system can meet mining industry measurement, machine guiding/control, building prison
The demand of the hi-Fixs such as survey, interior.Equally, the enhancing service realizing the Big Dipper is also required to build ground base navigation system.
Time synchronization technique is the key technology of ground base navigation system, according to ground navigator fix principle, between base station when
Between synchronization accuracy directly affect navigator fix performance.According to the difference of signal transmission medium, Time synchronization technique can be divided into wirelessly
With wired two kinds.Wherein, the wire communication method such as fiber optic communication is difficult to be affected by the external environment, have higher certainty of measurement with
And preferable interference free performance.However, wired mode can be subject to the constraints such as topography and geomorphology, by contrast, radio communication is more
Can adapt to the demand at ground base navigation system flexible cloth station, therefore range of application is wider.
Satellite system, after measuring clock correction by radio communication, adjusts atomic frequency the stability using atomic clock
Keep and system time synchronization, but atomic clock involves great expense and is unsuitable for the large-scale application of ground base navigation system.Locata adopts
TimeLoc Time synchronization technique, while providing precision positioning, only need to use and be furnished with the receiver of temperature compensating crystal oscillator and receive list
Just it is capable of time synchronized between station to signal.However, in the case of can not ignoring troposphere impact, the time of Locata is same
Step technology needs to model by tropospheric high accuracy, which increases the complexity of technology realization, is unfavorable for pushing away on a large scale
Wide and use.
Content of the invention
The technical problem to be solved in the present invention is that：The technical problem existing for prior art, the present invention provides one
Plant high precision, the impact timing tracking accuracy for the tropospheric delay can be overcome, realize precise synchronization between low cost station
Ground base navigation method, system time synchronization.
For solving above-mentioned technical problem, the present invention employs the following technical solutions：
A kind of ground base navigation method, system time synchronization, its flow process is：
S1：The timing signal of slave station tracking lock main website；
S2：After tenacious tracking, slave station clock frequency and main website are consistent, and carry out two-way Time transfer receiver；Main website to from
Stand direction, if main website t1The timing signal in moment is by from standing in t2Reception arrives, and comparison result is t2-t1, slave station to main website side
To if slave station t3The timing signal in moment is by main website in t4Reception arrives, and comparison result is t4-t3；
S3：Pseudorange and equipment delay between measuring station is distinguished during two-way Time transfer receiver；Described equipment delay is tA+rA、
tB+rB, wherein tABe in website A in the communication process of website B website A transmitter module circuit delay, rBIt is to arrive at a station in website A
Website B receiver module circuit delay in the communication process of point B；tBIt is the website B transmitting in the communication process of website A in website B
Modular circuit postpones, rABe in website B in the communication process of website A website A receiver module circuit delay；
S4：Collect main website measurement result；
S5：Calculate clock error between stations △ t ', slave station adjusts clock as side-play amount；That is, tied according to two-way Time transfer receiver
Fruit and equipment delay (tB+rB,tA+rA) calculate clock error between stations：
Adjust local clock using this clock error between stations；Main website broadcasts the premise that signal continues tracking lock in above process
Under, using half-duplex mode of operation, realize two-way Time transfer receiver using the navigation signal that base station is broadcast.
As a further improvement on the present invention：Set up clock error between stations measurement model, described clock error between stations in above process
Measurement model is used for analyzing the main source of error of clock correction measurement, including signal trace measurement error, equipment delay calibration error
And the measurement error of signal space propagation delay.
Compared with prior art, it is an advantage of the current invention that：
1st, the present invention is for receiver user, when the time synchronized of website is that each base station has unified signal transmitting
Carve, according to this basic feature, clock error between stations on the basis of navigation signal x time for the definition.
2nd, clock error between stations model of the present invention, its clock correction certainty of measurement depends on tracking accuracy, time delay self calibration
Precision and troposphere time delay round-off error.
3rd, in the present invention, two-way Time transfer receiver method can eliminate troposphere impact, and timing tracking accuracy between station is promoted to
The level suitable with receiver tracking navigation signal precision, theoretical analysis and test result shows that timing tracking accuracy is better than 1ns.
4th, the present invention is according to clock error between stations model, and between standing, time synchronism equipment should possess the tracking measurement to timing signal
Function and equipment transmitting-receiving combination latency measurement function；For realizing two-way Time transfer receiver, should possess synthesis and the transmitting work(of signal
Can, due to the navigation signal broadcast using half-duplex mode of operation, available base station, reduce the complexity of equipment realization；For
Revise clock error between stations, also should possess local clock adjustment and calibration function, this function can combine low cost by Digital processing device
Temperature compensating crystal oscillator realize.
5th, the present invention breaches ground base navigation system precise synchronization technology, overcomes tropospheric delay same to the time
The impact of step precision, split-second precision in the case of not increasing navigator hardware complexity it is achieved that between the station of low cost
Synchronous.
Brief description
Fig. 1 be in concrete application example of the present invention station between signal transmission delay schematic diagram.
Fig. 2 is that in concrete application example of the present invention, between station, two-way time half-duplex compares principle schematic.
Fig. 3 be in concrete application example of the present invention station between time synchronized schematic flow sheet.
Specific embodiment
Below with reference to Figure of description and specific embodiment, the present invention is described in further details.
The time synchronized of ground base navigation system refers to：Slave station time synchronized, in main station time, locks including temporal frequency
And time difference measurement.As shown in figure 3, the ground base navigation method, system time synchronization (time synchronized between standing) of the present invention, concrete stream
Cheng Wei：
S1：The timing signal of slave station tracking lock main website；
S2：After tenacious tracking, slave station clock frequency and main website are consistent, and carry out two-way Time transfer receiver；
S3：Pseudorange and equipment delay between measuring station is distinguished during two-way Time transfer receiver；
S4：Collect main website measurement result；
S5：Calculate clock error between stations △ t ', slave station adjusts clock as side-play amount.That is, tied according to two-way Time transfer receiver
Fruit and equipment delay calculate clock error between stations, adjust local clock using this clock correction.
In above process, the present invention needs to set up clock error between stations measurement model, and this clock error between stations measurement model is used for dividing
The main source of error of analysis clock correction measurement, passes including signal trace measurement error, equipment delay calibration error and signal space
The measurement error that sowing time prolongs.
In above process, the present invention based on two-way Time transfer receiver clock correction measure, main website is broadcast signal persistently with
In the situation of track locking, using half-duplex mode of operation, realize two-way Time transfer receiver using the navigation signal that base station is broadcast.
In step S3 of said process, the present invention needs the signal propagation group of measuring apparatus transmission channel and receiving channel
Close time delay.
In a concrete application example, as shown in figure 1, signal transmission delay schematic diagram, ground base navigation system between for station
Site apparatus include receiving and transmitter module, receive and transmitter module shares a digital baseband signal processing unit.Wherein, connect
Receive module and include ADC, down coversion passage, reception antenna, transmitter module includes DAC, up-conversion passage, transmitting antenna.In signal
In propagation, existence time postpones item, includes following delay by the communication process of website A to website B：Website A transmitter module circuit prolongs
T lateA, spatial transmission delay τAB, website B receiver module circuit delay rB；Included by the propagation delay of website B to website A：Website
B transmitter module circuit delay tB, spatial transmission delay τBA, website A receiver module circuit delay rA.Wherein, equipment delay is tA+
rA、tB+rB, spatial transmission time delay is：Spatial transmission postpones τAB, spatial transmission postpone τBA.
Next, setting up slave site A to the time transmitted model of website B.As shown in figure 1, website B is in t2Moment detects
The timing signal that website A produces.Now, the time of website A is t1+tA+τAB+rB, due to website between there is clock correction △ t, therefore：
t1+tA+τAB+rB+ △ t=t2(1)
Thus, clock error between stations are obtained：
△ t=t2-t1-tA-τAB-rB(2)
By eliminating clock error between stations △ t, different websites can generate navigation signal simultaneously.However, during due to transmitter module
Prolong inconsistent, when through identical propagation distance, the time reaching receiver user is different, thus causing user's positioning meter
Calculate error.Therefore, each website should setup time be synchronous on the basis of signal x time, and defines new clock error between stations △ t ',
Meet：
△ t '=tB-tA-△t (3)
(2) are substituted into (3), obtains：
△ t '=t1-t2+(tB+rB)+τAB(4)
After measuring △ t ', as time offset, the clock of website B is modified, you can realize the website time same
Step.
Timing tracking accuracy depends on the measurement error of △ t ', including：Receiver is to t1Tracking measurement error, during equipment
Prolong (tB+rB) calibration error and signal space propagation delay measurement error σ (τAB).Wherein, σ (τAB) pass containing troposphere
Broadcast delay error, in the case of without accurate model correction, this error up to meter level, far above tracking measurement error and group
Close time delay calibration error, become the topmost source of error of time synchronized between station.Degree of precision troposphere can be set up between star ground pass
Broadcast model, however, in the case of ground base navigation system altitude angle is relatively low, mapping model deviation is larger.In order to avoid troposphere passes
Broadcast the impact that model error brings to clock correction certainty of measurement, the present invention proposes using clock between two-way Time transfer receiver method measuring station
Difference.
As shown in Fig. 2 bi-directional half-duplex Time transfer receiver schematic diagram between for station.Two-way Time transfer receiver method is a kind of high accuracy
Clock error measuring method, in the case of both direction spatial transmission time delay approximately equal, even if propagation delay is unknown, still can essence
Really measure clock correction.In ground base navigation system, site location is fixed, and two-way propagation time delay has short-term stability.Therefore, duplex or
Semiduplex mode all can meet high-acruracy survey demand.In order to avoid near-far interference, website can broadcast navigation in different time-gap
Signal, according to semiduplex mode, just can be utilized the navigation signal that website is broadcast to realize time synchronized between station.Semiduplex mode
Under, the bidirectional measurement process between website is as shown in Figure 2.
According to the time relationship of in figure, A sends out the B time receiving and can draw formula (2), and then obtains formula (4), and B sends out the A time receiving,
Can draw：
△ t=t3+tB+τBA+rA-t4(5)
Formula (5) is substituted into (3), obtains：
- △ t '=t3+(tA+rA)+τBA-t4(6)
Obtained with formula (6) according to formula (4)：
Because two-way propagation time delay is consistent, i.e. τAB=τBA, formula (7) can be changed to：
According to (8), the certainty of measurement of △ t ' is only with timing signal t1,t3Tracking measurement error and equipment delay (tA+
rA),(tB+rB) calibration error relevant.Site apparatus belong to isomorphism design, and negligible above-mentioned error is in the difference of equipment room, then
Clock correction certainty of measurement σ (△ t ') is represented by：
In formula, σtranRepresent timing signal tracking measurement error, σchanRepresent equipment delay calibration error.Using identical
Signal system, because operating distance is shorter, meets σchan<σtran, therefore：
σ(△t′)<σtran(10)
When timing signal adopts the navigation signal of DSSS mode, tracking measurement error is represented by：
In formula, BnFor loop noise bandwidth, D is that correlator is spaced in front and back, TcohFor coherent integration time, C/N0Carry for intermediate frequency
Make an uproar ratio.Take D=1, loop integral time TcohTake 1ms, under different carrier-to-noise ratios, the relation of certainty of measurement and loop bandwidth is entered
Row emulation.Simulation result shows：When loop bandwidth is less than 20Hz, carrier-to-noise ratio C/N0>In the case of 50dBHz, tracking accuracy is better than
1ns, according to formula (10), website timing tracking accuracy is better than to navigation signal tracking accuracy.
From the foregoing, it will be observed that the present invention has redefined clock error between stations on the basis of timing signal x time, establish clock correction
Measurement model, analyzes the main source of error of clock correction measurement, including tracking measurement error, equipment delay calibration error and letter
The measurement error of number spatial transmission time delay.Carry out two-way Time transfer receiver on the basis of the locking of unidirectional temporal frequency, using half pair
Work mode of operation, to allow the navigation signal of time-division system as timing signal, it is to avoid increases Design of Signal and equipment realization
Complexity, in addition, the method for the present invention can effectively overcome the impact of tropospheric delay, TOA measurement accuracy is promoted to tracking
The precision level of navigation signal.
The above is only the preferred embodiment of the present invention, protection scope of the present invention is not limited merely to above-described embodiment,
All technical schemes belonging under thinking of the present invention belong to protection scope of the present invention.It should be pointed out that for the art
For those of ordinary skill, some improvements and modifications without departing from the principles of the present invention, should be regarded as the protection of the present invention
Scope.
Claims (2)
1. a kind of ground base navigation method, system time synchronization is it is characterised in that flow process is：
S1：The timing signal of slave station tracking lock main website；
S2：After tenacious tracking, slave station clock frequency and main website are consistent, and carry out two-way Time transfer receiver；Main website is to slave station side
To if main website t1The timing signal in moment is by from standing in t2Reception arrives, and comparison result is t2-t1, slave station to main website direction,
If slave station t3The timing signal in moment is by main website in t4Reception arrives, and comparison result is t4-t3；
S3：Pseudorange and equipment delay between measuring station is distinguished during two-way Time transfer receiver；Described equipment delay is tA+rA、tB+
rB, wherein tABe in website A in the communication process of website B website A transmitter module circuit delay, rBIt is in website A to website B
Communication process in website B receiver module circuit delay；tBBe in website B in the communication process of website A website B transmitter module
Circuit delay, rABe in website B in the communication process of website A website A receiver module circuit delay；
S4：Collect main website measurement result；
S5：Calculate clock error between stations △ t ', slave station adjusts clock as side-play amount；That is, according to two-way Time transfer receiver result with
And equipment delay (tB+rB,tA+rA) calculate clock error between stations：
Adjust local clock using this clock error between stations；On the premise of main website broadcasts the lasting tracking lock of signal in above process,
Using half-duplex mode of operation, realize two-way Time transfer receiver using the navigation signal that base station is broadcast.
2. ground base navigation method, system time synchronization according to claim 1 is it is characterised in that set up in above process
Clock error between stations measurement model, described clock error between stations measurement model is used for analyzing the main source of error of clock correction measurement, including signal
The measurement error of tracking measurement error, equipment delay calibration error and signal space propagation delay.
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| CN106533528B (en) * | 2016-09-27 | 2019-04-05 | 北京无线电计量测试研究所 | The two-way time compares compression and the calculation method of modem transmitted data amount |
| CN107635280A (en) * | 2017-08-24 | 2018-01-26 | 中国电子科技集团公司第五十四研究所 | Signal source method for synchronizing time based on signal fusing and frequency difference On-line Estimation |
| CN108123684B (en) * | 2017-12-19 | 2021-05-25 | 中国科学院深圳先进技术研究院 | Digital down-conversion processing method and device |
| CN112566237B (en) * | 2020-11-30 | 2022-11-15 | 中国科学院国家授时中心 | Time synchronization method based on multi-node networking |
| CN113507742B (en) * | 2021-07-09 | 2022-04-29 | 电子科技大学 | Time synchronization method for ground-based navigation positioning system |
| CN115085847A (en) * | 2022-06-13 | 2022-09-20 | 中国电子科技集团公司第十研究所 | Multi-user clock error measuring method |
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