CN108919312A - Independent navigation signal enhancing method based on low orbit satellite - Google Patents
Independent navigation signal enhancing method based on low orbit satellite Download PDFInfo
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- CN108919312A CN108919312A CN201810414742.7A CN201810414742A CN108919312A CN 108919312 A CN108919312 A CN 108919312A CN 201810414742 A CN201810414742 A CN 201810414742A CN 108919312 A CN108919312 A CN 108919312A
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/33—Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/35—Constructional details or hardware or software details of the signal processing chain
- G01S19/37—Hardware or software details of the signal processing chain
Abstract
The invention discloses the independent navigation signal enhancing methods based on low orbit satellite, it realizes that the load includes GNSS receiving module, main control module, transmitting module, high steady clock module, at least a set of GNSS signal receiving antenna and at least a set of enhancement information transmitting antenna using the load being equipped on low orbit satellite；GNSS receiving module is used to acquisition and tracking navigation satellite signal, autonomous orbit determination and autonomous time service on planet of going forward side by side；Main control module is used to and GNSS receiving module and transmitting module interaction data；Transmitting module is used to that the result data of autonomous orbit determination on star and autonomous time service is encoded into text and carries out signal modulation, is broadcast；High steady clock module is used to provide time and frequency standards.The present invention carries out navigator fix by joint low orbit satellite navigation enhancement information and navigation satellite signal, can effectively improve the precision, availability and reliability of navigator fix.In addition, the present invention does not depend on earth station, ground enhancing technology is compared, application is more flexible.
Description
Technical field
The invention belongs to aerospace fields and field of satellite navigation, and in particular to the independent navigation letter based on low orbit satellite
Number Enhancement Method.
Background technique
Global Satellite Navigation System (GNSS) is capable of providing in global range continuously real-time positioning service, by widely
Multiple fields applied to the development of the national economy.Existing GNSS system can well solve most application demand, so
And its there is also certain fragility, including：(1) signal is easy to be interfered, and GNSS signal reaches the letter in ground-plane antenna mouth face
Number intensity is about -150dBw to -160dBw, tens dB also lower than noise.It, may once there is the stronger interference source of signal on ground
Satellite positioning service in very wide range is caused to be paralysed；(2) signal ability through walls is weak, can not solve signal blocks and indoor positioning
Problem；(3) at present in about 12 hours or 24 hours high rail navigation satellite orbital period, the corresponding single of middle rail passes by visible arc
Duan Yuewei several hours, the opposite geometric configuration variation between satellite and ground receiver is slower, accordingly causes precision positioning
Need the convergent time long.More than there is a problem of due to existing GNSS system, need further to build navigation enhancing system
System is to further expand and improve GNSS navigator fix performance and system.
Major part satellite-based navigation enhancing system is all to utilize ground monitoring network meter by the way of information enhancement at present
It calculates in the information of track, clock deviation, ionospheric error, integrity index etc. on note to telecommunication satellite, recycles telecommunication satellite
It is forwarded to terrestrial user.User terminal decodes to obtain information, is used further to correct the locating effect that local observation obtains higher precision.
Information enhancement can be described as a kind of function of making something perfect even more perfect, and in the effective region GNSS, he is able to ascend the service of GNSS positioning
Performance is done locating effect more preferable；But the region that GNSS can not work or positioning performance is bad, information enhancement are also incompetent
For power.The important topic of GNSS research so how to solve the problems, such as GNSS signal fragility, wherein by space-based or
The form of ground, which carries out enhancing to GNSS signal, becomes improvement GNSS signal fragility, improves the important hand of its navigator fix performance
Section.The equipment such as existing GNSS signal enhancements, including pseudo satellite, pseudolite, GPS transponder are all ground enhancements, service range
Very little, and equipment is expensive, it is difficult to it is widely applied.
Summary of the invention
It is certainly leading the object of the present invention is to provide a kind of low orbit satellite independent navigation enhancing load and based on low orbit satellite
Boat signal enhancing method.
Low orbit satellite independent navigation provided by the invention enhances load, includes at least：
GNSS receiving module, main control module, transmitting module, high steady clock module, at least a set of GNSS signal receiving antenna,
And at least a set of enhancement information transmitting antenna；
GNSS signal receiving antenna, GNSS receiving module, main control module, transmitting module, enhancement information transmitting antenna are sequentially
It is connected；
The GNSS receiving module is used to according to the received GNSS navigation satellite signal of GNSS signal receiving antenna, capture with
The track whole world or area navigation satellite-signal, carry out autonomous orbit determination and autonomous time service on star；And it exports second pulse signal and carries out whole star
Time service and taming high steady clock module；
The main control module be used to power and with GNSS receiving module and transmitting module interaction data；
The transmitting module is used to that the result data of autonomous orbit determination on star and autonomous time service is encoded into text and carries out letter
Number modulation, obtain low orbit satellite navigate enhancement information, broadcast by the enhancement information transmitting antenna；
The high steady clock module connects the GNSS receiving module and the transmitting module simultaneously, defends for providing low rail
The time and frequency standards of star navigation enhancement information transmitting.
Further, the main control module is also used to and Integrated Electronic System interaction data.
The main control module be also used to Integrated Electronic System interaction data, including：
The working condition of low orbit satellite independent navigation enhancing load is sent to Integrated Electronic System；
Receive and respond the observing and controlling instruction of Integrated Electronic System transmission.
The main control module be also used to Integrated Electronic System interaction data, further include：
External enhancement information is read from Integrated Electronic System, and is transmitted to GNSS receiving module, GNSS receiving module combines
External enhancement information and GNSS navigation satellite signal carry out autonomous orbit determination and autonomous time service on star.
Further, the transmitting module carries out signal modulation, specifically includes：
The corresponding track of previous moment and clock deviation are extrapolated to subsequent time, the track of extrapolation and clock deviation are compiled into electricity
Text, and signal modulation is carried out in the subsequent time；Meanwhile rising edge or the decline for the ranging code for generating text and high steady clock
Edge and subsequent time alignment.
Further, the GNSS receiving module and the transmitting module add filter respectively, to avoid transmitting signal
Interfere the reception of GNSS navigation satellite signal.
Independent navigation signal enhancing method provided by the invention based on low orbit satellite, includes at least：
According to the time difference that autonomous time service determines, low orbit satellite local zone time was adapted on the GNSS system time；
The low orbit satellite navigation enhancement information and navigation satellite generated in conjunction with aforementioned low orbit satellite independent navigation enhancing load
Signal carries out alignment by union.
When multiple low rails navigation enhancing satellites cooperate, one-way or bi-directional ranging between star is carried out by inter-satellite link,
According to the difference of the measured value of inter-satellite link distance and theoretical value, it is inclined to determine that multiple low rail navigation enhance intersatellite relative time clock
Difference realizes that the relative time of multiple low rail navigation enhancing satellites is synchronous according to relative time clock deviation；
The low rail navigation enhancing satellite assignment has the claim 1~6 low orbit satellite independent navigation enhancing load
Low orbit satellite.
Further, realize that the relative time of multiple low rail navigation enhancing satellites is synchronous by inter-satellite link, including：
Select a low orbit satellite as reference star, reference star emits distance measuring signal and itself position to other low orbit satellites
It sets, obtains measured value of the reference star at a distance from other low orbit satellites；
Other low orbit satellites pass through and GNSS navigation satellite one-way timing；
Other low orbit satellites calculate self-position, calculate the theoretical value with reference star distance further according to reference star position；
By the difference of measured value and theoretical value, the relative time clock deviation between other low orbit satellites and reference star is determined, from
And realize that relative time is synchronous.
When multiple low rail navigation enhancing satellites cooperate, formation flight is carried out to multiple low rail navigation enhancing satellites,
Synchronization the same area is set to have 4 and visible above low rail navigation enhancing satellite；
The low rail navigation enhancing satellite assignment has the claim 1~6 low orbit satellite independent navigation enhancing load
Low orbit satellite.
The present invention is based on one for being implemented as low orbit satellite of the independent navigation signal enhancement system of low orbit satellite to have
Load is imitated, which should be provided simultaneously with to day reception, the in-orbit function of handling, emit over the ground.In particular, the load should have
The ability of double frequency or multifrequency GNSS signal acquisition and tracking, can it is in-orbit and meanwhile receive existing GPS, Beidou, GLONASS,
The signal of the navigation system such as Galileo, and realize autonomous precise orbit determination and time service on star.Meanwhile load need to be equipped with it is high performance
Frequency source and clock tame circuit and guarantee that time reference and GNSS on star have higher accuracy.Finally independently being determined on star
The information codings such as satellite orbit, speed, clock deviation at telegraph text data, after generating ranging code using high steady clock and modulate text,
Navigation enhancement information is generated to broadcast to the ground.Ground receiver can receive existing navigation signal and simultaneously from low orbit satellite
Navigation enhancement information, carries out alignment by union, to improve the availability of satellite navigation and positioning service, the performances such as convergence time.
The invention has the characteristics that and beneficial effect：
(1) present invention can not directly rely on ground monitoring station, tracking station, control station, that is, can provide navigation enhancing service；
The limitation that ground is built a station can be broken through, there is good independent navigation ability；It is not afraid of ground interference, there is stronger capability to resist destruction；
In addition, in ocean and the region that can not build earth station such as overseas, navigation enhancing performance will not be remarkably decreased.
(2) compared with existing middle high rail navigation satellite, the present invention is based on the independent navigation signal enhancing sides of low orbit satellite
There is method geometric position to change fast advantage, can effectively shorten precision positioning convergence time；In the case where observation condition is severe,
Effective observation number can be increased, improve the availability and reliability of navigator fix service.
(3) low orbit satellite navigation enhancement information can the stronger signal of transmitting ratio pilot signal power, these signals have one
Fixed ability through walls, can realize indoor positioning to a certain degree.
(4) flexible form of low orbit satellite navigation enhancement information, can not depend on earth station, realize that independent navigation enhances function
Energy；External enhancement information raising orbit determination in real time and time service performance, the track and clock deviation of higher precision, which can also be used, to be effectively reduced
Its user equivalent range error improves reinforcing effect.
(5) it although the overlay area of low orbit satellite navigation enhancement information is limited, can be realized by modes such as formation flights
The emphasis of key area enhances；Whole world enhancing can also be realized by global networking；The item of interference is received in area navigation receiver
Under part, enhancement information can still keep continuous work.
Detailed description of the invention
Fig. 1 is the schematic diagram that low orbit satellite independent navigation of the present invention enhances load；
Fig. 2 is the transmitting timing diagram of low orbit satellite navigation enhancement information；
Fig. 3 is the schematic diagram of the independent navigation signal enhancement system based on low orbit satellite.
Specific embodiment
In order to illustrate more clearly of the present invention and/or technical solution in the prior art, Detailed description of the invention sheet will be compareed below
The specific embodiment of invention.It should be evident that drawings in the following description are only some embodiments of the invention, for this
For the those of ordinary skill of field, without creative efforts, it can also be obtained according to these attached drawings others
Attached drawing, and obtain other embodiments.
It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not intended to limit the present invention.
In addition, technical characteristic involved in the various embodiments of the present invention described below is as long as they do not conflict with each other
It can be combined with each other.
Low orbit satellite independent navigation shown in FIG. 1 enhances load, including GNSS receiving module, main control module, transmitting module
With high steady clock module.The GNSS receiving module be used to the whole world such as acquisition and tracking GPS, GLONASS, Beidou, Galileo or
Area navigation satellite-signal carries out autonomous orbit determination and time service on star.Autonomous orbit determination can utilize pseudorange, the carrier wave phase of GNSS on star
Position, doppler measurement and satellite orbit dynamic information obtain real-time, smooth, reliable track letter by way of filtering
Breath and corresponding temporal information.More specifically, the GNSS receiving module can realize three functions：Export 1PPS (pulse per second (PPS) letter
Number) carry out whole star time service；1PPS or 10M clock signal is exported for taming high steady clock module；Output track and clock deviation are to master
Control module.
As the GNSS receiving module of low orbit satellite, the time service and time synchronization of whole star need to be responsible for, therefore PPS output is very
It is important.PPS is very crucial to satellite gravity anomaly, camera exposure control, communication payload etc..It is constrained using dynamics of orbits defeated
Orbit determination result out can be effectively reduced the uncertainty of GNSS one-way timing, improve the accuracy of PPS.Since GNSS receives mould
Block is equipped with common temperature compensation type quartz crystal oscillator TCXO, short-term stability about 10-6~10-7, it is unable to satisfy navigation enhancement information hair
Penetrate the requirement to index of mutually making an uproar.But the PPS signal of GNSS receiving module output is aligned with the markers of navigation satellite, thus is had preferably
Long-term stability, can be used for taming high steady clock module, to improve its frequency accuracy.In addition, GNSS receiving module calculates
Obtained track, clock deviation can be transmitted to main control module, are transmitted to other load by main control module, such as have the phase for staring mode
Airborne lotus, the communication payload for having dexterous communication function, number posting lotus etc..It is carried for supporting the navigation of ground enhancement mode to enhance
Lotus, GNSS receiving module can also further increase the precision of autonomous orbit determination and time service by receiving external enhancement information.More
Body, the external enhancement information infused on ground can be sent to main control module by whole star Integrated Electronic System, then be forwarded to GNSS
Receiving module.External enhancement information may include the navigation satellite track of actual measurement or forecast, clock deviation parameter, satellite end hardware prolong
Late, the information such as the decimal deviation of carrier phase, ionosphere correction.External enhancement information can also be led to by the directly upper note in ground
Cross data relay satellite forwarding.
In present embodiment, the main control module includes three functions：Complete machine power supply, the number with Integrated Electronic System
According to interaction and control GNSS receiving module and transmitting module.More specifically, the power supply system of main control module connects low orbit satellite
Power-supply system, for be responsible for low orbit satellite independent navigation enhancing load power supply, pressure stabilizing, ripple and Surge suppression.With synthesis
The data interaction of electronics specifically includes the content of three aspects：(1) low orbit satellite independent navigation enhances the acquisition of loaded-up condition and turns
Hair；(2) parsing and execution of observing and controlling instruction；(3) external enhancement information circulation hair.Low orbit satellite independent navigation enhances loaded-up condition
Acquisition refer to forwarding, by low orbit satellite independent navigation enhancing load working condition be sent to Integrated Electronic System.Work shape
State includes open state, the operating mode of complete machine, the operating temperature, orbit determination of low orbit satellite independent navigation enhancing each subfunction of load
State and the track, speed, the clock deviation parameter that determine etc..These working conditions can be used as the foundation of center machine breakdown judge,
It can be packaged by being passed under observing and controlling channel, for monitoring the working condition of low orbit satellite independent navigation enhancing load.Observing and controlling instruction
Parsing and execution refer to, the control instruction that response Integrated Electronic System is sent, including open and close subfunction, change orbit determination strategy
Mode, control enhancement information emit, and clock is tamed etc..For supporting the load of terrestrial information enhancing, also by main control module from comprehensive
It closes electronic system to read enhancement information and be transmitted to GNSS receiving module, for improving the precision of autonomous orbit determination in real time and time service.
In addition, main control module can also have data storage function.
In present embodiment, the transmitting module at least should include three functions：Text generation, signal modulation and letter
Number transmitting.More specifically, text, which generates, includes：Track, clock deviation and the space-based integrity monitoring that GNSS receiving module is provided
Relevant field, layout are broadcast at message format.The rising edge for the ranging code that text needs and high steady clock generates or under
Drop is along alignment, so the modulation of text has real-time.And orbit computation, text generate to calculate and require to expend the time, so
Directly the navigation message of generation is modulated in distance measuring signal and is not able to satisfy real-time condition.In order to meet the real-time item of text
Part needs to carry out track and clock deviation the extrapolation of short time, in advance by after message coding, then is modulated in the correct time
It is issued on distance measuring signal and carrier wave.The telegraph text content of enhancement information of navigating modulation includes but is not limited to current satellite rail
Road, speed, clock deviation, clock drift, trajectory accuracy index, clock accuracy index, approve- useful index and navigation satellite integrity refer to
Mark etc..Since the visible segmental arc of low orbit satellite is shorter, the period of navigation message is unsuitable too long.Text excessive cycle may cause head
Secondary positioning time is elongated, also increases the probability that can not completely solve text, and can not completely solve text will affect real-time navigation
The availability of positioning.Low orbit satellite visible arc segment length representative value is 18~20 minutes, and text length suggestion is no more than 1 minute.
In the present invention, telegraph text content includes but is not limited to that satellite orbit, speed, clock deviation, clock drift, trajectory accuracy index, clock accuracy refer to
Mark, approve- useful index and integrity index of navigation satellite etc..
Signal modulation includes text modulation, ranging code modulation etc..In order to ensure carrier wave and ranging code along alignment, transmitting module
Crystal oscillator stability and accuracy should all meet the requirements, so being proposed with high stability crystal oscillator, chip-scale atomic clock or atomic clock.It is brilliant
The requirement of the second stability of vibration is substantially 10-10Magnitude, unmodulated carrier phase noise power spectrum density are not answered at f0 ± 10Hz
Higher than -60dBc/Hz, f0For the centre frequency of navigation enhancing signal.Otherwise the start-up phase potential difference of carrier wave and ranging code can not be ensured
Parameter influences carrier phase tracking loop performance.Transmission power is adjusted to specified by power amplifier after signal modulation
Power level is launched by enhancement information transmitting antenna.Signal modulating method of the present invention includes but is not limited to
BPSK, QPSK, 8PSK, BOC, MBOC, CBOC, AltBOC, TMBOC etc..
The high steady clock module is the nucleus module of low orbit satellite independent navigation enhancing load, it is main provide transmitting when
Frequency benchmark.Can navigation enhancement information be played reinforcing effect, be largely dependent on height by ground receiver acquisition and tracking
Steady clock module performance.High steady clock module refers to the higher clock module of frequency stability, and the typical high steady clock second stablizes
Degree is better than 10-9.The clock for meeting high steady condition includes but is not limited to constant-temperature crystal oscillator (OCXO), chip-scale atomic clock (CSAC), micro-
Type atomic clock and other types atomic clock.High steady clock module has in-orbit taming ability, tames and provides using GNSS signal
Its frequency accuracy.The key performance of high steady clock module includes frequency accuracy, stability and ageing rate.Wherein, stability
It is all the intrinsic index of clock module itself with ageing rate, accuracy needs to tame by GNSS time signal high-precision with GNSS
Clock alignment is spent, frequency accuracy deficiency will affect doppler measurement, or even influence signal capture.Frequency stability is in frequency
Domain is expressed as index of mutually making an uproar, and is expressed as shake (Jitter) index in time-domain.Stability deficiency will affect carrier phase and survey
Consistency away from code, or even the tracking of carrier loop is influenced, lead to frequent losing lock.The high stability crystal oscillator of navigation enhancing loading demands
Frequency accuracy is better than 10-10, the second stability of frequency source is better than 10-10.Ageing rate refers to that the speed of the variation of frequency, ageing rate are inclined
Low-frequency accuracy drops in conference.It tames, frequency accuracy can be corrected by taming circuit, therefore if progress is in-orbit
Particular/special requirement is not done to the ageing rate of high steady clock module.
For that can receive GNSS satellite signal, low orbit satellite independent navigation enhancing load of the present invention further include one or more sets with
The connected GNSS receiving antenna of GNSS receiving module, GNSS receiving antenna is for receiving GPS, Beidou, GLONASS, Galileo
Etc. navigation system satellite-signal.In view of the complexity of low orbit satellite gesture stability, some satellites need to be equipped with two sets or
It is cover GNSS receiving antennas to guarantee the continuity of real-time track more.
For that can send navigation enhancement information, low orbit satellite independent navigation of the present invention enhancing load also include one or more sets with
The connected enhancement information transmitting antenna of transmitting module.The number of enhancement information transmitting antenna depends on the frequency point of navigation enhancement information
Number.Load is enhanced to the low orbit satellite independent navigation for supporting multifrequency point navigation enhancement information simultaneously, needs to install multiple enhancings
Information transmitting antenna.To make navigation enhancing signal have certain ability through walls, realizes indoor positioning, low orbit satellite can be improved and lead
The power of boat enhancing signal.
Since the GNSS signal received is very faint, substantially in -160dBw magnitude.And enhancement information of navigating is about several
The dBw even magnitude of tens dBw.The geometric envelope of satellite is limited, and transmitting module and GNSS receiving module space length are closer,
Therefore need to ensure that interference signal does not receive for signal transmitting, i.e. transceiver insulation problem.When especially receiving and transmitting signal frequency is closer to,
It should be specifically noted that the filter of GNSS receiving module and the filter of transmitting module are chosen, ensures receive-transmit isolation, avoid itself
The interference that receiving and transmitting signal generates.
Fig. 2 show low orbit satellite independent navigation enhancing load it is in-orbit be autonomously generated low orbit satellite navigation enhancement information when
Sequence schematic diagram, two time shafts as shown in the figure respectively indicate the spaceborne clock of LEO (low-orbit satellite) and GNSS system time.LEO
Spaceborne clock is limited, the spaceborne clock of LEO by time service autonomous on star and GNSS system time unifying by time service precision
The time that the time of maintenance and GNSS system maintain still has a system time differences.
In Fig. 2, Ta indicates the time that GNSS receiving module (i.e. spaceborne receiver) is sampled according to local clock.With
For the spaceborne receiver of 1Hz sampling, the sampling time is usually at the whole second of local clock.Due to the spaceborne clock of LEO and GNSS
System time has differences, and the corresponding GNSS system time in sampling time is denoted as Ga, and the two is objectively same time point, still
In different times under system, the corresponding time is different.In order to realize single star timing function of LEO, the navigation enhancement information of LEO
Text and ranging code modulation when need and local clock the whole second be aligned.It is subsequent fixed since the Ta moment just receives signal
Rail time service calculating and message coding require the time, catch up with text is broadcast away at the Ta moment be it is impossible, at the soonest
The location status at Ta moment can be broadcast by waiting next moment.If Ta is Tp at next whole moment second of local clock, that
It needs to complete orbit determination time service calculating and message coding before the Tp moment arrives.Assuming that orbit determination and time service calculating are complete at the To moment
At message coding is completed at the Te moment, then can broadcast at the Tp moment.But what the Tp moment needed to broadcast is that the Tp moment is corresponding
Status information, rather than the status information at Ta moment, it is therefore desirable to extrapolate to the state of track.When orbit computation,
The To moment needs to complete orbit determination and extrapolation calculates, and the track and clock deviation parameter at Tp moment is obtained, then by the satellitosis of extrapolation
In information preparation to navigation message, signal modulation, transmitting are carried out to the Tp moment.When just can guarantee that the Tp moment broadcasts satellite Tp in this way
The status information at quarter, while the alignment of whole moment second Tp of the rising edge (or failing edge) and local clock of text and ranging code.
When low orbit satellite navigation augmentation system and existing GNSS signal realize alignment by union, uniform time reference is needed.Cause
This, autonomous time service needs to calculate accurate system time differences using the carrier phase and Pseudo-range Observations at Ta moment on star
Ta-Ga.It, can be by local zone time Ta and Tp reduction to GNSS system time Ga and Gp by this system time differences.It should infuse
Meaning, Ga and Gp are no longer the whole second under GNSS system time frame.
Fig. 3 show the schematic diagram of the independent navigation signal enhancement system based on low orbit satellite, the independent navigation signal
Enhancing system includes：Navigation satellite, low rail navigation enhancing satellite, ground based augmentation system and user terminal.The navigation satellite is
The satellite navigation system in the whole world such as some GPS, GLONASS, Beidou, Galieo or region, has space base when providing high-precision
Quasi- and transmitting navigation signal ability.
The low rail navigation enhancing satellite assignment has the low orbit satellite of low orbit satellite independent navigation enhancing load, has and leads
Boat enhancing function, receives GNSS signal and carries out autonomous orbit determination and time service on star, and has the steady clock module of height of high stability
It keeps time, meanwhile, it generates low orbit satellite navigation enhancement information and broadcasts to the ground.
The ground based augmentation system includes several tracking stations, data center and upper note station.Tracking station has track navigation
The ability of satellite-signal calculates the enhancement information of navigation satellite, such as track, clock deviation, ionosphere information by data center, then
Carry out forecast appropriate.The enhancement information of calculating is defended by note on upper note station or repeater satellite to the low rail navigation enhancing
Star.The low rail navigation enhancing satellite can be by the ground enhancement information of ground based augmentation system, to further increase orbit determination in real time
With the precision of time service.
Ground based augmentation system not necessarily feature for independent navigation signal enhancement system of the present invention, but it is preferred that it is special
Sign.It should be noted that the precision of orbit determination in real time and time service can be improved in the ground based augmentation system, but there is no ground based augmentation system, this hair
Bright independent navigation signal enhancement system can also work normally.
In the present invention, the navigation enhancing ground receiver positioned at ground receives navigation satellite signal simultaneously and low orbit satellite is led
Boat enhancement information, and realize alignment by union, to improve navigator fix performance.
Navigation enhancing ground receiver carries out alignment by union using observational equation shown in formula (1)：
In formula (1)：
Pi,GAnd Li,GRespectively indicate the Pseudo-range Observations and carrier phase observation data of i-th of frequency point GNSS satellite, Pi,LWith
Li,LRespectively indicate the Pseudo-range Observations and carrier phase observation data of low orbit satellite navigation i-th of frequency point of enhancement information, wherein carry
The form of wave phase observation expression distance；
ρ and δorbRespectively indicate geometric distance and satellite orbital error between standing star；
WithRespectively indicate the satellite end clock deviation of GNSS signal and low orbit satellite navigation enhancement information；
δtrIndicate navigation enhancing ground receiver generator terminal clock deviation；
T and IiRespectively indicate the ionosphere delay error of tropospheric delay and i-th of frequency point；
Br,iAnd Bs,iIt respectively indicates the relevant hardware deviation of receiver end under i-th of frequency point and the relevant hardware of satellite end is inclined
Difference；
br,iAnd bs,iIt is related to satellite end to respectively indicate the relevant original carrier phase deviation of receiver end under i-th of frequency point
Original carrier phase deviation；
λiIndicate the wavelength of i-th of frequency point
NiIndicate the carrier phase ambiguity of i-th of frequency point.
MPiIndicate the Multipath Errors of i-th of frequency point；
∈ indicates receiver noise.
Low orbit satellite navigate enhancement information pseudorange and carrier wave most of error source expression-form and existing GNSS
Navigation signal is consistent, can apply existing empirical model or Parameter Estimation Method row is eliminated.It is significant to note that low rail is defended
The receiver end clock deviation and satellite end clock deviation item of star navigation enhancement information.Navigation enhancing ground receiver can simultaneously acquisition and tracking it is more
A GNSS satellite signal, thus the local GNSS system time can be maintained, this time maintains precision about in several nanoseconds to tens
The level of nanosecond.The ranging code rising edge (or failing edge) of the navigation enhancement information of low orbit satellite transmitting is and low orbit satellite is local
The whole second of clock is aligned, rather than be aligned with the whole second of GNSS system time.It needs to determine system time according to autonomous time service
Low orbit satellite local zone time is adapted to the GNSS system time up again after difference.The variation characteristic of this system time difference and existing
GNSS satellite variation characteristic is different, thus needs specially treated.The precision of autonomous time service is better than navigation enhancing ground receiver on star
The machine time maintains precision, and low rail navigation enhancing satellite can just play the effect for improving navigation and positioning accuracy, and otherwise can only solve can
With property problem.
When multiple low rails navigation enhancing satellites cooperate, it can be realized by way of inter-satellite link one-way or bi-directional between star
Ranging, to further increase the relative time synchronization accuracy between low orbit satellite.Inter-satellite link passes through one-way or bi-directional survey
Away from form can realize inter-satellite accurate time transmission.Carrying out the synchronous method of relative time using inter-satellite link is：Select a low rail
Satellite emits distance measuring signal and itself position to other low orbit satellites as reference star, reference star；All low orbit satellites are all
By realizing one-way timing with GNSS satellite；Other low orbit satellites calculate the position of itself, count further according to the position of reference star
Calculate the theoretical value of distance.Itself relative time clock between reference star is determined by the difference of inter-satellite link measured value and theoretical value
Deviation.
Multiple low rail navigation enhancing satellites can realize the local signal enhancing of key area by way of formation flight,
It can be designed as constellation, the navigation enhancing service of global range be provided.Local signal enhancing refers to, by satellite formation flying,
There are 4 and visible above low rail navigation enhancing satellite in the same region, and the low orbit satellite of each visible low rail navigation enhancing satellite is certainly
Relative time synchronization accuracy is more accurate between leading boat enhancing load.When ground G NSS signal interferes, low rail can be used to lead
Boat enhancing satellite-signal realizes individually positioning.The strategy for being designed as constellation mainly utilizes global communications satellite constellation or remote sensing
Satellite constellation carries navigation enhancing load, is allowed to have navigation enhancement information emission function.It can so realize in global range
GNSS navigation satellite signal and low orbit satellite navigation enhancement information alignment by union.
For GNSS navigation satellite signal and multiple low orbit satellites navigation enhancement information alignment by union problem, it is contemplated that between star
Link can realize that track inter-satellite precision relative time is synchronous, and the observational equation of alignment by union is represented by：
To keep succinct, formula (2) only used Pseudo-range Observations, the mode and pseudorange class of carrier phase observation data processing
Seemingly, but additional consideration fuzziness parameter is needed.
In formula (2)：
Pi,GAnd Pi,LRespectively indicate the Pseudo-range Observations of GNSS satellite and low orbit satellite navigation i-th of frequency point of enhancement information；
(x, y, z) indicates user's end position；
CGIndicate the difference of receiver local clock and GNSS system time；
CL-GIndicate the reference star time system and the difference of GNSS system time of low rail navigation enhancing satellite；
εGAnd εLRespectively indicate the pseudorange observation noise of GNSS navigation satellite signal and low orbit satellite navigation enhancement information.
Based on observational equation shown in formula (2), positioning calculation is carried out using existing navigation and positioning algorithm.
Specific embodiment described herein is only to give an example to the invention patent spirit.The invention patent institute
Belonging to those skilled in the art can make various modifications or additions to the described embodiments or using similar
Mode substitute, but without departing from the spirit or beyond the scope defined by the appended claims of the invention patent.
Claims (10)
1. low orbit satellite independent navigation enhances load, characterized in that include at least：
GNSS receiving module, main control module, transmitting module, high steady clock module, at least a set of GNSS signal receiving antenna and
At least a set of enhancement information transmitting antenna；
GNSS signal receiving antenna, GNSS receiving module, main control module, transmitting module, enhancement information transmitting antenna are sequentially connected；
The GNSS receiving module is used to according to the received GNSS navigation satellite signal of GNSS signal receiving antenna, and acquisition and tracking is complete
Ball or area navigation satellite-signal carry out autonomous orbit determination and autonomous time service on star；And export second pulse signal carry out whole star time service,
And tame high steady clock module；
The main control module be used to power and with GNSS receiving module and transmitting module interaction data；
The transmitting module is used to that the result data of autonomous orbit determination on star and autonomous time service is encoded into text and carries out signal tune
System obtains low orbit satellite navigation enhancement information, is broadcast by the enhancement information transmitting antenna；
The high steady clock module connects the GNSS receiving module and the transmitting module simultaneously, leads for providing low orbit satellite
The time and frequency standards of enhancement information of navigating transmitting.
2. low orbit satellite independent navigation as described in claim 1 enhances load, it is characterized in that：
The main control module is also used to and Integrated Electronic System interaction data.
3. low orbit satellite independent navigation as claimed in claim 2 enhances load, it is characterized in that：
The main control module be also used to Integrated Electronic System interaction data, including：
The working condition of low orbit satellite independent navigation enhancing load is sent to Integrated Electronic System；
Receive and respond the observing and controlling instruction of Integrated Electronic System transmission.
4. low orbit satellite independent navigation as claimed in claim 2 enhances load, it is characterized in that：
The main control module be also used to Integrated Electronic System interaction data, further include：External increase is read from Integrated Electronic System
Strong information, and be transmitted to GNSS receiving module, GNSS receiving module combine external enhancement information and GNSS navigation satellite signal into
Autonomous orbit determination and autonomous time service on planet.
5. low orbit satellite independent navigation as described in claim 1 enhances load, it is characterized in that：
The transmitting module carries out signal modulation, specifically includes：
The corresponding track of previous moment and clock deviation are extrapolated to subsequent time, the track of extrapolation and clock deviation are compiled into text, and
Signal modulation is carried out in the subsequent time；Meanwhile the rising edge or failing edge of the ranging code for generating text and high steady clock, with
And subsequent time alignment.
6. low orbit satellite independent navigation as described in claim 1 enhances load, it is characterized in that：
The GNSS receiving module and the transmitting module add filter respectively, defend to avoid transmitting signal interference GNSS navigation
The reception of star signal.
7. the independent navigation signal enhancing method based on low orbit satellite, characterized in that include at least：
According to the time difference that autonomous time service determines, low orbit satellite local zone time was adapted on the GNSS system time；
The low orbit satellite independent navigation in conjunction with described in claim 1~6 enhances the low orbit satellite navigation enhancement information that load generates
And navigation satellite signal, carry out alignment by union.
8. the independent navigation signal enhancing method based on low orbit satellite as claimed in claim 7, it is characterized in that：
When multiple low rails navigation enhancing satellites cooperate, one-way or bi-directional ranging between star is carried out by inter-satellite link, according to
The measured value of inter-satellite link distance and the difference of theoretical value determine that multiple low rail navigation enhance intersatellite relative time clock deviation,
Realize that the relative time of multiple low rail navigation enhancing satellites is synchronous according to relative time clock deviation；
The low rail navigation enhancing satellite assignment has the low of the claim 1~6 low orbit satellite independent navigation enhancing load
Rail satellite.
9. the independent navigation signal enhancing method based on low orbit satellite as claimed in claim 8, it is characterized in that：
Realize that the relative time of multiple low rail navigation enhancing satellites is synchronous by inter-satellite link, including：
Select a low orbit satellite as reference star, reference star is obtained to other low orbit satellites transmitting distance measuring signal and itself position
Obtain measured value of the reference star at a distance from other low orbit satellites；
Other low orbit satellites pass through and GNSS navigation satellite one-way timing；
Other low orbit satellites calculate self-position, calculate the theoretical value with reference star distance further according to reference star position；
By the difference of measured value and theoretical value, the relative time clock deviation between other low orbit satellites and reference star is determined, thus real
Existing relative time is synchronous.
10. the independent navigation signal enhancing method based on low orbit satellite as claimed in claim 7, it is characterized in that：
When multiple low rail navigation enhancing satellites cooperate, formation flight is carried out to multiple low rail navigation enhancing satellites, is made same
One moment the same area has 4 and visible above low rail navigation enhancing satellite；
The low rail navigation enhancing satellite assignment has the low of the claim 1~6 low orbit satellite independent navigation enhancing load
Rail satellite.
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