CN101858981A - Method for realizing high sensitivity and quick first positioning of satellite navigation receiver - Google Patents
Method for realizing high sensitivity and quick first positioning of satellite navigation receiver Download PDFInfo
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Abstract
The present invention provides a method for realizing high sensitivity and quick first positioning of satellite navigation receiver. The method comprises the following steps: generating navigation message with update interval of 24 hours by a ground control center included in a global navigation satellite system and uploading to each navigation satellite, repeatedly broadcasting the navigation message with update interval of 24 hours by each navigation satellite to the satellite navigation receiver; in each update interval of the navigation message with update interval of 24 hours, the satellite navigation receiver only requires receiving a whole ephemeris under a strong signal state and can realize quick first positioning with the formerly received satellite ephemeris and an observation distance between the currently each visible navigation satellite and the satellite navigation receiver even when the satellite navigation receiver at the current time is in a weakest signal state and can not receive the satellite ephemeris. The method of the invention can greatly improve the sensitivity and quick first positioning capacity of the satellite navigation receiver.
Description
Technical field
The present invention relates to GLONASS (Global Navigation Satellite System), relate more specifically to a kind of satellite navigation receiver high sensitivity and method of locating first fast of realizing.
Background technology
Global Navigation Satellite System (GNSS) extensively had been used in the location and the navigation field of mobile device in recent years.At present, GNSS comprises Beidou satellite navigation system (COMPASS), and the Galilean satellite positioning system (GALILEO) of European Union of GPS (GPS), Muscovite GLONASS satellite navigation system (GLONASS), the China of the U.S., and the usable satellite number reaches more than 100.The ultimate principle that in the GNSS system satellite navigation receiver is positioned is, at first measure the Navsat of known location and the distance between the satellite navigation receiver, the data of comprehensive many Navsats are obtained the particular location of satellite navigation receiver then.In present GNSS system, satellite navigation receiver is according to the particular location (as shown in Figure 1) of determining himself at least from the navigation message of four Navsats.
Continuous expansion along with the GNSS range of application, sensitivity to satellite navigation receiver requires also more and more higher, highly sensitive receptivity can make satellite navigation receiver still can realize the location and follow the tracks of under indoor or scene that other satellite-signals are more weak, thereby has expanded the usable range of GNSS greatly.
For most of satellite navigation receivers in the GNSS system, sensitivity index comprises the index under a plurality of scenes, is respectively: tracking sensitivity, acquisition sensitivity and initial start sensitivity.At present, for example in gps system, can realize tracking sensitivity at-satellite navigation receiver below the 160dBm, simultaneously, the sensitivity of initial start and acquisition sensitivity also can reach respectively-142dBm and-below the 148dBm.
Satellite navigation receiver at first needs to finish to from the catching of the satellite-signal of Navsat, and finishing and catching needed lowest signal intensity is acquisition sensitivity; Can keep after catching satellite-signal is followed the tracks of needed lowest signal intensity is tracking sensitivity.In order to realize the location, satellite navigation receiver also needs the navigation message of demodulation Navsat transmission, and corresponding, the needed lowest signal intensity of demodulation navigation message is decoded message sensitivity.In above definition, tracking sensitivity is the highest, and acquisition sensitivity takes second place, and decoded message sensitivity is the poorest.
The primary positioning time of satellite navigation receiver (TTFF) is meant at this device from system start-up to finishing for the first time successful time that location Calculation spent.The all above-mentioned sensitivity of the primary positioning time of satellite navigation receiver and this device has substantial connection.
High sensitivity (High Sensitivity) and fast first station-keeping ability (fast TTFF) be at present and the common requirement of GLONASS (Global Navigation Satellite System) in the future.But the design of the navigation message in the present GNSS system directly causes existing satellite navigation receiver to be restricted in the ability aspect high sensitivity and the quick location.This can be described as the inadequate natural endowment of the navigation message of present GLONASS (Global Navigation Satellite System).In existing GLONASS (Global Navigation Satellite System), the navigation message term of validity that all Navsats are broadcast (or upgrading at interval) is all shorter, usually has only several hrs (＜=4 hours), that is to say, within during this period of time, identical navigation message is repeated to broadcast, and surpasses during this period of time that the navigation message content will be updated, and then is repeated to broadcast.
In the term of validity of the satellite ephemeris that formerly receives, satellite navigation receiver does not need to receive new satellite ephemeris can position calculating, thereby primary positioning time is shortened.If but the satellite ephemeris that had before received lost efficacy, the location Calculation first of this device can only just can be carried out after successfully receiving satellite ephemeris, thereby primary positioning time will depend on that satellite ephemeris receives the time that is spent.And satellite ephemeris receives success or not, and the time that is spent is depended on the intensity of the satellite-signal that satellite navigation receiver receives again.So the sensitivity of the navigation message term of validity and primary positioning time and navigation receiving trap has direct relation.
In order to overcome the existing too short such restriction of the satellite navigation system navigation message term of validity, extra ground or space backup system are widely adopted.But without exception, extra development and maintenance cost costliness, and limitation is still arranged.
In sum, need provide a kind of simple possible, and can fundamentally make things convenient for realization satellite navigation receiver high sensitivity and the quick method of location first to seem very necessary.
Summary of the invention
One or more problems in view of the above the invention provides a kind of realization satellite navigation receiver high sensitivity of novelty and the method for locating first fast.
According to the realization satellite navigation receiver high sensitivity of the embodiment of the invention and the method for locating first fast, comprising: the ground control centre that GLONASS (Global Navigation Satellite System) comprised is created to upgrade and is spaced apart 24 hours navigation message and is uploaded to every Navsat that GLONASS (Global Navigation Satellite System) comprises; Every Navsat that GLONASS (Global Navigation Satellite System) comprised repeats earthward to broadcast to upgrade and is spaced apart 24 hours navigation message; And be spaced apart in 24 hours each of navigation message upgrade at interval in renewal, the renewal that each satellite navigation receiver utilization that GLONASS (Global Navigation Satellite System) comprised receives is spaced apart in 24 hours navigation message and the GLONASS (Global Navigation Satellite System) determines its current location for its visible Navsat and the observed range between it.
Wherein, upgrade the navigation message that is spaced apart 24 hours and comprise following content at least: correct parameter, satellite ephemeris, ionosphere information, system time parameter, earth sensing parameter and satellite almanac with reference to the moment, satellite clock.Particularly, satellite ephemeris comprises following content at least: describe Navsat with reference to the location parameter of present position constantly, describe Navsat in speed parameter and sun optical pressure parameter (1 or a plurality of) with reference to travelling speed constantly with cartesian coordinate system with cartesian coordinate system; System time parameter is used for GNSS time being associated with UTC Universal Time Coordinated and GNSS time being associated with other GNSS time; Earth sensing parameter is used to provide the conversion parameter between the earth's core fixed coordinate system and the geocentric inertial coordinate system; Satellite clock corrects parameter and comprises following content at least: with reference to satellite clock deviation, satellite clock drift about and the satellite clock drift rate constantly.
Wherein, can Navsat be described in residing position of the reference moment and travelling speed by Cartesian coordinates mode in the fixed coordinate system of the earth's core or the Cartesian coordinates mode in the geocentric inertial coordinate system.The satellite navigation receiver directly one or more Navsats from GLONASS (Global Navigation Satellite System) receives the navigation message that renewal is spaced apart 24 hours, also can obtain to upgrade from the ground backup system by wired or wireless mode to be spaced apart 24 hours navigation message.
In the present invention, satellite navigation receiver only needs to download a navigation message in each renewal at interval of navigation message, just can use the navigation message of being downloaded to determine the position of Navsat, and help tracking satellite-signal in excess time (even under utmost point weak signal conditions).With respect to the GLONASS (Global Navigation Satellite System) of using existing navigation message, the present invention has improved the sensitivity and the quick station-keeping ability of satellite navigation receiver greatly.
Description of drawings
From below in conjunction with the present invention may be better understood the description of accompanying drawing to the specific embodiment of the present invention, wherein:
Fig. 1 shows satellite navigation receiver in the GNSS system and receives synoptic diagram from the sight of the navigation message of four Navsats simultaneously;
Fig. 2 shows the logic diagram of the composition structure of gps system;
Fig. 3 shows satellite navigation receiver and finishes the logical view of location process first;
Fig. 4 shows the logic diagram of the composition structure of AGPS system;
Fig. 5 shows the structural representation of a base unit of the navigation message that gps system uses;
Fig. 6 shows the structural representation according to a base unit of the navigation message of the embodiment of the invention.
Embodiment
To describe the feature and the exemplary embodiment of various aspects of the present invention below in detail.Many details have been contained in following description, so that complete understanding of the present invention is provided.But, it will be apparent to one skilled in the art that the present invention can implement under the situation of some details in not needing these details.Description to embodiment only is in order to provide the clearer understanding to the present invention by example of the present invention is shown below.Any concrete configuration and the algorithm that are proposed below the present invention never is limited to, but any modification, replacement and the improvement that have covered coherent element, parts and algorithm under the premise of without departing from the spirit of the present invention.
Be example below with the gps system, describe in detail according to the realization satellite navigation receiver high sensitivity of the embodiment of the invention and the method for locating first fast.What those skilled in the art should understand that is, the principle of work of other GNSS systems such as COMPASS system, GLONASS system and GALILEO system and the principle of work of gps system are similar, so hereinafter the explanation of doing in conjunction with gps system is equally applicable to these GNSS systems.
At first, provide the explanation of some Essential Terms in the gps system that will use subsequently:
The renewal of satellite ephemeris is (that is, the time interval between twice content update of satellite ephemeris) at interval, and in the period, the parameter constant that satellite ephemeris comprised only needs to receive the each startup location Calculation that once just can be used in this period at this section.In addition, because the content of navigation message is constant, so just is highly advantageous to and helps the tracking of navigation signal.In gps system, the renewal of satellite ephemeris was generally 2 hours at interval.
The term of validity of satellite ephemeris, in the period, the satellite orbit and the spaceborne clock accuracy that calculate according to the parameter that satellite ephemeris comprised satisfy the navigator fix requirement at this section.The term of validity of satellite ephemeris also can be called the serviceable life of satellite ephemeris.In gps system, the term of validity of satellite ephemeris was generally 2-4 hour.That is to say that satellite orbit and the common precision of spaceborne clock of utilizing the satellite ephemeris that received before 2 hours to calculate should be secure, but can not be with the tracking of helping navigation signal, because variation has taken place the ephemeris content of newly broadcasting.
The recurrence interval of satellite ephemeris, in the period, the satellite ephemeris that comprises same content is broadcast repeatedly at this section.In gps system, the recurrence interval of satellite ephemeris is 30 seconds.
Fig. 2 shows the logic diagram of the composition structure of gps system.As shown in Figure 2, gps system comprises space segment 202, Ground Control part 204 and customer equipment part 206.
Space segment 202 is formed by being evenly distributed on 24 Navsats that the inclination angle is about (4 of each orbital planes) on 6 orbital planes of 55 °.The distribution of Navsat make any time on earth all can observe 4 above Navsats Anywhere.In gps system, all navigator fix information of customer equipment part all is to calculate according to the satellite ephemeris that Navsat sends.Satellite ephemeris is actually the series of parameters of the tracks of describing Navsat.
Ground Control part (being also referred to as the ground control centre) 204 is made up of 1 main control station, 5 monitoring stations and 3 ground control stations.The monitoring station all is equipped with accurate atomic clock and receiver that can all visible Navsats of continuous coverage.The monitoring station is sent to main control station with the moonscope data (comprising ionosphere and weather data) that obtain through after the rough handling.Main control station is collected tracking data from each monitoring station, calculates the track and the timing parameter of Navsat, then the result is delivered to 3 ground control stations.Ground Control stands in every Navsat and moves to it when overhead, and these navigation datas and main control station instruction are injected into Navsat.This injection and was carried out last injection to every Navsat once a day before Navsat built on stilts control station reach.
The availability of the satellite ephemeris of before having collected when powering on according to the degree of accuracy of satellite navigation receiver self time and satellite navigation receiver, satellite navigation receiver may experience cold start-up, the warm startup or warm start process (in most cases being warm the startup).When warm the startup, satellite navigation receiver does not have available effective satellite ephemeris usually, and just knows himself time roughly.Around under the relatively spacious situation of environment, satellite navigation receiver need spend time of hundreds of milliseconds usually and catch navigation signal.And under the situation in for example being in the more weak environment of urban canyons area or signal such as indoor, satellite navigation receiver is before catching navigation signal, (for example, tens of seconds) come the three-dimensional search in deadline, frequency and signal intensity territory may to need to spend the longer time.In case capture navigation signal, satellite navigation receiver begins navigation signal is followed the trail of immediately, and after inserting navigation signal, begin immediately to carry out and Navsat between bit synchronous.
Fig. 3 shows satellite navigation receiver and finishes the logical view of location process first.Because signal intensity and efficiency of algorithm is different, this process may need to spend the time of hundreds of milliseconds to the several seconds.Satellite navigation receiver is being under the situation of spacious environment, need about 18 seconds time of cost download complete satellite ephemeris, and need several minutes time of cost download complete satellite ephemeris or can't finish download at all in that the situation that is in the more weak environment of signal is next for complete satellite ephemeris.Satellite navigation receiver is finished after the download from the satellite ephemeris of 3～4 Navsats, can determine its residing particular location immediately.Be under the situation of weak signal environment, signal obtains to download with satellite ephemeris all to be needed to take a long time, and realizes locating first thereby make navigational satellite receiver need spend considerable time; And be under the situation of spacious environment, navigational satellite receiver realizes that fast the major obstacle of location then is the time consumption (common about 18 seconds) that satellite ephemeris is downloaded first.
Assistant GPS system (AGPS) is a kind of quick technology of station-keeping ability first of gps system that is used to improve.Fig. 4 shows the logic diagram of the composition structure of AGPS system.As shown in Figure 4, in the AGPS system, wide area reference net (Wide Area Reference Network is called for short WARN) 402 receives the navigation message from Navsat, and offer Serving Mobile Location Center (Serving Mobile Location Center, be called for short SMLC) 404; 504 pairs of navigation messages of SMLC are handled, and the satellite ephemeris that will obtain from navigation message by (MSC) 406 of mobile switching centre and radio network controller (RNC) 408 when the request that receives from satellite navigation receiver offers satellite navigation receiver.That is to say, the AGPS system provides one to be in ground satellite ephemeris source for satellite navigation receiver, thereby saved satellite navigation receiver and downloaded the time of satellite ephemeris, and then significantly shortened satellite navigation receiver and realized the time of location first from Navsat.Because only be 2～4 hours the serviceable life of the satellite ephemeris of current use, so when satellite navigation receiver can't directly download satellite ephemeris from Navsat but have with the AGPS system between mobile communications network when being connected, SMLC need be based on the request from each satellite navigation receiver, and per 2 hours to satellite ephemeris of satellite navigation receiver transmission.In addition, the AGPS system can also provide such as precise time to satellite navigation receiver, and the position of the tabulation of visible Navsat, the Doppler frequency of every Navsat, encoding phase, special time etc. helps to accelerate the information that satellite navigation receiver obtains navigation signal.
Satellite ephemeris expansion (EE) also is a kind of technology that is used to improve the quick station-keeping ability of gps system.Particularly, the EE technology is based on the satellite ephemeris of being downloaded by the WARN among satellite navigation receiver or the AGPS, technology such as orbit determination and clock match generates in addition satellite ephemeris that a kind of term of validity reaches a couple of days and replaces satellite ephemeris by Navsat broadcasting via satellite, realizes locating first and need not to download from Navsat thereby the term of validity that makes satellite navigation receiver can utilize the EE technology to generate in a period of time reaches the satellite ephemeris of a couple of days.
Utilize AGPS and EE technology, satellite navigation receiver is finished and is located the required time first and can second shorten to the several seconds even shorten in 1 second from tens of.
Around under the relatively spacious situation of environment, the navigation satellite signal intensity that gps satellite navigation receiving trap receives generally between-130dBm between-the 125.5dBm.Yet, under some extreme cases, for example be in urban canyons, under leaf covers or signal such as indoor the is more weak environment, owing to signal reflex, reason such as hinder, penetrate, the navigation signal that finally arrives the receiving antenna of satellite navigation receiver can be attenuated-30dB or more.Under this environment, the satellite navigation receiver with general trace ability can't be worked, so need a kind of more highly sensitive satellite navigation receiver that has.
When the signal intensity of navigation signal drops to a certain degree, satellite navigation receiver will be difficult to the tracing navigation signal and download satellite ephemeris.At first, the signal tracing parameter that is designed for general signal intensity no longer can be used for obtaining and carry out input or keep the required enough gains of signal tracing.Secondly, bit error rate (BER) is along with the rapid variation of attenuation of signal intensity, thereby even makes that having kept signal tracing also can't successfully decode to navigation message.
The sensitivity of satellite navigation receiver depends primarily on two aspects: the one, and the gain and the noiseproof feature of the whole signal path of satellite navigation receiver front end, the 2nd, the algorithm performance of baseband portion.In base band signal process, in order to obtain to be enough to carry out the processing gain of the signal to noise ratio (snr) of input, the relevant and non-coherent accumulation that need unite.Yet non-coherent accumulation is subjected to the influence of square pulse shaping decay (SL).Equation (1) has provided the approximate of the processing gain of uniting relevant and non-coherent accumulation.For fixing total integration period T
I, increase relevant period T c than increasing the incoherent cycle and can more effectively obtain higher processing gain.Yet under the situation of bit of not knowing to navigate, coherent accumulation is limited in 1 bit period, so promptly because the data transfer rate of gps system is that the 50bps coherent accumulation is limited in the 20ms.For sensitivity improving is arrived-160dBm, need on a plurality of bits, carry out coherent accumulation.So, need to utilize effective navigation bit and bit boundaries to carry out data and remove.Therefore,, then can use these navigation bits, perhaps can use the new navigation message that comprises satellite ephemeris and almanac to reverse the navigation bit from AGPS if the previous navigation bit of collecting was still effective.
Though AGPS and EE technology can be improved the sensitivity of satellite navigation receiver and station-keeping ability first, also there are some limitation in they.
In the AGPS technology, because satellite navigation receiver need come by the communication facilities in the mobile communications networks such as mobile switching centre and radio network controller to receive satellite ephemeris from Serving Mobile Location Center, so when be in both be not moved network cover, also can't be directly when Navsat is downloaded the zone (for example forest, valley etc.) of satellite ephemeris, satellite navigation receiver also can't obtain satellite ephemeris from the AGPS system.Therefore, the realization of AGPS systemic-function is subjected to the restriction of connectedness of the mobile communications network at satellite navigation receiver place.Simultaneously, set up and safeguard that the AGPS system also needs to expend a large amount of funds and energy.
In addition, the EE technology can not be provided for accelerating the supplementary that satellite navigation receiver obtains navigation signal, can not improve the tracking sensitivity of satellite navigation receiver to navigation signal.The EE technology can realize on server, also can realize on the satellite navigation receiver equipment of itself.When the EE technology when realizing (for example in the AGPS system, realizing) on the server, satellite navigation receiver need obtain server reaches a couple of days by the term of validity of EE technology generation satellite ephemeris from server by for example wired or wireless communication network, therefore the realization of EE technology is subjected to the restriction of the connectedness of satellite navigation receiver place communication network, and the foundation of server and safeguard and also need to expend a large amount of funds and experience.In addition, under situation about realizing on the satellite navigation receiver equipment of itself, be subjected to the restriction of the quantity of the validity that the local earth points to parameter, the local satellite ephemeris of downloading and/or quality etc. for the EE technology.
In addition, AGPS and EE technology only some condition precedent (such as, network connectivty and availability of data) down useful.In other words, if can not be satisfied (this situation often takes place in daily life), also can't utilize AGPS and EE technology to realize the quick location and the high sensitive of satellite navigation receiver such as the condition precedent of network connectivty and availability of data etc.
The main cause of the birth defect of GPS, AGPS and EE technology is the design of existing navigation message.Fig. 5 shows the structural representation of a base unit of the navigation message that gps system uses.As shown in Figure 5, the base unit of navigation message is the prime frame of long 1500 bits, and transfer rate is 50 bps, transmits the prime frame that finishes 750 seconds.Wherein, a prime frame comprises 5 subframes, and the 1st, 2,3 subframes repeat once per 30 seconds, and content was upgraded once in per 2 hours, and the content term of validity is 4 hours, comprises the information of satellite ephemeris, and is essential by the navigation receiving trap is positioned.4th, 5 subframes then provide the information of satellite almanac, and content was upgraded once in general per 6 days, and its content is only just upgraded after Navsat injects new navigation data.
Under weak signal environment, independent satellite navigation receiver is difficult to follow the trail of so frequent ephemeris and upgrades.Operate as normal in two hours in the past, and do not mean that satellite navigation receiver can be in ensuing two hours operate as normal, if can not download ephemeris on time.The navigation message that received before two hours can not be used as the auxiliary data of the tracking sensitivity that improves satellite navigation receiver in ensuing two hours.For the startup under the normal signal condition, if the beginning part of the 1st subframe is lost, then satellite navigation receiver must be waited for 30 seconds and just can obtain next the 1st subframe, to download complete satellite ephemeris.Successful startup before 4 hours can't help to shorten the primary positioning time (TTFF) when next time starting, because need take time the download satellite ephemeris once more.Say that to a certain extent all effort of above-described various technology all just attempt to improve by the short defective of limited operating life (2-4 hour) that overcomes existing satellite ephemeris the sensitivity and the quick station-keeping ability of satellite navigation receiver.The serviceable life of satellite ephemeris is long more, does not need above-mentioned various ancillary techniques more.
For the high sensitivity that realizes satellite navigation receiver and location first fast, the present invention attempts to propose that a kind of content update speed is low as far as possible, the content repetition rate is high as far as possible, the ephemeris content is short as far as possible and long as far as possible navigation message of ephemeris life-span.
In gps system, existing navigation message comprises that mainly satellite ephemeris, satellite clock correct the Almanac of parameter, ionosphere information (being represented by Klobuchar ionosphere correction model), Coordinated Universal Time(UTC) (UTC) parameter and whole satellites information such as (that is the satellite almanacs of the information of the summary track of relevant all Navsats of record).Wherein, common only need the renewals with 6 days the time interval such as Almanac of ionosphere information, UTC parameter (being used for the gps system time was associated with the Coordinated Universal Time(UTC)) and whole satellites get final product; And because Navsat has adopted degree of accuracy ± 1 * 10
-12～± 1 * 10
-13Atomic clock, so under the situation of not introducing appreciable error, can or correct parameter with the longer time interval to satellite clock and upgrade every 12 hours.Yet, because the satellite ephemeris (hereinafter being called the GPS ephemeris) in the gps system is an orbit of describing Navsat with the Keplerian orbit parameter and the orbit perturbation correction of frequent variations, so navigation message needs frequent updating, cause satellite navigation receiver when carrying out cold start-up or warm the startup, all to need download navigation text again at every turn.
Proposed so a kind of navigation message according to the embodiment of the invention, it can comprise following content: satellite clock corrects parameter, satellite ephemeris, ionosphere information, system time parameter, earth sensing parameter and satellite almanac.Wherein, satellite clock corrects similar in parameter, ionosphere information and satellite almanac and the existing gps navigation message.System time parameter is used for the gps system time being associated with UTC Universal Time Coordinated and the gps system time being associated with other GNSS system times.Earth sensing parameter is used to provide the conversion parameter between the earth's core fixed coordinate system and the geocentric inertial coordinate system.Satellite ephemeris comprises at least with cartesian coordinate system describes Navsat with reference to the location parameter of present position constantly, describe Navsat in speed parameter and sun optical pressure parameter (for example, 2 sun optical pressure parameters) with reference to travelling speed constantly with cartesian coordinate system.
Table 1 has provided the contents list according to the navigation message of the embodiment of the invention.
Table 1
| Clauses and subclauses | Note | |
| ??1 | Satellite clock corrects parameter | Af0: with reference to moment satellite clock deviation, unit is a second af1: the satellite clock drift, unit is af2 second/second: the satellite clock drift rate, unit is ^2 second/second |
| ??2 | Satellite ephemeris | Cartesian coordinates (3 parameters), speed component (3 parameters), 1-2 sun optical pressure parameter |
| ??3 | Ionosphere information | Klobuchar ionosphere correction model |
| ??4 | System time parameter | Be used for the parameter that the gps system time is associated with UTC is used for parameter with gps system time and other GNSS time correlations connection |
| ??5 | The earth points to (EOP) data | Polar motion of globe and information such as (UT1-UTC) |
| ??6 | The satellite almanac | With the identical form of existing GPS almanac |
According to the renewal of the navigation message of the embodiment of the invention at interval and the term of validity be 24 hours.Correcting the navigation message that adopts with respect to present GPS aspect parameter, ionosphere information and the satellite almanac according to the navigation message of the embodiment of the invention at satellite clock does not change, and satellite ephemeris only comprises that (the gps satellite ephemeris comprises 12 parameters to 7-8 parameter at least at present, 6 kepler parameters wherein, 6 harmonic constants), system time parameter comprises 2 parameters (at present gps satellite ephemeris only comprise 1 UTC parameter), and the earth points to data and then comprises polar motion of globe and information such as (UT1-UTC).
Gps system is being implemented when of the present invention, suppose under the situation of message transmission rate (50bps) that gps system adopts and each subframe lengths of navigation message constant (300 bit), a base unit according to the navigation message of the embodiment of the invention, be expected to be included in 4 subframes by data compression, wherein satellite ephemeris only takies the length of 2 subframes.The general download that only needs to finish in 12 seconds satellite ephemeris of satellite navigation receiver.Even under the situation of having lost first satellite ephemeris subframe, satellite navigation receiver also only needs can finish in 24 seconds the download of satellite ephemeris.Fig. 6 shows the structural representation according to a base unit of the navigation message of the embodiment of the invention.
For existing GNSS system (for example GPS and GLONASS), be distributed in the observation information such as distance and bearing of satellite ground tracking station continuous acquisition every day in the whole world to satellite, be aggregated into a data processing enter then, and be used for calculating accurate satellite orbit.Based on the accurate satellite orbit of observation period, data processing centre (DPC) can accurately forecast the satellite orbit of (a few hours were to several days) in following a period of time.For GPS, its central station is divided into a plurality of periods (every 2-4 hour) with the satellite orbit of forecast, and with the satellite orbit of each period by match, overlap Doppler parameter and multinomial perturbation parameter is represented with one.And the navigation message that adopts the present invention to propose, the ground control centre of gps system does not need the satellite orbit of following a period of time of directly forecast after the accurate Calculation of finishing the satellite orbit of observation period.The method that replaces is, choose the information of the determined accurate track point of observation period least significant end, comprise satellite position, the speed in this moment and the sun optical pressure parameter that is estimated, and with these parameters as new ephemeris parameter, adding other has related parameter, generates new navigation message together.
After receiving the satellite ephemeris that Navsat broadcasts, satellite navigation receiver at first calculates residing position of moment Navsat and the speed of leaving the satellite antenna of Navsat at navigation signal, and the error of spaceborne clock; The satellite orbit that the Navsat that provides according to satellite ephemeris is provided calculates other position and the speed of Navsats constantly with reference to initial position and velocity information (and sun optical pressure parameter) constantly by the track numerical integral method.
Describe below according to reference to initial position and velocity information and optical pressure parameter constantly, calculate the position of other moment Navsats and the processing of speed.Particularly, suppose a certain with reference to moment t
0, the position of Navsat such as equation (2) are depicted as r
0, speed such as equation (3) are depicted as
Acceleration such as equation (4) are depicted as
Can be according to Navsat at this moment t
0Position, speed and acceleration, from this t constantly
0By to a repeated integral of speed with to the double integral of acceleration, obtain Navsat at the position of time t r (t), to t constantly shown in equation (5).
r
0＝r(t
0)(2)
Wherein first half is represented the acceleration that terrestrial attraction causes in the equation (4), and a (.) is illustrated in the perturbation acceleration of t constantly, P
0Expression optical pressure parameter, GM represents the terrestrial gravitation constant.
At the Navsat of space motion, its at any time the acceleration of t mainly by the decision of its present position.The external force that puts on satellite mainly comprises terrestrial gravitation, the gravitation of the sun and the moon, and sunshine is to the radiation pressure (sun optical pressure) of Navsat solar panel.3 of fronts can be according to the satellite present position, by the existing model database accurate Calculation that is built in the satellite navigation receiver; And the correlation parameter of sun optical pressure then needs navigation message to provide.By these parameters, can accurately calculate because of the acceleration that radiation produced of sunshine to the Navsat solar panel.For from reference to constantly to the numerical integration of moment t, need choose specific integral time step-length and the Runge-Kutta of specific exponent number and inferior dawn this etc. integrator realize.The exponent number of integration step and integrator is chosen compromise and the balance of dependence for computational accuracy and calculated amount.Numerical integration can only obtain with the integration step be at interval each integral time point the position and the speed of discontinuous Navsat, if desired in the integration period any time Navsat position and speed, then to adopt method such as Lagrange to carry out interpolation.
The track numerical integration is to carry out in geocentric inertial coordinate system (ECI), and the location Calculation of satellite navigation receiver is carried out in the earth's core fixed coordinate system (ECEF).If initial position that satellite ephemeris provides and speed are to be in the ECEF coordinate system, then need before numerical integration, be transformed into the ECI coordinate system, and also need to be transformed into back again the ECEF coordinate system by the track of numerical integration.These two processes are just in time opposite, and conversion can be by the Matrix C of following formulate from ECEF to ECI
ECEF ECIFinish:
Wherein, matrix A, B, C, D describe polar motion of globe respectively, earth rotation, nutating and precession.The EOP (table 1) that is provided by the satellite ephemeris according to the embodiment of the invention can be used to generate A and the B matrix that polar motion of globe and rotation are described.
In the gps system that the navigation message that provides according to the embodiment of the invention is provided, the ground control centre is created navigation message and is uploaded to every Navsat; Every Navsat repeats to broadcast this navigation message earthward; Each satellite navigation receiver is determined its current location according to this navigation message and himself and for the observed range between its visible Navsat.
What it may occur to persons skilled in the art that is, satellite navigation receiver can be a kind of real-time system, and also can be the navigation message that receives of a kind of utilization carries out the equipment of playback process to himself working line.Satellite navigation receiver can directly receive come from Navsat renewal at interval (or term of validity) be 24 hours navigation message, also can be from other ground backup systems by wired or wireless data transfer mode or network system, even by the copying data medium, obtain indirectly that to upgrade (or term of validity) at interval be 24 hours navigation message.In addition; those skilled in the art should be understood that; although the present invention is that 24 hours navigation message is that example is illustrated with a kind of upgrade (or term of validity) at interval, utilize other upgrade (or term of validity) at interval than the renewal of navigation message in the existing system at interval (or term of validity) longer navigation message realize that the high sensitivity of satellite navigation receiver and the method for locating first fast also should be included in the scope of protection of the invention.
In addition, what those skilled in the art should understand that is, although above is that example describes the present invention with GPS, set forth above upgrade (or term of validity) at interval be 24 hours navigation message and utilize this navigation message realize the high sensitivity of satellite navigation receiver and fast the method for location be equally applicable in other GNSS systems such as COMPASS system, GLONASS system and GALILEO system.
When the navigation message that uses according to the embodiment of the invention, satellite navigation receiver upgrades at interval in each of navigation message only needs to download a navigation message in (24 hours), and navigation message that just can use is downloaded in excess time is determined the current location of Navsat.Under the situation in being in the more weak environment of signal, because satellite navigation receiver has received effective navigation message, so need not to obtain effective navigation message indirectly by ground any backup system, so the quick station-keeping ability of independent satellite navigation receiver and high sensitivity are equivalent to by the satellite navigation receiver of AGPS system.In addition, utilize according to the station-keeping ability of the satellite navigation receiver of the navigation message of the embodiment of the invention and sensitivity and can not be subjected to restriction such as aspects such as the connectedness of mobile communications network and availability of datas.
Below the present invention has been described with reference to specific embodiments of the invention, but those skilled in the art all understand, can carry out various modifications, combination and change to these specific embodiments, and can not break away from the spirit and scope of the present invention that limit by claims or its equivalent.
Can come execution in step with hardware or software as required.Notice that without departing from the scope of the invention, the process flow diagram that can provide adds step, therefrom removes step or revise wherein step in this instructions.In general, process flow diagram just is used to refer to a kind of possible sequence of the basic operation that is used to realize function.
Embodiments of the invention can utilize programming universal digital computer, utilize special IC, programmable logic device (PLD), field programmable gate array, light, chemistry, biological, system quantum or nanometer engineering, assembly and mechanism to realize.In general, function of the present invention can be realized by any means known in the art.Can use distributed or networked system, assembly and circuit.The communication of data or to transmit can be wired, wireless or by any other means.
Also will recognize, according to the needs of application-specific, one or more can perhaps even in some cases being removed or being deactivated in the key element shown in the accompanying drawing by more separating or more integrated mode realizes.Program or code that realization can be stored in the machine readable media are carried out above-mentioned any method to allow computing machine, also within the spirit and scope of the present invention.
In addition, it only is exemplary that any signal arrows in the accompanying drawing should be considered to, rather than restrictive, unless concrete indication is arranged in addition.Separate or the ability of combination when not knowing when term is also contemplated as to make, the combination of assembly or step also will be considered to put down in writing.
Claims (9)
1. realize satellite navigation receiver high sensitivity and the method for locating first fast for one kind, comprising:
The ground control centre that GLONASS (Global Navigation Satellite System) comprised is created to upgrade and is spaced apart 24 hours navigation message and is uploaded to every Navsat that described GLONASS (Global Navigation Satellite System) comprises;
Every Navsat that described GLONASS (Global Navigation Satellite System) comprised repeats to broadcast described renewal earthward and is spaced apart 24 hours navigation message; And
Be spaced apart in 24 hours each of navigation message upgrade at interval in described renewal, the described renewal that each satellite navigation receiver utilization that described GLONASS (Global Navigation Satellite System) comprised receives is spaced apart in 24 hours navigation message and the described GLONASS (Global Navigation Satellite System) determines its current location for its visible Navsat and the observed range between it.
2. realization satellite navigation receiver high sensitivity according to claim 1 and the method for locating first fast, it is characterized in that, described renewal is spaced apart 24 hours navigation message and comprises following content at least: with reference to constantly, satellite clock corrects parameter, satellite ephemeris, ionosphere information, system time parameter, the earth and points to parameter and satellite almanac.
3. realization satellite navigation receiver high sensitivity according to claim 2 and the method for locating first fast, it is characterized in that described satellite ephemeris comprises following content at least: describe Navsat with reference to the location parameter of present position constantly, describe Navsat in speed parameter and sun optical pressure parameter with reference to travelling speed constantly with cartesian coordinate system with cartesian coordinate system.
4. realization satellite navigation receiver high sensitivity according to claim 2 and the method for locating first fast, it is characterized in that described system time parameter is used for described GNSS time being associated with UTC Universal Time Coordinated and described GNSS time being associated with other GNSS time.
5. realization satellite navigation receiver high sensitivity according to claim 2 and the method for locating first fast is characterized in that, described earth sensing parameter is used to provide the conversion parameter between the earth's core fixed coordinate system and the geocentric inertial coordinate system.
6. realization satellite navigation receiver high sensitivity according to claim 2 and the method for locating first fast, it is characterized in that described satellite clock corrects parameter and comprises following content at least: with reference to satellite clock deviation, satellite clock drift about and the satellite clock drift rate constantly.
7. realization satellite navigation receiver high sensitivity according to claim 3 and the method for locating first fast, it is characterized in that, describe Navsat in residing position of the reference moment and travelling speed with Cartesian coordinates mode in the fixed coordinate system of the earth's core or the Cartesian coordinates mode in the geocentric inertial coordinate system.
8. the realization satellite navigation receiver high sensitivity according to claim 3 and the quick method of location first is characterized in that, described satellite ephemeris comprises 1 or a plurality of sun optical pressure parameter.
9. according to each described realization satellite navigation receiver high sensitivity in the claim 1 to 8 and the quick method of location first, it is characterized in that, the described satellite navigation receiver directly one or more Navsats from described GLONASS (Global Navigation Satellite System) receives the navigation message that described renewal is spaced apart 24 hours, perhaps obtains the navigation message that described renewal is spaced apart 24 hours by wired or wireless mode from the ground backup system.
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| US16836509P | 2009-04-10 | 2009-04-10 | |
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| CN109639431A (en) * | 2018-11-19 | 2019-04-16 | 中国科学院光电研究院 | A kind of text authentication method, equipment, system and medium |
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| CN111123309A (en) * | 2019-12-31 | 2020-05-08 | 泰斗微电子科技有限公司 | Method, device and equipment for testing receiver |
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Application publication date: 20101013 |