CN101493512B - Management method for global positioning system receiver navigation message - Google Patents
Management method for global positioning system receiver navigation message Download PDFInfo
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Abstract
The invention relates to the field of global satellite positioning and navigation, such as a GPS system, in particular to a navigation message management method which is used for a GPS receiving machine. The method comprises the steps as follows: the receiving machine internally comprises three parts of navigation message spaces: one part is used for receiving demodulation data, another part is used for memorizing backup and the third part is used for calculation. When the demodulation is completed and the calibration is passed, the navigation message in the demodulation navigation message space is updated and caculated; if the demodulation is not completed or the calibration is not passed, within the validity period of the message and when comforming with a certain synchronous condition, the navigation message is updated and calculated by the backup navigation message so as to realize the calculation of the user position till that the demodulation navigation message is available. The navigation message management method has clear structure, simple management, safety and reliability, can greatly reduce the time required for positioning after catching the satellite, and greatly improves the hot booting positioning speed, warm booting positioning speed and re-positioning speed after loss of signal.
Description
Technical field
The present invention relates to global positioning satellite and navigation field, gps system for example, particularly a kind of field that is used for the navigation message management method of GPS receiver.
Background technology
Global positioning satellite and navigational system, for example GPS (GPS) comprises one group of satellite constellation (the Navstar satellite is otherwise known as) that sends gps signal, this gps signal can be received the position that machine is used for determining this receiver.Satellite orbit is arranged in a plurality of planes, so that any on earth position can both receive this kind signal from least four satellites.More typical situation is that most on earth places can both receive this kind signal from six above satellites.
The gps signal that each gps satellite transmitted all is a Direct Sequence Spread Spectrum Signal.The signal of commercial use is relevant with standard setting service (SPS), and is referred to as the direct sequence two-phase spread-spectrum signal of thick sign indicating number (C/A sign indicating number), under the carrier wave of 1575.42MHz, has the speed of per second 1.023 million chips.Pseudo noise (PN) sequence length is 1023 chips, corresponding to 1 millisecond time cycle.The PN sign indicating number that each satellites transmits is different (Gold sign indicating number) makes signal to send simultaneously from several satellites, and received simultaneously by a receiver, and is almost noiseless each other.Term " satellite asterisk " is relevant with this PN sign indicating number, can be in order to indicate different gps satellites.
The modulation signal of GPS is the combinational code of navigation message (the D sign indicating number is otherwise known as) and PN sign indicating number.The speed of navigation message is per second 50 bits.The base unit of D sign indicating number is the prime frame of one 1500 bit, and prime frame is divided into the subframe of 5 300 bits again.Wherein subframe one has comprised identification code, star kind data length of time, satellite clock corrected parameter information.Subframe two and subframe three have comprised real-time gps satellite ephemeris (ephemeris), and ephemeris is the main content of current navigator fix information.Utilize subframe one to the information of subframe three promptly can realize the location, finish the basic task of location.Subframe four and subframe five have comprised the health status of 1-32 satellite, the almanac (almanac) of UTC calibration information and ionospheric corrections parameter and 1-32 satellite.Almanac is the simplified subset of satellite ephemeris parameter, is used to predict visible satellite and Doppler frequency deviation thereof with respect to receiver.Almanac was broadcasted once in per 12.5 minutes, and the life-span is a week, can extend to 2 months.
(Coordinate Universal Time UTC) is a kind of time scale of international standard to the mediation universal time.It is that the time scale UT1 input of benchmark is formed by the time scale that drives from atomic clock with earth speed of rotation.Atomic time from atomic clock has the scale advantage of uniform, and based on the time scale of earth speed of rotation at a lot of application scenarios no less important.For being in harmonious proportion two kinds of times, it is long that the second long strictness of UTC equals the second of atomic time, and international earth rotation office of while (IERS) is responsible for determining to be suitably in UTC and adds deduct on the time leap second, makes that UTC and universal time are synchronous.
GPS is to satisfy the needs of precision positioning and navigation, points out just to have set up the time system of own special use in system design and test.Be reference with UTC (USNO) during gps system.UTC (USNO) is more than 20 the caesium standard group that atom USNO-US Naval Observatory (USNO) utilization is held, and chronometer data forms the UTC version of oneself.UTC (USNO) remains in the 1 μ s of UTC.GPS is a continuous time scale, without adjusting leap second.Overlap 0 o'clock on the 6th 1980 days with UTC (NSNO) during gps system.GPS control section makes it to be in UTC (NSNO) the 1 μ s when regulating gps system.
One of main target of GPS receiver is to determine the time of arrival of PN sign indicating number.Term " between the GPS arrival " refers to that gps satellite PN sign indicating number arrives the time of GPS receiver.This is to compare with the signal of reception and " slip " local reference is finished until aliging in time with received signal by the PN reference signal that this locality is produced.By being referred to as multiplying each other and integral process of " being correlated with ", these two signals are compared mutually.When two signals were alignment in time, the result of output was maximum.
Be included in the navigation message, make the GPS receiver can be accurately and determine the local UTC time reliably with time-of-week (TOW) data of absolute time signal correction connection.The TOW data are transmitted by the time interval in 6 seconds by all satellites.The GPS receiver can use the absolute time signal to determine the position exactly.In case known the place, position, can be by utilizing between receiver and the satellite, the clear and definite time that computable propagation delay comes compensated receiver to obtain from satellite navigation message obtains.
Term " GPS start-up time " is one of important indicator of weighing GPS baseband processing chip performance.GPS comprises warm start time, startup temperature time and cold start-up time start-up time.Term " start-up time " is meant that the GPS receiver is from power on to exporting the mistiming of positioning result first.Term " warm start time " is meant the start-up time under known receiver location and gps satellite ephemeris situation.Term " startup temperature time " is meant the start-up time at known receiver location, user time and gps satellite almanac.Term " cold start-up time " is meant the start-up time in no any prior imformation.
Term " GPS recaptures the time " is one of important indicator of weighing GPS baseband processing chip performance.Term " is recaptured the time " and is meant the GPS receiver under the normal situation of following the tracks of gps satellite and locating, because of a variety of causes satellite-signal disappearance, and then signal reproduction, get constantly from signal reproduction, to catching the satellite mistiming constantly again.Similarly, term " reorientation time " is meant the GPS receiver under the normal situation of following the tracks of gps satellite and locating, because of a variety of causes satellite-signal disappearance, and then signal reproduction, get constantly from signal reproduction, to the mistiming of reorientating.
The GPS receiver often runs into the situation of gps signal disappearance, particularly under the situation that the GPS receiver moves and shelter is more.A typical occasion is the vehicle GPS location receiver that travels in the city.The vehicle that travels often meets with blocking of shelters such as different types of rridges, buildings, tunnel, makes receiver can't receive the gps signal of enough signal to noise ratio (S/N ratio)s.The time span of these signal deletions often from second level do not wait by several minutes.When reappearing after the signal deletion, recapture and the reorientation time of GPS receiver is one of core capabilities of GPS user's care, thereby has attracted considerable research.
Summary of the invention
The purpose of this invention is to provide a kind of navigation message management method that is used for GPS receiver, its method comprises: receiver inside has comprised three parts of navigation message spaces, a portion is used for storage backup in order to place demodulating data, and portion is used to resolve.When demodulation is finished, the content update in the demodulation navigation message is resolved navigation message, complete if demodulation does not have, if in the term of validity of text, and meet under certain synchronous condition, then with backing up more new Algorithm navigation message of navigation message.
The invention provides a kind of navigation message management method that is used for GPS receiver, wherein, receiver inside has comprised three part navigation message spaces, demodulation navigation message space, the navigation message space is resolved in backup navigation message space, and concrete steps are:
When the navigation message demodulation is finished and verification is passed through, then, realize resolving of receiver location with the text that the demodulates navigation message in new Algorithm navigation message space more;
The text that utilization demodulates upgrades the navigation message in backup navigation message space;
If demodulation is not finished or verification is not passed through, whether the backup text that detects this satellite exists;
If the backup navigation message exists, then detect the backup text that changes satellite and whether be within the term of validity, otherwise etc. text to be demodulated finish demodulation and verification is passed through;
If the backup navigation message is in the term of validity, satisfying according to different sights after respective synchronization requires, more the new Algorithm navigation message is realized resolving of receiver location, finishes demodulation and verification is passed through until the demodulation text.
Further, described demodulation navigation message space is used to place the navigation message that demodulates.
Further, described backup navigation message space is used for the navigation message that the storage backup demodulation is finished and verification is passed through.
Further, describedly resolve the navigation message that the navigation message space is used to resolve receiver location.
Further, described demodulation navigation message each search channel allocation of space is one.
Further, totally 32 in described backup navigation message space, one of every satellite distribution.
Further, describedly resolve each one of the channel allocation of search of navigation message space.
Further, described demodulation navigation message space is a hardware text demodulation buffer memory.
Further, described demodulation navigation message space is stored among the RAM.
Further, described backup navigation message space is stored in the non-loss storer of power down.
Further, described backup navigation message space is stored among the Flash.
Further, the described navigation message space of resolving is stored among the RAM.
Further, described demodulation text is finished demodulation and is meant that subframe one to subframe three demodulation are finished in whole five frame navigation messages.
Further, the renewal rate of described backup navigation message is adjustable, and its renewal rate and power consumption are inversely proportional to.
Further, whether expired method comprises following steps to described detection backup text:
Extract first TOW in the backup navigation message;
Be transformed into the second is unit;
Read the current time among the real-time clock RTC from baseband processing chip;
Be transformed into second number, i.e. second TOW of time in this week;
These two TOW relatively are if its difference is less than default thresholding then think that this navigation message is effective, if greater than default thresholding then think that this navigation message has exceeded the term of validity.
Further, described synchronization scenarios comprises warm start and the start-up time startup temperature less than the navigation message term of validity, and two kinds of situations of reorientation behind the signal deletion.
Further, described warm start and start-up time are less than using the backup navigation message to comprise following steps under the startup temperature situation of the navigation message term of validity:
Catch the prediction satellite;
If acquisition success then carries out bit synchronous, catch if get nowhere then continue to implement;
If the bit synchronous success then detects whether there is the frame synchronization priori this moment;
If there is not priori, then proceed frame synchronization until the frame synchronization success, otherwise, then utilize priori to upgrade a second counter, finish frame synchronization;
Read the backup navigation message of respective satellite;
Whether detect the backup navigation message expired;
If it is expired that the backup navigation message does not have, then utilize more new Algorithm navigation message of backup navigation message, can use until the demodulation navigation message.
Further, reorientation uses the backup navigation message to comprise following steps down behind the described signal deletion:
The signal deletion satellite of recapturing;
If acquisition success detects then whether the frame synchronization priori is arranged this moment, catch if get nowhere then continue to implement;
If there is not the synchronous priori of bit, then proceed bit synchronous until the bit synchronous success, otherwise, then utilize priori to upgrade millisecond counter, promptly finish bit synchronous;
Utilize the frame synchronization priori to upgrade a second counter, finish frame synchronization;
Read the backup navigation message of respective satellite;
Whether detect the backup navigation message expired;
If it is expired that the backup navigation message does not have, then utilize more new Algorithm navigation message of backup navigation message, can use until the demodulation navigation message.
Further, described frame synchronization prior imformation is meant other satellite subframes initial code position of finishing frame synchronization.
Further, described frame synchronization prior imformation is meant from absolute second level information under the UTC/GPST time coordinate of real-time clock accurately.
Further, described bit synchronous prior imformation is to have finished preceding this satellite navigation message bit reference position of signal deletion of bit synchronous.
Further, described bit synchronous prior imformation is from the absolute Millisecond information under the UTC/GPST time coordinate of real-time clock accurately.
Further, described thresholding is smaller or equal to the numerical value of the navigation message term of validity.
Further, described thresholding is the numerical value between 1800 seconds to 3600 seconds.
Further, described real-time clock RTC can be upgraded by the UTC time that baseband chip calculates.
This navigation message management method clear in structure that the present invention proposes, management is simple, and is safe and reliable, reduces the location required time greatly after can catching satellite, greatly improves the warm start locating speed, reorientation speed behind startup temperature locating speed and the signal deletion.
Description of drawings
Fig. 1 is the synoptic diagram that typical GPS receiver realizes the location;
Fig. 2 is a typical GPS receiver positioning flow;
Fig. 3 A is existing navigation message management method beat one synoptic diagram;
Fig. 3 B is existing navigation message management method beat two synoptic diagram;
Fig. 4 is another existing navigation message management method synoptic diagram;
Fig. 5 is the navigation message management method entire block diagram of a preferred embodiment of the present invention;
Fig. 6 is that preferred embodiment of the present invention utilizes navigation message management method of the present invention to be applied to warm start and the process flow diagram of startup interval than short startup temperature;
Fig. 7 is that preferred embodiment of the present invention utilizes navigation message management method of the present invention to be applied to the process flow diagram of reorientation behind the signal deletion.
Embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.
The GPS baseband chip is a chip of handling baseband signal in the GPS receiver, is the core in the whole GPS receiver.The whole bag of tricks of the present invention is all realized in the GPS baseband chip.For simplicity, " receiver " all refers to " GPS baseband chip " among the present invention.
Fig. 1 has described a typical GPS receiver and has realized the method for location.Pseudorange 102 between the position 101 of known four satellites and this four satellites and the receiver promptly can calculate the position 103 of receiver and the error amount of relative satellite time of receiver time by so-called " pseudorange observation equation ".As shown in the formula:
Wherein: ρ
iBe the pseudorange between satellite and the receiver;
x
Sati, y
Sati, z
SatiBe the coordinate of each visible satellite under the ECEF coordinate system;
x
User, y
User, z
UserBe the coordinate of receiver under the ECEF coordinate system;
Bu=C Δ t
BiasC is the light velocity, Δ t
BiasDifference for receiver clock and user clock.
Term " ECEF coordinate system " is meant the earth's core earth coordinate system that is connected, and its XY plane overlaps with earth equatorial plane, and X-axis is pointed to 0 longitudinal, and Y-axis is pointed to 90 ° of directions of east longitude, Z axle and equatorial plane quadrature, sensing north geographic pole.This coordinate system rotates with earth rotation.
More than four satellites when visible, above-mentioned equation is an overdetermined equation, can obtain optimum solution under the prerequisite of least square.
As mentioned above, obtaining the position of satellite and the pseudorange of satellite distance receiver is the necessary and sufficient condition that realizes the location.And satellite position can be by the navigation message on the PN sign indicating number that is modulated at satellites transmits in conjunction with calculating the launch time of this satellite.The skilled person should be familiar with in concrete computation process this area, because do not giving unnecessary details.And pseudorange is to be obtained by launch time.Thereby, realize that the necessary and sufficient condition of location can be converted to acquisition launch time and navigation message, that is: gps system needs the launch time and the navigation message of at least 4 satellites just can realize three-dimensional localization.As indicated above, the term of validity of ICD files specify navigation message is two hours.In warm start, start-up time is at interval less than the startup temperature of the navigation message term of validity, and blocked under the situation of losing and then catching again because of satellite, because it is not far to upgrade the navigation message time phase difference from last time, the navigation message that upgraded last time does not often surpass the navigation message term of validity, thereby can directly use in theory.In case in these cases and obtained the correct satellites transmits time, use effective last stored text and need not wait for the complete positioning calculation of promptly can realizing of new text demodulation, thereby reduced the warm start time widely, startup temperature time and reorientation time.
Fig. 2 has described a typical GPS receiver positioning flow.Process shown in Figure 2 is from receiver power-up initializing 201, finishes until calculating receiver location 206.Usually enter trapped state 202 after receiver powers on, satellite, the carrier frequency of this satellite and the code phase of PN sign indicating number in the search sight line.Search to carrier frequency under this state is coarse, usually hundreds of hertz magnitude.Enter frequency pulling state 203 afterwards, local frequency pulling to and the satellite carrier frequency differ several hertz magnitude, carry out bit synchronous simultaneously.After finishing frequency pulling, receiver enters tracking mode 204, finishes frame synchronization, promptly can enter demodulation text state 205, and the text demodulation of modulating on the carrier wave is come out to be used for to calculate receiver location 206 times at subsequently the state that resolves.
Fig. 3 A and Fig. 3 B have described an existing navigation message management method design diagram jointly.This method has comprised two identical demodulation navigation message spaces 302 and 303, realizes separating being in harmonious proportion to calculate with two beats and carries out synchronously.What Fig. 3 A described is the situation of beat one, the situation of the beat two that Fig. 3 B describes.Beat for the moment, as shown in Figure 3A, intermediate frequency satellite-signal 301 is removed in the receiver demodulation, demodulation result is placed in the demodulation navigation message space 1, simultaneously last beat demodulation is finished, the navigation message that is placed in the demodulation navigation message space 2 carries out verification 304, if verification is by promptly resolving receiver location 305.Correspondingly, during beat two, shown in Fig. 3 B, intermediate frequency satellite-signal 301 is removed in the receiver demodulation, demodulation result is placed in the demodulation navigation message space 2, simultaneously last beat demodulation is finished, the navigation message that is placed in the demodulation navigation message space 2 carries out verification 304, if verification is by promptly resolving receiver location 305.The switching in text space utilizes clock 306 to carry out, and fixing at interval of its switching instant is the time of demodulation text, and for whole 5 frame navigation messages, its clock is spaced apart 30 seconds.
Though this kind method is simple in structure, a little less than being highly brittle.If in case signal deletion or demodulation mistake occur, when switching to next beat, not by can't realizing the location, and the navigation message in another navigation message space of this moment is likely complete available during the verification text in demodulating process.On the other hand, at interval less than situations such as reorientations behind the startup temperature of the navigation message term of validity and the signal deletion, the text that demodulation is before come out very might be still available for warm start, start-up time.This method can only wait for passively that for these situations new text demodulation finishes, and this needs the time of at least 18 seconds (subframe one is to subframe three information) usually.The typical commercial GPS receiver warm start time is all within 10 seconds, and for the urban forests of frequently blocking, continuing 18 seconds good time of receptions may realize.
Fig. 4 has described another existing navigation message management method synoptic diagram.This kind method is improved at method shown in Figure 3.Similar with method shown in Figure 3, this method has also comprised two navigation message spaces: demodulation navigation message space 402 and resolve navigation message space 404.402 sole duties of demodulation navigation message space are used for the demodulation navigation message, are used to resolve receiver location and resolve 404 sole duties of navigation message space.Similar with method shown in Figure 3, intermediate frequency satellite-signal 401 is removed in the receiver demodulation, demodulation result is placed in the demodulation navigation message space, and then navigation message is carried out verification 403, if verification not by continue demodulation; If verification by with the text that the demodulates navigation message in the new Algorithm navigation message space more.Like this in case demodulation for the first time correct after, just the navigation message that always latest update is arranged is with resolving receiver location, for the urban forests of frequently blocking, as long as the time of blocking is not very longly just can realize continuous positioning.
But this method for warm start, start-up time at interval less than the situations such as startup temperature of the navigation message term of validity, can only wait for passively that still new text demodulation finishes, this needs the time of at least 18 seconds (subframe one is to the satellite-orbit information of subframe three) to this method usually for these situations.And the receiver text that demodulation is come out when moving last time might still be within the available life.The typical commercial GPS receiver warm start time is all within 10 seconds.And for the urban forests of frequently blocking, continuing 18 seconds good time of receptions may realize.On the other hand, in the city, the time that satellite is blocked may be very long, and the satellite that is blocked, may be caught by other passages after losing through blocking for a long time, and original demodulation text is still available.This method for this situation also can only be passively demodulation navigation message again.
Fig. 5 is the navigation message management method entire block diagram of a preferred embodiment of the present invention.Utilize this method can solve above-mentioned all problems, can after catching satellite, reduce the location required time greatly, greatly improve the warm start locating speed, reorientation speed behind startup temperature location and the signal deletion.This method includes three navigation message spaces: demodulation navigation message space 502, and sole duty is used to place the navigation message that demodulates, and each follows the tracks of one of channel allocation; Backup navigation message space is used for the navigation message that the storage backup demodulation is complete and verification is passed through, one of every satellite distribution, totally 32; Resolve the navigation message space, be used to place in order to resolve the navigation message of receiver location, each follows the tracks of one of channel allocation.Demodulation navigation message space can be hard-wired text demodulation buffer memory, also can be in the baseband processor sheet or the space of distributing among the RAM outside the sheet.Similarly, resolving navigation message can be in the baseband processor sheet or the space of distributing among the RAM outside the sheet.Similar with method shown in Figure 4, intermediate frequency satellite-signal 501 is removed in the receiver demodulation, demodulation result is placed in the demodulation navigation message space 502, and then navigation message is carried out verification 503.If subframe one to subframe three information and verification that demodulate in the five frame navigation messages are passed through,, and then resolve receiver location 509 then with the text that the demodulates navigation message in the new Algorithm navigation message space 504 more.If verification is not by then continuing demodulation.More upgrade backup navigation message space 503 new Algorithm navigation message space the time.Backup navigation message space is stored in after the power down in the nonvolatile memory, in the Flash storer, to guarantee that restarting these information after the power down can be retained and be used.The frequency adjustable of its renewal, and can being controlled on lower renewal frequency, as 30 seconds once or longer, to prolong the Flash reading-writing life-span and to reduce power consumption.Backup navigation space and every gps satellite are directly related, rather than relevant with receiver channel.Every satellite is all with its corresponding backup navigation space in other words, to guarantee that the whichever passage is caught this satellite as long as navigation message is within the available life and can uses the backup navigation message, thereby solved the satellite that is blocked through blocking for a long time after losing, may have been caught by other passages and problem that original correct demodulation text can not be utilized.
When the demodulation text is not ready for, do not finish receiving as navigation message, whether perhaps verification is not passed through, then detect the backup navigation message and exist.Term " demodulation navigation message can with " instructs the complete and verification of avionics literary composition demodulation to pass through.If the backup navigation message exists, and is within the term of validity, promptly can be satisfying specific synchronous requirement after in order to new Algorithm navigation message more, the realization continuous positioning can be used until the demodulation navigation message.As follows when detecting the backup text: as at first extract TOW (Time of Week was a unit with the 6 seconds) information in the backup navigation message, and to be transformed into the second to be on the quantity of unit in the method for the term of validity.Further, read the second number of time in the current time and this week of being transformed among the real-time clock RTC from baseband processing chip, i.e. second TOW, its computing formula is:
TOW
RTC＝Date×86400+Hour×3600+Min×60+Sec
Wherein what day Date is, its span is 0～6, and Hour is the UTC hourage, and Min is UTC the number of minutes, and Sec is UTC number second.
Real-time clock RTC is comprised in GPS baseband chip inside.This real-time clock can be upgraded by the UTC time (Coordinated Universal Time(UTC)) that baseband chip calculates.This clock can be independently-powered by the outer battery of sheet simultaneously, still can operate as normal under the situation of assurance system power down.
Further, these two TOW relatively are if its difference is less than default thresholding then think that this navigation message is effective, if greater than default thresholding then think that this navigation message has exceeded the term of validity.This thresholding was got the numerical value smaller or equal to the navigation message term of validity usually, as 2000 seconds.
Use the synchronous requirement of backing up navigation message that the restriction of different brackets is arranged according to different situations, mainly be divided into warm start and start-up time at interval less than two kinds of situations of reorientation behind the startup temperature of the navigation message term of validity and the signal deletion, its detail will describe in detail in Fig. 6 and Fig. 7.
Fig. 6 describes is that preferred embodiment of the present invention utilizes navigation message management method of the present invention to be applied to warm start and start-up time at interval less than the process flow diagram of the startup temperature of the navigation message term of validity, uses the synchronous condition of backup navigation message to judge and is included in the whole flow process.For warm start and start-up time at interval less than the startup temperature of the navigation message term of validity, start after the initialization 601, utilize corresponding prediction algorithm prediction to start satellite 602, and then these satellites caught 603.If acquisition success 604 then carries out bit synchronous 605, catch if get nowhere then continue to implement.As everyone knows, the navigation message in the GPS C/A coded signal is through the BPSK modulation, and each data bit of navigation message comprises 20 sign indicating number cycles, and promptly the cycle of each data symbols is 20ms.Receiver finished carrier synchronization and pseudo-code synchronously after, need carry out bit synchronization, promptly find the initial code cycle of data bit.If bit synchronous success then detects whether the frame synchronization priori is arranged this moment, if do not have priori then proceed frame synchronization 609.Term " frame synchronization " is meant the initial code cycle of finding the navigation message subframe.Frame synchronization is a second above part to the contribution of launch time.Term " frame synchronization priori " is meant about a subframe initial code position, perhaps absolute second level information under the UTC/GPST time coordinate.Such information can be from other satellites of finishing frame synchronization, also can be from real-time clock accurately.Can skip the link of conventional frame synchronization if there is such prior imformation to exist, and directly utilize prior imformation to upgrade a second counter 612, promptly finish the process of frame synchronization.
Further, after finishing frame synchronization 610 or upgrading second counter 612, read the backup navigation message 611 of respective satellite in the backup text space.And then read local zone time 613, and utilize the method that provides among Fig. 5 to judge that whether available the backup text 614, if available, then, can use, and then use more new Algorithm text of the demodulation text that demodulates until the demodulation text with backup text new Algorithm text 615 more; If the backup navigation message is unavailable, then wait the navigation message to be demodulated can be with 616, and then the demodulation navigation message that demodulates of use new Algorithm navigation message more.
Utilize this method can reduce the location that the demodulation text brings to greatest extent and postpone, can improve warm start and start-up time widely at interval less than positioning time of the startup temperature of the navigation message term of validity.
Fig. 7 is that preferred embodiment of the present invention utilizes navigation message management method of the present invention to be applied to the process flow diagram of reorientation behind the signal deletion.Its basic procedure and process shown in Figure 6 are basic identical, for no other reason than that possessed a lot of prior imformations when recapturing, use the synchronous requirement of backup navigation message more wide in range, because the locating speed when recapturing is higher.
Initialization is recaptured after the passage 701, catches and loses satellite 702.If acquisition success 703 then carries out bit synchronous 605, catch if get nowhere then continue to implement.If acquisition success detects then whether bit synchronous priori 704 is arranged this moment, if do not have priori then proceed bit synchronous 705.Bit synchronous the contribution of launch time is second and millisecond between part.Term " bit synchronous priori " is meant about sub-navigation message bit reference position, perhaps the absolute Millisecond information under the UTC/GPST time coordinate.Such information can be from the bits of synchronization information of finishing before this satellite-signal disappearance, also can be from real-time clock accurately.Can skip the link of conventional bit synchronous 705 if there is such prior imformation to exist, and directly utilize prior imformation to upgrade millisecond counter 708, promptly finish bit synchronous.
Further, after finishing bit synchronous 706 or upgrading millisecond counter 708, utilize the frame synchronization prior imformation to upgrade a second counter 707, promptly finish frame synchronization.Such frame synchronization prior imformation can be from other satellites of finishing frame synchronization, also can be from real-time clock accurately.Further, read the backup navigation message 709 of respective satellite in the backup text space.And then read local zone time 710, and utilize the method that provides among Fig. 5 to judge that whether available the backup text 711, if available, then, can use, and then use more new Algorithm text of the demodulation text that demodulates until the demodulation text with backup text new Algorithm text 712 more; If the backup text is unavailable, then wait the text to be demodulated can be with 713, and then the demodulation text that demodulates of use new Algorithm text more.
Utilize this method can reduce the location that the demodulation text brings to greatest extent and postpone, can improve reorientation speed behind the signal deletion widely.
Although method and apparatus of the present invention is described with reference to gps satellite, should be appreciated that these principles are equally applicable to adopt the positioning system of the combination of pseudo-satelite (pseudolites) or satellite and pseudo-satelite.Pseudo-satelite is a kind of transmitter based on ground, and it is propagated and is modulated at L frequency range PN sign indicating number (similar to gps signal) on the ripple signal, and normally synchronous with gps time.Each transmitter can be endowed the PN sign indicating number of a uniqueness, thereby allows to be discerned by remote receiver.Pseudo-satelite is with under these circumstances, that is, and and from the gps signal disappearance of orbiter, as tunnel, mine, buildings or other closed area and obviously block.Here employed term " satellite " comprises the equivalence of pseudo-satelite or pseudo-satelite, and employed here term gps signal comprises the signal from the similar GPS of pseudo-satelite or pseudo-satelite equivalence.
In the discussion in front, the present invention describes with reference to american global positioning system (GPS).Yet, should be appreciated that these methods are equally applicable to similar global position system, as Muscovite GLONASS (Glonass) system, the Big Dipper 1 and the Big Dipper 2 systems of Galileo (Galileo) system in Europe and China.Employed term " GPS " also comprises some global position systems like this, as Muscovite GLONASS (Glonass) system, and the Big Dipper 1 and the Big Dipper 2 systems of Galileo (Galileo) system in Europe and China.Term " gps signal " comprises the signal from other global position systems.
Above, the navigation message management method that is used for GPS receiver has been described.Although the present invention describes with reference to specific embodiment, clearly, the one skilled in the art under the situation of invention scope that non-migration claims are limited and spirit, can also make various modifications and changes to these embodiment.Therefore, instructions and accompanying drawing are descriptive, rather than determinate.
Claims (19)
1. navigation message management method that is used for GPS receiver, it is characterized in that, receiver inside has comprised three part navigation message spaces: be used to place the navigation message that demodulates demodulation navigation message space, be used for the backup navigation message space of the navigation message that the storage backup demodulation is finished and verification is passed through and be used to resolve receiver location navigation message resolve the navigation message space, concrete steps are:
When the navigation message demodulation is finished and verification is passed through, then, realize resolving of receiver location with the text that the demodulates navigation message in new Algorithm navigation message space more;
The text that utilization demodulates upgrades the navigation message in backup navigation message space;
If demodulation is not finished or verification is not passed through, whether the backup navigation message that detects this satellite exists;
If the backup navigation message exists, whether the backup navigation message that then detects this satellite is within the term of validity, otherwise etc. navigation message to be demodulated finish demodulation and verification is passed through;
If the backup navigation message is in the term of validity, startup temperature in warm start and start-up time less than the navigation message term of validity, and satisfy under two kinds of situations of reorientation behind the signal deletion after the respective synchronization requirement, new Algorithm navigation message more, realize resolving of receiver location, finish demodulation and verification is passed through until the demodulation navigation message;
Wherein, described warm start and start-up time are less than using the backup navigation message to comprise following steps under the startup temperature situation of the navigation message term of validity:
Catch the prediction satellite;
If acquisition success then carries out bit synchronous, catch if get nowhere then continue to implement;
If the bit synchronous success then detects whether there is the frame synchronization priori this moment;
If there is not priori, then proceed frame synchronization until the frame synchronization success, otherwise, then utilize priori to upgrade a second counter, finish frame synchronization;
Read the backup navigation message of respective satellite;
Whether detect the backup navigation message expired; And
If it is expired that the backup navigation message does not have, then utilize more new Algorithm navigation message of backup navigation message, can use until the demodulation navigation message;
Reorientation uses the backup navigation message to comprise following steps down behind the described signal deletion:
The signal deletion satellite of recapturing;
If acquisition success detects then whether the frame synchronization priori is arranged this moment, catch if get nowhere then continue to implement;
If there is not the synchronous priori of bit, then proceed bit synchronous until the bit synchronous success, otherwise, then utilize priori to upgrade millisecond counter, promptly finish bit synchronous;
Utilize the frame synchronization priori to upgrade a second counter, finish frame synchronization;
Read the backup navigation message of respective satellite;
Whether detect the backup navigation message expired; And
If it is expired that the backup navigation message does not have, then utilize more new Algorithm navigation message of backup navigation message, can use until the demodulation navigation message.
2. method according to claim 1 is characterized in that, each follows the tracks of one of channel allocation described demodulation navigation message space.
3. method according to claim 1 is characterized in that, totally 32 in described backup navigation message space, one of every satellite distribution.
4. method according to claim 1 is characterized in that, describedly resolves the navigation message space each follows the tracks of one of channel allocation.
5. method according to claim 1 is characterized in that, described demodulation navigation message space is a hardware text demodulation buffer memory.
6. method according to claim 1 is characterized in that, described demodulation navigation message space is stored among the RAM.
7. method according to claim 1 is characterized in that, described backup navigation message space is stored in the non-loss storer of power down.
8. method according to claim 1 is characterized in that, described backup navigation message space is stored among the Flash.
9. method according to claim 1 is characterized in that, the described navigation message space of resolving is stored among the RAM.
10. method according to claim 1 is characterized in that, described demodulation navigation message is finished demodulation and is meant that subframe one to subframe three demodulation are finished in whole five frame navigation messages.
11. method according to claim 1 is characterized in that, the renewal rate of described backup navigation message is adjustable, and its renewal rate and power consumption are inversely proportional to.
12. method according to claim 1 is characterized in that, whether expired method comprises following steps to described detection backup navigation message:
Extract first TOW in the backup navigation message;
Be transformed into the second is unit;
Read the current time among the real-time clock RTC from baseband processing chip;
Be transformed into second number, i.e. second TOW of time in this week;
These two TOW relatively are if its difference is less than default thresholding then think that this backup navigation message is effective, if greater than default thresholding then think that this backup navigation message has exceeded the term of validity.
13. method according to claim 1 is characterized in that, described frame synchronization prior imformation is meant other satellite subframes initial code position of finishing frame synchronization.
14. method according to claim 1 is characterized in that, described frame synchronization prior imformation is meant from absolute second level information under the UTC/GPST time coordinate of real-time clock accurately.
15. method according to claim 1 is characterized in that, described bit synchronous prior imformation is to have finished preceding this satellite demodulation navigation message bit reference position of signal deletion of bit synchronous.
16. method according to claim 1 is characterized in that, described bit synchronous prior imformation is from the absolute Millisecond information under the UTC/GPST time coordinate of real-time clock accurately.
17. method according to claim 12 is characterized in that, described thresholding is smaller or equal to the numerical value of the navigation message term of validity.
18. method according to claim 12 is characterized in that, described thresholding is the numerical value between 1800 seconds to 3600 seconds.
19. method according to claim 12 is characterized in that, described real-time clock RTC can be upgraded by the UTC time that baseband chip calculates.
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| CN102565820B (en) * | 2010-12-29 | 2013-11-13 | 安凯(广州)微电子技术有限公司 | Method and system for acquiring ephemeris data |
| CN106571862B (en) * | 2016-10-31 | 2019-08-27 | 深圳市德赛微电子技术有限公司 | A kind of rapid frame synchronization method of GPS receiver |
| CN107329148A (en) * | 2017-01-25 | 2017-11-07 | 问众智能信息科技（北京）有限公司 | A kind of method and system for improving GPS location speed after onboard system is reset |
| CN107748373B (en) * | 2017-09-25 | 2019-12-13 | 千寻位置网络有限公司 | Satellite navigation message data collection method |
| CN107884787A (en) * | 2017-11-23 | 2018-04-06 | 深圳开阳电子股份有限公司 | A kind of method, apparatus and satellite navigation receiver of the demodulation of GNSS texts |
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