CN102981171B - Global position system (GPS) satellite carrier frequency detection method and detection device and GPS receiver - Google Patents
Global position system (GPS) satellite carrier frequency detection method and detection device and GPS receiver Download PDFInfo
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- CN102981171B CN102981171B CN201210433704.9A CN201210433704A CN102981171B CN 102981171 B CN102981171 B CN 102981171B CN 201210433704 A CN201210433704 A CN 201210433704A CN 102981171 B CN102981171 B CN 102981171B
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Abstract
The invention discloses a global position system (GPS) satellite carrier frequency detection method, a detection device and a GPS receiver. The GPS satellite carrier frequency detection method is a method used for detecting whether a detection value of a carrier frequency of a GPS satellite which does not participate in locating services. The method includes a first step of calculating the movement velocity of the GPS receiver through utilization of location information and Doppler information of a satellite which is chosen to be used for GPS positioning, and obtaining a Doppler frequency calculation value of the carrier frequency of the GPS satellite which does not participate in the locating services, a second step of comparing the Doppler frequency calculation value of the carrier frequency of the GPS satellite which does not participate in the locating services and a Doppler frequency measured value of a digital carrier frequency locked loop of the GPS satellite, and a third step of ensuring that the Doppler frequency measured value of the digital carrier frequency locked loop of the GPS satellite which does not participate in the locating services is wrong when the Doppler frequency calculation value is inconsistent with the Doppler frequency measured value.
Description
The application is the divisional application of the application for a patent for invention that application number is 200910158460.6, denomination of invention is " the carrier frequency detection method of gps satellite and device and GPS receiver " submitted on June 30th, 2009.
Technical field
Present invention relates in general to a kind of GPS(GPS) technology, especially relate to the technology for detection of the carrier frequency of gps satellite.
Background technology
As shown in Figure 1, general GPS receiver is mainly made up of antenna 10, prime amplifier 20, radio frequency-intermediate frequency (RF/IF) transducer 30, modulus (A/D) transducer 40, digital baseband processor 50, navigating processor 60 and control display unit 70.The radiofrequency signal (RF) of gps satellite transmitting receives by antenna 10, and by passive bandpass filter (not shown) filtering, to reduce to be with outer Radio frequency interference (RFI).Then, radiofrequency signal is by prime amplifier 20 pre-amplifications, and down-converted to intermediate frequency (IF) signal by RF/IF transducer 30, use modulus (A/D) transducer 40 to IF signal sampling and digitizing, the digital medium-frequency signal (also referred to as digital baseband signal) obtaining is sent into digital baseband processor (DBP) 50 and is processed again.Digital baseband processor 50 mainly completes following functions: search of satellite, traction tracking satellite; Navigation message data-signal is carried out to despreading, demodulate navigation message data; Carrying out pseudo range measurement, carrier phase measurement and Doppler frequency deviation measures.For realizing despreading, the demodulation of spread-spectrum signal, in DBP, comprise digital pseudo-code delay lock loop (DDLL), digital carrier phaselocked loop (DPLL) and digital carrier FLL (DFLL).The satellite information obtaining from intermediate frequency data demodulation is sent to navigating processor 60 and positions calculating, determines user's Position, Velocity and Time (PVT) information.As can see from Figure 1, navigating processor 60 comprises: select star device 610 for selecting corresponding satellite information to process, speed calculating apparatus 620 and position and clock resolver 630, for determining PVT information, and comprise after-treatment device 640.Finally, PVT information is intuitively shown on the screen of GPS receiver by controlling display unit 70.
In the processing procedure of GPS receiver, pseudo-code delay lock loop, digital carrier phaselocked loop and digital carrier FLL are vital to the performance impact of receiver.Pseudo-code delay lock loop is for measuring the time of reception of pseudo-code, and the value of this time of reception has directly determined the measuring accuracy of pseudorange.Digital carrier phaselocked loop is for carrier phase measurement, and digital carrier FLL is measured for the Doppler frequency deviation of carrier wave, and these two measured values are for the carrier phase of baseband signal and peeling off of Doppler frequency.If there is deviation in carrier phase-locked loop, carrier wave FLL and pseudo-code delay lock loop, can directly cause the pseudo range measurement of satellite inaccurate, thereby make the final user PVT information of calculating occur deviation, this deviation is unacceptable many times.
Due to carrier phase-locked loop, FLL and the decisive role of pseudo-code delay lock loop to GPS receiver performance, this three's design is also vital.Because the reaction velocity of carrier wave FLL is fast compared with pseudo-code delay lock loop, so all can consider while generally design that the Doppler shift value that carrier wave FLL is obtained is for revising pseudo-code delay lock loop, if skew appears in the tracking frequencies of carrier wave FLL, can cause the skew of pseudo-code delay lock loop.Fig. 2 shows the carrier doppler frequency shift (FS) schematic diagram over time that static receiver carrier phase-locked loop is followed the tracks of under normal circumstances.As can be seen from Figure 2, under normal circumstances, the carrier doppler frequency deviation Changing Pattern that DFLL follows the tracks of is very level and smooth reducing or increase.
In the time that deviation appears in the carrier doppler frequency deviation of DFLL tracking, situation is from different shown in Fig. 2.Fig. 3 shows and follows the tracks of when abnormal when FLL, the carrier doppler frequency of output.All occurred following the tracks of as can be seen from Figure 3 the problem that skew appears in Doppler frequency in 500s, 1000s and 1500s position, side-play amount is in 200Hz-400Hz left and right, and this has directly caused positioning result and more than actual position deviation 100m.Its reason mainly, in weak signal situation, because the impact of noise and multipath is difficult to the long-term stability that ensures that FLL is followed the tracks of, in the time of frequency of occurrences deviation, is used carrier lock to detect and also cannot reflect that whether tracking is normal.
Summary of the invention
An object of the present invention is, propose a kind of method and apparatus, occur abnormal frequency deviation by the carrier wave that uses the method and device can effectively detect satellite.
Another object of the present invention is, proposes a kind of method and apparatus, by using the testing result of frequency shift (FS) of the carrier wave that the method and device can be based on to gps satellite to remotivate rapidly catching of satellite to there is the abnormal frequency deviation of carrier wave.
Another object of the present invention is, proposes a kind of method and apparatus, by using the testing result of frequency shift (FS) of the carrier wave that the method and device can be based on to gps satellite to avoid being judged as the select of satellite that abnormal frequency deviation appears in carrier wave for location.
Another object of the present invention is to propose a kind of method and apparatus, by using the method whether correct with the carrier frequency detected value that device can detect the gps satellite that has neither part nor lot in location.
A further object of the present invention is to propose a kind of GPS receiver that uses at least one said method and/or device.
According to an aspect of the present invention, a kind of method of Doppler shift of the carrier frequency for detection of gps satellite has been proposed, comprise: a. is for every satellite in all satellites on following the tracks of the carrier frequency of calculating every satellite Doppler frequency changing value in the given time; B. calculate the mean value of the Doppler frequency changing value of the carrier frequency of all satellites on following the tracks of; If c. the Doppler frequency changing value of the carrier frequency of in all satellites in described tracking or multi-satellite had both been greater than the mean value and the product of setting weight of described Doppler frequency changing value, and be greater than again setting threshold, judge that abnormal frequency deviation appears in the carrier wave of described or multi-satellite.
Correspondingly, the present invention has also proposed a kind of Doppler shift pick-up unit of the carrier frequency for detection of gps satellite, comprise: frequency offset computations device, it is designed for for every satellite in all satellites on following the tracks of, the carrier frequency of calculating every satellite Doppler frequency changing value in the given time, and calculate the mean value of the Doppler frequency changing value of the carrier frequency of all satellites on following the tracks of; Frequency is with inclined to one side pick-up unit, if wherein the Doppler frequency changing value of the carrier frequency of in all satellites in described tracking or multi-satellite had both been greater than the mean value and the product of setting weight of described Doppler frequency changing value, and be greater than again setting threshold, described frequency judges that with inclined to one side pick-up unit abnormal frequency deviation appears in the carrier wave of described or multi-satellite.
According to another aspect of the present invention, in the method for the Doppler shift of the above-mentioned carrier frequency for detection of gps satellite, described step c further comprises: when the Doppler frequency changing value of the carrier frequency of described or multi-satellite had both been greater than the mean value of described Doppler frequency changing value and the product of the first weight, and while being greater than first threshold again, there is abnormal frequency deviation in the carrier wave of judging described one or multi-satellite, and, described method further comprises: d. excites the recapture that occurs described or the multi-satellite of abnormal frequency deviation to being judged as carrier wave.
Correspondingly, the present invention has also proposed a kind of GPS receiver, comprise digital baseband processor and navigating processor, wherein said navigating processor comprises above-mentioned Doppler shift pick-up unit, wherein in the time that described Doppler shift pick-up unit judges that abnormal frequency deviation appears in the carrier wave of or multi-satellite, described Doppler shift pick-up unit notice digital baseband processor excites the recapture that occurs described or the multi-satellite of abnormal frequency deviation to being judged as carrier wave.
According to another aspect of the present invention, in the method for the Doppler shift of the above-mentioned carrier frequency for detection of gps satellite, described step c further comprises: when the Doppler frequency changing value of the carrier frequency of described or multi-satellite had both been greater than the mean value of described Doppler frequency changing value and the product of the second weight, and while being greater than Second Threshold again, there is abnormal frequency deviation in the carrier wave of judging described one or multi-satellite, and described method further comprises: e. does not select for location being judged as carrier wave and occurring described one or the multi-satellite of abnormal frequency deviation.
Correspondingly, the present invention has also proposed a kind of GPS receiver, comprise digital baseband processor and navigating processor, wherein said navigating processor comprises above-mentioned Doppler shift pick-up unit and for selecting the star device that selects of star, wherein: in the time that described Doppler shift pick-up unit judges that abnormal frequency deviation appears in the carrier wave of or multi-satellite, described Doppler shift pick-up unit notice select star device will be not described one or multi-satellite select for locating.
According to a further aspect of the invention, a kind of whether correct method of carrier frequency detected value of gps satellite for detection of having neither part nor lot in location has been proposed, comprise: a. utilizes positional information and the doppler information of the satellite that is selected for GPS location, calculate the movement velocity of GPS receiver, and described in obtaining by Doppler frequency deviation computing formula, have neither part nor lot in the Doppler frequency calculating value of the carrier frequency of the gps satellite of location; B. the digital carrier FLL doppler frequency measurement value of the described Doppler frequency calculating value of the carrier frequency of the described gps satellite that has neither part nor lot in location and this gps satellite is compared; And c. is when described Doppler frequency calculating value and described doppler frequency measurement value are when inconsistent, the digital carrier FLL doppler frequency measurement value that has neither part nor lot in the gps satellite of location described in determining is wrong.
Correspondingly, the present invention has also proposed a kind of doppler frequency measurement value detection device, comprise: frequency offset calculation device and frequency deviation Difference test device, described frequency offset calculation device is for utilizing positional information and the doppler information of the satellite that is selected for GPS location, calculate the movement velocity of GPS receiver, and described in obtaining by Doppler frequency deviation computing formula, have neither part nor lot in the Doppler frequency calculating value of the gps satellite of location; Described frequency deviation Difference test device is for comparing the digital carrier FLL doppler frequency measurement value of the described Doppler frequency calculating value of the described gps satellite that has neither part nor lot in location and this gps satellite, and when described Doppler frequency calculating value and described doppler frequency measurement value are when inconsistent, the digital carrier FLL doppler frequency measurement value that has neither part nor lot in the gps satellite of location described in judgement is wrong.
Correspondingly, the present invention has also proposed a kind of GPS receiver, comprise digital baseband processor and navigating processor, wherein said navigating processor comprises above-mentioned doppler frequency measurement value detection device, wherein, in the time that described doppler frequency measurement value detection device judges that the digital carrier FLL doppler frequency measurement value of the gps satellite that has neither part nor lot in location is wrong, described doppler frequency measurement value detection device notice digital baseband processor excites the recapture that this is had neither part nor lot in to the gps satellite of location.
Use according to method and/or the device of the Doppler shift of the carrier frequency for detection of gps satellite of the present invention, can effectively from followed the tracks of multi-satellite, determine whether the DFLL of the carrier wave of certain satellite goes wrong.
In addition, in said method according to the present invention and corresponding GPS receiver, can occur that to carrier wave the satellite of abnormal frequency deviation excites recapture and follows the tracks of based on testing result, a satellite number that makes a normal satellite number of following the tracks of and can be used for locating improves a lot while not using according to detection method of the present invention, for example, the satellite of normally a following the tracks of number can be increased to 20% left and right.
In addition, in said method according to the present invention and corresponding GPS receiver, due to not by being judged as the select of satellite that abnormal frequency deviation appears in carrier wave for location, therefore can avoid the select of satellite that abnormal frequency deviation is appearred in carrier wave for location, thereby improve the positioning precision of GPS receiver.
In addition, utilize the whether correct method of the carrier frequency detected value of gps satellite for detection of having neither part nor lot in location according to the present invention and corresponding doppler frequency measurement value detection device and GPS receiver, can effectively avoid the satellite of vicious tool doppler frequency measurement value to be selected into for location Calculation, thereby improve the positioning precision of GPS receiver under weak signal.
Brief description of the drawings
The present invention can, by reference to hereinafter given description and being better understood by reference to the accompanying drawings, wherein use same or analogous Reference numeral to represent identical or similar parts in institute's drawings attached.Described accompanying drawing comprises in this manual and forms the part of this instructions together with detailed description below, and is used for further illustrating the preferred embodiments of the present invention and explains principle and advantage of the present invention.In the accompanying drawings:
Fig. 1 shows the structural drawing of GPS receiver of the prior art;
Fig. 2 shows the carrier doppler frequency deviation variation diagram that DFLL follows the tracks of under normal circumstances;
The carrier doppler frequency that Fig. 3 shows FLL follows the tracks of abnormal time output;
That Fig. 4 shows is according to an embodiment of the invention, for detection of the process flow diagram of the method for the Doppler shift of the carrier wave of gps satellite;
That Fig. 5 shows is according to an embodiment of the invention, for detection of the Doppler shift of the carrier wave of gps satellite and excite as required the process flow diagram of the method for satellite recapture;
Fig. 6 shows wherein the structural drawing of the GPS receiver of the method shown in can execution graph 5;
That Fig. 7 shows is according to an embodiment of the invention, for detection of the Doppler shift of the carrier wave of gps satellite and do not select as required the process flow diagram of satellite for the method for locating;
Fig. 8 shows wherein the structural drawing of the GPS receiver of the method shown in can execution graph 7;
That Fig. 9 shows is according to an embodiment of the invention, for detection of the process flow diagram of the whether correct method of DFLL doppler frequency measurement value;
Figure 10 shows wherein the structural drawing of the GPS receiver of the method shown in can execution graph 9; And
Figure 11 shows an example of the frequency deviation testing result obtaining by use method as shown in Figure 5.
Embodiment
In connection with accompanying drawing, example embodiment of the present invention is described hereinafter.All features of actual embodiment are not described for clarity and conciseness, in instructions.But, should understand, in the process of any this practical embodiments of exploitation, must make much decisions specific to embodiment, to realize developer's objectives, and these decisions may change to some extent along with the difference of embodiment.In addition,, although will also be appreciated that development is likely very complicated and time-consuming, concerning having benefited from those skilled in the art of present disclosure, this development is only routine task.
At this, also it should be noted is that, for fear of the details because of unnecessary fuzzy the present invention, only show in the accompanying drawings with according to the closely-related apparatus structure of the solution of the present invention, and omitted other details little with relation of the present invention.
As mentioned at the beginning, due in weak signal situation, the impact of noise and multipath is difficult to the long-term stability that ensures that FLL is followed the tracks of, and therefore skew easily appears in the carrier frequency of satellite.
According to the characteristics of motion of the characteristics of motion of gps satellite and receiver, the computing formula of the Doppler frequency size of carrier wave is disclosed in " GPS principle and application " (second edition) of showing people such as Elliott D.Kaplan the 42nd page:
Wherein, f
tit is the frequency of satellite emission signal;
V
rit is satellite and user's relative velocity vector;
A is the rectilinear direction unit vector of pointing to user along satellite;
C is velocity of propagation;
Dot product V
ra represents the radial vector of relative velocity vector along the line of satellite.
Can learn by above formula, under truth, the variation size of Doppler frequency can be estimated, if the peak acceleration of known receiver is that 0.5g(g is acceleration of gravity), can estimate the maximal increment of Doppler frequency within the unit interval (obtaining) be in the time that this acceleration is in the unit vector direction of rectilinear direction of pointing to user along satellite:
When having this acceleration when receiver, all can there is larger variation in the multi-satellite carrier doppler frequency of following the tracks of, and in the time that certain moment only has 1-2 satellite carrier Doppler frequency of tracking that larger variation occurs, can think that the DFLL that follows the tracks of this satellite carrier goes wrong.Based on this thinking, the present invention proposes a kind of method of Doppler shift of the carrier frequency for detection of gps satellite, wherein, the DFLL carrier doppler frequency shift (FS) of the satellite that calculating is followed the tracks of variable quantity within a certain period of time, if variable quantity meets some requirements, think that the carrier wave of the satellite in described tracking has problem, has occurred abnormal frequency deviation.
That Fig. 4 shows is according to an embodiment of the invention, for detection of the process flow diagram of the method for the Doppler shift of the carrier frequency of gps satellite, comprising following steps:
S410: for every satellite in all N satellites on following the tracks of, the carrier frequency of calculating every satellite Doppler frequency changing value Δ f in the given time
di(i=1,2 ... N);
S420: the mean value that calculates the Doppler frequency changing value of all satellites on following the tracks of according to following equation:
S430: if there is the Doppler frequency changing value of or multi-satellite in all satellites on following the tracks of
w is for setting weight, and Δ f
dibe greater than setting threshold THRESH1, judge that abnormal frequency deviation appears in this of tracking or the carrier wave of multi-satellite.Wherein weight w and setting threshold THRESH1 can determine by emulation.For example, a kind of Weight Determination is: having in the data of the abnormal frequency deviation in many places, detect by setting different weighted values, then add up the probability that testing result is correct, thereby obtain suitable weighted value.General this weighted value is set between 1.5-3.0.
Especially, wherein calculate the Doppler frequency changing value Δ f of every satellite
dstep comprise: for described every satellite, with the Doppler frequency value f of the current time t of digital carrier FLL
di(t) deduct Doppler frequency value f before of the described schedule time (for example, supposing to represent with m unit interval)
di(t-m), obtain the Doppler frequency changing value Δ f of respective satellite
di=f
di(t)-f
di(t-m).Especially, wherein m is chosen as between 10 to 20 conventionally.For example, unit interval above can be 500ms.
Especially faster in situation, by utilizing said method, can obtain good testing result at DFLL Doppler shift.
Corresponding to the method for setting forth according to Fig. 4, according to one embodiment of present invention, a kind of Doppler shift pick-up unit of the carrier frequency for detection of gps satellite is proposed.This Doppler shift pick-up unit comprises: frequency offset computations device, it is designed for the processing in step S410 and the S420 that carries out said method,, calculate the Doppler frequency changing value in the given time of carrier frequency of the each satellite on following the tracks of, and the mean value that changes of the Doppler frequency of the carrier frequency of satellite in all tracking; And frequency is with inclined to one side pick-up unit, it is designed for the processing in the step S430 that carries out said method,, result of calculation based on frequency offset computations device detects the Doppler frequency changing value of the carrier frequency of the satellite in each tracking, and whether the corresponding satellite carrier that judgement is followed the tracks of whereby occurs abnormal frequency deviation.At this, do not draw separately in the accompanying drawings the schematic diagram of Doppler shift pick-up unit, its structure can referring in Fig. 6 for example by 600 parts that represent and be below described in more detail.
By method recited above and Doppler shift pick-up unit, can effectively from followed the tracks of multi-satellite, determine whether the DFLL of the carrier wave of certain satellite goes wrong.
Based on the method described in Fig. 4, can in the case of the abnormal frequency deviation of Doppler of carrier frequency that gps satellite detected, take corresponding countermeasure for different application situation.
Fig. 5 show according to another embodiment of the present invention for detection of Doppler shift and excite as required the process flow diagram that carrier wave is occurred to the method for the recapture of the satellite of abnormal frequency deviation.
In the method shown in Fig. 5, step S510 to S530 corresponds respectively to the step S410 to S430 shown in Fig. 4, therefore, and for just no longer having described in detail at this for purpose of brevity of instructions.The difference of the method shown in the method shown in Fig. 5 and Fig. 4 is, has increased step S540: excite the recapture that occurs the satellite of abnormal frequency deviation to being judged as carrier wave.
Fig. 6 shows wherein the structural drawing of the GPS receiver of the method shown in can execution graph 5.As can be seen from Figure 6, comprise Doppler shift pick-up unit 600 mentioned above at navigating processor 60, and this Doppler shift pick-up unit 600 comprises that frequency offset computations device 650 and frequency are with inclined to one side pick-up unit 660.The data that digital baseband processor 50 is exported are imported in frequency offset computations device 650.In frequency offset computations device 650, carry out in conjunction with the processing in step S510 and the S520 of the method described in Fig. 5,, calculate the Doppler frequency changing value in the given time of carrier frequency of the each satellite on following the tracks of, and the mean value that changes of the Doppler frequency of the carrier frequency of satellite in all tracking.Follow the processing in the step S530 that carries out said method in inclined to one side pick-up unit 660 in frequency,, result of calculation based on frequency offset computations device 650 detects the Doppler frequency changing value of the satellite in each tracking, and whether the carrier wave of the respective satellite that judgement is followed the tracks of whereby occurs abnormal frequency deviation.If determine that certain DFLL loop tracks has problem, Doppler shift pick-up unit 600 is notified digital baseband processor 50, excites the recapture that occurs the satellite of abnormal frequency deviation to being judged as carrier wave.
By this for detection of Doppler shift and excite as required the method and the corresponding GPS receiver that carrier wave are occurred to the recapture of the satellite of abnormal frequency deviation, can go wrong (abnormal frequency deviation appears in the carrier wave of judging this satellite) afterwards at the DFLL of definite carrier wave for certain satellite, by exciting, the recapture of this satellite be reduced to the positioning error of introducing due to this problem.
In addition, selecting in star process, select for location for fear of DFLL being followed the tracks of to the satellite information of makeing mistakes larger, can select star strategy with reference to Doppler shift amount selecting to add in star device.Therefore, the invention allows for a kind of method of selecting satellite, the method is the method based on setting forth according to Fig. 4 also.Fig. 7 shows this detection Doppler shift and does not select as required carrier frequency to occur the process flow diagram of the method for the abnormal satellite of skew.
In the method shown in Fig. 7, step S710 to S730 corresponds respectively to the step S410 to S430 shown in Fig. 4, be to have increased step S740 with the difference of the method shown in Fig. 4, wherein not by be detected carrier wave occur abnormal frequency deviation respective satellite select for location.
Fig. 8 shows wherein the structural drawing of the GPS receiver of the method shown in can execution graph 7.As can be seen from Figure 8, in navigating processor 60, increased equally mentioned above, comprise frequency offset computations device 650 and the frequency Doppler shift pick-up unit 600 with inclined to one side pick-up unit 660.Wherein Doppler shift pick-up unit 600 is carried out and identical function set forth in fig. 6.The difference of the GPS receiver shown in the GPS receiver shown in Fig. 8 and Fig. 6 is, if determine that certain FLL loop tracks has problem, Doppler shift pick-up unit 600 notices select star device 610 not by corresponding the select of satellite for location.
By method and the corresponding GPS receiver of this selection satellite, can effectively avoid FLL to follow the tracks of the satellite information selection that makes mistakes larger for location, thereby ensure the positioning precision of GPS.
Certainly also possible that, the method for setting forth by Fig. 5 above and the method set forth by Fig. 7 are combined, obtain first respectively the Doppler frequency changing value of each satellite on following the tracks of and the mean value of the Doppler frequency changing value of all satellites; Then judge whether certain satellite carrier of following the tracks of occurs abnormal frequency deviation; In the situation that detecting satellite carrier and occurring abnormal frequency deviation, excite recapture and/or avoid respective satellite to select for location.Correspondingly, in GPS receiver, also can comprise from Doppler shift pick-up unit 600 to digital baseband processor 50 and to the signal stream that selects star device 610 simultaneously.Although do not provide corresponding method flow diagram and/or structure drawing of device at this, those skilled in the art can draw out corresponding method flow diagram and/or structure drawing of device according to foregoing description easily.
In addition, it should be noted that, weight and threshold value in the method flow diagram shown in the weight in the method flow diagram shown in Fig. 5 and threshold value and Fig. 7 can be the same or different.
For the satellite that has neither part nor lot in location, according to another embodiment of the present invention, a kind of whether correct method of carrier frequency detected value of gps satellite for detection of having neither part nor lot in location is also proposed.Fig. 9 shows the process flow diagram of the method, comprising following steps:
S910: by being selected for positional information and the doppler information of satellite of GPS location, calculate the movement velocity of GPS receiver, in the case of participate in location satellite information, doppler information correct, the receiver movement velocity of now calculating is correct, thereby can obtain the Doppler frequency calculating value of the carrier frequency of the satellite that has neither part nor lot in location by following Doppler frequency deviation computing formula:
S920: the Doppler frequency calculating value of carrier frequency and the DFLL doppler frequency measurement value of this satellite of the satellite that has neither part nor lot in location are compared;
S930: when Doppler frequency calculating value and doppler frequency measurement value are when inconsistent, ensureing can to conclude that the DFLL doppler frequency measurement value of this satellite is wrong under the condition that this satellite position calculation is correct.
Corresponding to the method for setting forth according to Fig. 9, according to one embodiment of present invention, a kind of whether correct doppler frequency measurement value detection device of gps satellite carrier frequency detected value for detection of having neither part nor lot in location is proposed.This doppler frequency measurement value detection device comprises: frequency offset calculation device and frequency deviation Difference test device.In frequency offset calculation device, carry out the processing in the step S910 of said method,, by being selected for positional information and the doppler information of satellite of GPS location, calculate the movement velocity of GPS receiver, and calculate the Doppler frequency calculating value of the carrier frequency of the satellite that has neither part nor lot in location by described Doppler frequency deviation computing formula.The satellite information of locating in hypothesis participation and doppler information are correct, this Doppler frequency calculating value is correct.Subsequently, in frequency deviation Difference test device, carry out the processing in step S920 and the S930 of said method,, to have neither part nor lot in the Doppler frequency calculating value of position location satellite and the DFLL doppler frequency measurement value of this satellite compares, judge that whereby whether the DFLL doppler frequency measurement value of respective satellite is correct.If this doppler frequency measurement value is incorrect, illustrate that this satellite can not be used to location Calculation, thereby this doppler frequency measurement value detection device can notify digital baseband processor to excite the recapture that this is had neither part nor lot in to the gps satellite of location.At this, do not draw separately in the accompanying drawings the schematic diagram of doppler frequency measurement value detection device, can referring in Figure 10 for example by 601 parts that represent.
Figure 10 shows wherein the structural drawing of the GPS receiver of the method shown in can execution graph 9.As can be seen from Figure 10, in navigating processor, increased doppler frequency measurement value detection device 601 mentioned above, that comprise frequency offset calculation device 680 and frequency deviation Difference test device 690.In the time that doppler frequency measurement value detection device 601 judges that the doppler frequency measurement value of respective satellite is incorrect, doppler frequency measurement value detection device 601 notifies digital baseband processor 50 to excite the recapture that this is had neither part nor lot in to the gps satellite of location.
Especially, wherein said frequency offset calculation device 680 is realized with software mode.
By the whether correct method of this carrier frequency detected value of gps satellite for detection of having neither part nor lot in location and corresponding doppler frequency measurement value detection device and GPS receiver, effectively avoid the satellite of vicious tool DFLL doppler frequency measurement value to be selected into for location Calculation, thereby improved the positioning precision of GPS receiver.
In addition according to still another embodiment of the invention, for the ease of improving the positioning precision of GPS receiver, also above method described in conjunction with Figure 5 and/or method described in conjunction with Figure 7 and method described in conjunction with Figure 9 can be combined.On the one hand, obtain respectively the Doppler frequency changing value of each satellite followed the tracks of and the mean value of the Doppler frequency changing value of all satellites; Then judge whether certain satellite carrier of following the tracks of occurs abnormal frequency deviation; In the situation that detecting satellite carrier and occurring abnormal frequency deviation, excite recapture and/or avoid respective satellite to select for location; On the other hand, can will have neither part nor lot in the Doppler frequency calculating value of position location satellite and the DFLL doppler frequency measurement value of this satellite compares, judge that whereby whether the DFLL doppler frequency measurement value of respective satellite is correct.If this doppler frequency measurement value is incorrect, illustrates that this satellite can not be used to location Calculation, and excite the recapture that this is had neither part nor lot in to the gps satellite of location.Correspondingly, in GPS receiver, can comprise Doppler shift pick-up unit 600 and doppler frequency measurement value detection device 601 and corresponding signal stream simultaneously.Although do not provide corresponding method flow diagram and/or structure drawing of device at this, those skilled in the art can draw out corresponding method flow diagram and/or structure drawing of device according to foregoing description easily.
In above-mentioned the whole bag of tricks, all can be using the carrier-to-noise ratio of satellite (CNR) as with reference to condition.For example, can in said method, increase following steps: whether the CNR of the satellite to be detected that judgement is relevant is greater than predetermined threshold, in the time that CNR is stronger, for example, in the time that CNR is more than or equal to predetermined threshold THRESH3, think that this satellite-signal is believable, and DFLL Doppler shift is normal, the result of above-mentioned detection method is invalid, and according to not exciting the recapture that occurs the satellite of abnormal frequency deviation to being judged as carrier wave in the method for Fig. 5, and/or selecting for location being judged as carrier wave and occurring described one or the multi-satellite of abnormal frequency deviation according to not affecting in the method for Fig. 7, and/or according in the method for Fig. 9, the DFLL doppler frequency measurement value of determining respective satellite is correct and can be selected for location, in the time that CNR is less than predetermined threshold THRESH3, the result of above-mentioned detection method is effective, and can carry out corresponding operation or processing.Wherein threshold value THRESH3 can determine by emulation.
According to another embodiment, in the method for the Doppler shift of the above-mentioned carrier frequency for detection of gps satellite and/or for detection of the carrier frequency detected value of gps satellite that has neither part nor lot in location in whether correct method, in order to improve the reliability of detection, also propose to get in N the detection method of M., in testing process, on continuous time interval, repeat for N time to detect, and testing result is counted, if wherein at least M testing result all judges that abnormal frequency deviation appears in the carrier wave of respective satellite, think that the carrier wave of described or multi-satellite occurs that the result of determination of abnormal frequency deviation is effective, and/or the DFLL doppler frequency measurement value that at least M testing result has neither part nor lot in the gps satellite of location described in all judging is wrong, the result of determination that has neither part nor lot in the digital carrier FLL doppler frequency measurement value mistake of the gps satellite of location described in thinking is effective.Wherein, M and N are positive integer and M≤N.After operation like this, effectively reduce the probability of false detection of detection method.
When using after Doppler shift detection method, can effectively reduce Satellite Doppler Method tracking and be forbidden the pseudorange causing to be forbidden.Figure 10 has provided an exemplary that uses the above result obtaining in conjunction with the method according to this invention described in Fig. 5, wherein hwfrq represents the carrier doppler frequency that DFLL follows the tracks of, swfrq represents the carrier doppler frequency of calculating by receiver speed, there is skew in the frequency that DFLL follows the tracks of in the drawings, side-play amount is detected in 200Hz left and right, excite thus the recapture that occurs the satellite of abnormal frequency deviation frequency deviation to being judged as carrier wave, thereby a normal tracking satellite number that makes a normal satellite number of following the tracks of and can be used for locating is significantly improved while not using according to detection method of the present invention, and can improve significantly the positioning precision of GPS receiver under weak signal.
Finally, also it should be noted that, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thereby the process, method, article or the equipment that make to comprise a series of key elements not only comprise those key elements, but also comprise other key elements of clearly not listing, or be also included as the intrinsic key element of this process, method, article or equipment.In addition, the in the situation that of more restrictions not, the key element being limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment that comprises described key element and also have other identical element.
Although describe by reference to the accompanying drawings above embodiments of the invention in detail, it should be understood that embodiment described above is just for the present invention is described, and be not construed as limiting the invention.For a person skilled in the art, can make various changes and modifications and not deviate from the spirit and scope of the invention above-mentioned embodiment.Therefore, scope of the present invention is only limited by appended claim and equivalents thereof.
Claims (8)
1. for detection of the whether correct method of carrier frequency detected value of gps satellite that has neither part nor lot in location, comprising:
A. the positional information and the doppler information that utilize the satellite that is selected for GPS location, calculate the movement velocity of GPS receiver, and described in obtaining by Doppler frequency deviation computing formula, have neither part nor lot in the Doppler frequency calculating value of the carrier frequency of the gps satellite of location;
B. the digital carrier FLL doppler frequency measurement value of the described Doppler frequency calculating value of the carrier frequency of the described gps satellite that has neither part nor lot in location and this gps satellite is compared; And
C. when described Doppler frequency calculating value and described doppler frequency measurement value are when inconsistent, the digital carrier FLL doppler frequency measurement value that has neither part nor lot in the gps satellite of location described in determining is wrong.
2. method according to claim 1, also comprises:
Whether the carrier-to-noise ratio CNR that has neither part nor lot in the gps satellite of location described in judgement is greater than predetermined threshold; And
In the time that the CNR of the described gps satellite that has neither part nor lot in location is greater than this predetermined threshold, judge that the result of determination of digital carrier FLL doppler frequency measurement value mistake of the gps satellite that has neither part nor lot in location is invalid.
3. method according to claim 1 and 2, also comprise: on continuous time interval, repeat described step a for N time to step c, if it is wrong having neither part nor lot in the digital carrier FLL doppler frequency measurement value of the gps satellite of location described in wherein at least judging for M time, the result of determination that has neither part nor lot in the digital carrier FLL doppler frequency measurement value mistake of the gps satellite of location described in judging is effective, wherein, M and N are positive integer and M≤N.
4. one kind for detection of the whether correct doppler frequency measurement value detection device (601) of carrier frequency detected value of gps satellite that has neither part nor lot in location, comprise: frequency offset calculation device (680) and frequency deviation Difference test device (690)
Described frequency offset calculation device (680) is for utilizing positional information and the doppler information of the satellite that is selected for GPS location, calculate the movement velocity of GPS receiver, and described in obtaining by Doppler frequency deviation computing formula, have neither part nor lot in the Doppler frequency calculating value of the gps satellite of location;
Described frequency deviation Difference test device (690) is for comparing the digital carrier FLL doppler frequency measurement value of the described Doppler frequency calculating value of the described gps satellite that has neither part nor lot in location and this gps satellite, and when described Doppler frequency calculating value and described doppler frequency measurement value are when inconsistent, the digital carrier FLL doppler frequency measurement value that has neither part nor lot in the gps satellite of location described in judgement is wrong.
5. doppler frequency measurement value detection device according to claim 4 (601), wherein said frequency offset calculation device (680) is that software is realized.
6. a GPS (GPS) receiver, comprise digital baseband processor (50) and navigating processor (60), wherein said navigating processor (60) comprises according to the doppler frequency measurement value detection device (601) described in claim 4 or 5
Wherein, in the time that described doppler frequency measurement value detection device (601) judges that the digital carrier FLL doppler frequency measurement value of gps satellite that has neither part nor lot in location is wrong, described doppler frequency measurement value detection device (601) notice digital baseband processor (50) excites the recapture that this is had neither part nor lot in to the gps satellite of location.
7. GPS receiver according to claim 6, whether the carrier-to-noise ratio CNR that wherein has neither part nor lot in the gps satellite of location described in judgement is greater than predetermined threshold, in the time that the CNR of the described gps satellite that has neither part nor lot in location is greater than this predetermined threshold, do not affect navigating processor (60) by the described satellite that has neither part nor lot in location for location Calculation.
8. according to the GPS receiver described in claim 6 or 7, wherein said doppler frequency measurement value detection device (601) repeats for N time and calculates and judge on continuous time interval, if it is wrong having neither part nor lot in the digital carrier FLL doppler frequency measurement value of the gps satellite of location described in wherein at least judging for M time, the result of determination that has neither part nor lot in the digital carrier FLL doppler frequency measurement value mistake of the gps satellite of location described in judging is effective, wherein, M and N are positive integer and M≤N.
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