CN103116172B - False detection method of satellite navigation signal and satellite navigation positioning receiver - Google Patents
False detection method of satellite navigation signal and satellite navigation positioning receiver Download PDFInfo
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- CN103116172B CN103116172B CN201310022065.1A CN201310022065A CN103116172B CN 103116172 B CN103116172 B CN 103116172B CN 201310022065 A CN201310022065 A CN 201310022065A CN 103116172 B CN103116172 B CN 103116172B
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Abstract
The invention discloses a false detection method of a satellite navigation signal. Based on an initial position of a receiver, the method calculates a general location parameter, relative to the receiver, of a satellite, wherein the general location parameter is corresponding to the received satellite navigation signal, if the general location parameter is not within an observation vision field of the receiver, the general location parameter is judged to be a false signal, and the method further carries out false detection through calculating error distance of a spatial position of the satellite. The invention further discloses a satellite navigation positioning receiver. Through the above way, the method detects the false navigation signal through analyzing navigation message contents, strengthens anti-spoofing ability of the receiver, and further has the advantages of being low in implementation cost, strong in expansibility, capable of being firmly combined with the application mode of the receiver and the like.
Description
Technical field
The present invention relates to satellite navigation field, particularly relate to false detection method and the satellite navigation location receiver of satellite navigation signals.
Background technology
Along with GPS and " Big Dipper " satellite navigation location and time service business are in the generally application of China, national economy is had to the industry department of material impact, as communication, electric power, traffic etc., not only the accuracy of satellite navigation location and time service business is had higher requirements, its dependence is also strengthened greatly, mainly or completely via satellite navigator fix and time service provides infrastructure service and technical support, therefore the security of satellite navigation location and time service business proposed to requirements at the higher level.
The real satellite that disguises oneself as navigation signal carries out duplicity interference to satellite navigation receiver and has become the important threat of one that satellite navigation location and Timing Receiver face.If satellite navigation location and Timing Receiver are not taked the measures such as effective identification, detection for this false curve through camouflage, once so this false curve is received and this signal is resolved to the false navigator fix of acquisition and time service information, making receiver produce wrong position and time, will be huge to the negative effect of important sector of the national economy so.Particularly time service type satellite navigation receiver, utilize such receiver can obtain temporal information accurately, meet the application that time precision, time synchronized etc. are had higher requirements, if but this temporal information is distorted arbitrarily, replaces and confuse by false curve, bring confusion can to so national economy, social life, even affect social stability.
In the prior art, mainly laying particular emphasis on the detection research at signals layer for the detection method of false satellite navigation signals, is that the situation such as centre carrier frequency, waveform, frequency spectrum, power of the satellite navigation signals to receiving is carried out static state or performance analysis.The detection application that these methods are false satellite navigation signals provides reference frame, but in some concrete applications, these methods are difficult to and the combining closely of practical application condition, and therefore aspect dirigibility, practicality, accuracy, validity and the technical costs of application, do not have advantage.
Summary of the invention
The technical matters that the present invention mainly solves is to provide a kind of false detection method and satellite navigation location receiver of satellite navigation signals, can initial position and almanac based on receiver carry out falseness detection to satellite navigation signals.
For solving the problems of the technologies described above, the technical scheme that the present invention adopts is: a kind of false detection method of satellite navigation signals is provided, and the method comprises, in the time that receiver is started shooting, carry out initial alignment by this receiver, obtain the initial position of this receiver according to positioning result, receive and tracking satellite navigation signal, calculate the general location parameter of the satellite corresponding with this satellite navigation signals according to the reference almanac of this initial position and this receiver storage, judge that according to this general location parameter this satellite is whether in the observation visual field of this receiver, while being no, determine that this satellite navigation signals is spurious signal in judged result, in judged result when being, calculate the reference locus of this satellite with reference to almanac according to this, calculate the current locus of this satellite according to the current almanac in this satellite navigation signals, and calculate the reference locus of this satellite and deserve the error distance between front space position, judge whether this error distance is greater than threshold value, in the time that this error distance is greater than this threshold value, determine that this satellite navigation signals is spurious signal, in the time that this error distance is less than or equal to this threshold value, determine that this satellite navigation signals is actual signal, replace this with reference to almanac with this current almanac.
In another embodiment of the false detection method of satellite navigation signals of the present invention, this general location parameter comprises position angle and the elevation angle.
In another embodiment of the false detection method of satellite navigation signals of the present invention, this initial position is that the positioning result of continuous several times initial alignment is carried out to the position that mean value computation obtains.
In another embodiment of the false detection method of satellite navigation signals of the present invention, this initial alignment is at least 10 times, the threshold condition of this mean value computation comprises: three-dimensional accuracy geometric factor <3, satellite number >=5, the residual error <0.01 of the least square iteration of positioning calculation, repeatedly the difference <30 rice of the longitude and latitude between the positioning result of initial alignment, elevation.
In another embodiment of the false detection method of satellite navigation signals of the present invention, after this initial position is determined, the location parameter of outside this receiver determined of this receiver is input to this receiver, and this initial position is proofreaied and correct.
In another embodiment of the false detection method of satellite navigation signals of the present invention, in the time that the acquisition time of this current almanac and this interval with reference to the update time of almanac are less than or equal to 1 day, this threshold value is 1 kilometer; When large 1 day of the acquisition time of this current almanac and this interval with reference to the update time of almanac, and while being less than or equal to 5 days, this threshold value was 5 kilometers; In the time that the acquisition time of this current almanac and this interval with reference to the update time of almanac are greater than 5 days, this threshold value is 10 kilometers.
The present invention also provides a kind of satellite navigation location receiver, and this receiver comprises: positioning unit, carry out initial alignment for this receiver, and calculate the initial position of this receiver according to positioning result; Signal element, for receiving and tracking satellite navigation signal, calculates the general location parameter of the satellite corresponding with this satellite navigation signals according to the reference almanac of this initial position and this receiver storage; The first judging unit, for judging that according to this general location parameter this satellite is whether in the observation visual field of this receiver; Performance element, when being no in the judged result of this first judging unit, determines that this satellite-signal is spurious signal; Computing unit, for in the judged result of this first judging unit when being, calculate the reference locus of this satellite with reference to almanac according to this, calculate the current locus of this satellite according to the current almanac in this satellite navigation signals, and calculate this with reference to locus and deserve the error distance between front space position; The second judging unit, for judging whether this error distance is greater than threshold value; This performance element is further used in the time that this error distance is greater than this threshold value, determines that this satellite navigation signals is spurious signal; And in the time that this error distance is less than or equal to this threshold value, determine that this satellite navigation signals is actual signal, replace this with reference to almanac with this current almanac.
In another embodiment of satellite navigation location receiver of the present invention, this general location parameter comprises position angle and the elevation angle.
In another embodiment of satellite navigation location receiver of the present invention, in the time that the acquisition time of this current almanac and this interval with reference to the update time of almanac are less than or equal to 1 day, this threshold value is 1 kilometer; When large 1 day of the acquisition time of this current almanac and this interval with reference to the update time of almanac, and while being less than or equal to 5 days, this threshold value was 5 kilometers; In the time that the acquisition time of this current almanac and this interval with reference to the update time of almanac are greater than 5 days, this threshold value is 10 kilometers.
The invention has the beneficial effects as follows: by the initial position in conjunction with receiver with reference to almanac, calculate the general location parameter of the satellite that the satellite navigation signals that receives is corresponding, determine that according to general location parameter satellite is whether in the receiver observation visual field, with this, navigation signal being carried out to falseness detects, do not need additionally to increase hardware facility, there is the advantages such as implementation method is flexible, extendability is strong, cost is low, can strengthen anti-deception ability.
Brief description of the drawings
Fig. 1 is the schematic flow sheet of false detection method first embodiment of the satellite navigation signals according to the present invention;
Fig. 2 is the schematic flow sheet of false detection method second embodiment of the satellite navigation signals according to the present invention;
Fig. 3 is the structural representation of satellite navigation location receiver the first embodiment according to the present invention;
Fig. 4 is the structural representation of satellite navigation location receiver the second embodiment according to the present invention;
Fig. 5 is the schematic flow sheet of false detection method the 3rd embodiment of the satellite navigation signals according to the present invention;
Fig. 6 is the schematic flow sheet of false detection method the 4th embodiment of the satellite navigation signals according to the present invention;
Fig. 7 is the structural representation of satellite navigation location receiver the 3rd embodiment according to the present invention;
Fig. 8 is the structural representation of satellite navigation location receiver the 4th embodiment according to the present invention;
Fig. 9 is the schematic flow sheet of false detection method the 5th embodiment of the satellite navigation signals according to the present invention;
Figure 10 is the structural representation of satellite navigation location receiver the 5th embodiment according to the present invention;
Figure 11 is the schematic flow sheet of false detection method the 6th embodiment of the satellite navigation signals according to the present invention.
Embodiment
First, what need to explicitly point out is that the method that the embodiment of the present invention adopts is based on the satellite navigation signals receiving is carried out after demodulation, can obtain the information such as navigation message wherein, and therefore the embodiment of the present invention is a kind of anti-deception measures in information aspect.
Below in conjunction with drawings and Examples, the present invention is described in detail.
Fig. 1 has shown the schematic flow sheet of false detection method first embodiment of satellite navigation signals of the present invention.This falseness detection method comprises the following steps:
Step S101: in the time that receiver is started shooting, carry out initial alignment by receiver, obtain the initial position of receiver according to positioning result.
Wherein, first to determine the initial position of satellite navigation location receiver.Receiver in the embodiment of the present invention is fixedly mounted on a certain position conventionally, or not mobile time service type receiver in the long period.Therefore, the residing position coordinates of this receiver, the initial position of this receiver both can utilize the machine to position acquisition, also can obtain according to known accurate location information, utilized the accurate location coordinate that receiver outside obtains to be input to receiver inside as a reference or to proofread and correct foundation.In the time positioning, normally in the time that starting shooting for the first time, receiver carries out, in order to ensure the accuracy of initial alignment, generally need continuous several times location, for example be taken to few 10 continuous positioning results, the positioning result of these at least 10 initial alignments is carried out to mean value computation, the threshold condition of mean value computation comprises: PDOP (Position Dilution of Precision, three-dimensional accuracy geometric factor) <3, satellite number >=5, the residual error <0.01 of least square iteration when positioning calculation, multiple bearing result longitude and latitude each other, the difference <30 rice of elevation.Using the position of this mean value computation as the initial position of this receiver.Certainly, after this initial position is determined, also the location parameter of outside this receiver determined of this receiver can be input to this receiver, so that this initial position is proofreaied and correct, improve the accuracy of initial position.
Step S102: receive and tracking satellite navigation signal, calculate the general location parameter of the satellite corresponding with satellite navigation signals according to the reference almanac of initial position and receiver storage.
Wherein, in satellite navigation signals, comprise navigation message, in navigation message, include the information such as satellite ephemeris, almanac, satellite clock, satellite health situation and precision.In the time utilizing satellite to position, determine that in advance satellite is vital in the position in space, especially receiver instrumented satellite navigation signal is from the satellite spatial position in that moment of satellite launch, this need to take out satellite orbit parameter from navigation message, be ephemeris, calculate satellite physical location at that time.Each satellite, except broadcasting the ephemeris of oneself, is also broadcasted the simple ephemeris of all satellites in constellation in navigation message, and the latter is called almanac.Almanac is used for estimating the apparent position of satellite, and the precision of its parameter does not have ephemeris parameter accurate like that.Therefore, say from purposes, almanac comprises the Position Approximate of whole satellites, forecasts for satellite position; Ephemeris is the exact position of the satellite that observes of present receiving machine, for location.Utilize ephemeris or almanac to calculate satellite spatial position equation:
Wherein, (X
i, Y
i, Z
i) be the locus of satellite in the body-fixed coordinate system taking the earth's core as initial point, r is the distance of satellite to the earth's core, and Ω is right ascension of ascending node, and i is inclination of satellite orbit, and Φ is the argument of perigee.Here, parameter r, Ω, i and Φ can be obtained by ephemeris or almanac.
Utilize almanac and local position, can calculate position angle and the elevation angle of satellite with respect to observation ground, can calculate thus satellite and duration that locality can observe, the time of occurrence that satellite elevation angle is greater than 5 °.
Utilize the ultimate principle equation that satellite positions to be:
In formula, (X, Y, Z) is receiver location, (X
i, Y
i, Z
i) be satellite position, in the body-fixed coordinate system that this Jun Yi the earth's core, two positions is initial point, c is the light velocity, Δ t is the clock correction of receiver and satellite, ρ
ithe pseudorange of receiver to satellite, i=1,2,3,4 show at least to need 4 satellites to resolve.As can be seen here, in order to determine the position at receiver place, need to know the locus of satellite, and satellite is to the pseudorange between receiver, then carries out certain error correction, just can obtain receiver location comparatively accurately.(X
i, Y
i, Z
i) be the position that obtains satellite by ephemeris or almanac, and ρ
ito obtain by pseudo-random code ranging.
Receiver receives after satellite navigation signals constantly tracking satellite navigation signal, and from satellite navigation signals, obtain navigation message, the embodiment of the present invention is utilized the almanac in navigation message, by the locus of satellite being calculated and relatively carrying out falseness and detect.Wherein, must have accurately almanac as a reference, the last time can be obtained and be to come from almanac in true navigation signal as a reference, this almanac is stored, claims this almanac for reference to almanac here.Because the data volume of almanac is larger, the update cycle is longer, and provides the general location information of satellite, use almanac to calculate satellite position and can only reach a kilometer precision for level, but this kilometer class precision can remain unchanged in a long time.Therefore, receive the reference almanac obtaining and be accurately under prerequisite in initial alignment process, be also accurately by this satellite position calculating with reference to almanac in a long time in its accuracy rating.
For the satellite navigation signals receiving, both comprised and newly entered the satellite navigation signals that the satellite in the receiver visual field sends, also may receive false satellite navigation signals.False satellite navigation signals can be divided into by producing method: production and relay type.Production is the autonomous deception navigation signal producing of deception device, and object is receiver to be resolved depart from actual position or time; Relay type is to forward the navigation signal postponing through certain, also can make receiver produce errors present or temporal information.In step S102, navigation message in the satellite navigation signals receiving is resolved, therefrom can obtain the identity information of this satellite, it is satellite identifier, then according to this satellite identifier, utilize the volume coordinate position that can obtain this satellite with reference to almanac, for ease of explanation, the volume coordinate positional representation of this satellite obtaining by reference to almanac is (X
i, Y
i, Z
i), and and receiver in a coordinate system.Then by co-ordinates of satellite (X
i, Y
i, Z
i) and receiver coordinate (X, Y, Z) can calculate the general location parameter of this satellite with respect to this receiver, this general location parameter comprises the parameter such as position angle, the elevation angle of this satellite with respect to ground receiver, because the coordinate in same coordinate system of this satellite and receiver all obtains, therefore general location parameter is easy to obtain, and can reflect the relative position relation of this satellite and ground receiver.
Taking satellite with respect to the position angle of receiver and the elevation angle as example, its computation process is as follows: first, in the topocentric coordinate system taking receiver as initial point, calculate the rectangular coordinate of satellite with respect to receiver:
Wherein, (x in topocentric coordinate system
n, y
e, z
u) be the position of satellite with respect to receiver, L, B are respectively geodetic longitude and the geodetic latitudes of receiver, (X, Y, Z) is the position of receiver, (X
i, Y
i, Z
i) be the locus of satellite.
Then, by the relation between rectangular space coordinate and polar coordinates:
Wherein
el is satellite elevation angle, and Az is satellite aximuth.Draw position angle and the elevation angle of satellite:
Step S103: judge that according to general location parameter satellite is whether in the observation visual field of receiver; While being no, determine that satellite navigation signals is spurious signal in judged result.
Wherein, because satellite moves on planned orbit around the earth, therefore the time in each satellite process overhead, a certain region, and position angle and the elevation angle with respect to receiver can and be calculated with reference to almanac according to receiver initial position in this overhead, region.If what receive is real satellite navigation signals, this satellite azimuth angle and elevation angle calculating can reflect in the observation visual field of current satellite in region, receiver place; If what receive is false satellite navigation signals, the position angle and the elevation angle that calculate so this satellite of observation are just likely within sweep of the eye not observable in receiver current location.For example, when receiver normally receives the navigation signal that satellite sends, need satellite to be greater than 5 ° with respect to the elevation angle of receiver, and the elevation angle calculating is 1 °, what this manifest error explanation received is spurious signal.After definite satellite navigation signals is spurious signal, receiver can send early warning, for example by early warning pilot lamp glimmer alarm, stop location and/or time service information output.
By the present embodiment, only need to just can calculate the general location of satellite with respect to receiver according to almanac and receiver initial position, for can straightforward judgement being not spurious signal at the satellite in the observation visual field, there is the simple advantage of implementation method.
Fig. 2 is the schematic flow sheet of false detection method second embodiment of satellite navigation signals of the present invention.Step S201, S202, S203 and step S207 in Fig. 2 has the technical characterictic identical with step S101, S102, S103 in Fig. 1, repeats no more herein.And in step S203, whether satellite is detected in the observation visual field of receiver, testing result is in the observation visual field of receiver region, is also not enough to illustrate that whether satellite navigation signals is true, also needs further received satellite navigation signals to be carried out to falseness and detects.This is because calculate position angle and the elevation angle of satellite with respect to receiver, is that the summary of satellite position is calculated, and can't get on and judge more accurately from the volume coordinate position of satellite.If the judged result of step S203 is yes, carry out step S204.
Step S204: according to the reference locus that calculates satellite with reference to almanac, calculate the current locus of satellite according to the current almanac in satellite navigation signals, and calculate the error distance between reference locus and the current locus of satellite.
Wherein, two computation processes have first been needed.First calculating is according to the satellite identity in received navigation message, i.e. satellite identifier, and with reference to almanac, this satellite is carried out to track calculating, and can obtain the locus of this satellite, use coordinate (X herein
sr, Y
sr, Z
sr) represent the co-ordinates of satellite that obtains by reference to almanac, and be referred to as satellite with reference to locus.From aforementioned, because the almanac update cycle is longer, after after a while, utilize almanac that previous time period obtains during to satellite spatial position calculation, accuracy meeting declines, but within a period of time, in 10 days, its error precision but still has higher stability, normally in the error range of kilometer level; Second calculating is according to the satellite identity in received navigation message and upgrades almanac, i.e. current almanac, and the locus of calculating this satellite, uses coordinate (X herein
sc, Y
sc, Z
sc) represent the co-ordinates of satellite that obtains by current almanac, and be referred to as the current locus of satellite.Then, satellite is compared with reference to locus and the current locus of this satellite, calculate exactly the distance between these two locus,
Here be referred to as the error distance of these two locus.
Step S205: whether error in judgement distance is greater than threshold value, if so, performs step S207, if not, execution step S206.
Wherein, choosing and T update time with reference to almanac of threshold value
fand the acquisition time T of current almanac
cinterval have relation, for example, work as T
c-T
f≤ 1 day, threshold settings was 1 kilometer; As 1 day <T
c-T
f≤ 5 days, threshold settings was 5 kilometers; Work as T
c-T
f>5 days, threshold settings is 10 kilometers.
Step S206: determine that satellite navigation signals is actual signal, replace with reference to almanac with current almanac.
Wherein, if error distance is less than or equal to threshold value, show that received satellite navigation signals has higher confidence level, can receive navigation message wherein, and replace with reference to almanac with current almanac, replace using current almanac as new reference almanac existing with reference to almanac, and by the acquisition time T of this current almanac
cas T update time of new reference almanac
f, this current almanac will be served as the reference almanac of late detection (such as start next time).
If error distance is greater than this threshold value, illustrate that the satellite spatial position that the navigation message by receiving calculates is equipped with relatively large deviation with respect to the reference space bit of this satellite, this deviation has exceeded to be utilized with reference to almanac, within the regular hour, calculate the error range of satellite spatial position, and there is confidence level the reference locus of satellite, therefore perform step S207, judge that the satellite navigation signals receiving is false navigation signal.
After step S207, can further carry out false navigation signal early warning, for example by early warning pilot lamp glimmer alarm, stop location and/or time service information output.
The present embodiment is to judge that at above-mentioned the first embodiment satellite navigation signals is not on the basis of spurious signal, utilize the locus of calculating respectively this satellite with reference to almanac and current almanac, and the difference of these two result of calculations of comparison, if difference is excessive, exceed the thresholding arranging, can obtain the conclusion that current received satellite navigation signals is spurious signal.This embodiment contributes to further to strengthen the falseness of satellite navigation signals is detected.
Fig. 3 has shown the structural representation of satellite navigation location receiver the first embodiment of the present invention.This receiver is except having the composition of general navigation neceiver, also comprise that this satellite navigation location receiver comprises positioning unit 301, signal element 302, the first judging unit 303 and performance element 304 for satellite navigation signals being carried out to the false structure composition detecting.
Wherein, positioning unit 301, for carry out initial alignment in the time that receiver is started shooting, obtains the initial position of receiver according to positioning result.In the time of receiver initialization, the navigation message content that positioning unit 301 utilizes signal element 302 to obtain, carry out initial alignment, in order to ensure the accuracy of initial alignment, generally need continuous several times location, for example be taken to few 10 continuous positioning results, the positioning result of these at least 10 initial alignments is carried out to mean value computation, obtain thus the initial position of receiver.Positioning unit 301 also can be proofreaied and correct in the outside definite location parameter of receiver by receipt source, determines the accuracy of initial position to improve positioning unit 301.
Signal element 302, for receiving and tracking satellite navigation signal, calculates the general location parameter of the satellite corresponding with satellite navigation signals according to the reference almanac of receiver initial position and receiver storage.Wherein, receiver initial position is to be provided by positioning unit 301, be the almanac in the true navigation message that is received and stored by signal element 302 with reference to almanac, this almanac derives from real satellite navigation signals, can determine more exactly the locus of satellite.The general location parameter of satellite refers to the parameter such as position angle, the elevation angle of satellite with respect to ground receiver, reflects the relative position relation of this satellite and ground receiver.
The first judging unit 303, for judging that according to general location parameter this satellite is whether in the observation visual field of this receiver.This is because receiver is subject to geographic position of living in and figure of the earth structural limitations, its observation visual field is limited, Navsat moves along satellite orbit with respect to the earth simultaneously, in a certain period, this satellite is just in time through the receiver observation visual field, and receiver is received the navigation signal that this satellite sends, so by reflecting that to this satellite general location calculation of parameter this satellite is in the observation visual field of receiver; If receive false satellite navigation signals, the general location parameter that just may calculate this satellite can not reflect in the current observation visual field that is in receiver of this satellite.Receive on the one hand the navigation signal that this satellite sends, on the other hand by counter this satellite of releasing of this navigation signal not in the observation visual field of receiver, this self-contradictory presentation of results this navigation signal be not to derive from this satellite, be therefore false satellite navigation signals.The first judging unit 303 receives the result of calculation of signal element 302 to satellite general location parameter, judges that thus this satellite is whether in the observation visual field of receiver.
Performance element 304, for while being no, determining that this satellite navigation signals is spurious signal in the judged result of the first judging unit 303, performance element 304 can also be made early warning, for example close location and/or time service information output channel, open sound alarm, pilot lamp alarm etc.
Fig. 4 has shown the structural representation of satellite navigation location receiver the second embodiment of the present invention.Positioning unit 401 in Fig. 4, signal element 402, the first judging unit 403 have and positioning unit 301 corresponding in Fig. 3, signal element 302, technical characterictic that the first judging unit 303 is identical, repeat no more herein.The key distinction is, judging this satellite when the first judging unit 403 according to satellite general location parameter is in the observation visual field at receiver time, need to further carry out falseness and detect.
Computing unit 405 be exactly in the judged result of the first judging unit 403 when being, complete following computation process.First, first calculating is satellite identity in the navigation message receiving according to signal element 402 and the reference almanac of storage, and this satellite is carried out to track calculating, can obtain the reference locus of this satellite; Second calculating is satellite identity in the navigation message receiving according to signal element 402 and almanac wherein, is referred to as current almanac here about this almanac, calculates the current locus of this satellite.Then, the current locus of the reference locus of satellite and this satellite is compared, calculate exactly the distance between these two locus, be referred to as the error distance of these two locus here.
The second judging unit 406 compares the error distance being obtained by computing unit 405 and threshold value, whether is greater than threshold value for error in judgement distance.
In performance element 404, carry out corresponding operation according to the judged result of the second judging unit 406.If error distance is greater than this threshold value, illustrate that the current satellite spatial position that the navigation message by receiving calculates is equipped with relatively large deviation with respect to the reference space bit of this satellite, this deviation has exceeded utilizes the error range of calculating satellite spatial position with reference to almanac, and there is confidence level the reference locus of satellite, therefore can judge that received satellite navigation signals is false navigation signal.If be less than or equal to threshold value, show that received satellite navigation signals has higher confidence level, be actual signal, can receive navigation message wherein, and replace with reference to almanac, for late detection with current almanac.
By satellite navigation location receiver the first and second embodiment of the present invention, make this satellite navigation location receiver to carry out falseness based on the almanac in satellite navigation signals and detect, strengthen the anti-deception ability of this receiver.
Fig. 5 has shown the schematic flow sheet of the false satellite navigation signals detection method of the present invention the 3rd embodiment.This embodiment is mainly that the ephemeris based in navigation message carries out falseness detection to the satellite navigation signals receiving.
In step S501, first to from the satellite navigation signals receiving, obtain with reference to ephemeris, and record this update time with reference to ephemeris.Herein, called reference ephemeris refers to receiver differentiates to be the ephemeris obtaining real satellite navigation signals from receiving, and this ephemeris is along with passage of time is constantly updated and preserves.Meanwhile, the correct time being updated with reference to ephemeris also goes on record.At the receiver start work initial stage, can utilize the true and false of some known accurate information judgement satellite navigation signals that receive, the accurate location of for example known receiver, whether the determined receiver location of satellite navigation signals that receives of inspection is correct thus, and then instead pushes away the true and false of ephemeris in received satellite navigation signals.
Step S502 refers to that receiver constantly receives and tracking satellite navigation signal, obtains current ephemeris from the satellite-signal receiving, and records the acquisition time of this current ephemeris, and calculating and with reference to time interval of update time of ephemeris.In step S501, the last update time with reference to ephemeris, uses T
rxrepresent, and the acquisition time of current ephemeris in step S502, T used
cxrepresent, calculate the time interval of these two times, i.e. T
cx-T
rx, it should meet the update frequency value of Navsat broadcast ephemeris, because Navsat always upgrades ephemeris with certain frequency, and keeps this update frequency constant.
Then, step S503 judges whether this time interval meets broadcast ephemeris update frequency value; While being no, determine that satellite navigation signals is spurious signal in judged result.For example, this update frequency value is 2 hours/time, if the acquisition time of current ephemeris equals ephemeris update frequency value with the interval of the last update time with reference to ephemeris, as this time interval equals 2 hours, or in its vicinity, as between 1 hour little error burst scope 58 points to 2 hours 2 points, show that the current ephemeris obtaining is normal; If this time interval is obviously greater than or is significantly less than the update frequency value of broadcast ephemeris, show that current ephemeris derives from spurious signal, the satellite navigation signals that received is spurious signal, determine be spurious signal after, can also carry out false navigation signal early warning, for example by early warning pilot lamp glimmer alarm, stop location and (or) time service information output.
Fig. 6 is the schematic flow sheet of false detection method the 4th embodiment of satellite navigation signals of the present invention.Step S601, S602 in Fig. 6, S603, S607 have the technical characterictic identical with step S501, S502, S503 in Fig. 5, repeat no more herein.And in step S603 to current ephemeris acquisition time with whether meet ephemeris update frequency value with reference to the time interval of ephemeris update time and judge, if judged result be yes, also need further received satellite navigation signals to be carried out to falseness detection.
Step S604 judges that at step S603 the time interval meets on the basis of ephemeris update frequency value, further utilizes respectively with reference to ephemeris and current ephemeris the locus of satellite is calculated.Mainly complete following computation process.First calculating is according to the satellite identifier in received navigation message, and the reference ephemeris obtaining at step S601, and this satellite is carried out to track calculating, can obtain the locus of this satellite, uses coordinate (X herein
sp, Y
sp, Z
sp) represent the co-ordinates of satellite that obtains by reference to ephemeris, and be referred to as satellite with reference to locus.From aforementioned, because ephemeris upgrades comparatively fast, upgrade once as every 2 hours, before and after upgrading, ephemeris utilize the error precision of the satellite spatial position that two different ephemeris computation obtain can be at meter level.Second calculating is according to the satellite identifier in received navigation message and current ephemeris, and the locus of calculating this satellite, uses coordinate (X herein
sf, Y
sf, Z
sf) represent the co-ordinates of satellite that obtains by current ephemeris, and be referred to as the current locus of satellite.Then, this satellite is compared with reference to locus and the current locus of satellite, calculate exactly the distance between these two locus,
Here be referred to as the error distance of these two locus.
In step S605, the error distance that step S604 is obtained and default threshold value compare judgement, and for example threshold settings is 10 meters.If error distance is greater than threshold value, enter step S607, illustrate that the current satellite spatial position that the navigation message by receiving calculates is equipped with relatively large deviation with respect to the reference space bit of this satellite, this deviation has exceeded the error range of utilizing ephemeris to upgrade calculating satellite spatial position, front and back, and the reference locus of the satellite that process is differentiated is believable, therefore the current locus of satellite is insincere, can judge that received satellite navigation signals is false navigation signal, can also carry out false navigation signal early warning, for example, by the alarm of glimmering of early warning pilot lamp, stop location and (or) time service information output.
Step S606 is the situation that is less than or equal to threshold value for error distance in step S605, can determine that received satellite navigation signals is actual signal, replace existing with reference to ephemeris with the current ephemeris in received navigation message, always replace using current ephemeris as new reference star existing with reference to ephemeris, and update time using the acquisition time of this current ephemeris as new reference ephemeris.
The update frequency of the third and fourth embodiment of the false detection method of satellite navigation signals of the present invention based on to ephemeris in the satellite navigation signals receiving, and the distance error that ephemeris changes the satellite spatial position causing detects, and with threshold value comparison, thereby carry out detection and the early warning of spurious signal.The method has been utilized the feature rule of ephemeris, and applicable to carrying out spurious signal detection in different satellite navigation systems, applied range, realizes cost low, has strengthened the anti-deception ability of satellite navigation location receiver.
Fig. 7 has shown the structural representation of the 3rd embodiment of satellite navigation location receiver of the present invention.This receiver, except having the composition of general navigation neceiver, also comprises for satellite navigation signals being carried out to the false structure composition detecting.
Signal element 701 receives and follows the tracks of satellite navigation signals, obtains the navigation message in satellite navigation signals.On the one hand, signal element 701 will be upgraded with reference to ephemeris from the satellite navigation signals receiving, and records this update time with reference to ephemeris.Herein, called reference ephemeris refers to receiver differentiates to be the ephemeris obtaining real satellite navigation signals from receiving, and this ephemeris is along with passage of time is constantly updated and preserves.Meanwhile, the correct time being updated with reference to ephemeris also goes on record.On the other hand, signal element 701 is also constantly obtained current ephemeris from the satellite navigation signals receiving, and record the acquisition time of this current ephemeris, but the satellite navigation signals receiving had both comprised and had newly entered the satellite navigation signals that the Navsat in the receiver visual field sends, also may receive false satellite navigation signals, there is false possibility in current ephemeris therefore.
For this reason, the first judging unit 702 is according to the update time with reference to ephemeris in signal element 701, and the acquisition time of current ephemeris from the satellite navigation signals receiving, calculate the interval of these two times, this time interval should meet the update frequency value of Navsat broadcast ephemeris, for example, this update frequency value is 2 hours/time.If the acquisition time of current ephemeris equals ephemeris update frequency value with the interval of the acquisition time with reference to ephemeris, as this time interval equals 2 hours, or in its vicinity, as between 1 hour interval range 58 points to 2 hours 2 points, show that the current ephemeris obtaining is normal, meets the update frequency value of Navsat broadcast ephemeris; If this time interval is obviously greater than or is significantly less than the update frequency value of ephemeris, show that this time interval do not meet the update frequency value of Navsat broadcast ephemeris, illustrate that current ephemeris derives from false navigation signal.
In the time that between the first judging unit 702 judgements, interval does not meet the update frequency value of Navsat broadcast ephemeris, this result is submitted to performance element 703, determine that by performance element 703 satellite navigation signals receiving is spurious signal.In addition, performance element 703 can also be made early warning, for example, close location and/or time service information output channel, opens sound alarm, pilot lamp alarm etc.
Fig. 8 has shown the structural representation of satellite navigation location receiver the 4th embodiment of the present invention.Signal element 801 in Fig. 8, the first judging unit 802 have and signal element corresponding in Fig. 7 701, technical characterictic that the first judging unit 702 is identical, repeat no more herein.Difference is mainly, in the time that the first judging unit 802 judges that the acquisition time of current ephemeris meets broadcast ephemeris update frequency value with the time interval of the update time with reference to ephemeris, can not be defined as spurious signal and carry out early warning by performance element 803, need to further carry out falseness and detect.
Computing unit 804 be exactly in the judged result of the first judging unit 802 when being, complete following computation process.First, first calculating is satellite identifier in the navigation message receiving according to signal element 801 and with reference to ephemeris, and this satellite is carried out to track calculating, can obtain the reference locus of this satellite; Second calculating is satellite identifier and the current ephemeris in the navigation message receiving according to signal element 801, the current locus of calculating this satellite.Then, the current locus of the reference locus of satellite and this satellite is compared, calculate exactly the distance between these two locus, be referred to as the error distance of these two locus here.
The second judging unit 805 compares the error distance being obtained by computing unit 804 and threshold value, for judging whether this error distance is greater than threshold value.Here the satellite spatial position being obtained by ephemeris computation has higher precision, and therefore this threshold value also has very high precision, and for example setting threshold value is 10 meters.
Then,, in performance element 803, carry out corresponding operation according to the judged result of the second judging unit 805.Be greater than threshold value if obtain error distance at the second judging unit 805, illustrate that the current satellite spatial position that the navigation message by receiving calculates is equipped with relatively large deviation with respect to the reference space bit of this satellite, this deviation has exceeded utilizes the error range with reference to ephemeris computation satellite spatial position, and there is confidence level the reference locus of satellite, therefore can judge that received satellite navigation signals is false navigation signal, can also carry out early warning.Be less than or equal to threshold value if obtain error distance at the second judging unit 805, show that received satellite navigation signals has higher confidence level, it is actual signal, can receive navigation message wherein, and replace with reference to ephemeris with current ephemeris, always replace existingly with reference to ephemeris using current ephemeris as new reference star, and update time using the acquisition time of this current ephemeris as new reference ephemeris, for late detection.
By satellite navigation location receiver the third and fourth embodiment of the present invention, make this satellite navigation location receiver to carry out falseness based on the ephemeris in satellite navigation signals and detect, strengthen the anti-deception ability of this receiver.
Fig. 9 has shown the schematic flow sheet of the false satellite navigation signals detection method of the present invention the 5th embodiment.This embodiment is mainly that satellite clock and the ephemeris based in navigation message carries out falseness detection to the satellite navigation signals receiving.
Step S901, in the time that receiver is started shooting, carries out initial alignment by this receiver, obtains the initial position of this receiver according to positioning result.Step S101 shown in definite method and Fig. 1 of receiver initial position is similar, repeats no more.
Step S902 refers to that receiver constantly receives and tracking satellite navigation signal, and further therefrom obtains current ephemeris and satellite clock.Then, satellite clock and ephemeris in the satellite navigation signals based on receiving, and the initial position of receiver, need to complete following computation process.First calculating is according to the satellite ephemeris in received navigation message, calculates the locus of satellite, with coordinate (X
sv, Y
sv, Z
sv) represent the satellite spatial position that obtains by ephemeris, then according to the initial position of the acquired receiver of step S901, represent the initial position of receiver with coordinate (X, Y, Z), calculate the distance of satellite to receiver,
Distance that result of calculation is referred to as star.Second calculating is based on pseudo-random code ranging principle, receiver utilizes PN code delay locked loop (DLL, be called for short code tracking loop) the tracking pseudo-code of receiver is aimed at the pseudo-code of the satellite navigation signals receiving in time, by the benchmark pseudo-code contrast of the tracking pseudo-code of receiver and receiver, obtain the time difference Δ T of these two kinds of pseudo-codes again
1, represent the light velocity with c, obtain pseudorange ρ=c Δ T
1.Consider again the impact of clock correction, according to the satellite clock T in received navigation message
s, and the local clock T of receiver
r, obtained clock correction Δ T
2=T
r-T
s, by this clock correction, pseudorange ρ is revised, obtaining revised pseudorange is c (Δ T
1-Δ T
2), be referred to as to revise pseudorange.Then, then to the star obtaining distance and calculating through the pseudorange of clock correction correction, be mainly the difference that obtains the two,
Be referred to as error distance, in application, get the absolute value of this error distance.
Step S903, whether error in judgement distance is greater than threshold value, and threshold value is for example set as 30 meters.
If error distance is greater than this threshold value, enter step S904, determine that this satellite navigation signals is spurious signal.This is because obtained the initial position accurately of receiver at step S901, if the satellite navigation signals receiving is real, revise so pseudorange and star apart from should be basically identical, or the error of the two is less than threshold value.Otherwise, due to the falseness of satellite clock or the falseness of satellite ephemeris can be reflected to revise pseudorange and star apart between have larger error distance, explanation is spurious signal.And can carry out false navigation signal early warning, for example by early warning pilot lamp glimmer alarm, stop location and/or time service information output.
Step S905 is less than or equal to the situation of threshold value for error distance in step S903, can determine that received satellite navigation signals is actual signal, and store this ephemeris and satellite clock.
The 5th embodiment of the false detection method of satellite navigation signals of the present invention based on to receive satellite navigation signals in ephemeris and satellite clock, calculate star ground distance and revise pseudorange, and by the distance error of the two and threshold value comparison, thereby carry out detection and the early warning of spurious signal.The method has been utilized satnav principle and pseudo-random code ranging principle, and applicable to carrying out spurious signal detection in different satellite navigation systems, applied range, realizes cost low, has strengthened the anti-deception ability of satellite navigation location receiver.
Figure 10 has shown the structural representation of satellite navigation location receiver the 5th embodiment of the present invention.This receiver, except having the composition of general navigation neceiver, also comprises for satellite navigation signals being carried out to the false structure composition detecting.
Wherein, positioning unit 1001, for in the time that receiver is started shooting initialization, the navigation message content of utilizing signal element 1002 to obtain, carries out initial alignment to receiver, in order to ensure the accuracy of initial alignment, generally need continuous several times location, for example be taken to few 10 continuous positioning results, these at least 10 positioning results are carried out to mean value computation, obtain thus the initial position of this receiver.Positioning unit 1001 also can be proofreaied and correct in the outside definite location parameter of this receiver by receipt source, determines the accuracy of initial position to improve positioning unit 1001.
Signal element 1002 for receiving and tracking satellite navigation signal, is obtained ephemeris and satellite clock from this satellite navigation signals.
Satellite clock and ephemeris in the satellite navigation signals of computing unit 1003 based on receiving, and the initial position of the receiver of being determined by positioning unit 1001, need to complete following computation process.First calculating is according to the ephemeris in received navigation message, calculates the locus of satellite, then according to the initial position of the definite receiver of positioning unit 1001, calculates the distance of satellite to receiver, distance that result of calculation is referred to as star.Second calculating is according to pseudo-random code ranging principle, satellite to be calculated to the pseudorange of receiver, and according to the satellite clock in received navigation message and receiver clock, calculates clock correction, and pseudorange is revised, and result of calculation is referred to as to revise pseudorange.Then, to the star obtaining distance and revise pseudorange carry out computational analysis, be mainly the difference that obtains the two, be referred to as error distance, in application, get the absolute value of this error distance.
Judging unit 1004 is for the error distance being obtained by computing unit 1003 and threshold value are compared, for judging whether this error distance is greater than threshold value.This threshold value also has very high precision, and for example setting threshold value is 30 meters.
Performance element 1005 is carried out corresponding operating according to the judged result of judging unit 1004.If error distance is greater than threshold value, illustrate that satellite clock and ephemeris that the navigation message by receiving obtains do not conform to the actual conditions, this is because positioning unit 1001 has obtained the initial position accurately of receiver, if the satellite navigation signals receiving is real, revise so pseudorange and star apart from should be basically identical, or the error distance of the two is less than threshold value.Otherwise, due to the falseness of satellite clock or the falseness of satellite ephemeris can be reflected to revise pseudorange and star apart between have larger error distance, can determine that received satellite navigation signals is spurious signal, and can carry out false navigation signal early warning, for example by early warning pilot lamp glimmer alarm, stop location and/or time service information output.Be less than or equal to the situation of threshold value for error distance, can determine that received satellite navigation signals is actual signal, performance element 1005 this ephemeris of storage and satellite clocks.
The false detection method embodiment of above-mentioned satellite navigation signals has introduced respectively by almanac, ephemeris and satellite clock in navigation message, satellite navigation signals is carried out to falseness and detect.In order further to improve the false probability detecting of satellite navigation signals, improve accuracy in detection, said method can be used in combination.Figure 11 has shown the schematic flow sheet of the 6th embodiment of the false detection method of satellite navigation signals of the present invention.
Step S1101 receives satellite navigation signals, resolve navigation message, obtain the parameters in avionics literary composition, as ephemeris, almanac, satellite clock etc., then the parameter different according to these, carry out detecting based on the falseness of almanac at step S1102 respectively, specific implementation method is with reference to figure 1 and embodiment illustrated in fig. 2; Carry out detecting based on the falseness of ephemeris at step S1103, specific implementation method is with reference to figure 5 and embodiment illustrated in fig. 6; Carry out detecting based on the falseness of satellite clock and ephemeris at step S1104, specific implementation method is with reference to embodiment illustrated in fig. 9.And step S1102, S1103, S1104 can carry out to select a mode as required, also can be used in combination, for example, in the time that step S1102 can not detect spurious signal, in order to improve detection probability, then enable step S1103 or S1104 detects.Two kinds of methods for example choosing again wherein detect simultaneously, or use these three kinds of methods to detect simultaneously, strengthen accuracy in detection.Step S1105 comprehensively judges testing result according to the detection mode of step S1102, S1103, S1104, for example, in the time that step S1102, S1103, S1104 detect simultaneously, in step S1105, can adopt while wherein having at least two kinds of detection modes to obtain false detection results, just provide final effectively false detection results, be conducive to like this strengthen the false accuracy detecting.
By the way, the false detection method of satellite navigation signals of the present invention and receiver can based on receive satellite navigation signals in navigation message content, calculate by almanac, ephemeris, satellite clock satellite locus, star apart from, revise pseudorange, error of calculation distance, and compare with reference thresholds, thereby the false information of the satellite navigation signals that receives of judgement, have method flexible and varied, there is high accuracy and confidence level, realize the advantages such as cost is low.
The foregoing is only embodiments of the invention; not thereby limit the scope of the claims of the present invention; every equivalent flow process conversion that utilizes instructions of the present invention and accompanying drawing content to do, or be directly or indirectly used in other relevant technical fields, be all in like manner included in scope of patent protection of the present invention.
Claims (7)
1. a false detection method for satellite navigation signals, is characterized in that, described false detection method comprises:
In the time that receiver is started shooting, carry out initial alignment by described receiver, obtain the initial position of described receiver according to positioning result;
Receive and tracking satellite navigation signal, calculate the general location parameter of the satellite corresponding with described satellite navigation signals according to the reference almanac of described initial position and described receiver storage;
Judge that according to described general location parameter described satellite is whether in the observation visual field of described receiver;
While being no, determine that described satellite navigation signals is spurious signal in judged result;
In judged result when being, according to the described reference locus that calculates described satellite with reference to almanac, calculate the current locus of described satellite according to the current almanac in described satellite navigation signals, and calculate the error distance between reference locus and the described current locus of described satellite, judge whether described error distance is greater than threshold value, in the time that described error distance is greater than described threshold value, determine that described satellite navigation signals is spurious signal, in the time that described error distance is less than or equal to described threshold value, determine that described satellite navigation signals is actual signal, described with reference to almanac with described current almanac replacement.
2. the false detection method of satellite navigation signals according to claim 1, is characterized in that, described general location parameter comprises position angle and the elevation angle.
3. the false detection method of satellite navigation signals according to claim 1, is characterized in that, described initial position is that the positioning result of continuous several times initial alignment is carried out to the position that mean value computation obtains.
4. the false detection method of satellite navigation signals according to claim 3, it is characterized in that, described initial alignment at least carries out 10 times, the threshold condition of described mean value computation comprises: three-dimensional accuracy geometric factor <3, satellite number >=5, the residual error <0.01 of the least square iteration of positioning calculation, repeatedly the difference <30 rice of the longitude and latitude between the positioning result of initial alignment, elevation.
5. according to the false detection method of the satellite navigation signals described in claim 3 or 4, it is characterized in that, after described initial position is determined, the location parameter of the outside described receiver of determining of described receiver is input to described receiver, so that described initial position is proofreaied and correct.
6. the false detection method of satellite navigation signals according to claim 1, is characterized in that, in the time that the acquisition time of described current almanac and the interval of the described update time with reference to almanac are less than or equal to 1 day, described threshold value is 1 kilometer; When acquisition time and the interval of the described update time with reference to almanac of described current almanac are greater than 1 day, and while being less than or equal to 5 days, described threshold value is 5 kilometers; In the time that the acquisition time of described current almanac and the interval of the described update time with reference to almanac are greater than 5 days, described threshold value is 10 kilometers.
7. a satellite navigation location receiver, is characterized in that, described receiver comprises:
Positioning unit, for carry out initial alignment in the time that described receiver is started shooting, obtains the initial position of described receiver according to positioning result;
Signal element, for receiving and tracking satellite navigation signal, calculates the general location parameter of the satellite corresponding with described satellite navigation signals according to the reference almanac of described initial position and described receiver storage;
The first judging unit, for judging that according to described general location parameter described satellite is whether in the observation visual field of described receiver;
Performance element, when being no in the judged result of described the first judging unit, determines that described satellite navigation signals is spurious signal;
Computing unit, for in the judged result of described the first judging unit when being, according to the described reference locus that calculates described satellite with reference to almanac, calculate the current locus of described satellite according to the current almanac in described satellite navigation signals, and calculate described with reference to the error distance between locus and described current locus;
The second judging unit, for judging whether described error distance is greater than threshold value;
Described performance element is further used in the time that described error distance is greater than described threshold value, determines that described satellite navigation signals is spurious signal; And in the time that described error distance is less than or equal to described threshold value, determine that described satellite navigation signals is actual signal, described with reference to almanac with described current almanac replacement.
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Address after: 210007 Jiangsu Province, Nanjing city high tech Development Zone Huidalu Beidou No. 6 Building Room 205 Patentee after: Compass Navigation, Jiangsu Communication Technology Co., Ltd. Address before: Yudaojie Baixia District of Nanjing City, Jiangsu province 210007 No. 58-1 Ming Imperial building 10 floor Patentee before: Compass Navigation, Jiangsu Communication Technology Co., Ltd. |