CN101539619A - Carrier wave aided tracking method used in high-dynamic double frequency GPS - Google Patents

Abstract

The invention relates to a carrier wave aided tracking method used in a high-dynamic double frequency GPS, which is as follows: a carrier wave phase lock tracking loop and a pseucode delay locked loop are executed for regulating carrier wave NCO and C/A code NCO of local L1 frequency points to generate guess values deferred by an L1 carrier wave phase and a C/A code; a half codeless method is used for tracking L1-P (Y) signals by using a pseucode delay locked loop (DLL); an L2-P code generator is initialized; according to the guess value of an L1 loop carrier wave phase, reference oscillator frequency offset dissolved by a positioning resolving module, phase demodulation difference of an L2 carrier wave phase lock tracking loop (PLL), the carrier wave phase value of L2 frequency points is jointly estimated; a carrier wave NCO is regulated, and the local L2 signal carrier wave is recurred; the half codeless method is used for precisely tracking input L2 signals. The L2-P carrier wave tracking using the method can obtain higher tracking accuracy, lower tracking threshold and more stable loop in high-dynamic environment.

Description

A kind of dynamic double-frequency GPS carrier wave aided tracking method of height that is used for

Technical field

The present invention relates to a kind of double-frequency GPS system, relate in particular to a kind of high dynamic double-frequency GPS carrier wave aided tracking method that is used for.

Background technology

GPS (GPS) comprises some satellites, every satellite sends distance measuring signal on the 1575.42MHz that is called as L1 and L2 frequency and two carrier frequencies of 1227.60MHz, and the method for textual informations such as ephemeris and almanac by bi-phase modulated is modulated on the distance measuring signal.GPS receiver receives the signal from multi-satellite, and utilizes the carrier wave of local reproduction to measure and obtain the time delay of (1) signal arrival receiver with pseudo-code; (2) Doppler frequency of signal carrier skew; (3) be modulated at textual information on the signal.Receiver utilizes these information then, measures its position and speed with a kind of known method.

The signal of L1 frequency is modulated by two pseudo-random codes (adding the navigation message data).These two kinds of sign indicating numbers are respectively thick/intercepting and capturing sign indicating numbers (C/A sign indicating number) and accurate sign indicating number (P sign indicating number).The signal of L2 frequency is only modulated by accurate sign indicating number (P sign indicating number).Because U.S. government has started anti-deception (AS) mode of operation to gps satellite at present, the P sign indicating number is encrypted to constitute so-called Y sign indicating number, and only the user for U.S. government's special permission uses.Therefore common single-frequency GPS receiver only receives and handles the C/A coded signal of L1 frequency, finishes location and navigation feature.

Free electron in the ionosphere of earth surface can influence electromagnetic wave propagation, wherein also comprises gps satellite signal., can the error that this part influence produces be incorporated in the calculating at the common receiver of L1 frequency work for only, hinder it to locate more accurately.And ionospheric delay is relevant with frequency, in fact just can basically it be eliminated so do the range finding measurement with dual-frequency receiver.

The receiver location that utilizes pseudo-random code ranging to calculate, its accuracy rating is a meter level.If want to reach the bearing accuracy of centimetre-sized, just need utilize the metrical information of carrier phase, determine the distance of gps satellite to receiver, this need solve the problem of " carrier cycle blur level ".For the signal of independent L1 frequency, receiver must determine within the carrier cycle of its position to one by the sequential of sign indicating number, promptly in 19 centimetres.This needs tediously long, time-consuming calculating, and need be to the estimation of ionospheric refraction.Yet, if use the signal of L1 and two frequencies of L2 simultaneously, make up their measured value, can obtain the difference wavelength is 86 centimetres.Utilize difference wavelength (wide lane) can make the search of integer ambiguity more effective.This is for the user in the motion and need the application scenario of real-time positioning, if reach the bearing accuracy of centimetre-sized, resolving fast of ambiguity of carrier in full period is to wish very much and the sin qua non.

The problem of using the L2 signal is that the sign indicating number that is contained in wherein is encrypted, and this just makes unauthorized user can't directly use the information measurement pseudorange and the carrier phase of L2 frequency.And the demand of double frequency metrical information has been promoted to obtain the development of the technology of L2 frequency pseudorange and carrier phase measurement value, and these technology are divided into not to be had sign indicating number and half and does not have a sign indicating number technology, and these technology are without the required cipher-text information of full powers interrogation signal.Patent 98122756.2 and 96191598.6 mentioned two kinds do not need enciphered message and follow the tracks of the L2 signal partly do not have a code tracking technology, recover the measured value of L2 frequency carrier phase.Document K.T.Woo, " Optimum semicodeless carrier-phasetracking of L2, " Navigation, vol.47, pp.82-99, Summer 2000. have summed up the technology of the no sign indicating number half nothing sign indicating number of various tracking L2 frequency signals.

Owing to not having about Y coded signal the A to Z of, not having sign indicating number and partly do not have code plan is operated on the low-down signal to noise ratio (S/N ratio), this just requires the bandwidth of track loop very narrow, and this has reduced the serviceability of not having high dynamic environment under the outside subsidiary conditions conversely.Under high dynamic environment, the carrier track of L2 itself can't be worked often.This patent has proposed a kind of trace information of the L1 of use frequency carrier wave ring, in conjunction with the skew of receiver reference oscillator frequencies, and the method that auxiliary L2 frequency is followed the tracks of.This method makes GPS double frequency half not have the sign indicating number receiver in high dynamic environment, can obtain more performance.

Summary of the invention

The object of the present invention is to provide a kind of high dynamic double-frequency GPS carrier wave aided tracking method that is used for, the signal that can use L1 frequency and L2 frequency to receive under high dynamic condition is determined its Position And Velocity.

The dynamic double-frequency GPS carrier wave aided tracking method of height that is used for of the present invention comprises the steps:

The first step: carry out carrier wave NCO and C/A sign indicating number NCO that phase-locked track loop of carrier wave and pseudo-code delay locked loop are regulated local L1 frequency, produce the valuation of L1 carrier phase and C/A code delay;

Second step: the L1-P sign indicating number generator of C/A sign indicating number control based on this locality produces, produce the P sign indicating number of local reproduction, utilize and partly do not have code method, use a pseudo-code delay locked loop (DLL) to L1-P (Y) signal trace;

The 3rd step: the phase place of the P sign indicating number that produces based on the L1-P code generator, realize initialization to the L2-P code generator;

The 4th step: according to the estimated value of L1 loop carrier phase place, the reference oscillator frequencies side-play amount that the positioning calculation module solves, and the phase demodulation error of the phase-locked track loop of L2 carrier wave (PLL), unite the carrier phase value of estimating the L2 frequency, regulate a carrier wave NCO, the L2 signal carrier that reproduction is local;

The 5th step: regulate local L2-P sign indicating number NCO by the auxiliary L2 pseudo-code delay lock loop (DLL) of this carrier phase valuation, the L2-P sign indicating number that reproduction is local utilizes and does not partly have the accurate tracking of code method to input L2 signal.

Beneficial effect of the present invention:

Make the carrier track of L2-P in this way can in high dynamic environment, bring benefit aspect three: the tracking accuracy that (1) is higher; (2) lower tracking thresholding; (3) loop is more stable.

Description of drawings

Fig. 1 is the functional block diagram of the GPS receiver of constructing according to the present invention;

Fig. 2 is included in the functional block diagram of the L1 carrier phase spinner in Fig. 1 receiver;

Fig. 3 is included in the functional block diagram of the L1 CA code correlator in Fig. 1 receiver;

Fig. 4 is included in the functional block diagram of the L1 P code correlator in Fig. 1 receiver;

Fig. 5 is included in the functional block diagram of the L2 carrier phase spinner in Fig. 1 receiver;

Fig. 6 is included in the functional block diagram of the L2 P code correlator in Fig. 1 receiver;

Fig. 7 is included in the functional block diagram of crystal oscillator and receiver components relation in Fig. 1 receiver

Embodiment

For making purpose of the present invention, technical scheme and advantage clearer, with reference to the accompanying drawings and embodiment, the present invention is described in further detail.

Now with reference to the embodiment of detailed general plotting of the present invention, its example is represented in the accompanying drawings, Fig. 1 has described a GPS receiver, it receives the signal of gps satellite by antenna 1, the signal that receives amplifies by low noise amplifier 2, and separated device (splitter) 3 is separated into L1 signal and L2 signal, and separation vessel is sent to low-converter 4 with the L1 signal then, and the L2 signal is sent to low-converter 27.

L1 low-converter 4 is a frequency that is suitable for analog/digital converter 5 with the L1 signal that receives from the L1 frequency transitions, analog/digital converter 5 is taken a sample with the sampling rate of the nyquist sampling theorem signal after to down coversion, and produce a digital signal corresponding, be sent to phase rotation device 7 along number bus 6, the valuation that phase rotation device 7 receives from the L1 carrier phase angle of digital controlled oscillator (NCO) 8, φ _L1Based on this valuation, this phase rotation device produces base band homophase (I) component and base band quadrature (Q) component.

More specifically, as depicted in figure 1, phase rotation device 7 is from phase angle valuation φ _L1In cosine table 101 and sine table 102, produce two values, i.e. cos (φ _L1) and sin (φ _L1).Multiplier 103 and 104 rotates this phasing degree and mutual an angle of 90 degrees to sampling value, to produce I road sampling value 105 and Q road sampling value 106 with these two the digital signal sampling values that go up on duty.This I, Q sampling value are passed to C/A code correlator 11 along number bus 9, and the Q sampling value is passed to P code correlator 12 along number bus 10 simultaneously.

As depicted in figure 2, L1C/A code correlator 11 comprises C/A sign indicating number code table 201 and 6 multipliers 205,206,207,208,209,210.L1 C/A yardage controlled oscillator (NCO) 13 is according to the auxiliary control of L1 C/A code delay locking ring (DLL) down in L1 carrier phase-locked loop (PLL), the valuation that produces a code phase, τ _cThis valuation is sent in the C/A sign indicating number code table 201.According to the pseudo-random code that is stored in the corresponding gps satellite in the code table in advance, C/A sign indicating number code table is created in code phase valuation τ _cInstant pseudo-random code 203 constantly, and produce the hysteresis pseudo-random code 202 corresponding to instant pseudo-random code hysteresis half-chip (chip) and the leading pseudo-random code 204 of leading half-chip (chip).The I sampling value 105 of the process phase place rotation of transmitting along number bus 9 and Q sampling value 106 multiply each other with hysteresis branch road reproduction L1 C/A sign indicating number 202, instant branch road reproduction L1 C/A sign indicating number 203, leading branch road reproduction L1 C/A sign indicating number 204 these 3 tunnel pseudo-random codes respectively, obtain 6 tunnel multiplied result mIE _L1C211, mIP _L1C212, mI _L1C213, mQE _L1C214, mQP _L1C215, mQL _L1C216.Then, this 6 tunnel multiplied result will be sent to L1C/A integration totalizer (I﹠amp; D) 15 add up.

In addition, as depicted in figure 3, L1P code correlator 12 comprises P sign indicating number code table 301, P sign indicating number generator 302 and 3 multipliers 306,307,308.L1P yardage controlled oscillator (NCO) 14 is according to the control of L1 P code delay locking ring (DLL) under L1 carrier phase-locked loop (PLL) is auxiliary, the valuation that produces a code phase, τ _L1PThis valuation is sent in the P sign indicating number code table 301.P sign indicating number generator in time produces corresponding P sign indicating number according to clock control information simultaneously, is stored in the P sign indicating number code table 301.P sign indicating number code table is according to code phase valuation τ _L1P, produce this instant pseudo-random code 304 constantly, and produce hysteresis pseudo-random code 303 corresponding to instant pseudo-random code hysteresis half-chip (chip), and the leading pseudo-random code 305 of leading half-chip (chip).The Q sampling value of the process phase place rotation of transmitting along number bus 10 multiplies each other in multiplier 306,307 and 308 with hysteresis branch road reproduction L1C/A sign indicating number 202, instant branch road reproduction L1 C/A sign indicating number 203 and leading branch road reproduction L1 C/A sign indicating number 204 these 3 tunnel pseudo-random codes respectively, obtains 3 tunnel multiplied result mQE _L1P309, mQP _L1P310, mQL _L1P311.Then, this 6 tunnel multiplied result will be sent to W sign indicating number width integration totalizer (I﹠amp; D) 19 add up.

6 road mIE as a result that come out in the C/A code correlator _L1C211, mIP _L1C212, mIL _L1C213, mQE _L1C214, mQP _L1C215, mQL _L1C216, enter L1C/A pre-detection integration totalizer and add up.When the predetermined time of adding up reached, the integration totalizer obtained 6 road accumulation result IE _L1C, IP _L1C, IL _L1C, QE _L1C, QP _L1C, QL _L1CIntegration totalizer 15 is given L1 carrier phase-locked loop (PLL) 16, L1 C/A code delay locking ring (DLL) 17 and navigation calculation module (not illustrating in the drawings) this 6 road accumulation result, and then, zero clearing is also carried out the next round operation that adds up.Receiver is by conventional method, according to IP _L1C, QP _L1C2 tunnel results select to meet dynamically and the bandwidth of accuracy requirement, use 3 rank phase-locked loops (PLL) to follow the tracks of carrier wave.According to IE _L1C, IL _L1C, QE _L1C, QL _L1C4 tunnel results use delay lock loop (DLL) tracking code, and as known to those skilled in the art, use the valuation of phase angle tracking error to provide Carrier-aided tracking by conventional methods in L1 C/A code delay locking ring (DLL) 17.

Three road mQE as a result that come out in the L1P code correlator 12 _L1P309, mQP _L1P310, mQL _L1P311, enter W sign indicating number width integration totalizer 19.W sign indicating number width integration totalizer 19 is three independently integration totalizers, and it is according to the operation that adds up of the time width of W sign indicating number, and aligns with the edge of W sign indicating number.In the moment of W sign indicating number bit flipping, W sign indicating number width integration totalizer is finished the operation that adds up, and the result is passed to next link handle, and simultaneously totalizer is carried out clear operation and adds up to carry out next round.MQP _L1P310 W sign indicating number width accumulation result wQP _L1P20 are taken as the valuation of W sign indicating number, This valuation

Respectively with mQE _L1P309 and mQL _L1P311 W sign indicating number width accumulation result wQE _L1P, wQL _L1PMultiply each other by multiplier 21 and multiplier 22, remove and be modulated at wQE _L1PAnd wQL _L1POn the influence of W sign indicating number, obtain peeling off the nQE as a result after the W sign indicating number _L1P, nQL _L1PSimultaneously, this valuation wQP _L1P20 are sent to time-delay buffer 23, with removing the same W sign indicating number that is modulated on the L2 signal.

Remove W sign indicating number W sign indicating number width accumulation result nQE afterwards _L1P, nQL _L1PBe sent to L1P pre-detection integration totalizer 24, carry out secondary integration and add up.When the predetermined time of adding up reaches, the integration totalizer is passed to L1P code delay locking ring (DLL) 25 to accumulation result, use DLL to estimate that reproduction P sign indicating number corresponds to the phase delay of P sign indicating number in the input signal by conventional method, and adjust P sign indicating number NCO, the P sign indicating number is followed the tracks of.And as known to those skilled in the art, use the valuation of L1C/A phase angle tracking error that Carrier-aided tracking is provided in L1P DLL by conventional methods.

With reference to Fig. 1, separation vessel 3 is sent to low-converter 27 to the L2 signal.L2 low-converter 27 is a frequency that is suitable for analog/digital converter 28 with the L2 signal that receives from the L2 frequency transitions also.This analog/digital converter 28 is taken a sample with the sampling rate that the satisfies nyquist sampling theorem signal after to down coversion equally, and produces a digital signal corresponding, and it is sent to L2 carrier phase spinner 30 along number bus 29.The valuation that phase rotation device 30 receives from the L2 carrier phase angle of L2 carrier number controlled oscillator (NCO) 31, φ _L2Based on this valuation, this phase rotation device produces base band homophase (I) component and base band quadrature (Q) component.

More specifically, as depicted in figure 5, phase rotation device 30 is from phase angle valuation φ _L2In cosine table 401 and sine table 402, produce two values, i.e. cos (φ _L2) and sin (φ _L2).Multiplier 403 and multiplier 404 are actually sampling value are rotated this phasing degree and mutual an angle of 90 degrees, these two the digital signal sampling values 29 that go up on duty to produce I and Q sampling value.This I, Q sampling value are passed to L2P code correlator 33 along number bus 32.

Refer again to Fig. 1, the valuation that L2P code correlator 33 receives from the L2 P code phase of L2 P yardage controlled oscillator (NCO) 34, τ _L1PBased on this valuation, this code correlator produces, and this locality leading, instant and that lag behind reappears the P sign indicating number.In correlator, the I, the Q sampling value that send along number bus 32 multiply each other with this three tunnel pseudo-random code respectively, obtain 6 tunnel multiplied result.

As depicted in figure 6, L2 P code correlator 33 comprises P sign indicating number code table 501, P sign indicating number generator 517 and 6 multipliers 505,506,507,508,509,510.L2 P yardage controlled oscillator (NCO) 34 is according to the control of L2 P code delay locking ring (DLL) under L2 carrier phase-locked loop (PLL) is auxiliary, the valuation that produces a code phase, τ _L2PThis valuation is sent in the P sign indicating number code table 501.P sign indicating number generator 517 in time produces corresponding P sign indicating number according to clock control information simultaneously, is stored in the P sign indicating number code table 501.P sign indicating number code table is according to code phase valuation τ _L1P, produce this instant pseudo-random code 503 constantly, and produce hysteresis pseudo-random code 502 corresponding to instant pseudo-random code hysteresis half-chip (chip), and the leading pseudo-random code 504 of leading half-chip (chip).The I of the process phase place rotation of transmitting along number bus 32, Q sampling value multiply each other in multiplier 505,506,507,508,509 and 510 with hysteresis branch road reproduction L2 P sign indicating number 502, instant branch road reproduction L2 P sign indicating number 503 and leading branch road reproduction L2 P sign indicating number 504 these 3 tunnel pseudo-random codes respectively, obtain 6 tunnel multiplied result mIE _L2P511, mIP _L2P512, mIL _L2P513, mQE _L2P514, mQP _L2P515, mQL _L2P516.Then, this 6 tunnel multiplied result will be sent to L2 W sign indicating number width integration totalizer (I﹠amp; D) 35 add up.

6 road mIE as a result that come out in the L2P code correlator 33 _L2P511, mIP _L2P512, mIL _L2P513, mQE _L2P514, mQP _L2P515, mQL _L2P516, enter L2 W sign indicating number width integration totalizer 35.L2 W sign indicating number width integration totalizer 35 is 6 independently integration totalizers, and 6 road signals of input are added up respectively, adds up in the moment of W sign indicating number bit flipping and finishes, and obtains 6 road wIE as a result _L2P, wIP _L2P, wIL _L2P, wQE _L2P, wQP _L2P, wQL _L2PThis 6 road accumulation result is sent to L2 W code correlator 37 along number bus 36.In L2W code correlator 37, the wIE that transmits along number bus 36 _L2P, wIP _L2P, wIL _L2P, wQE _L2P, wQP _L2P, wQL _L2P6 tunnel results respectively be stored in the valuation of this moment W sign indicating number in the time-delay buffer 23 before

Multiply each other, obtain 6 the tunnel and eliminate the L2 accumulation result nIE that the W sign indicating number influences _L2P, nIP _L2P, nIL _L2P, nQE _L2P, nQP _L2P, nQL _L2P

Remove W sign indicating number W sign indicating number width accumulation result nIE afterwards _L2P, nIP _L2P, nIL _L2P, nQE _L2P, nQP _L2P, nQL _L2PBe sent to L2 P pre-detection integration totalizer 38, carry out secondary integration and add up.When the predetermined time of adding up reaches, the integration totalizer is passed to L2 carrier phase locking ring (PLL) 39 and L2 P code delay locking ring (DLL) 40 to accumulation result, in order to estimate that carrier phase angle tracking error valuation and reproduction P sign indicating number correspond to the phase delay of P sign indicating number in the input signal, and adjust L2 carrier number controlled oscillator (NCO) and L2 P yardage controlled oscillator (NCO), so that carrier wave and P sign indicating number are followed the tracks of.

Particularly, as shown in Figure 7, antenna 1 receives the signal of gps satellite, by obtaining amplifying signal 701 behind the low noise amplifier 2.It and separated device (splitter) 3 are separated into L1 signal 702 and L2 signal 703.Its frequency is respectively:

f _r1＝f _t1+f _d1

f _r2＝f _t2+f _d2

Wherein, f _T1, f _T2For the L1 signal of satellites transmits and the rf frequency of L2 signal, be respectively 1575.42MHz and 1227.6MHz.f _D1, f _D2Be because the frequency shift (FS) that relative motion causes between satellite and the receiver also is called Doppler frequency, satisfy following relational expression between them:

$\frac{f_{d1}}{{\mathrm{<figure-callout\; id="2"\; label="f\; d"\; filenames="A20091008047400172.png"\; state="\{\{state\}\}">f</figure-callout>}}_d}=\frac{f_{t1}}{{\mathrm{<figure-callout\; id="2"\; label="f\; t"\; filenames="A20091008047400172.png"\; state="\{\{state\}\}">f</figure-callout>}}_t}=\frac{154}{120}$

Because the influence of ionospheric refraction, can make f _D1, f _D2Relation not strictly satisfy following formula.But this influence is very little, to such an extent as to when estimated frequency, can ignore this factor.

The L1 radiofrequency signal 702 of L1 low-converter 4 after the amplification of the local reference frequency signal 706 of L1 local oscillator 704 output and input multiplies each other the L1 intermediate-freuqncy signal 708 of the difference of two frequencies of output.The L2 radiofrequency signal 703 of L2 low-converter 27 after the amplification of the local reference frequency signal 707 of L2 local oscillator 705 output and input multiplies each other the L2 intermediate-freuqncy signal 709 of the difference of two frequencies of output.

L1 local oscillator 704 is frequency multipliers, and it receives the input clock 711 with reference to crystal oscillator 710, and its frequency is amplified a suitable multiple k ₁Obtain the local reference frequency signal 706 of L1, they satisfy following relational expression:

f _LO1＝k ₁□(f _ref+Δf)

F wherein _RefBe the nominal output signal frequency of crystal oscillator 710 nominals, Δ f is the frequency of the crystal oscillator 710 actual signals of exporting and the frequency f of nominal _RefPoor, k ₁Be the multiple of L1 local oscillator 704 frequencys multiplication, f _LO1It is the actual frequency of the reference signal of L1 local oscillator 704 outputs.In like manner, can obtain the actual frequency of the reference signal 707 of L2 local oscillator 705 outputs:

f _LO2＝k ₂□(f _ref+Δf)

Because the signal frequency of low-converter output is poor for two signal frequencies of input, satisfies following formula so can obtain the frequency of L1 intermediate-freuqncy signal 708 and L2 intermediate-freuqncy signal 709:

f _i1＝f _r1-f _LO1＝f _t1+f _d1-k ₁□(f _ref+Δf)

f _i2＝f _r2-f _LO2＝f _t2+f _d2-k ₂□(f _ref+Δf)

As previously mentioned, L1 intermediate-freuqncy signal 708 and L2 intermediate-freuqncy signal 709 obtain digital medium-frequency signal 6 and 29 through analog/digital converter (ADC) 5 and 28 sample varianceizations, enter phase rotation device 7 and 30. Phase rotation device 7 and 30 valuations that receive from the L1 and the L2 carrier phase angle of digital controlled oscillator (NCO) 8 and 31, φ _L1And φ _L2Based on this valuation, this phase rotation device produces base band homophase (I) component and base band quadrature (Q) component.When loop stability was followed the tracks of, the frequency of this base band homophase (I) component and base band quadrature (Q) component was 0.

The nominal frequency of the signal of carrier number controlled oscillator this moment (NCO) output is f _NCO1And f _NCO2, but because the clock of NCO work also is to come from reference crystal oscillator 710, so the frequency of the actual signal of its output is respectively

With

Because the signal frequency of phase rotation device output is 0, then the signal frequency of NCO output equates with the intermediate-freuqncy signal frequency of input, so can obtain following relational expression:

Its f _I1And f _I2Nominally be the centre frequency of NCO work, satisfy f _I1=f _T1-k ₁f _Ref, f _I2=f _T2-k ₂f _Ref

Simplify the above-mentioned relation formula, can obtain

Promptly

f _N2Be Doppler's auxiliary quantity f _AidWherein, the frequency difference Δ f of crystal oscillator can use method well-known to those skilled in the art to obtain in the process of navigation calculation.

Return Fig. 1, receiver in control L2 carrier wave NCO with controlled quentity controlled variable f _L2Be divided into 2 part f _AidAnd f _Calf _AidThe frequency deviation of the receiver reference crystal oscillator that is solved by the trace information and the positioning calculation module of L1 frequency obtains, and it is dynamic that it is used to eliminate the sighting distance of L2 signal, f _CalBe L2 frequency phaselocked loop (PLL) to eliminating the estimation of the signal residue Doppler frequency of sighting distance after dynamically, wherein f _L2=f _Cal+ f _AidUniting the phase error that estimates the L2 signal carrier is sent in the L2 carrier number controlled oscillator 31 and is used for the L2 carrier signal is carried out accurate tracking.

L2 frequency estimator 42 receives the estimation 43 of navigation calculation module to the frequency difference Δ f of crystal oscillator, and the L1 on L1 carrier phase-locked loop road 16 name Doppler estimated value f _N1The L2-P integration add up finish after, i.e. each Δ T _L2Control interval, the L1 frequency of this moment is measured Doppler frequency f _N1And the above-mentioned formula of frequency deviation Δ f substitution of receiver reference crystal oscillator obtains new f _Aid, and upgrade f _L2=f _Cal+ f _AidBe written among the L2 carrier wave NCO.Simultaneously, after sighting distance dynamically was eliminated, receiver can be to Δ T _L2The accumulation result of time remakes M time the second level and adds up that (M also can equal 1, promptly not doing secondary adds up), obtain 6 road accumulation result L2P-sIE, L2P-sIP, L2P-sIL, L2P-sQE, L2P-sQP and L2P-sQL, so that before loop phase detector phase demodulation, obtain higher signal to noise ratio (S/N ratio), thus when reducing phase demodulation to the noise item square extra snr loss who brings.At each M Δ T _L2Control interval, the loop phase detector estimates M Δ T according to the accumulation result of L2P-sIP and L2P-sQP _L2Residue in time differs, and obtains new inherent spurious frequency deviation controlled quentity controlled variable f by the carrier phase-locked loop (PLL) of a narrower loop bandwidth _Cal, in order to upgrade f _L2

Claims (1)

1, a kind of dynamic double-frequency GPS carrier wave aided tracking method of height that is used for is characterized in that: comprise the steps:

The first step: carry out carrier wave NCO and C/A sign indicating number NCO that phase-locked track loop of carrier wave and pseudo-code delay locked loop are regulated local L1 frequency, produce the valuation of L1 carrier phase and C/A code delay;

Second step: the L1-P sign indicating number generator of C/A sign indicating number control based on this locality produces, produce the P sign indicating number of local reproduction, utilize and partly do not have code method, use a pseudo-code delay locked loop (DLL) to L1-P (Y) signal trace;

The 3rd step: the phase place of the P sign indicating number that produces based on the l1-P code generator, realize initialization to the L2-P code generator;

The 4th step: according to the estimated value of Ll loop carrier phase place, the reference oscillator frequencies side-play amount that the positioning calculation module solves, and the phase demodulation error of the phase-locked track loop of L2 carrier wave (PLL), unite the carrier phase value of estimating the L2 frequency, regulate a carrier wave NCO, the L2 signal carrier that reproduction is local;

The 5th step: regulate local L2-P sign indicating number NCO by the auxiliary L2 pseudo-code delay lock loop (DLL) of this carrier phase valuation, the L2-P sign indicating number that reproduction is local utilizes and does not partly have the accurate tracking of code method to input L2 signal.

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