CN103017731A - System for measuring P(Y) code phase difference of multi-path GPS (global position system) signals - Google Patents
System for measuring P(Y) code phase difference of multi-path GPS (global position system) signals Download PDFInfo
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Abstract
The invention discloses a system for measuring P(Y) code phase difference of multi-path GPS (global position system) signals. The system comprises a direct signal acquisition and tracking module, an array multiplier module and a height measuring module. According to a quadrature modulation characteristic of a GPS, orthogonal signals and in-phase signals of received satellite signal are extracted, C/A codes and P(Y) codes are separated from the signals, the equidistant same delay is respectively performed on the signals, the cross-correlation calculation is performed on the delayed signals and reflected signals, different delay code pieces can generate different non-coherent integration values, and thus the P(Y) code phase difference of the multi-path GPS signals is obtained. The measuring system reduces the complexity of hardware receiving equipment, and meanwhile, the measuring accuracy is improved.
Description
Technical field
The present invention relates to a kind of measurement of phase code, more particularly, refer to that a kind of direct signal of Navsat of utilizing replaces local signal and reflected signal to carry out computing cross-correlation, utilize cross correlation results to carry out the estimation of multichannel gps signal P (Y) code phase difference, and then the result that will estimate is applied in sea level height measurement, Ocean Wind-field inverting, aircraft survey appearance, deformation monitoring etc. application facet.
Background technology
In recent years, the application advantage such as, round-the-clock round-the-clock with it based on the microwave remote sensing technique of GLONASS (Global Navigation Satellite System) reflected signal, multisignal source, wide covering, high-spatial and temporal resolution shows wide application prospect in the remote sensing field.The GPS measuring technique that develops rapidly makes geodesic the assuming an entirely new aspect of tradition, brings the field depth technological revolution at quarter to survey field.The GPS measuring technique is at sea, land and sky At any points point, receives continuously direct projection or the reflected signal of gps satellite by antenna, and calculates the three-dimensional velocity of three-dimensional coordinate, sea level elevation, motion carrier of survey station point and time etc.
Generally adopt the GPS receiver device to finish in this technical field at present, because the C/A code cycle is short, realize that related algorithm is convenient in the GPS receiver, a lot of researchists carry out sea level height by the C/A code phase difference of measuring the multichannel gps signal and measure.Aspect the experiment of bank base, the people such as Martin-Neira process respectively direct signal and reflected signal in the bridge experiment of carrying out the earliest, have been issued to the altimetry precision of 3m in the situation of only utilizing the C/A code phase; The people such as Treuhaft utilize local signal and direct projection and reflected signal to carry out related operation in the maar experiment, the method of utilizing nonlinear parameter to estimate has been extracted the carrier phase difference of direct projection and reflected signal, and average in the time at 1s, obtained the altimetry precision of 2cm; The people such as the people such as Ruffini and Rivas utilize respectively the carrier phase of coded signal to obtain the altimetry precision of 3.1cm and 5cm in the harbour under the condition of smooth.Aspect airborne experiment, Lowe has obtained the altimetry precision of 60cm in experiment, and thinks and on average can make for a long time altimetry precision be increased to the 5cm magnitude.
By above-mentioned experiment, it is not high as seen to utilize the C/A code to carry out the altimetry precision of multichannel gps signal phase differential.For the problems referred to above, the present invention proposes a kind of sea of direct signal and reflected signal simple crosscorrelation that utilizes and surveys high method, the method is utilized the gps signal structure and characteristics, homophase (comprising the C/A code) component to direct signal carries out quadrature and separates with quadrature (comprising P (Y) code) component, adopt the direct signal after quadrature separates to replace local signal and reflected signal to carry out respectively related operation, utilize cross correlation results to carry out the phase difference estimation of multichannel gps signal, thereby realize that the receiver position is apart from the height measurement of reflecting surface.This system has avoided the generation of local signal in the reflected signal processing, has reduced the complexity of receiving equipment, and utilizes P (Y) coded signal with higher spreading gain to improve the estimated accuracy of phase differential.
Summary of the invention
The purpose of this invention is to provide a kind of multichannel gps signal P(Y) measuring system of code phase difference, this system is by obtaining the effect of hardware with Verilog HDL language design at fpga chip.In the present invention, adopt the method for capturing and tracing of time domain pseudo-code serial carrier wave serial that the direct projection digital medium-frequency signal is carried out acquisition and tracking; Adopt array multiplier to carry out the computing of the related power value of multichannel direct projection digital baseband signal and reflection digital fundamental frequency signal; Adopt the tracking peak method that the direct projection digital baseband signal of multichannel different delayed time and the related power value of reflection digital fundamental frequency signal are carried out peak detection process; And according to the space geometry of sea surface reflection relation the range difference between direct signal and the reflected signal and elevation of satellite are processed, obtain signal processing platform to the relative altitude of reflecting surface.
A kind of multichannel gps signal P(Y of the present invention) measuring system of code phase difference, this measuring system include direct signal acquisition and tracking module (10), array multiplier module (20), height measurement module (30);
Direct signal acquisition and tracking module (10) is used for direct projection digital medium-frequency signal s
D-IF(n) catch, the demodulation of tracking and navigation message, obtain carrier frequency control word F
CW, reflector satellite elevation angle ε is anti--straight length of delay N, straight-Ji quadrature s
D-BB-P(n), straight-Ji homophase s
D-BB-C(n); Wherein, reflector satellite elevation angle ε exports to height measurement module (30); Carrier frequency control word F
CW, straight-Ji quadrature s
D-BB-P(n), straight-Ji homophase s
D-BB-C(n), anti--straight length of delay N exports to respectively array multiplier module (20);
Array multiplier module (20) utilizes multipath delay device array to reflection digital intermediate-freuqncy signal s
R-IF(n), straight-Ji quadrature s
D-BB-P(n) and straight-Ji homophase s
D-BB-C(n) process, obtain the straight-positive intercorrelation performance number of Ji X
P(τ
n) and straight-Ji homophase simple crosscorrelation performance number X
C(τ
n), and output to height measurement module (30);
Height measurement module (30) comprises instead-Ji quadrature power values curve fitting module (304), anti--Ji homophase performance number curve fitting module (305), P(Y) and yard peak detection block (302), C/A code peak detection block (303), high computational module (301);
Instead-Ji quadrature power values curve fitting module (304) with a plurality of anti--Ji quadrature power values, i.e. anti--Ji quadrature initial gain value X
P (0), anti--Ji quadrature the first performance number X
P (1), anti--Ji quadrature the second performance number X
P (2)..., anti--Ji quadrature M performance number X
P (M)According to scattered signal related power model＜| YD (Δ, f) |
2Carry out curve fitting output P(Y) the One-dimensional power value-time delay function X of code
P (τ)
Instead-Ji homophase performance number curve fitting module (305) with a plurality of anti--Ji homophase performance number, i.e. anti--Ji homophase initial gain value X
C (0), anti--Ji homophase the first performance number X
C (1), anti--Ji homophase the second performance number X
C (2), anti--Ji homophase M performance number X
C (M)According to scattered signal related power model＜| YS (Δ, f) |
2Carry out curve fitting the One-dimensional power value of output C code-time delay function X
C (τ)
P(Y) the code peak value detects mould (302) piece to P(Y) the One-dimensional power value of code-time delay function X
P (τ)Adopt the peak time tracking method, simulate peak point, calculate time delay value corresponding to peak point, be translated into again the range difference ρ between reflected signal and the direct signal
p
C/A code peak detection block (303) is to the One-dimensional power value of C/A code-time delay function X
C (τ)Adopt the peak time tracking method, simulate peak point, calculate time delay value corresponding to peak point, be translated into again the range difference ρ between reflected signal and the direct signal
c
High computational module (301) is to multichannel P(Y) code phase difference calculates the range difference ρ of direct signal and reflected signal
p, the multichannel code phase difference calculates the range difference ρ of direct signal and reflected signal
c, reflector satellite elevation angle ε processes, according to the space geometry relation of sea surface reflection, the computing formula of the relative altitude of signal processing platform and reflection spot is
Wherein h represents the relative altitude of signal processing platform and reflection spot, then
h
pThe height measurement results of the phase differential of expression multichannel gps signal P (Y) code,
h
cThe height measurement results of the phase differential of expression multichannel gps signal C/A code, both altimetry precisions can compare.
The advantage of the measuring system of multichannel gps signal P of the present invention (Y) code phase difference is:
1. utilize P (Y) code phase difference to survey the demand that height can satisfy different observation platforms, also satisfy high precision simultaneously and survey high demand.
2. it is high looser to the requirement of environment to utilize P (Y) code phase difference to survey, and range of application is unrestricted, has the characteristics of remote sensing satellite signal measurement, i.e. wide covering, high-spatial and temporal resolution etc.
3. in signal is processed, utilize the direct signal that receives to replace local signal and reflected signal to carry out the processing mode of computing cross-correlation, avoided the generation local signal, reduced the hardware complexity of receiving equipment.
4. utilize the C/A code phase difference of multichannel gps signal to survey the high measurement result that obtains, can with the P(Y that utilizes the multichannel gps signal) code phase difference surveys the high measurement result that obtains and carries out accuracy comparison.Contrast as can be known P(Y) code measuring accuracy higher.
Description of drawings
Fig. 1 is the present invention's P (Y) code phase difference of utilizing the multichannel gps signal, the configuration diagram that the C/A code phase difference is carried out the simple crosscorrelation height measuring device.
Fig. 2 is array multiplier modular structure diagram of the present invention.
Fig. 3 is the present invention's height measurement module configuration diagram.
Embodiment
Exist two kinds of ranging codes of C/A code and P (Y) code on the gps signal, the C/A code only is modulated on the L1 carrier signal, and the cycle is 1ms, and code check is 1.023Mcps; And P (Y) code is modulated on L1 and the L2 carrier signal simultaneously, and the cycle is 7 days, and code check is 10.23Mcps.
Referring to shown in Figure 1, the present invention is that a kind of direct signal of Navsat of utilizing replaces local signal and reflected signal to carry out computing cross-correlation, P (Y) code phase difference of utilizing different simple crosscorrelation performance numbers to carry out the multichannel gps signal is estimated, and then realizing that sea level height measurements, Ocean Wind-field inverting, aircraft survey the measuring system of appearance, deformation monitoring etc., the measuring system of the P code phase difference of this multichannel gps signal includes direct signal acquisition and tracking module 10, array multiplier module 20, measurement module 30 highly.This system is by obtaining the effect of hardware with Verilog HDL language design at the fpga chip of GPS receiver.
(1) direct signal acquisition and tracking module 10
Direct signal acquisition and tracking module 10 is used for the direct projection digital medium-frequency signal s of the gps satellite that rapid abutting joint receives
D-IF(n) signal catch, the demodulation of tracking and navigation message.
In the present invention, direct signal acquisition and tracking module 10 adopted in July, 2006, and the 4th phase of the 27th volume, the algorithm of mentioning in " remote measuring and controlling " disclosed " FPGA of GPS receiver baseband signal processing module realizes " obtains respectively carrier frequency control word F
CW, reflector satellite elevation angle ε, reflected signal with respect to the phase retardation estimated value N(of direct signal referred to as instead-straight length of delay N), quadrature component (the comprising P(Y) code of direct projection digital baseband signal) s
D-BB-P(n) (referred to as directly-Ji quadrature s
D-BB-PAnd the in-phase component of direct projection digital baseband signal (comprising the C/A code) s (n))
D-BB-C(n) (referred to as directly-Ji homophase s
D-BB-C(n)); Wherein, reflector satellite elevation angle ε exports to height measurement module 30; Carrier frequency control word F
CW, straight-Ji quadrature s
D-BB-P(n), straight-Ji homophase s
D-BB-C(n), anti--straight length of delay N exports to respectively array multiplier module 20.
s
D-BB-P(n) and s
D-BB-C(n) (n) expression discrete time in.
(2) the array multiplier module 20
Participate in shown in Figure 2ly, array multiplier module 20 is utilized the reflection digital intermediate-freuqncy signal s of multipath delay device array to receiving
R-IF(n), straight-Ji quadrature s
D-BB-P(n) and straight-Ji homophase s
D-BB-C(n) process, obtain the straight-positive intercorrelation performance number of Ji X
P(τ
n) and straight-Ji homophase simple crosscorrelation performance number X
C(τ
n), and output to height measurement module 30.τ
nThe span of expression correlation time, namely 0, Δ ..., the M Δ.
Described straight-the positive intercorrelation performance number of Ji X
P(τ
n) refer to reflection digital intermediate-freuqncy signal s
R-IF(n) with straight-Ji quadrature s
D-BB-PThe simple crosscorrelation performance number of different delay distance signal (n).
Described straight-Ji homophase simple crosscorrelation performance number X
C(τ
n) refer to reflection digital intermediate-freuqncy signal s
R-IF(n) with straight-Ji homophase s
D-BB-CThe simple crosscorrelation performance number of different delay distance signal (n).
Particularly, 20 pairs of reflection digital intermediate-freuqncy signals of array multiplier module s
R-IF(n), straight-Ji quadrature s
D-BB-P(n) and straight-Ji homophase s
D-BB-C(n) treatment step is as follows:
Step 201: carrier wave NCO is according to carrier frequency control word F
CWProduce sine wave and the cosine wave (CW) of respective frequencies, the waveform of generation depends on that what deposit among the ROM is sine table or cosine table;
Step 202: in the sinusoidal multiplier with reflection digital intermediate-freuqncy signal s
R-IF(n) and the sinusoidal signal of sine table output multiply each other quadrature component (the comprising P(Y) code of output reflection digital baseband signal) s
R-P(n) (referred to as instead-Ji quadrature s
R-P(n));
The cosine multiplier is with reflection digital intermediate-freuqncy signal s
R-IF(n) and the cosine signal of cosine table output multiply each other the in-phase component of output reflection digital baseband signal (comprising the C/A code) s
R-C(n) (referred to as instead-Ji homophase s
R-C(n)).
Step 203: delayer p will straight-Ji quadrature s
D-BB-P(n) postpone N chronomere, namely signal will convert to and postpone straight-Ji quadrature s
D-BB-P(n-N Δ); N be the mode of employing direct projection closed loop reflection open loop of direct signal acquisition and tracking module output to the estimated value of reflected signal with respect to the phase retardation of direct signal, Δ is the time step that postpones; In like manner can get:
Delayer p1 will postpone directly-Ji quadrature s
D-BB-P(n-N Δ) postpones 1 time step Δ, and namely signal will convert first to and postpone straight-Ji quadrature s
D-BB-P(n-N Δ-Δ);
Delayer p2 postpones straight-Ji quadrature s with first
D-BB-P(n-N Δ-Δ) postpones 1 time step Δ, and namely signal will convert second to and postpone straight-Ji quadrature s
D-BB-P(n-N Δ-2 Δ);
Delayer pM postpones straight-Ji quadrature s with M-1
D-BB-P(n-N Δ-(M-1) Δ) postpones 1 time step Δ, and namely signal will convert M to and postpone straight-Ji quadrature s
D-BB-P(n-N Δ-M Δ);
Delayer c will straight-Ji homophase s
D-BB-C(n) postpone N chronomere, namely signal will convert to and postpone straight-Ji homophase s
D-BB-C(n-N Δ); N be the mode of employing direct projection closed loop reflection open loop of direct signal acquisition and tracking module output to the estimated value of reflected signal with respect to the phase retardation of direct signal, Δ is the time step that postpones; In like manner can get:
Delayer c1 will postpone directly-Ji homophase s
D-BB-C(n-N Δ) postpones 1 time step Δ, and namely signal will convert first to and postpone straight-Ji homophase s
D-BB-C(n-N Δ-Δ);
Delayer c2 postpones straight-Ji homophase s with first
D-BB-C(n-N Δ-Δ) postpones 1 time step Δ, and namely signal will convert second to and postpone straight-Ji homophase s
D-BB-C(n-N Δ-2 Δ);
Delayer cM postpones straight-Ji homophase s with M-1
D-BB-C(n-N Δ-(M-1) Δ) postpones 1 time step Δ, and namely signal will convert M to and postpone straight-Ji homophase s
D-BB-C(n-N Δ-M Δ);
Step 204: multiplier p0 will anti--Ji quadrature s
R-P(n) with postpone straight-Ji quadrature s
D-BB-P(n-N Δ) multiplies each other, and obtains anti--Ji quadrature initial cross-correlation value S
R-D-P (0)In like manner can get:
Multiplier p1 will anti--Ji quadrature s
R-P(n) postpone straight-Ji quadrature s with first
D-BB-P(n-N Δ-Δ) multiplies each other, and obtains anti--Ji quadrature the first cross correlation value S
R-D-P (1)
Multiplier p2 will anti--Ji quadrature s
R-P(n) postpone straight-Ji quadrature s with second
D-BB-P(n-N Δ-2 Δ) multiplies each other, and obtains anti--Ji quadrature the second cross correlation value S
R-D-P (2)
Multiplier pM will anti--Ji quadrature s
R-P(n) postpone straight-Ji quadrature s with M
D-BB-P(n-N Δ-M Δ) multiplies each other, and obtains anti--Ji quadrature M cross correlation value S
R-D-P (M)
Multiplier c0 will anti--Ji homophase s
R-C(n) with postpone straight-Ji homophase s
D-BB-C(n-N Δ) multiplies each other, and obtains anti--Ji homophase initial cross-correlation value S
R-D-C (0)
Multiplier c1 will anti--Ji homophase s
R-C(n) postpone straight-Ji homophase s with first
D-BB-C(n-N Δ-Δ) multiplies each other, and obtains anti--Ji homophase the first cross correlation value S
R-D-C (1)
Multiplier c2 will anti--Ji homophase s
R-C(n) postpone straight-Ji homophase s with second
D-BB-C(n-N Δ-2 Δ) multiplies each other, and obtains anti--Ji homophase the second cross correlation value S
R-D-C (2)
Multiplier cM will anti--Ji homophase s
R-C(n) postpone straight-Ji homophase s with M
D-BB-C(n-N Δ-M Δ) multiplies each other, and obtains anti--Ji homophase M cross correlation value S
R-D-C(M);
Step 205: the cumulative unit p0 of integration will anti--Ji quadrature initial cross-correlation value S
R-D-P (0)Within preliminary examination integral time, add up, do not blocked anti--Ji quadrature initial gain value Y
P (0)
The cumulative unit p1 of integration will anti--Ji quadrature the first cross correlation value S
R-D-P (1)Within preliminary examination integral time, add up, do not blocked anti--Ji quadrature the first performance number Y
P (1)
The cumulative unit p2 of integration will anti--Ji quadrature the second cross correlation value S
R-D-P (2)Within preliminary examination integral time, add up, do not blocked anti--Ji quadrature the second performance number Y
P (2)
The cumulative unit pM of integration will anti--Ji quadrature M cross correlation value S
R-D-P (M)Within preliminary examination integral time, add up, do not blocked anti--Ji quadrature M performance number Y
P (M)
The cumulative unit c0 of integration will anti--Ji homophase initial cross-correlation value S
R-D-C (0)Within preliminary examination integral time, add up, do not blocked anti--Ji homophase initial gain value Y
C (0)
The cumulative unit c1 of integration will anti--Ji homophase the first cross correlation value S
R-D-C (1)Within preliminary examination integral time, add up, do not blocked anti--Ji homophase the first performance number Y
C (1)
The cumulative unit c2 of integration will anti--Ji homophase the second cross correlation value S
R-D-C (2)Within preliminary examination integral time, add up, do not blocked anti--Ji homophase the second performance number Y
C (2)
The cumulative unit cM of integration will anti--Ji homophase M cross correlation value S
R-D-C (M)Within preliminary examination integral time, add up, do not blocked anti--Ji homophase M performance number Y
C (M)
Step 206: cropper p0 will not block instead-Ji quadrature initial gain value Y
P (0)Carry out the truncation of 12 bits, obtain anti--Ji quadrature initial gain value X
P (0)
Cropper p1 will not block instead-Ji quadrature the first performance number Y
P (1)Carry out the truncation of 12 bits, obtain anti--Ji quadrature the first performance number X
P (1)
Cropper p2 will not block instead-Ji quadrature the second performance number Y
P (2)Carry out the truncation of 12 bits, obtain anti--Ji quadrature the second performance number X
P (2)
Cropper pM will not block instead-Ji quadrature M performance number Y
P (M)Carry out the truncation of 12 bits, obtain anti--Ji quadrature M performance number X
P (M)
Cropper c0 will not block instead-Ji homophase initial gain value Y
C (0)Carry out the truncation of 12 bits, obtain anti--Ji homophase initial gain value X
C (0)
Cropper c1 will not block instead-Ji homophase the first performance number Y
C (1)Carry out the truncation of 12 bits, obtain anti--Ji homophase the first performance number X
C (1)
Cropper c2 will not block instead-Ji homophase the second performance number Y
C (2)Carry out the truncation of 12 bits, obtain anti--Ji homophase the second performance number X
C (2)
Cropper cM will not block instead-Ji homophase M performance number Y
C (M)Carry out the truncation of 12 bits, obtain anti--Ji homophase M performance number X
C (M)
In the present invention, adopt arrange multiplier, delayer, integration totalizer, cropper of array format to carry out the computing of the related power value of multichannel direct projection digital baseband signal and reflection digital fundamental frequency signal, realized in signal is processed, the direct signal that utilization receives replaces local signal and reflected signal to carry out the processing mode of computing cross-correlation, avoid the generation local signal, reduced the hardware complexity of receiving equipment.
(3) height measurement module 30
Referring to shown in Figure 3, height measurement module 30 includes instead-Ji quadrature power values curve fitting module 304, instead-Ji homophase performance number curve fitting module 305, P code peak detection block 302, C code peak detection block 303, high computational module 301.
In the present invention, record preserve lower a plurality of croppers outputs anti--Ji quadrature power values and anti--Ji homophase performance number, use scattered signal related power model＜| YS (Δ, f) |
2Obtain two-dimentional performance number-time delay-Doppler's function.And the scattered signal related power model that adopts＜| YS (Δ, f) |
2It is the function of time delay step delta and Doppler frequency f two variablees.
D
2(r) square value of expression antenna gain has determined antenna coverage;
Λ
2[Δ (r)] represents anti--Ji quadrature power values or anti--Ji homophase performance number, determined to wait delay zone;
S[Δ f (r)] expression grade Doppler region, wherein Δ f (r)=f
c-f
0, i.e. Doppler frequency difference;
R
r 2(r) the expression receiver to the distance of scattering point square;
σ
0(r) d
2R represents normalization double-basis scattering cross-section, and the size of scattering cross-section has determined to be called as the zone, sea of irradiated region; d
2The expression two-dimensional integration;
R represents distance vector;
A
2The square value of expression amplitude factor;
T
2The square value that represents integral time;
W
2The expression additive white Gaussian noise.
Instead-Ji quadrature power values curve fitting module 304 with a plurality of anti--Ji quadrature power values, i.e. anti--Ji quadrature initial gain value X
P (0), anti--Ji quadrature the first performance number X
P (1), anti--Ji quadrature the second performance number X
P (2)..., anti--Ji quadrature M performance number X
P (M)According to scattered signal related power model＜| YS (Δ, f) |
2Carry out curve fitting the One-dimensional power value of output P code-time delay function X
P (τ)
Instead-Ji homophase performance number curve fitting module 305 with a plurality of anti--Ji homophase performance number, i.e. anti--Ji homophase initial gain value X
C (0), anti--Ji homophase the first performance number X
C (1), anti--Ji homophase the second performance number X
C (2), anti--Ji homophase M performance number X
C (M)According to scattered signal related power model＜| YS (Δ, f) |
2Carry out curve fitting the One-dimensional power value of output C code-time delay function X
C (τ)
P(Y) 302 couples of P(Y of code peak detection block) the One-dimensional power value of code-time delay function X
P (τ)Adopt the peak time tracking method, simulate peak point, calculate time delay value corresponding to peak point, be translated into again the range difference ρ between reflected signal and the direct signal
p
The One-dimensional power value of 303 pairs of C/A codes of C/A code peak detection block-time delay function X
C (τ)Adopt the peak time tracking method, simulate peak point, calculate time delay value corresponding to peak point, be translated into again the range difference ρ between reflected signal and the direct signal
c
301 couples of multichannel P(Y of high computational module) code phase difference is calculated the range difference ρ of direct signal and reflected signal
p(P(Y) code peak detection block output), multichannel C/A code phase difference is calculated the range difference ρ of direct signal and reflected signal
c(output of C code peak detection block), reflector satellite elevation angle ε (output of direct signal acquisition and tracking module) process, and according to the space geometry relation of sea surface reflection, the computing formula of the relative altitude of signal processing platform and reflection spot is
Wherein h represents the relative altitude of signal processing platform and reflection spot, then has
h
pThe height measurement results of the phase differential of expression multichannel gps signal P (Y) code,
h
cThe height measurement results of the phase differential of expression multichannel gps signal C/A code, both altimetry precisions can compare.
In the present invention, the reflected signal that high computational module 301 calculates and the phase differential between the direct signal can carry out multiple application, survey appearance, deformation monitoring etc. such as sea level height measurement, Ocean Wind-field inverting, aircraft, be measured as example with sea level height among the present invention.
The P(Y that utilizes the multichannel gps signal that the present invention relates to) code phase difference is surveyed high measuring system, essence is to utilize the direct signal of Navsat to replace local signal and reflected signal to carry out computing cross-correlation, utilize the gps signal structure and characteristics, homophase (comprising the C/A code) component to direct signal carries out quadrature and separates with quadrature (comprising P (Y) code) component, adopt the direct signal after quadrature separates to replace local signal and reflected signal to carry out respectively related operation, utilize cross correlation results to carry out the phase difference estimation of multichannel gps signal, thereby realize that the receiver position is apart from the height measurement of reflecting surface.This system has avoided the generation of local signal in the reflected signal processing, has reduced the complexity of receiving equipment, and utilizes P (Y) coded signal with higher spreading gain to improve the estimated accuracy of phase differential.Fast development along with navigational satellite system, a plurality of navigational satellite systems will be arranged in the space and deposit, the navigation satellite signal resource becomes increasingly abundant, and it will be more and more stronger utilizing the direct signal of Navsat and reflected signal to carry out technology operational feasibility and validity that computing cross-correlation calculates the phase differential of multichannel gps signal.
Claims (3)
1. the multichannel gps signal P(Y) measuring system of code phase difference is characterized in that: this measuring system includes direct signal acquisition and tracking module (10), array multiplier module (20), height measurement module (30);
Direct signal acquisition and tracking module (10) is used for direct projection digital medium-frequency signal s
D-IF(n) catch, the demodulation of tracking and navigation message, obtain carrier frequency control word F
CW, reflector satellite elevation angle ε is anti--straight length of delay N, straight-Ji quadrature s
D-BB-P(n), straight-Ji homophase s
D-BB-C(n); Wherein, reflector satellite elevation angle ε exports to height measurement module (30); Carrier frequency control word F
CW, straight-Ji quadrature s
D-BB-P(n), straight-Ji homophase s
D-BB-C(n), anti--straight length of delay N exports to respectively array multiplier module (20);
Array multiplier module (20) utilizes multipath delay device array to reflection digital intermediate-freuqncy signal s
R-IF(n), straight-Ji quadrature s
D-BB-P(n) and straight-Ji homophase s
D-BB-C(n) process, obtain the straight-positive intercorrelation performance number of Ji X
P(τ
n) and straight-Ji homophase simple crosscorrelation performance number X
C(τ
n), and output to height measurement module (30);
Height measurement module (30) comprises instead-Ji quadrature power values curve fitting module (304), anti--Ji homophase performance number curve fitting module (305), P(Y) and yard peak detection block (302), C/A code peak detection block (303), high computational module (301);
Instead-Ji quadrature power values curve fitting module (304) with a plurality of anti--Ji quadrature power values, i.e. anti--Ji quadrature initial gain value X
P (0), anti--Ji quadrature the first performance number X
P (1), anti--Ji quadrature the second performance number X
P (2)..., anti--Ji quadrature M performance number X
P (M)According to scattered signal related power model＜| YS (Δ, f) |
2Carry out curve fitting output P(Y) the One-dimensional power value-time delay function X of code
P (τ)
Instead-Ji homophase performance number curve fitting module (305) with a plurality of anti--Ji homophase performance number, i.e. anti--Ji homophase initial gain value X
C (0), anti--Ji homophase the first performance number X
C (1), anti--Ji homophase the second performance number X
C (2), anti--Ji homophase M performance number X
C (M)According to scattered signal related power model＜| YS (Δ, f) |
2Carry out curve fitting the One-dimensional power value of output C code-time delay function X
C (τ)
P(Y) the code peak value detects mould (302) piece to P(Y) the One-dimensional power value of code-time delay function X
P (τ)Adopt the peak time tracking method, simulate peak point, calculate time delay value corresponding to peak point, be translated into again the range difference ρ between reflected signal and the direct signal
p
C/A code peak detection block (303) is to the One-dimensional power value of C/A code-time delay function X
C (τ)Adopt the peak time tracking method, simulate peak point, calculate time delay value corresponding to peak point, be translated into again the range difference ρ between reflected signal and the direct signal
c
High computational module (301) is to multichannel P(Y) code phase difference calculates the range difference ρ of direct signal and reflected signal
p, the multichannel code phase difference calculates the range difference ρ of direct signal and reflected signal
c, reflector satellite elevation angle ε processes, according to the space geometry relation of sea surface reflection, the computing formula of the relative altitude of signal processing platform and reflection spot is
Wherein h represents the relative altitude of signal processing platform and reflection spot, then
h
pThe height measurement results of the phase differential of expression multichannel gps signal P (Y) code,
h
cThe height measurement results of the phase differential of expression multichannel gps signal C/A code, both altimetry precisions can compare.
2. the multichannel gps signal P(Y according to claim 1) measuring system of code phase difference, it is characterized in that: array multiplier module (20) is to reflection digital intermediate-freuqncy signal s
R-IF(n), straight-Ji quadrature s
D-BB-P (n)Directly-Ji homophase s
D-BB-C(n) treatment step is as follows:
Step 201: carrier wave NCO is according to carrier frequency control word F
CWProduce sine wave and the cosine wave (CW) of respective frequencies, the waveform of generation depends on that what deposit among the ROM is sine table or cosine table;
Step 202: in the sinusoidal multiplier with reflection digital intermediate-freuqncy signal s
R-IF(n) and the sinusoidal signal of sine table output multiply each other the quadrature component of output reflection digital baseband signal, i.e. anti--Ji quadrature s
R-P(n);
The cosine multiplier is with reflection digital intermediate-freuqncy signal s
R-IF(n) and the cosine signal of cosine table output multiply each other the in-phase component of output reflection digital baseband signal, i.e. anti--Ji homophase s
R-C(n).
Step 203: delayer p will straight-Ji quadrature s
D-BB-P(n) postpone N chronomere, namely signal will convert to and postpone straight-Ji quadrature s
D-BB-P(n-N Δ); N be the mode of employing direct projection closed loop reflection open loop of direct signal acquisition and tracking module output to the estimated value of reflected signal with respect to the phase retardation of direct signal, Δ is the time step that postpones; In like manner can get:
Delayer p1 will postpone directly-Ji quadrature s
D-BB-P(n-N Δ) postpones 1 time step Δ, and namely signal will convert first to and postpone straight-Ji quadrature s
D-BB-P(n-N Δ-Δ);
Delayer p2 postpones straight-Ji quadrature s with first
D-BB-P(n-N Δ-Δ) postpones 1 time step Δ, and namely signal will convert second to and postpone straight-Ji quadrature s
D-BB-P(n-N Δ-2 Δ);
Delayer pM postpones straight-Ji quadrature s with M-1
D-BB-P(n-N Δ-(M-1) Δ) postpones 1 time step Δ, and namely signal will convert M to and postpone straight-Ji quadrature s
D-BB-P(n-N Δ-M Δ);
Delayer c will straight-Ji homophase s
D-BB-C(n) postpone N chronomere, namely signal will convert to and postpone straight-Ji homophase s
D-BB-C(n-N Δ); N be the mode of employing direct projection closed loop reflection open loop of direct signal acquisition and tracking module output to the estimated value of reflected signal with respect to the phase retardation of direct signal, Δ is the time step that postpones; In like manner can get:
Delayer c1 will postpone directly-Ji homophase s
D-BB-C(n-N Δ) postpones 1 time step Δ, and namely signal will convert first to and postpone straight-Ji homophase s
D-BB-C(n-N Δ-Δ);
Delayer c2 postpones straight-Ji homophase s with first
D-BB-C(n-N Δ-Δ) postpones 1 time step Δ, and namely signal will convert second to and postpone straight-Ji homophase s
D-BB-C(n-N Δ-2 Δ);
Delayer cM postpones straight-Ji homophase s with M-1
D-BB-C(n-N Δ-(M-1) Δ) postpones 1 time step Δ, and namely signal will convert M to and postpone straight-Ji homophase s
D-BB-C(n-N Δ-M Δ);
Step 204: multiplier p0 will anti--Ji quadrature s
R-P(n) with postpone straight-Ji quadrature s
D-BB-P(n-N Δ) multiplies each other, and obtains anti--Ji quadrature initial cross-correlation value S
R-D-P (0)In like manner can get:
Multiplier p1 will anti--Ji quadrature s
R-P(n) postpone straight-Ji quadrature s with first
D-BB-P(n-N Δ-Δ) multiplies each other, and obtains anti--Ji quadrature the first cross correlation value S
R-D-P (1)
Multiplier p2 will anti--Ji quadrature s
R-P(n) postpone straight-Ji quadrature s with second
D-BB-P(n-N Δ-2 Δ) multiplies each other, and obtains anti--Ji quadrature the second cross correlation value S
R-D-P (2)
Multiplier pM will anti--Ji quadrature s
R-P(n) postpone straight-Ji quadrature s with M
D-BB-P(n-N Δ-M Δ) multiplies each other, and obtains anti--Ji quadrature M cross correlation value S
R-D-P (M)
Multiplier c0 will anti--Ji homophase s
R-C(n) with postpone straight-Ji homophase s
D-BB-C(n-N Δ) multiplies each other, and obtains anti--Ji homophase initial cross-correlation value S
R-D-C (0)
Multiplier c1 will anti--Ji homophase s
R-C(n) postpone straight-Ji homophase s with first
D-BB-C(n-N Δ-Δ) multiplies each other, and obtains anti--Ji homophase the first cross correlation value S
R-D-C (1)
Multiplier c2 will anti--Ji homophase s
R-C(n) postpone straight-Ji homophase s with second
D-BB-C(n-N Δ-2 Δ) multiplies each other, and obtains anti--Ji homophase the second cross correlation value S
R-D-C (2)
Multiplier cM will anti--Ji homophase s
R-C(n) postpone straight-Ji homophase s with M
D-BB-C(n-N Δ-M Δ) multiplies each other, and obtains anti--Ji homophase M cross correlation value S
R-D-C(M);
Step 205: the cumulative unit p0 of integration will anti--Ji quadrature initial cross-correlation value S
R-D-P (0)Within preliminary examination integral time, add up, do not blocked anti--Ji quadrature initial gain value Y
P (0)
The cumulative unit p1 of integration will anti--Ji quadrature the first cross correlation value S
R-D-P (1)Within preliminary examination integral time, add up, do not blocked anti--Ji quadrature the first performance number Y
P (1)
The cumulative unit p2 of integration will anti--Ji quadrature the second cross correlation value S
R-D-P (2)Within preliminary examination integral time, add up, do not blocked anti--Ji quadrature the second performance number Y
P (2)
The cumulative unit pM of integration will anti--Ji quadrature M cross correlation value S
R-D-P (M)Within preliminary examination integral time, add up, do not blocked anti--Ji quadrature M performance number Y
P (M)
The cumulative unit c0 of integration will anti--Ji homophase initial cross-correlation value S
R-D-C (0)Within preliminary examination integral time, add up, do not blocked anti--Ji homophase initial gain value Y
C-(0)
The cumulative unit c1 of integration will anti--Ji homophase the first cross correlation value S
R-D-C (1)Within preliminary examination integral time, add up, do not blocked anti--Ji homophase the first performance number Y
C (1)
The cumulative unit c2 of integration will anti--Ji homophase the second cross correlation value S
R-D-C (2)Within preliminary examination integral time, add up, do not blocked anti--Ji homophase the second performance number Y
C (2)
The cumulative unit cM of integration will anti--Ji homophase M cross correlation value S
R-D-C (M)Within preliminary examination integral time, add up, do not blocked anti--Ji homophase M performance number Y
C (M)
Step 206: cropper p0 will not block instead-Ji quadrature initial gain value Y
P (0)Carry out the truncation of 12 bits, obtain anti--Ji quadrature initial gain value X
P (0)
Cropper p1 will not block instead-Ji quadrature the first performance number Y
P (1)Carry out the truncation of 12 bits, obtain anti--Ji quadrature the first performance number X
P (1)
Cropper p2 will not block instead-Ji quadrature the second performance number Y
P (2)Carry out the truncation of 12 bits, obtain anti--Ji quadrature the second performance number X
P (2)
Cropper pM will not block instead-Ji quadrature M performance number Y
P (M)Carry out the truncation of 12 bits, obtain anti--Ji quadrature M performance number X
P (M)
Cropper c0 will not block instead-Ji homophase initial gain value Y
C (0)Carry out the truncation of 12 bits, obtain anti--Ji homophase initial gain value X
C (0)
Cropper c1 will not block instead-Ji homophase the first performance number Y
C (1)Carry out the truncation of 12 bits, obtain anti--Ji homophase the first performance number X
C (1)
Cropper c2 will not block instead-Ji homophase the second performance number Y
C (2)Carry out the truncation of 12 bits, obtain anti--Ji homophase the second performance number X
C (2)
Cropper cM will not block instead-Ji homophase M performance number Y
C (M)Carry out the truncation of 12 bits, obtain anti--Ji homophase M performance number X
C (M)
3. the multichannel gps signal P(Y according to claim 1) measuring system of code phase difference, it is characterized in that: this system is by obtaining the effect of hardware with Verilog HDL language design at fpga chip.
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