CN102279402B - Frequency domain coherent joint capture method of GNSS data/pilot mixed signal - Google Patents

Abstract

The invention relates to a frequency domain coherent joint capture method of a GNSS data/pilot mixed signal, more particularly to a coherent joint capture method of a GNSS data/pilot mixed signal. According to a traditional single-channel capture method, energies of a new-system navigation signal can not fully utilized, so that capture performance is poor; however, the above-mentioned problem can be solved according to the invention. The method comprises the following steps that: with utilization of a phase relationship between a data channel signal and a pilot channel signal, coherent processing is carried out on the signals of the two channels aiming at a GNSS data/pilot mixed signal, and then capture is completed. The invention is suitable for application in a capture process of a GNSS data/pilot mixed signal.

Description

The frequency domain of a kind of GNSS data/pilot tone mixed signal joint acquisition method that is concerned with

Technical field

The present invention relates to the relevant joint acquisition method of GNSS data/pilot tone mixed signal.

Background technology

Modernization GNSS (GLONASS (Global Navigation Satellite System)) has adopted many advanced persons' technology in the design of navigation signal, and the bearing accuracy of system and antijamming capability are greatly improved.Wherein, the use of data/pilot tone mixed signal is exactly an innovation greatly.According to the ultimate principle of satnav, receiver user need extract pseudorange and navigation message from navigation signal, calculate user and intersatellite spacing from and satellite position after just can carry out final customer location and resolve.Traditional GPS L1C/A coded signal is carried on one road signal during with two kinds of information of same and transmits, so receiver user can only obtain all information by this road signal.Yet when system is user under the rugged surroundings (as indoor) when the navigator fix service is provided, the shortcoming of sort signal structure just displays.Because signal is modulated by navigation message, so can occur unknown phase overturn along with the variation of telegraph text data.When receiver user carries out coherent accumulation to signal correlation values in acquisition procedure, unknown bit reversal will limit the effective coherent accumulation time, and then limit the acquisition sensitivity of receiver.Therefore, for improving the system performance under the rugged surroundings, modernized GNSS has adopted the double-channel signal structure of data (data) signal hybrid pilots (pilot) signals, i.e. D/P mixed signal.Like this, the accurate pseudorange information that provides is provided the uncomfortable guidance avionics literary composition of pilot channel information; Data channel is then mainly broadcast navigation message.Using two kinds of maximum mixed structures at present is that homophase mixes and quadrature hybrid, and for example Galileo E1 OS and E6 signal have adopted the homophase mixing, and GPS L5C signal and GALILEO E5 signal have then adopted quadrature hybrid.

If use traditional one-channel signal catching method to catch two paths of signals in the D/P mixed signal respectively, in each processing procedure, have at least 50% mixed signal energy to be fully used so.When signal transmission power one timing, for obtaining good acquisition performance, receiver user just must improve the signal to noise ratio (S/N ratio) of prize judgment variable by long data accumulation, and then obtain the more reliable result that catches, but this processing will bring the remarkable increase of calculated amount and prolong capture time.Therefore, improve the utilization factor of signal energy, reducing calculated load will be a kind of effective means that realizes catching fast under the rugged surroundings D/P mixed signal.

At present, for the research of D/P mixed signal catching method some progress have been arranged, wherein the two paths of signals cooperation that proposes based on the design feature of data and pilot signal and the mutual relationship thought of catching is subjected to extensive concern.What occur at first is incoherent joint acquisition method, utilize data and pilot signal homology with the characteristics of propagating the path, the single channel of two passages is caught correlation carry out linear noncoherent accumulation, the signal to noise ratio (S/N ratio) of the new judgment variables of generation can be equivalent to the result in original two cycles of one-channel signal coherent accumulation.Like this, utilize the data of one-period just can obtain the effect in two cycles, its capacity usage ratio significantly improves.But owing to taked the processing of summed square, the correlativity between two channel phases can not be fully utilized.

Summary of the invention

The present invention causes the low problem of acquisition performance in order to solve the energy that traditional single channel catching method can not take full advantage of the New System navigation signal, thereby the relevant joint acquisition method of frequency domain of a kind of GNSS data/pilot tone mixed signal is provided.

The frequency domain of a kind of GNSS data/pilot tone mixed signal joint acquisition method that is concerned with,

The GNSS satellite-signal of transmitter emission is with facies pattern data/pilot tone mixed signal, and is described with facies pattern data/pilot tone mixed signal C _Sp[n] expression formula is:

$C_{\mathrm{sp}}\left[n\right]=\left\{\begin{array}{cc}{C}_D\left[n\right]-C_P\left[n\right]& d\left[n\right]=1\\ C_D\left[n\right]+C_P\left[n\right]& d\left[n\right]=-1\end{array}\right.;$

C _D[n] is the spread spectrum primary key of data-signal D; C _D/P[n] is the spread spectrum primary key of pilot signal P;

Then the concrete steps with the relevant joint acquisition method of the frequency domain of facies pattern data/pilot tone mixed signal are:

Steps A 1, receiver receive with facies pattern data/pilot tone mixed signal, and obtain digital medium-frequency signal with facies pattern data/pilot tone mixed signal after mixing, sampling and the quantification of receiver radio frequency front end and be described

In the formula, n represents the sequence number of sampled point;

Steps A 2, the digital medium-frequency signal that steps A 1 is obtained

In I, Q two paths of signals carry out carrier wave respectively and peel off, obtain to remove I, the Q two-way intermediate-freuqncy signal of carrier wave;

I, the addition of Q two-way digital intermediate frequency signal of steps A 3, removal carrier wave that steps A 2 is obtained, and the result after the addition carried out Fast Fourier Transform (FFT), obtain transformation results;

Steps A 4, employing time delay step-by-step controller are controlled local pn code generator, produce two kinds of local spread-spectrum code signals of D+P phase combination mode and D-P phase combination mode;

Steps A 5, two kinds of local spread-spectrum code signals of steps A 4 described D+P phase combination modes and D-P phase combination mode are carried out Fast Fourier Transform (FFT) respectively and got complex conjugate and handle, obtain two groups of results;

Steps A 6, two groups of results that steps A 5 is obtained multiply each other with the transformation results that steps A 3 obtains respectively, obtain two groups of results after multiplying each other, and the result after described two groups are multiplied each other carries out invert fast fourier transformation respectively, obtain result after two groups of conversion;

Result's delivery respectively after steps A 7, the two groups of conversion that steps A 6 is obtained, and carry out square operation respectively and handle, two groups of square operation results obtained, that is:

With

Steps A 8, two groups of square operation results that steps A 7 is obtained pass through formula:

$S_{\mathrm{CC}}^{\mathrm{sp}}(\mathrm{\τ},F_D)=\max \{S_{-}^{\mathrm{sp}}\left({\mathrm{\τ},F}_D\right),S_{+}^{\mathrm{sp}}\left({\mathrm{\τ},F}_D\right)\}$

Compare, obtain maximum judgment variables result

Steps A 9, the maximum judgment variables result that steps A 8 is obtained deliver to the threshold judgement device and carry out threshold judgement, if described maximum judgment variables result is greater than default thresholding, then assert acquisition success, finish the relevant joint acquisition of frequency domain of GNSS data/pilot tone mixed signal, enter tracing process; Otherwise, then assert and catch failure, return steps A 1 and catch again.

The digital medium-frequency signal that described in the described steps A 2 steps A 1 is obtained

In I, Q two paths of signals carry out the concrete grammar that carrier wave peels off respectively and be: at first produce carrier signal cos (2 π F corresponding to the in-phase branch of different Doppler frequencies by frequency step controller control local carrier oscillator _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN), then with carrier signal cos (the 2 π F of in-phase branch _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN) multiply each other with I road and the Q road signal of digital intermediate frequency signal respectively, realize that carrier wave peels off.

The present invention also provides the frequency domain of another kind of GNSS data/pilot tone mixed signal relevant joint acquisition method, and in this method, the GNSS satellite-signal of transmitter emission is orthogonal type data/pilot tone mixed signal, and described orthogonal type data/pilot tone mixed signal is:

$C_{\mathrm{iq}}\left[n\right]=\left\{\begin{array}{cc}{C}_D\left[n\right]-j{C}_P\left[n\right]& d\left[n\right]=1\\ C_D\left[n\right]+{\mathrm{jC}}_P\left[n\right]& d\left[n\right]=-1\end{array}\right.;$

Then the concrete steps of the relevant joint acquisition method of the frequency domain of orthogonal type data/pilot tone mixed signal are:

Step B1, receiver receive orthogonal type data/pilot tone mixed signal, and described orthogonal type data/pilot tone mixed signal is obtained digital medium-frequency signal are after mixing, sampling and the quantification of receiver radio frequency front end

Step B2, the digital medium-frequency signal that step B1 is obtained

In I, Q two paths of signals carry out carrier wave respectively and peel off, obtain to remove I, the Q two-way intermediate-freuqncy signal of carrier wave;

Step B3, the I that will remove carrier wave, the addition of Q two-way digital intermediate frequency signal, and the result after the addition carried out Fast Fourier Transform (FFT), obtain transformation results;

Step B4, employing time delay step-by-step controller are controlled local pn code generator, produce two kinds of local spread-spectrum code signals of D+P phase combination mode and D-P phase combination mode;

Step B5, two kinds of local spread-spectrum code signals of step B4 described D+j*P phase combination mode and D-j*P phase combination mode are carried out Fast Fourier Transform (FFT) respectively and got complex conjugate and handle, obtain two groups of results;

Step B6, two groups of results that step B5 is obtained multiply each other with the transformation results that step B3 obtains respectively, obtain two groups of results after multiplying each other, and the result after described two groups multiplied each other carries out invert fast fourier transformation respectively, obtain result after two groups of conversion;

Result's delivery respectively after step B7, the two groups of conversion that step B6 is obtained, and carry out square operation respectively and handle, two groups of square operation results obtained, that is: With

Step B8, two groups of square operation results that step B7 is obtained pass through formula:

$S_{\mathrm{CC}}^{\mathrm{iq}}(\mathrm{\τ},F_D)=\max \{S_{-}^{\mathrm{iq}}\left({\mathrm{\τ},F}_D\right),S_{+}^{\mathrm{iq}}\left({\mathrm{\τ},F}_D\right)\}$

Compare, obtain maximum judgment variables result

Step B9, the maximum judgment variables result that step B8 is obtained deliver to the threshold judgement device and carry out threshold judgement, if described maximum judgment variables result is greater than default thresholding, then assert acquisition success, finish the relevant joint acquisition of frequency domain of GNSS data/pilot tone mixed signal, enter tracing process; Otherwise, then assert and catch failure, return step B1 and catch again.

The digital medium-frequency signal that described in the described step B2 step B1 is obtained

In I, Q two paths of signals carry out the concrete grammar that carrier wave peels off respectively and be: at first produce carrier signal cos (2 π F corresponding to the in-phase branch of different Doppler frequencies by frequency step controller control local carrier oscillator _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN), then with carrier signal cos (the 2 π F of in-phase branch _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN) multiply each other with I road and the Q road signal of digital intermediate frequency signal respectively, realize that carrier wave peels off.

Beneficial effect: the present invention adopts relevant joint acquisition method catching GNSS data/pilot tone mixed signal, than the method for catching of existing incoherent joint acquisition method to GNSS data/pilot tone mixed signal, correlativity utilization factor between its two channel phases is higher, therefore can effectively utilize the energy of pilot signal in the New System navigation signal more.And the present invention propagates the characteristics in path together according to data-signal and pilot signal homology, by the estimation to data passage and pilot channel phasetophase correlativity, provides judgment variables more reliably, can catch the navigation signal under the New System more effectively; The present invention simultaneously can effectively shorten the data accumulation time when being applied to weak signal and catching.

Description of drawings

Fig. 1 is the principle schematic of the relevant joint acquisition method of the frequency domain with facies pattern data/pilot tone mixed signal of the present invention; Fig. 2 is the principle schematic of the relevant joint acquisition method of frequency domain of orthogonal type data of the present invention/pilot tone mixed signal; Fig. 3 is with the relevant joint acquisition result schematic diagram of the frequency domain of facies pattern data/pilot tone mixed signal; Fig. 4 is the relevant joint acquisition result schematic diagram of the frequency domain of orthogonal type data of the present invention/pilot tone mixed signal; Fig. 5 is the relevant joint acquisition method of frequency domain and the existing single channel catching method method simulation result synoptic diagram with facies pattern data/pilot tone mixed signal of the present invention; Fig. 6 is the relevant joint acquisition method of frequency domain and the existing single channel catching method simulation result synoptic diagram of orthogonal type data of the present invention/pilot tone mixed signal.

Embodiment

Embodiment one, in conjunction with Fig. 1 and Fig. 2 this embodiment is described, the frequency domain of a kind of GNSS data/pilot tone mixed signal joint acquisition method that is concerned with,

The GNSS satellite-signal of transmitter emission is with facies pattern data/pilot tone mixed signal, and is described with facies pattern data/pilot tone mixed signal C _Sp[n] expression formula is:

$C_{\mathrm{sp}}\left[n\right]=\left\{\begin{array}{cc}{C}_D\left[n\right]-C_P\left[n\right]& d\left[n\right]=1\\ C_D\left[n\right]+C_P\left[n\right]& d\left[n\right]=-1\end{array}\right.;$

C _D[n] is the spread spectrum primary key of data-signal D; C _D/P[n] is the spread spectrum primary key of pilot signal P;

Then the concrete steps with the relevant joint acquisition method of the frequency domain of facies pattern data/pilot tone mixed signal are:

Steps A 1, receiver receive with facies pattern data/pilot tone mixed signal, and obtain digital medium-frequency signal with facies pattern data/pilot tone mixed signal after mixing, sampling and the quantification of receiver radio frequency front end and be described

In the formula, n represents the sequence number of sampled point;

Steps A 2, the digital medium-frequency signal that steps A 1 is obtained

In I, Q two paths of signals carry out carrier wave respectively and peel off, obtain to remove I, the Q two-way intermediate-freuqncy signal of carrier wave;

I, the addition of Q two-way digital intermediate frequency signal of steps A 3, removal carrier wave that steps A 2 is obtained, and the result after the addition carried out Fast Fourier Transform (FFT), obtain transformation results;

Steps A 4, employing time delay step-by-step controller are controlled local pn code generator, produce two kinds of local spread-spectrum code signals of D+P phase combination mode and D-P phase combination mode;

Steps A 5, two kinds of local spread-spectrum code signals of steps A 4 described D+P phase combination modes and D-P phase combination mode are carried out Fast Fourier Transform (FFT) respectively and got complex conjugate and handle, obtain two groups of results;

Steps A 6, two groups of results that steps A 5 is obtained multiply each other with the transformation results that steps A 3 obtains respectively, obtain two groups of results after multiplying each other, and the result after described two groups are multiplied each other carries out invert fast fourier transformation respectively, obtain result after two groups of conversion;

Result's delivery respectively after steps A 7, the two groups of conversion that steps A 6 is obtained, and carry out square operation respectively and handle, two groups of square operation results obtained, that is:

With

Steps A 8, two groups of square operation results that steps A 7 is obtained pass through formula:

$S_{\mathrm{CC}}^{\mathrm{sp}}(\mathrm{\τ},F_D)=\max \{S_{-}^{\mathrm{sp}}\left({\mathrm{\τ},F}_D\right),S_{+}^{\mathrm{sp}}\left({\mathrm{\τ},F}_D\right)\}$

Compare, obtain maximum judgment variables result

Steps A 9, the maximum judgment variables result that steps A 8 is obtained deliver to the threshold judgement device and carry out threshold judgement, if described maximum judgment variables result is greater than default thresholding, then assert acquisition success, finish the relevant joint acquisition of frequency domain of GNSS data/pilot tone mixed signal, enter tracing process; Otherwise, then assert and catch failure, return steps A 1 and catch again.

The digital medium-frequency signal that described in the described steps A 2 steps A 1 is obtained

In I, Q two paths of signals carry out the concrete grammar that carrier wave peels off respectively and be: at first produce carrier signal cos (2 π F corresponding to the in-phase branch of different Doppler frequencies by frequency step controller control local carrier oscillator _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN), then with carrier signal cos (the 2 π F of in-phase branch _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN) multiply each other with I road and the Q road signal of digital intermediate frequency signal respectively, realize that carrier wave peels off.

Embodiment two, in conjunction with Fig. 2 this embodiment is described, the frequency domain of a kind of GNSS data/pilot tone mixed signal joint acquisition method that is concerned with,

The GNSS satellite-signal of transmitter emission is orthogonal type data/pilot tone mixed signal, and described orthogonal type data/pilot tone mixed signal is:

$C_{\mathrm{iq}}\left[n\right]=\left\{\begin{array}{cc}{C}_D\left[n\right]-j{C}_P\left[n\right]& d\left[n\right]=1\\ C_D\left[n\right]+{\mathrm{jC}}_P\left[n\right]& d\left[n\right]=-1\end{array}\right.;$

C _D[n] is the spread spectrum primary key of data-signal D; C _D/P[n] is the spread spectrum primary key of pilot signal P; J is the mathematic sign of expression plural number;

Then the concrete steps of the relevant joint acquisition method of the frequency domain of orthogonal type data/pilot tone mixed signal are:

Step B1, receiver receive orthogonal type data/pilot tone mixed signal, and described orthogonal type data/pilot tone mixed signal is obtained digital medium-frequency signal are after mixing, sampling and the quantification of receiver radio frequency front end

Step B2, the digital medium-frequency signal that step B1 is obtained

In I, Q two paths of signals carry out carrier wave respectively and peel off, obtain to remove I, the Q two-way intermediate-freuqncy signal of carrier wave;

Step B3, the I that will remove carrier wave, the addition of Q two-way digital intermediate frequency signal, and the result after the addition carried out Fast Fourier Transform (FFT), obtain transformation results;

Step B4, employing time delay step-by-step controller are controlled local pn code generator, produce two kinds of local spread-spectrum code signals of D+P phase combination mode and D-P phase combination mode;

Step B5, two kinds of local spread-spectrum code signals of step B4 described D+j*P phase combination mode and D-j*P phase combination mode are carried out Fast Fourier Transform (FFT) respectively and got complex conjugate and handle, obtain two groups of results;

Step B6, two groups of results that step B5 is obtained multiply each other with the transformation results that step B3 obtains respectively, obtain two groups of results after multiplying each other, and the result after described two groups multiplied each other carries out invert fast fourier transformation respectively, obtain result after two groups of conversion;

Result's delivery respectively after step B7, the two groups of conversion that step B6 is obtained, and carry out square operation respectively and handle, two groups of square operation results obtained, that is:

With

Step B8, two groups of square operation results that step B7 is obtained pass through formula:

$S_{\mathrm{CC}}^{\mathrm{iq}}(\mathrm{\τ},F_D)=\max \{S_{-}^{\mathrm{iq}}\left({\mathrm{\τ},F}_D\right),S_{+}^{\mathrm{iq}}\left({\mathrm{\τ},F}_D\right)\}$

Compare, obtain maximum judgment variables result

Step B9, the maximum judgment variables result that step B8 is obtained deliver to the threshold judgement device and carry out threshold judgement, if described maximum judgment variables result is greater than default thresholding, then assert acquisition success, finish the relevant joint acquisition of frequency domain of GNSS data/pilot tone mixed signal, enter tracing process; Otherwise, then assert and catch failure, return step B1 and catch again.

The digital medium-frequency signal that described in the described step B2 step B1 is obtained

In I, Q two paths of signals carry out the concrete grammar that carrier wave peels off respectively and be: at first produce carrier signal cos (2 π F corresponding to the in-phase branch of different Doppler frequencies by frequency step controller control local carrier oscillator _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN), then with carrier signal cos (the 2 π F of in-phase branch _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN) multiply each other with I road and the Q road signal of digital intermediate frequency signal respectively, realize that carrier wave peels off.

Principle: utilized under the synchronous fully situation of supplementary at subcarrier, the intermediate frequency of the homophase D/P type mixed signal of single star and quadrature D/P type mixed signal receives signal model and can be expressed as

$y_{\mathrm{IF}}^{\mathrm{sp}}\left[n\right]=\mathrm{Ad}[n-{\mathrm{\τ}}_0/T_s]\left(C_D\right[{n-\mathrm{\τ}}_0/T_s]-\frac{1}{d[n-{\mathrm{\τ}}_0/T_s]}{C}_P[n-{\mathrm{\τ}}_0/T_s\left]\right)---\left(1\right)$

$\×\cos (2\mathrm{\π}{F}_{D0}n+{\mathrm{\φ}}_0)+n_s\left[n\right]$

$y_{\mathrm{IF}}^{\mathrm{iq}}\left[n\right]=\mathrm{Ad}[n-{\mathrm{\τ}}_0/T_s]\left(C_D\right[{n-\mathrm{\τ}}_0/T_s]-\frac{1}{d[n-{\mathrm{\τ}}_0/T_s]}{C}_P[n-{\mathrm{\τ}}_0/T_s\left]\right)---\left(2\right)$

$\×\cos (2\mathrm{\π}{F}_{D0}n+{\mathrm{\φ}}_0)+n_s\left[n\right]$

In the formula, A is single star signal amplitude; F _D0=(f _IF+ f _D0) T _s, f _IFBe intermediate frequency, f _D0Be Doppler shift, T _sIt is the sampling period; τ ₀Time delay; C _D/P[n] is the spread spectrum primary key on D road or P road; D[n] be the relative symbol of two paths of signals.

The phase ambiguity that pilot signal does not exist factor to cause according to bit reversal, so as if the relative phase that can pre-estimate out between data and the pilot portion, make comparisons with original phase relationship again, just can dope the position that bit reversal takes place, thereby provide reference for coherent accumulation.The essence of relevant associating thought is a kind of Maximum Likelihood Detection, and the coherent accumulation result when selecting phase relation the possibility maximum to occur exactly obtains the more reliable result of catching as judgment variables, thereby improves the signal capture performance.

Below by concrete emulation experiment, verify effect of the present invention:

Under the simulated conditions of table 1 and table 2, configuration f _{D, 0}=666Hz, τ ₀=1.5ms, C/N ₀=40dB-Hz can obtain the result that catches of this method, catches the result as shown in Figure 3 and Figure 4.The residing search unit of correlation peak position is consistent with preset value among two figure, has proved that this method can both successfully realize signal capture to two kinds of architecture signals.Because pseudo-code length and algorithm structure is different, so the absolute size of correlation also there are differences.

Under the situation of different carrier-to-noise ratios, Monte-Carlo emulation probability statistics through 10000 times, can obtain ROC (the Receiver Operation Curve) curve based on the relevant joint acquisition algorithm of frequency domain of two kinds of signal models, and the ROC curve that provides pilot signal single channel coherent acquisition method does reference, with the simulation result of facies pattern data/pilot tone mixed signal and pilot signal single channel coherent acquisition method as shown in Figure 5; The simulation result of orthogonal type data/pilot tone mixed signal and pilot signal single channel coherent acquisition method as shown in Figure 6; Curve 51 is the simulation curve of pilot signal single channel coherent acquisition method under 30dB-HZ; Curve 52 is the simulation curve of pilot signal single channel coherent acquisition method under 35dB-HZ; Curve 53 is the simulation curve of pilot signal single channel coherent acquisition method under 40dB-HZ; Curve 54 is of the present invention with the facies pattern data/simulation curve of pilot tone mixed signal coherent acquisition method under 30dB-HZ; Curve 55 the present invention are with the facies pattern data/simulation curve of pilot tone mixed signal coherent acquisition method under 35dB-HZ; Curve 56 the present invention are with the facies pattern data/simulation curve of pilot tone mixed signal coherent acquisition method under 40dB-HZ; Curve 61 is the simulation curve of pilot signal single channel coherent acquisition method under 30dB-HZ; Curve 62 is the simulation curve of pilot signal single channel coherent acquisition method under 40dB-HZ; The curve 63 orthogonal type data of the present invention/simulation curve of pilot tone mixed signal coherent acquisition method under 30dB-HZ; The curve 64 orthogonal type data of the present invention/simulation curve of pilot tone mixed signal coherent acquisition method under 40dB-HZ; The ROC curve is exactly the receiver performance curve, and the horizontal ordinate of curve is represented false-alarm probability, and ordinate is represented detection probability.

Acquisition algorithm ROC curve among analysis chart 5 and Fig. 6 as can be known, than the single channel acquisition algorithm, relevant unified algorithm has greatly improved to detection probability: when signal was more weak, the two differed at least 10 times, reduced gradually along with signal strengthens gap; Work as C/N ₀During=40dB-Hz, the detection probability of relevant unified algorithm is near 1, and the single channel acquisition algorithm does not also reach 0.5.And the superiority-inferiority on the two performance does not change with the change of signal model, only there are differences at concrete numerical value.

Table 1: homophase D/P type signal simulation condition

Table 2: quadrature D/P type signal simulation condition

Claims (4)

1. the relevant joint acquisition method of the frequency domain of GNSS data/pilot tone mixed signal is characterized in that:

The GNSS satellite-signal of transmitter emission is with facies pattern data/pilot tone mixed signal, and is described with facies pattern data/pilot tone mixed signal C _Sp[n] expression formula is:

$C_{\mathrm{sp}}\left[n\right]=\left\{\begin{array}{cc}{C}_D\left[n\right]-C_P\left[n\right]& d\left[n\right]=1\\ C_D\left[n\right]+C_P\left[n\right]& d\left[n\right]=-1\end{array}\right.;$

C _D[n] is the spread spectrum primary key of data-signal D; C _P[n] is the spread spectrum primary key of pilot signal P; D[n] be the relative symbol of two paths of signals; N is the sequence number of sampled point;

Then the concrete steps with the relevant joint acquisition method of the frequency domain of facies pattern data/pilot tone mixed signal are:

Steps A 1, receiver receive with facies pattern data/pilot tone mixed signal, and obtain digital medium-frequency signal with facies pattern data/pilot tone mixed signal after mixing, sampling and the quantification of receiver radio frequency front end and be described

In the formula, n represents the sequence number of sampled point;

Steps A 2, the digital medium-frequency signal that steps A 1 is obtained

In I, Q two paths of signals carry out carrier wave respectively and peel off, obtain to remove I, the Q two-way digital intermediate frequency signal of carrier wave;

I, the addition of Q two-way digital intermediate frequency signal of steps A 3, removal carrier wave that steps A 2 is obtained, and the result after the addition carried out Fast Fourier Transform (FFT), obtain transformation results;

Steps A 4, employing time delay step-by-step controller are controlled local pn code generator, produce two kinds of local spread-spectrum code signals of D+P phase combination mode and D-P phase combination mode;

Steps A 5, two kinds of local spread-spectrum code signals of steps A 4 described D+P phase combination modes and D-P phase combination mode are carried out Fast Fourier Transform (FFT) respectively and got complex conjugate and handle, obtain two groups of results;

Steps A 6, two groups of results that steps A 5 is obtained multiply each other with the transformation results that steps A 3 obtains respectively, obtain two groups of results after multiplying each other, and the result after described two groups are multiplied each other carries out invert fast fourier transformation respectively, obtain result after two groups of conversion;

Result's delivery respectively after steps A 7, the two groups of conversion that steps A 6 is obtained, and carry out square operation respectively and handle, two groups of square operation results obtained, that is:

With

Steps A 8, two groups of square operation results that steps A 7 is obtained pass through formula:

$S_{\mathrm{CC}}^{\mathrm{sp}}(\mathrm{\τ},F_D)=\max \{S_{-}^{\mathrm{sp}}(\mathrm{\τ},F_D),S_{+}^{\mathrm{sp}}(\mathrm{\τ},F_D)\}$

Compare, obtain maximum judgment variables result

Steps A 9, the maximum judgment variables result that steps A 8 is obtained deliver to the threshold judgement device and carry out threshold judgement, if described maximum judgment variables result is greater than default thresholding, then assert acquisition success, finish the relevant joint acquisition of frequency domain of GNSS data/pilot tone mixed signal, enter tracing process; Otherwise, then assert and catch failure, return steps A 1 and catch again.

2. the relevant joint acquisition method of the frequency domain of a kind of GNSS data according to claim 1/pilot tone mixed signal is characterized in that the digital medium-frequency signal that described in the described steps A 2 steps A 1 is obtained

In I, Q two paths of signals carry out the concrete grammar that carrier wave peels off respectively and be: at first produce carrier signal cos (2 π F corresponding to the in-phase branch of different Doppler frequencies by frequency step controller control local carrier oscillator _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN), then with carrier signal cos (the 2 π F of in-phase branch _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN) multiply each other with I road and the Q road signal of digital intermediate frequency signal respectively, realize that carrier wave peels off.

3. the relevant joint acquisition method of the frequency domain of GNSS data/pilot tone mixed signal is characterized in that:

The GNSS satellite-signal of transmitter emission is orthogonal type data/pilot tone mixed signal, and described orthogonal type data/pilot tone mixed signal is:

C _D[n] is the spread spectrum primary key of data-signal D; C _P[n] is the spread spectrum primary key of pilot signal P; D[n] be the relative symbol of two paths of signals; N is the sequence number of sampled point, and j is the mathematic sign of expression plural number;

Then the concrete steps of the relevant joint acquisition method of the frequency domain of orthogonal type data/pilot tone mixed signal are:

Step B1, receiver receive orthogonal type data/pilot tone mixed signal, and described orthogonal type data/pilot tone mixed signal is obtained digital medium-frequency signal are after mixing, sampling and the quantification of receiver radio frequency front end

Step B2, the digital medium-frequency signal that step B1 is obtained

In I, Q two paths of signals carry out carrier wave respectively and peel off, obtain to remove I, the Q two-way digital intermediate frequency signal of carrier wave;

Step B3, the I that will remove carrier wave, the addition of Q two-way digital intermediate frequency signal, and the result after the addition carried out Fast Fourier Transform (FFT), obtain transformation results;

Step B4, employing time delay step-by-step controller are controlled local pn code generator, produce two kinds of local spread-spectrum code signals of D+j*P phase combination mode and D-j*P phase combination mode,

Step B5, two kinds of local spread-spectrum code signals of step B4 described D+j*P phase combination mode and D-j*P phase combination mode are carried out Fast Fourier Transform (FFT) respectively and got complex conjugate and handle, obtain two groups of results;

Step B6, two groups of results that step B5 is obtained multiply each other with the transformation results that step B3 obtains respectively, obtain two groups of results after multiplying each other, and the result after described two groups multiplied each other carries out invert fast fourier transformation respectively, obtain result after two groups of conversion;

Result's delivery respectively after step B7, the two groups of conversion that step B6 is obtained, and carry out square operation respectively and handle, two groups of square operation results obtained, that is:

With

Step B8, two groups of square operation results that step B7 is obtained pass through formula:

$S_{\mathrm{CC}}^{\mathrm{iq}}(\mathrm{\τ},F_D)=\max \{S_{-}^{\mathrm{iq}}(\mathrm{\τ},F_D),S_{+}^{\mathrm{iq}}(\mathrm{\τ},F_D)\}$

Compare, obtain maximum judgment variables result

Step B9, the maximum judgment variables result that step B8 is obtained deliver to the threshold judgement device and carry out threshold judgement, if described maximum judgment variables result is greater than default thresholding, then assert acquisition success, finish the relevant joint acquisition of frequency domain of GNSS data/pilot tone mixed signal, enter tracing process; Otherwise, then assert and catch failure, return step B1 and catch again.

4. the relevant joint acquisition method of the frequency domain of a kind of GNSS data according to claim 3/pilot tone mixed signal is characterized in that the digital medium-frequency signal that described in the described step B2 step B1 is obtained In I, Q two paths of signals carry out the concrete grammar that carrier wave peels off respectively and be: at first produce carrier signal cos (2 π F corresponding to the in-phase branch of different Doppler frequencies by frequency step controller control local carrier oscillator _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN), then with carrier signal cos (the 2 π F of in-phase branch _DN) and the carrier signal-jsin of quadrature branch (2 π F _DN) multiply each other with I road and the Q road signal of digital intermediate frequency signal respectively, realize that carrier wave peels off.

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