CN106908810A - A kind of many long code complex navigation signal phase consistency calibration methods - Google Patents

Abstract

A method for calibrating the phase consistency of multi-long code composite navigation signals, which relates to the high-precision application field of navigation satellite systems; firstly, the pilot long code baseband sample point data and complex baseband navigation signals in the local composite navigation signals are extracted, and the two are correlated to obtain Correlation peak point serial number P; extract local data long code baseband samples according to the extraction length, and determine the number M of information bits contained in the data code branch of the navigation signal within the extraction length, and generate 2 ^M-1 possible information bits The samples are spread spectrum processed with the extracted local data long code baseband samples, and then processed with the extracted complex domain baseband navigation signals to determine the peak value of each correlation processing, and find the maximum value of each peak value and the corresponding sample point number d. Finally, the difference between D and P is calculated, and the phase consistency between the two long codes with the pilot code of the navigation signal as a reference is calculated according to the sampling rate. Realize the precise calibration of the phase consistency of each code under the combination of multiple long codes of the navigation signal generator.

Description

A Phase Consistency Calibration Method for Multiple Long Code Composite Navigation Signals

technical field

The invention relates to a high-precision application field of a navigation satellite system, in particular to a phase consistency calibration method of a multi-length code composite navigation signal.

Background technique

The Global Navigation Satellite System (GNSS) has become an infrastructure. In order to improve the utilization of the navigation signal frequency band and meet the needs of users with different positioning accuracy, modern navigation signals often use multiple navigation signal supports. In the way of multi-channel multiplexing, multiple navigation signals with different pseudo-random codes and modulation modes are loaded on the same carrier frequency point at the same time, such as the E1 signal in the Galileo satellite signal system, which uses CBOC (6,1 , 4/33) and BOC (15, 2.5) modulation methods to generate three branch navigation signals including E1B signal containing data, E1C signal and E1A signal containing pilot information. In addition, in the modern navigation signal system, in order to take into account the requirements of anti-jamming, fast capture and tracking, and higher precision, some navigation signals use various methods such as long pseudo-random codes, pilot codes, and data separation. GPS-III satellites In the L1C signal of the signal system, the period of the pilot branch L1Cp is 18s long.

In many high-precision applications of navigation satellite systems, in order to improve the ranging accuracy and acquisition speed of the receiver, it is necessary to obtain the precise time delay difference between the pseudo-random code phases of each navigation signal branch at the same frequency point, that is, precision Calibrate the phase consistency of the pseudo-random codes of each navigation signal branch at the same frequency point.

At present, the calibration method of the phase consistency of the navigation signal channel uses a high-speed oscilloscope to observe the envelope sink point in the constant-envelope navigation signal waveform. , and Frequency Control, Vol.52, No.11, pp1904-1911), this method can only realize simple BPSK modulation signal waveform, which is not suitable for modern multi-channel complex modulation signal waveform, and the calibration accuracy is poor, and the error reaches several 4～5ns.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art, provide a multi-long code composite navigation signal phase consistency calibration method, and realize the precise calibration of the phase consistency of each code under the multiple long code composite conditions of the navigation signal generator .

Above-mentioned purpose of the present invention is achieved by following technical scheme:

A multi-length code composite navigation signal phase consistency calibration method, the multi-length code composite navigation signal phase consistency calibration method includes the following steps:

Step (1), carry out synchronous sampling to the navigation signal and the second pulse signal output by the navigation signal generator through the high-speed A/D sampler; Obtain the sampling samples of the navigation signal sampling data and the second pulse signal sampling data; each sample corresponds to One navigation signal sampling data and one second pulse signal sampling data; wherein the second pulse signal sampling data includes the data of the level step segment and the level continuous segment; the navigation signal sampling data includes the pilot branch signal and the data branch signal, wherein The pilot branch signal and the data branch signal are composed of a pseudo-random spreading code of a long code;

Step (2), calculate the second pulse estimated value of the second pulse signal sampling data According to the second pulse voltage value and threshold value specified by the satellite system, the estimated value of the second pulse Judgment: Determine the sample point number of the second pulse signal sampling data level step segment, and the sample point number is numbered sequentially from 1;

Step (3), according to the sample point sequence number of the second pulse signal level step section, intercept the navigation signal sampling data in the corresponding sample point sequence number in the sampling sample; carry out Hilbert transform and down-conversion to the intercepted navigation signal sampling data Processing to obtain the complex domain baseband navigation signal;

Step (4), setting the extraction length of the baseband navigation signal in the complex number domain, the extraction length is the duration of the number of M information bits contained in the data branch signal in the baseband navigation signal in the complex number domain, M is a positive integer, and the calculation Obtain the point number N of the complex domain baseband navigation signal to be processed;

Step (5), according to the point number N of the complex domain baseband navigation signal to be processed, the pseudo-random spread spectrum code of the pilot frequency branch signal in step (1) is repeated periodically, and N points are intercepted from the starting point of the whole cycle The data, that is, the N local pilot long code sample data at the beginning of the entire cycle of the generated pilot pseudo-random spreading code;

The N local pilot long code sample data generated in step (6) and step (5) and the complex domain baseband navigation signal generated in step (3) are used for correlation calculation to obtain the peak value corresponding to the maximum correlation peak in the correlation calculation result Point sample number P;

Step (7), step (4) determine in the extraction length that comprises M information bits, generates 2 ^M-1 kinds of information bit samples b _l (n), wherein n is a positive integer, and N is a positive integer; n= 1, 2, 3...N; l is a positive integer, l=1, 2, 3...2 ^M-1 ; 2 ^M-1 kinds of information bit samples b _l (n) and the data branch signal in the sampling data Pseudo-random spreading code {y(n)|n=1,2,…,N} for spreading processing to get 2 ^M-1 kinds of local reference samples

Step (eight), according to the correlation calculation method in step (six), the ^2M-1 kinds of local reference samples generated in step (seven) respectively The complex number domain baseband navigation signal generated in the step (3) carries out correlation calculation; Determine the correlation peak value in each correlation processing result, obtain the peak point sample sequence number D corresponding to the maximum value in each correlation peak value;

Step (9), calculate the difference between the sample number P obtained in step (6) and the sample number D obtained in step (8), and calculate the time delay value Δt of the data code lag pilot according to the sampling rate, that is, the navigation signal The pilot branch signal is the reference, the phase consistency between the two long code signals of the pilot branch signal and the data branch signal; in the process of calibrating the phase consistency of the multi-long code composite navigation signal, if the navigation The signal contains multiple data long codes, and steps (1) to (9) are repeated to calculate the phase consistency between each data code and the pilot code.

In the above-mentioned multi-length code composite navigation signal phase consistency calibration method, in the step (1), the pseudo-random code period of the pilot signal and the data signal in the navigation signal is 1.5 seconds; the navigation information bit rate of the data signal modulation is 4kbps; the data sampling rate is adjusted according to the performance of the equipment used, and the adjustment rate is 1~10Gsa/s.

In the above-mentioned multi-length code composite navigation signal phase consistency calibration method, in the step (2), the second pulse estimated value The calculation method is: set the sampling data of the second pulse signal level step Wherein i is a positive integer, i=1, 2, 3...N; the modeling of the second pulse sequence number level step is: y _i =b ₀ +b ₁ ·i/f _s +ξ _i , where b ₀ is the initial level of sampling data; b ₁ is the level change rate; ξ _i is random noise; f _s is the sampling frequency; y _i is the level value after second pulse signal fitting; b0 and _{b1 :}

Compute second pulse estimate

In the above-mentioned multi-length code composite navigation signal phase consistency calibration method, in the step (2), the method for determining the sample point serial number of the second pulse signal sampling data level step section is: set the second pulse specified by the satellite system The high level of the voltage is A ₁ v, and the low level is 0V; it is estimated that the level change range of the second pulse step is 0~A ₁ v; the threshold value is set to A ₂ V; A ₁ is a positive integer; A ₂ It is a positive integer; 0<A ₂ <A ₁ ; the estimated value of the second pulse judge; when When it is greater than A ₂ , output the sample point sequence number of the sampling data level step segment.

In the above-mentioned multi-length code composite navigation signal phase consistency calibration method, in the step (3), carry out Hilbert transform and down-conversion processing to the intercepted navigation signal sampling data to obtain the complex number domain baseband navigation signal d(i) The method is:

Set the intercepted navigation signal sampling data as The length is Q, and Q is a positive integer;

in, Be the i-th complex number; i=1,2,3,...,Q;

c _i is the sample point of local carrier data; i=1,2,3,...,Q;

Among them, H() represents the Hilbert transform;

The local carrier data sample point c _i is:

Among them: j is the imaginary number unit;

f _s is the sampling frequency;

f _c is the known center frequency of the navigation signal;

i=1,2,3,...,Q.

In the above-mentioned multi-length code composite navigation signal phase consistency calibration method, in the step (4), the calculation method of the point number N of the complex domain baseband navigation signal to be processed is: the duration of each information bit is set as t _b , then the duration of the extraction length is M×t _b ; according to the sampling rate of f _s , that is, f _s points are obtained by sampling within 1 second, and the number of points N, N of the complex domain baseband navigation signal to be processed is obtained = M × t _b × f _s .

In the above-mentioned multi-length code composite navigation signal phase consistency calibration method, in the step (6), the calculation method of the serial number P corresponding to the maximum correlation peak is:

Extract the local sample data of N pilot pseudo-codes, and the calculation method of the complex frequency domain sample value C(k) of the local samples of the pilot pseudo-code is:

Wherein: c(n) is local pilot long code sample data;

n is the number in the calculation process, and the range of values is n=1,2,...,N-1;

j is the imaginary unit;

k is the sequence number of the complex frequency domain sample of the local sample of the pilot pseudo code;

Extract N baseband navigation signal data in the complex domain, and calculate the amplitude-frequency sample point D(g) of the navigation signal;

Wherein: D(n) is local data long code sample data;

n is the number in the calculation process, and the range of values is n=1,2,...,N-1;

j is the imaginary unit;

g is the serial number of the complex frequency domain sample point of the navigation signal;

Then calculate the amplitude-frequency sample point D(g) of the navigation signal and the complex-frequency domain sample value C(k) of the local sample of the pilot pseudo-code in the complex frequency domain, and obtain the correlation result z(n):

The maximum value in search z(n) is defined as sequence number P.

In the above-mentioned multi-length code composite navigation signal phase consistency calibration method, in the step (7), 2 ^M-1 kinds of information bit samples b _l (n) and the pseudo-random spread spectrum of the data branch signal in the sampling data The code {y(n)|n=1,2,...,N} performs spread spectrum processing and calculates the local reference samples The method is:

In the above-mentioned multi-length code composite navigation signal phase consistency calibration method, in the step (eight), the method for calculating the peak point sample sequence number D corresponding to the maximum value in each correlation peak value is:

Carry out 2 ^M-1 correlation calculations with formula (7) and formula (9) according to the method of formula (8), and get the result:

search The largest value is defined as the sequence number D.

In the above-mentioned multi-length code composite navigation signal phase consistency calibration method, in the step (nine), the calculation method of the time delay value Δt of the data code lagging pilot is:

Δt=(DP)/f _s (10).

Compared with the prior art, the present invention has the following advantages:

(1) The present invention adopts high-speed direct A/D sampling to the navigation signal, and performs phase consistency calibration in the digital domain, and the phase time delay relationship between the sample points in the digital processing can be precisely determined, which solves the problem of receiving different signals in the traditional test equipment The inconsistency of the zero value of the receiving device itself eliminates the calibration error caused by the inconsistency of the zero value of the receiving channel of the test device;

(2) The present invention adopts digital domain correlation processing to determine the starting point of the chip by the correlation peak value. The calibration accuracy depends on the sampling frequency. When the sampling frequency is 10 GHz, the accuracy can reach 0.2 ns, which is 4 ns relative to the traditional oscilloscope observation method. ~5ns, the calibration accuracy is improved by more than an order of magnitude;

(3) The present invention adopts and adopts partial pseudo-random code to carry out correlation processing, reduces the data sample point number of processing, under the situation of guaranteeing accuracy, greatly reduces the amount of data of digital signal processing;

(4) In the processed data, the present invention uses the local data samples modulated by all possible signal bits as a reference to ensure the accuracy of the correlation peak and the correctness of the initial point of the pseudo code.

Description of drawings

Fig. 1 is the flow chart of the phase consistency calibration method of multi-length code composite navigation signal of the present invention;

Fig. 2 is the power spectrum diagram of the multi-length code composite navigation serial number of the present invention;

Fig. 3 is a schematic diagram of acquisition of second pulse and step point of the navigation signal generator of the present invention;

Fig. 4 is a curve diagram of local pilot code and navigation signal correlation processing in the present invention;

Fig. 5 is the data code and navigation signal correlation processing graph of local spread spectrum of the present invention;

Fig. 6 is a schematic diagram of a method for calibrating phase consistency of a multi-length code composite navigation signal according to the present invention.

detailed description

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

As shown in Figure 1, it is a flow chart of the phase consistency calibration method of the multi-length code composite navigation signal. It can be seen from the figure that the phase consistency calibration method of the multi-length code composite navigation signal includes the following steps:

Step (1), carry out synchronous sampling to the navigation signal and the second pulse signal output by the navigation signal generator through the high-speed A/D sampler; Obtain the sampling samples of the navigation signal sampling data and the second pulse signal sampling data; each sample corresponds to One navigation signal sampling data and one second pulse signal sampling data; wherein the second pulse signal sampling data includes the data of the level step segment and the level continuous segment; the navigation signal sampling data includes the pilot branch signal and the data branch signal, wherein The pilot branch signal and the data branch signal are composed of a pseudo-random spreading code of a long code;

Among them, the pseudo-random code period of the pilot signal and data signal in the navigation signal is 1.5 seconds; the bit rate of the navigation information modulated by the data signal is 4kbps; the data sampling rate is adjusted according to the performance of the equipment used, and the adjustment rate is 1-10Gsa/s .

Step (2), calculate the second pulse estimated value of the second pulse signal sampling data According to the second pulse voltage value and threshold value specified by the satellite system, the estimated value of the second pulse Judgment: Determine the sample point number of the second pulse signal sampling data level step segment, and the sample point number is numbered sequentially from 1;

second pulse estimate The calculation method is: set the sampling data of the second pulse signal level step Wherein i is a positive integer, i=1, 2, 3...N; the modeling of the second pulse sequence number level step is: y _i =b ₀ +b ₁ ·i/f _s +ξ _i , where b ₀ is the initial level of sampling data; b ₁ is the level change rate; ξ _i is random noise; f _s is the sampling frequency; y _i is the level value after second pulse signal fitting; b0 and _{b1 :}

Compute second pulse estimate

The method to determine the sample point sequence number of the second pulse signal sampling data level step is as follows: set the high level of the second pulse voltage specified by the satellite system as A ₁ v, and the low level as 0V; estimate the voltage of the second pulse step segment The flat change range is 0～A ₁ v; the threshold value is set to A ₂ V; A ₁ is a positive integer; A ₂ is a positive integer; 0<A ₂ <A ₁ ; judge; when When it is greater than A ₂ , output the sample point sequence number of the sampling data level step segment.

Step (3), according to the sample point sequence number of the second pulse signal level step section, intercept the navigation signal sampling data in the corresponding sample point sequence number in the sampling sample; carry out Hilbert transform and down-conversion to the intercepted navigation signal sampling data Processing to obtain the complex domain baseband navigation signal;

The method of performing Hilbert transform and down-conversion processing on the intercepted navigation signal sampling data to obtain the complex domain baseband navigation signal d(i) is as follows:

Set the intercepted navigation signal sampling data as The length is Q, and Q is a positive integer;

in, Be the i-th complex number; i=1,2,3,...,Q;

c _i is the sample point of local carrier data; i=1,2,3,...,Q;

Among them, H() represents the Hilbert transform;

The local carrier data sample point c _i is:

Among them: j is the imaginary number unit;

f _s is the sampling frequency;

f _c is the known center frequency of the navigation signal;

i=1,2,3,...,Q.

Step (4), setting the extraction length of the baseband navigation signal in the complex number domain, the extraction length is the duration of the number of M information bits contained in the data branch signal in the baseband navigation signal in the complex number domain, M is a positive integer, and the calculation Obtain the point number N of the complex domain baseband navigation signal to be processed;

Among them, the calculation method of the point number N of the complex domain baseband navigation signal to be processed is: set the duration of each information bit as t _b , then the duration of the extraction length is M×t _b ; according to the sampling rate of f _s , that is, f _s points are sampled within 1 second, and the number N of points of the complex-domain baseband navigation signal to be processed is obtained, N=M×t _b ×f _s .

Step (5), according to the point number N of the complex domain baseband navigation signal to be processed, the pseudo-random spread spectrum code of the pilot frequency branch signal in step (1) is repeated periodically, and N points are intercepted from the starting point of the whole cycle The data, that is, the N local pilot long code sample data at the beginning of the entire cycle of the generated pilot pseudo-random spreading code;

The N local pilot long code sample data generated in step (6) and step (5) and the complex domain baseband navigation signal generated in step (3) are used for correlation calculation to obtain the peak value corresponding to the maximum correlation peak in the correlation calculation result Point sample number P;

The calculation method of the serial number P corresponding to the maximum correlation peak is:

Extract the local sample data of N pilot pseudo-codes, and the calculation method of the complex frequency domain sample value C(k) of the local samples of the pilot pseudo-code is:

Wherein: c(n) is local pilot long code sample data;

n is the number in the calculation process, and the range of values is n=1,2,...,N-1;

j is the imaginary unit;

k is the sequence number of the complex frequency domain sample of the local sample of the pilot pseudo code;

Extract N baseband navigation signal data in the complex domain, and calculate the amplitude-frequency sample point D(g) of the navigation signal;

Wherein: D(n) is local data long code sample data;

n is the number in the calculation process, and the range of values is n=1,2,...,N-1;

j is the imaginary unit;

g is the serial number of the complex frequency domain sample point of the navigation signal;

Then calculate the amplitude-frequency sample point D(g) of the navigation signal and the complex-frequency domain sample value C(k) of the local sample of the pilot pseudo-code in the complex frequency domain, and obtain the correlation result z(n):

The maximum value in search z(n) is defined as sequence number P.

Step (7), step (4) determine in the extraction length that comprises M information bits, generates 2 ^M-1 kinds of information bit samples b _l (n), wherein n is a positive integer, and N is a positive integer; n= 1, 2, 3...N; l is a positive integer, l=1, 2, 3...2 ^M-1 ; 2 ^M-1 kinds of information bit samples b _l (n) and the data branch signal in the sampling data Pseudo-random spreading code {y(n)n=1,2,…,N} for spreading processing to get 2 ^M-1 kinds of local reference samples

Perform spread spectrum processing on 2 ^M-1 kinds of information bit samples b _l (n) and the pseudo-random spread spectrum code {y(n)|n=1,2,…,N} of the data branch signal in the sampling data, and calculate local reference samples The method is:

Step (eight), according to the correlation calculation method in step (six), the ^2M-1 kinds of local reference samples generated in step (seven) respectively The complex number domain baseband navigation signal generated in the step (3) carries out correlation calculation; Determine the correlation peak value in each correlation processing result, obtain the peak point sample sequence number D corresponding to the maximum value in each correlation peak value;

The method of calculating the peak point sample number D corresponding to the maximum value in each correlation peak is:

Carry out 2 ^M-1 correlation calculations with formula (7) and formula (9) according to the method of formula (8), and get the result:

search The largest value is defined as the sequence number D.

Step (9), calculate the difference between the sample number P obtained in step (6) and the sample number D obtained in step (8), and calculate the time delay value Δt of the data code lag pilot according to the sampling rate, that is, the navigation signal The pilot branch signal is the reference, the phase consistency between the two long code signals of the pilot branch signal and the data branch signal; in the process of calibrating the phase consistency of the multi-long code composite navigation signal, if the navigation The signal contains multiple data long codes, and steps (1) to (9) are repeated to calculate the phase consistency between each data code and the pilot code.

The calculation method of the delay value Δt of the data code lagging behind the pilot is:

Δt=(DP)/f _s (10).

Example:

Figure 6 is a schematic diagram of the multi-length code composite navigation signal phase consistency calibration method, as can be seen from the figure, the main steps are as follows:

1. Use a high-speed A/D sampler to synchronously sample the navigation signal and the second pulse signal output by the navigation signal generator. Here, it is assumed that the center frequency of the navigation signal generated by the navigation signal generator is 1575.42MHz, and the navigation signal includes BOC (6,1 , 4/33) modulated pilot signal and BOC (1, 1) modulated data signal, the pseudo-random codes of the pilot signal and data signal are both long codes, the period of the pseudo-random code is 1.5 seconds, and the pilot signal is not modulated Data, the bit rate of the navigation information modulated on the data signal is 4kbps, the signal power spectrum is shown in Figure 2, and the data sampling rate is 5Gsa/s.

2. Process the second pulse signal, and read the sampling data of the second pulse signal level step The second pulse number level step can be modeled as y _i =b ₀ +b ₁ ·i/f _s +ξ _i , where b ₀ is the initial level of the sampled data, b ₁ is the level change rate, ξ _i is random noise, f _s is the sampling frequency, and b ₀ and b ₁ are calculated by linear fitting with the least square method:

Compute the second pulse estimate:

According to the judgment threshold value of the second pulse voltage value specified by the satellite system and the estimated second pulse value, determine the sample point number of the second pulse level step point, as shown in Figure 3.

3. Take the second pulse signal level step point sequence number as the reference point to intercept the navigation signal, and perform Hilbert transform and down-conversion processing on the signal to obtain the complex domain baseband navigation signal; the hypothetical sampled navigation signal data group is expressed as The length is Q, and the Hilbert transform is performed:

In the formula, H() means Hilbert transform, complex array

Generate a set of local carrier data according to the navigation signal center frequency f _c and sampling frequency f _s Among them, each carrier data sample point is:

right Perform down-conversion to obtain low-frequency signal data:

4. Set the data extraction length to 1 ms and the sampling rate to 5 Gsa/s, then adopt within 1 ms at a sampling rate of 5 Gsa/s, and N=5×10 ⁶ sample point data can be obtained.

After determining the number N of sample point data of the complex-domain baseband navigation signal to be processed, in order to perform correlation processing on the pilot branch long code in the navigation signal, it is necessary to generate N number of pilot pseudo-random codes at the beginning of the entire cycle on this basis. Local pilot long code sample data (the pilot pseudo-random spreading code is known).

5. Extract N pieces of navigation signal data and N pieces of local pilot long code sample data for correlation processing.

Firstly, the local pilot long code sample data is transformed into the complex domain by Fourier transform, and then conjugated to obtain the complex frequency domain sample value of the local pilot long code sample:

Where {c(n)|n=1,2,...,N} is the local pilot long code sample data.

Then the extracted N navigation signal data are subjected to Fourier transform to obtain the amplitude-frequency sample points of the navigation signal:

After multiplication in the complex frequency domain, an inverse Fourier transform is performed and the modulus is squared:

The obtained z(n) curve is shown in Figure 4, and the serial number P corresponding to the maximum value in z(n) is searched.

6. Extract local data long code baseband samples according to the extraction length, that is, generate N=5e6 local pilot long code sample data {y(n )|n=1,2,...,N};

7. Extract the number M of information bits contained in the data code branch of the navigation signal within the length, and generate 2 ^M-1 possible information bit samples. Here, the extracted length is 1 ms, and the navigation information bit rate is 4 kbps, so the extracted Data contains 4 bits of information. 4 bits of information, there are 2 ⁴ possible information, due to the square relationship in the correlation processing, 4 pairs of information bits with completely opposite information levels participate in the correlation processing to get the same result. Therefore, only 2 to ³ kinds of information bits need to be involved in the relevant processing to meet the actual needs.

There are eight types of fetching information bits as follows:

serial number information bit value 1 1 1 1 1 2 1 1 1 -1 3 1 1 -1 1 4 1 1 -1 -1 5 1 -1 1 1 6 1-1 1-1 7 1 -1 -1 1 8 1 -1 -1 -1

Generate 2 ^M-1 = 8 possible information bit samples at the sampling rate:

Respectively with the extracted local data long code baseband sample spread spectrum processing. Get 2 ^M-1 = 8 local reference samples after information spread spectrum processing:

Each local reference sample extracts N navigation signal data and carries out the correlation processing described in (4), obtains 8 sets of correlation values, determines the peak value of each correlation processing, and finds the maximum value of each peak value and the corresponding sample point number D, A set of correlation curves with the largest correlation peak is shown in FIG. 5 .

8. Calculate the difference between the serial numbers D and P of two sample points. Calculate the delay value of the data code lagging behind the pilot according to the sampling rate. This value is the phase consistency between the two long codes referenced by the pilot code of the navigation signal. .

Δt=(DP)/f _s (11)

9. If the navigation signal contains multiple data long codes, the same processing method is used to calculate the phase consistency between each data code and the pilot code.

The content that is not described in detail in the description of the present invention belongs to the well-known technology of those skilled in the art.

Claims (10)

1. A multi-long code composite navigation signal phase consistency calibration method is characterized by comprising the following steps: the multi-long code composite navigation signal phase consistency calibration method comprises the following steps:

synchronously sampling a navigation signal and a pulse per second signal output by a navigation signal generator through a high-speed A/D sampler; obtaining sampling samples of navigation signal sampling data and second pulse signal sampling data; each sample simultaneously corresponds to a navigation signal sampling data and a second pulse signal sampling data; wherein the second pulse signal sampling data comprises data of a level step section and a level duration section; the navigation signal sampling data comprises a pilot frequency branch signal and a data branch signal, wherein the pilot frequency branch signal and the data branch signal consist of a long-code pseudorandom spread spectrum code;

step (II) of calculating the pulse per second estimated value of the pulse per second signal sampling dataAccording to the second pulse voltage value and the threshold value specified by the satellite system, the second pulse estimation value is obtainedJudging; determining sample point serial numbers of a level step section of sampling data of the pulse-per-second signal, wherein the sample point serial numbers are sequentially numbered from 1;

intercepting navigation signal sampling data in corresponding sample point serial numbers in sampling samples according to the sample point serial numbers of the level step section of the pulse-per-second signal; performing Hilbert conversion and down-conversion processing on the intercepted navigation signal sampling data to obtain a complex field baseband navigation signal;

setting the extraction length of the complex field baseband navigation signal, wherein the extraction length is the time duration of the number of M information bits contained in a data branch signal in the complex field baseband navigation signal, M is a positive integer, and calculating to obtain the point number N of the complex field baseband navigation signal to be processed;

repeating the pseudo-random spread spectrum code of the pilot frequency branch signal in the step (one) according to the number N of the points of the complex field baseband navigation signal to be processed, and intercepting data of N points from the starting point of the whole period, namely generating N local pilot frequency long code sample data of the starting point of the whole period of the pilot frequency pseudo-random spread spectrum code;

carrying out correlation calculation on the N local pilot frequency long code sample data generated in the step (VI) and the complex field baseband navigation signal generated in the step (III) together to obtain a peak point sample serial number P corresponding to the maximum correlation peak in a correlation calculation result;

the extraction length determined in the step (seven) and the step (four) contains M information bitsGeneration of 2^M-1Seed information bit sample b_l(N), wherein N is a positive integer and N is a positive integer; n is 1,2,3 … … N; l is a positive integer, 1,2,3 … … 2^M-1(ii) a Will 2^M-1Seed information bit sample b_l(N) spreading the data branch signal with pseudo-random spreading code { y (N) | N ═ 1,2, …, N } in the sample data to obtain 2^M-1Local reference sample

Step (eight), according to the correlation calculation method in the step (six), respectively aiming at the 2 generated in the step (seven)^M-1Local reference samplePerforming correlation calculation on the complex field baseband navigation signals generated in the step (three); determining correlation peak values in the correlation processing results of each time to obtain peak value point sample serial numbers D corresponding to maximum values in the correlation peak values;

step (nine), the sample serial number P obtained in the step (six) and the sample serial number D obtained in the step (eight) are subjected to difference calculation, and a delay value delta t of data code lagging pilot frequency is obtained according to the sampling rate, namely the pilot frequency branch signal in the navigation signal is taken as reference, and the phase consistency between the pilot frequency branch signal and the data branch signal is obtained; and (3) in the process of calibrating the phase consistency of the multi-long code composite navigation signal, if the navigation signal contains various data long codes, repeating the steps (one) to (nine), and calculating the phase consistency between each data code and the pilot frequency code.

2. The phase consistency calibration method for the multiple long code composite navigation signal according to claim 1, characterized in that: in the step (one), the pseudo-random code period of the pilot signal and the data signal in the navigation signal is 1.5 seconds; the navigation information bit rate modulated by the data signal is 4 kbps; and adjusting the data sampling rate according to the performance of the used instrument and equipment, wherein the adjustment rate is 1-10 Gsa/s.

3. The phase consistency calibration method for the multiple long code composite navigation signal according to claim 1, characterized in that: in the second step, the estimated pulse per second valueThe calculation method comprises the following steps: sampling data for setting level step of pulse per second signalWherein i is a positive integer, i is 1,2,3 … N; the modeling of the pulse number per second level phase is as follows: y is_i＝b₀+b₁·i/f_s+ξ_iWherein b is₀Is the initial level of the sampled data; b₁Is the rate of change of level ξ_iIs random noise; f. of_sIs the sampling frequency; y is_iA level value fitted to the pulse-per-second signal; calculation of b by least squares linear fitting₀And b₁：

$\left[\begin{array}{c}{b}_0\\ b_1\end{array}\right]={\left[\begin{array}{cc}N-1& \underset{i=1}{\overset{N-1}{\&Sigma;}}(i-1)\\ \underset{i=1}{\overset{N-1}{\&Sigma;}}(i-1)& \underset{i=1}{\overset{N-1}{\&Sigma;}}{(i-1)}^2\end{array}\right]}^{-1}\&times;\left[\begin{array}{c}\underset{i=1}{\overset{N-1}{\&Sigma;}}{y}_i^{*}\\ \underset{i=1}{\overset{N-1}{\&Sigma;}}(i-1)y_i^{*}\end{array}\right]---\left(1\right)$

Calculating the pulse-per-second estimate

${\hat{y}}_i=b_0+b_1\&CenterDot;i/f_s---\left(2\right).$

4. The phase consistency calibration method for the multiple long code composite navigation signal according to claim 3, characterized in that: in the step (two), the method for determining the sample point sequence number of the sampling data level step section of the pulse-per-second signal comprises the following steps: setting a specified high level of the pulse per second voltage of the satellite system to A₁V, the low level is 0V; estimating the level change range of the second pulse step section to be 0-A₁v; setting the threshold value to A₂V；A₁Is a positive integer; a. the₂Is a positive integer; 0 < A₂＜A₁(ii) a Pulse-per-second estimationJudging; when in useGreater than A₂And outputting the sample point serial number of the sampled data level step section.

5. The phase consistency calibration method for the multiple long code composite navigation signal according to claim 1, characterized in that: in the step (iii), the method for obtaining the complex-domain baseband navigation signal d (i) by performing hilbert conversion and down-conversion on the intercepted navigation signal sampling data comprises:

setting the intercepted navigation signal sampling data asThe length is Q, and Q is a positive integer;

$d\left(i\right)=z_i^x\&CenterDot;c_i---\left(3\right)$

wherein,is the ith complex number; 1,2,3, … …, Q;

c_iis a local carrier data sample point; 1,2,3, … …, Q;

$z_i^x=\stackrel{\&OverBar;}{x}+H\left(\stackrel{\&OverBar;}{x}\right)---\left(4\right)$

wherein H () represents a hilbert transform;

local carrier data sample point c_iComprises the following steps:

$c_i=\exp \left\{j2\mathrm{\&pi;}\frac{f_c}{f_s}i\right\}---\left(5\right)$

wherein: j is an imaginary unit;

f_sis the sampling frequency;

f_cis a known navigation signal center frequency;

i＝1,2,3，……，Q。

6. the phase consistency calibration method for the multiple long code composite navigation signal according to claim 1, characterized in that: in the step (iv), the method for calculating the number N of points of the complex-domain baseband navigation signal to be processed includes: setting the duration of each information bit to t_bThe duration of the extraction length is M × t_b(ii) a According to sampling rate f_sI.e. sampling within 1 second to obtain f_sObtaining the number N of the points of the complex field baseband navigation signal to be processed, wherein the N is M × t_b×f_s。

7. The phase consistency calibration method for the multiple long code composite navigation signal according to claim 1, characterized in that: in the step (vi), the method for calculating the sequence number P corresponding to the maximum correlation peak includes:

n pilot frequency pseudo code local sample data are extracted, and the calculation method of the complex frequency domain sample value C (k) of the pilot frequency pseudo code local sample comprises the following steps:

$C\left(k\right)={\&lsqb;\underset{n=0}{\overset{N-1}{\&Sigma;}}c\left(n\right)\exp (-j\frac{2\mathrm{\&pi;}kn}{N})\&rsqb;}^{*},k=1,2,...,N---\left(6\right)$

wherein: c (n) is local pilot frequency long code sample data;

n is a number in the calculation process, and the value range N is 1,2, … and N-1;

j is an imaginary unit;

k is the serial number of the complex frequency domain sample of the pilot frequency pseudo code local sample;

extracting N complex field baseband navigation signal data, and calculating to obtain an amplitude-frequency sample point D (g) of the navigation signal;

$D\left(k\right)=\underset{n=0}{\overset{N-1}{\&Sigma;}}d\left(n\right)\exp (-j\frac{2\mathrm{\&pi;}kn}{N}),k=1,2,...,N---\left(7\right)$

wherein: d (n) is local data long code sample data;

n is a number in the calculation process, and the value range N is 1,2, … and N-1;

j is an imaginary unit;

g is the serial number of the complex frequency domain sample points of the navigation signal;

and then, calculating the amplitude-frequency sample points D (g) of the navigation signal and the complex frequency domain sample values C (k) of the pilot frequency pseudo code local samples in the complex frequency domain to obtain a correlation result z (n):

$z\left(n\right)={|\underset{k=0}{\overset{N-1}{\&Sigma;}}\&lsqb;C\left(k\right)D\left(g\right)\&rsqb;\exp \left(j\frac{2\mathrm{\&pi;}kn}{N}\right)|}^2,n=1,2,...,N---\left(8\right)$

the maximum value in the search z (n) is defined as the sequence number P.

8. The phase consistency calibration method for the multiple long code composite navigation signal according to claim 1, characterized in that: in the step (VII), 2 is added^M-1Seed information bit sample b_l(N) spreading the data branch signal with pseudo-random spreading code { y (N) | N ═ 1,2, …, N } in the sampled data, calculating local reference sampleThe method comprises the following steps:

${\stackrel{\&RightArrow;}{s}}_l=\{y\left(n\right)\&CenterDot;b_l\left(n\right)|n=1,2,...,N\},l=1,2,...,2^{M-1}---\left(9\right).$

9. the calibration method for phase consistency of multiple long code composite navigation signals according to one of claims 1 to 8, characterized in that: in the step (eight), the method for calculating the peak point sample number D corresponding to the maximum value in each correlation peak value includes:

the method of the formula (8) is carried out 2 by the formula (7) and the formula (9)^M-1Calculating the second order correlation to obtainAs a result:

${\stackrel{\&RightArrow;}{z}}_l\left(n\right)={|\underset{k=0}{\overset{N-1}{\&Sigma;}}\&lsqb;{\stackrel{\&RightArrow;}{s}}_{l}D\left(g\right)\&rsqb;\exp \left(j\frac{2\mathrm{\&pi;}kn}{N}\right)|}^2,n=1,2,...,N;l=1,2,...,2^{M-1};---\left(10\right)$

searchingThe medium maximum value is defined as the sequence number D.

10. The phase consistency calibration method for the multiple long code composite navigation signal according to claim 1, characterized in that: in the step (nine), the method for calculating the delay value Δ t of the data code lag pilot frequency includes:

Δt＝(D-P)/f_s(11)。