CN106908810B - It is a kind of how long code complex navigation signal phase consistency calibration method - Google Patents
It is a kind of how long code complex navigation signal phase consistency calibration method Download PDFInfo
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Abstract
It is a kind of how long code complex navigation signal phase consistency calibration method, be related to navigational satellite system high-precision applications field；Pilot tone long code baseband sample point data and complex base band navigation signal in local complex navigation signal are won first, and the two relevant treatment obtains correlation peak point serial number P；Local data long code baseband sample is won according to length is won, and determines and wins the information bit number M for including in numeric data code branch in navigation signal in length, generates 2M-1Kind possible information bit sample then is handled with the complex field base band navigation signal won respectively with the local data long code baseband sample spread processing won, is determined the peak value of each secondary relevant treatment, is asked maximum value and corresponding sample point serial number D in each peak value.Last D and P asks poor, and the phase equalization between two long codes for taking navigation signal pilot code as reference is calculated according to sample rate.Realize the precision calibration of the phase equalization of each code under a variety of long code combining cases of navigation signal generator.
Description
Technical Field
The invention relates to the field of high-precision application of a navigation satellite system, in particular to a multi-long code composite navigation signal phase consistency calibration method.
Background
In order to improve the utilization rate of a Navigation signal frequency band and meet user requirements of various positioning accuracies, a modern Navigation signal usually adopts a multi-Navigation signal branch composite mode, and simultaneously loads a plurality of Navigation signals of different pseudo-random codes and modulation modes, such as an E1 signal in a Galileo Satellite signal System, on the same carrier frequency point, and generates an E1B signal containing data and three branch Navigation signals of an E1C signal and an E1A signal containing pilot information by using a CBOC (6,1,4/33) and BOC (15, 2.5) modulation mode on a 1575.42MHz carrier frequency. In addition, in the modern navigation signal system, in order to meet the requirements of interference resistance, quick acquisition and tracking and higher precision, a plurality of means such as long pseudo-random codes, pilot codes and data separation are used for some navigation signals, and the period of a pilot branch L1Cp in an L1C signal of a signal system of a GPS-III satellite is longer than 18 s.
In many high-precision applications of a navigation satellite system, in order to improve the ranging precision and the capturing speed of a receiver, it is necessary to obtain an accurate time delay difference between pseudo-random code phases of each navigation signal branch of the same frequency point, that is, it is necessary to accurately calibrate the phase consistency of the pseudo-random codes of each navigation signal branch of the same frequency point.
At present, a calibration method for navigation signal channel phase consistency adopts a high-speed oscilloscope to observe an envelope depression point in a constant envelope navigation signal waveform, and a specific implementation method is disclosed in the literature of Absolute calibration of an a geographic timing system (IEEE Transmission on Ultrasonics, and Ferroelectrics, and frequency Control, Vol.52, No.11, pp 1904-1911).
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a method for calibrating the phase consistency of a multi-long-code composite navigation signal, so that the precise calibration of the phase consistency of each code under the condition of compounding multiple long codes of a navigation signal generator is realized.
The above purpose of the invention is realized by the following technical scheme:
a 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 bits, and 2 is generatedM-1Seed information bit sample bl(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 … … 2M-1(ii) a Will 2M-1Seed information bit sample bl(N) spreading the data branch signal with pseudo-random spreading code { y (N) | N ═ 1,2, …, N } in the sample data to obtain 2M-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 the correlation peak value in each correlation processing result to obtain the most correlation peak valueThe peak point sample number D corresponding to the large value;
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.
In the phase consistency calibration method for the multi-long code composite navigation signal, 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.
In the above calibration method for phase consistency of multiple long code composite navigation signals, in the second step, the pulse-per-second estimation 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 isi＝b0+b1·i/fs+ξiWherein b is0Is the initial level of the sampled data; b1Is the rate of change of level ξiIs random noise; f. ofsIs the sampling frequency; y isiA level value fitted to the pulse-per-second signal; calculation of b by least squares linear fitting0And b1：
Calculating the pulse-per-second estimate
In the above calibration method for phase consistency of multiple long code composite navigation signals, in the step (ii), the method for determining the sample point sequence number of the level step section of the pulse-per-second signal sampling data comprises: 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.
In the above calibration method for phase consistency of multiple long code composite navigation signals, in the step (three), the method of performing hilbert conversion and down-conversion processing on the intercepted navigation signal sample data to obtain a complex-domain baseband navigation signal d (i) includes:
setting the intercepted navigation signal sampling data asThe length is Q, and Q is a positive integer;
wherein,is the ith complex number; 1,2,3, … …, Q;
ciis a local carrier data sample point; 1,2,3, … …, Q;
wherein H () represents a hilbert transform;
local carrier data sample point ciComprises the following steps:
wherein: j is an imaginary unit;
fsis the sampling frequency;
fcis a known navigation signal center frequency;
i＝1,2,3，……，Q。
in the above calibration method for phase consistency of multiple long code composite navigation signals, in the step (four), the calculation method of the number N of points of the complex number field baseband navigation signal to be processed is: setting the duration of each information bit to tbThe duration of the picking length is M × tb(ii) a According to sampling rate fsI.e. sampling within 1 second to obtain fsObtaining the number N of the points of the complex field baseband navigation signal to be processed, wherein N is M multiplied by tb×fs。
In the above calibration method for phase consistency of multiple long code composite navigation signals, in the step (six), the method for calculating the sequence number P corresponding to the maximum correlation peak is as follows:
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:
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;
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):
the maximum value in the search z (n) is defined as the sequence number P.
In the above calibration method for phase consistency of multiple long code composite navigation signals, in the step (seventhly), 2 is usedM-1Seed information bit sample bl(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:
in the above calibration method for phase consistency of multiple long code composite navigation signals, 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-1And performing secondary correlation calculation to obtain a result:
searchingThe medium maximum value is defined as the sequence number D.
In the above calibration method for phase consistency of multiple long code composite navigation signals, in the step (nine), the method for calculating the delay value Δ t of the data code lagging pilot frequency is as follows:
Δt＝(D-P)/fs (10)。
compared with the prior art, the invention has the following advantages:
(1) the invention adopts high-speed direct A/D sampling to the navigation signal, carries out phase consistency calibration in a digital domain, can precisely determine the phase time delay relationship between sample points in digital processing, solves the problem of inconsistency of self zero values of receiving equipment when different signals are received in the traditional testing equipment, and eliminates the calibration error introduced by the inconsistency of self zero values of receiving channels of the testing equipment;
(2) the invention adopts digital domain correlation processing, determines the initial point of the code sheet through the correlation peak value, the calibration precision depends on the sampling frequency, when the sampling frequency is 10GHz, the precision can reach 0.2ns, the precision is 4-5 ns compared with the traditional oscilloscope observation method, and the calibration precision is improved by more than one order of magnitude;
(3) the invention adopts partial pseudo-random codes to carry out correlation processing, reduces the number of processed data sample points, and greatly reduces the data volume of digital signal processing under the condition of ensuring the precision;
(4) in the processed data, the local data sample modulated by all possible signal bits is used as a reference, so that the accuracy of a correlation peak value and the accuracy of the pseudo code starting point are ensured.
Drawings
FIG. 1 is a flow chart of a multi-long code composite navigation signal phase consistency calibration method of the present invention;
FIG. 2 is a power spectrum of a multiple long code composite navigation sequence number of the present invention;
FIG. 3 is a schematic diagram of a navigation signal generator pulse-per-second and step point acquisition according to the present invention;
FIG. 4 is a graph of a local pilot code and pilot signal correlation process according to the present invention;
FIG. 5 is a graph of the data code and pilot signal correlation process for local spreading according to the present invention;
fig. 6 is a schematic diagram of a multi-long code composite navigation signal phase consistency calibration method according to the present invention.
Detailed Description
The invention is described in further detail below with reference to the following figures and specific examples:
as shown in fig. 1, a flow chart of a calibration method for phase consistency of multiple long code composite navigation signals is shown, and it can be known that the calibration method for phase consistency of multiple long code composite navigation signals includes 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;
the pseudo-random code period of a pilot signal and a 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.
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 the sample point serial number of the level step section of the sampling data of the pulse-per-second signal, wherein the sample point serial number is started from 1Numbering in sequence;
pulse-per-second estimationThe 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 isi＝b0+b1·i/fs+ξiWherein b is0Is the initial level of the sampled data; b1Is the rate of change of level ξiIs random noise; f. ofsIs the sampling frequency; y isiA level value fitted to the pulse-per-second signal; calculation of b by least squares linear fitting0And b1：
Calculating the pulse-per-second estimate
The method for determining the sample point sequence number of the level step section of the sampling data 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.
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;
the method for obtaining the complex domain baseband navigation signal d (i) by performing Hilbert conversion and down-conversion processing on the intercepted navigation signal sampling data comprises the following steps:
setting the intercepted navigation signal sampling data asThe length is Q, and Q is a positive integer;
wherein,is the ith complex number; 1,2,3, … …, Q;
ciis a local carrier data sample point; 1,2,3, … …, Q;
wherein H () represents a hilbert transform;
local carrier data sample point ciComprises the following steps:
wherein: j is an imaginary unit;
fsis the sampling frequency;
fcis a known navigation signal center frequency;
i＝1,2,3，……，Q。
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;
the method for calculating the point number N of the complex-field baseband navigation signal to be processed comprises the following steps: setting the duration of each information bit to tbThe duration of the picking length is M × tb(ii) a According to sampling rate fsI.e. sampling within 1 second to obtain fsObtaining the number N of the points of the complex field baseband navigation signal to be processed, wherein N is M multiplied by tb×fs。
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 method for calculating the sequence number P corresponding to the maximum correlation peak comprises the following steps:
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:
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;
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):
the maximum value in the search z (n) is defined as the sequence number P.
The extraction length determined in the step (seven) and the step (four) contains M information bits, and 2 is generatedM-1Seed information bit sample bl(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 … … 2M-1(ii) a Will 2M-1Seed information bit sample bl(N) spreading the data branch signal with pseudo-random spreading code { y (N) N ═ 1,2, …, N } in the sampled data to obtain 2M-1Local reference sample
Will 2M-1Seed information bit sample bl(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:
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;
the method for calculating the peak point sample sequence number D corresponding to the maximum value in each correlation peak value comprises the following steps:
the method of the formula (8) is carried out 2 by the formula (7) and the formula (9)M-1And performing secondary correlation calculation to obtain a result:
searchingThe medium maximum value is defined as the sequence number D.
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.
The method for calculating the time delay value delta t of the data code lag pilot frequency comprises the following steps:
Δt＝(D-P)/fs (10)。
example (b):
as shown in fig. 6, which is a schematic diagram of a calibration method for phase consistency of multiple long code composite navigation signals, it can be known that the main steps are as follows:
1. the navigation signal and the pulse per second output by the navigation signal generator are synchronously sampled by a high-speed A/D sampler, wherein the center frequency of the navigation signal generated by the navigation signal generator is 1575.42MHz, the navigation signal comprises a pilot signal modulated by BOC (6,1,4/33) and a data signal modulated by BOC (1, 1), pseudo random codes of the pilot signal and the data signal are both long codes, the period of the pseudo random codes is 1.5 seconds, the pilot signal does not modulate data, the bit rate of navigation information modulated on the data signal is 4kbps, the power spectrum of the signal is shown in figure 2, and the data sampling rate is 5 Gsa/s.
2. Processing the pulse per second signal, and reading the sampled data of the level stage of the pulse per second signalThe pulse number of second level step can be modeled as yi＝b0+b1·i/fs+ξiWherein b is0For sampling the initial level of data, b1As rate of change of level, ξiAs random noise, fsFor sampling frequency, calculating b by least squares linear fitting0And b1：
Calculating a pulse per second estimated value:
according to the second pulse voltage value judgment threshold value and the estimated second pulse value specified by the satellite system, the sample point sequence number of the second pulse level jump point is determined, as shown in fig. 3.
3. Intercepting a navigation signal by taking the sequence number of the level jump point of the pulse-per-second signal as a reference point, and carrying out Hilbert conversion and down-conversion processing on the signal to obtain a complex-domain baseband navigation signal; the navigation signal data set sampled by hypothesis is expressed asLength Q, hilbert transform:
wherein H () representsHilbert transform, complex array
According to the central frequency f of navigation signalcAnd a sampling frequency fsGenerating a set of local carrier dataWherein, each carrier data sample point is:
to pairPerforming down-conversion to obtain low-frequency signal data:
4. if the data extraction length is set to 1ms and the sampling rate is 5Gsa/s, the data is extracted at the sampling rate of 5Gsa/s within 1ms, and N is 5 × 106Sample point data.
After determining the number N of sample point data of a complex-field baseband navigation signal to be processed, in order to perform correlation processing on a pilot branch long code in the navigation signal, N local pilot long code sample data (known pilot pseudorandom spreading code) at the beginning of a whole period of a pilot pseudorandom code needs to be generated on the basis.
5. And extracting N navigation signal data and N local pilot frequency long code sample data for correlation processing.
Firstly, carrying out Fourier transform on local pilot frequency long code sample data to transform the sample data to a complex domain, and then carrying out conjugation processing to obtain a complex frequency domain sample value of the local pilot frequency long code sample:
where { c (N) | N ═ 1,2, …, N } is the local pilot long code sample data.
Then, carrying out Fourier transform on the extracted N navigation signal data to obtain amplitude-frequency sample points of the navigation signals:
after multiplication in the complex frequency domain, inverse fourier transform is performed and the square of the modulus is found:
the obtained z (n) curve is shown in fig. 4, and the number P corresponding to the maximum value in z (n) is searched.
6. Extracting local data long code baseband samples according to the extraction length, namely generating 5e6 local pilot long code sample data { y (N) | N ═ 1,2, …, N } at the beginning of a data pseudorandom code whole period by using a sampling rate of 5 Gsa/s;
7. extracting the number M of information bits contained in data code branch in navigation signal in length to generate 2M-1There are possible information bit samples, here extracted length 1ms, navigation information bit rate 4kbps, so the extracted data contains 4 bits of information. 4 bits of information, there is 24For possible information, due to the square relationship in the correlation process, a pair of information bits with completely opposite information levels participate in the correlation process to obtain the same result. Therefore, only 2 is required to be performed3It suffices for the seed information bits to participate in the correlation process.
The information bits are taken as the following eight types:
| serial number | Information bit dereferencing |
| 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 |
Generation 2 at a sampling rateM-18 possible information bit samples:
and respectively carrying out spread spectrum processing on the extracted local data long code baseband samples. To obtain 2M-18 local reference samples after information spreading processing:
each local reference sample respectively extracts N navigation signal data to perform the correlation processing described in (4) to obtain 8 groups of correlation values, determines the peak value of each correlation processing, and finds the maximum value in each peak value and the corresponding sample point serial number D, wherein a group of correlation curves with the maximum correlation peak value are shown in fig. 5.
8. And the difference between the serial numbers D and P of the two sample points is calculated according to the sampling rate to obtain a delay value of the data code lagging the pilot frequency, and the delay value is the phase consistency between the two long codes taking the pilot frequency code of the navigation signal as the reference.
Δt＝(D-P)/fs (11)
9. If the navigation signal contains a plurality of data long codes, the same processing mode is adopted to calculate the phase consistency between each data code and the pilot frequency code.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known 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 2M-1Seed information bit sample bl(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 … … 2M-1(ii) a Will 2M-1Seed information bit sample bl(N) spreading the data branch signal with pseudo-random spreading code { y (N) | N ═ 1,2, …, N } in the sample data to obtain 2M-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 2, 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 isi＝b0+b1·i/fs+ξiWherein b is0Is the initial level of the sampled data; b1Is the rate of change of level ξiIs random noise; f. ofsIs the sampling frequency; y isiA level value fitted to the pulse-per-second signal; calculation of b by least squares linear fitting0And b1：
Calculating the pulse-per-second estimate
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 4, 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;
wherein,is the ith complex number; 1,2,3, … …, Q;
ciis a local carrier data sample point; 1,2,3, … …, Q;
wherein H () represents a hilbert transform;
intercepted navigation signal sampling data;
local carrier data sample point ciComprises the following steps:
wherein: j is an imaginary unit;
fsis the sampling frequency;
fcis 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 5, 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 tbThe duration of the picking length is M × tb(ii) a According to sampling rate fsI.e. sampling within 1 second to obtain fsObtaining the number N of the points of the complex field baseband navigation signal to be processed, wherein N is M multiplied by tb×fs。
7. The phase consistency calibration method for the multiple long code composite navigation signal according to claim 6, characterized in that: in the step (vi), the method for calculating the sequence number P corresponding to the maximum correlation peak includes:
extracting N pilot frequency pseudo code local sample data, complex frequency domain sample value C (k) of pilot frequency pseudo code local sample1) The calculation method comprises the following steps:
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;
k1the sequence number of the complex frequency domain sample which is 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 (k) of the navigation signal2)；
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;
k2the sequence number of the complex frequency domain sample point of the navigation signal;
then, for the complex frequency domain, the amplitude-frequency sample point D (k) of the navigation signal is processed2) Complex frequency domain sample value C (k) of pilot pseudo code local sample1) Calculation was performed to obtain correlation result z (n):
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 7, characterized in that: in the step (VII), 2 is addedM-1Seed information bit sample bl(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:
9. the phase consistency calibration method for the multiple long code composite navigation signal according to claim 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-1And performing secondary correlation calculation to obtain a result:
calculating a result of the complex field baseband navigation signal;
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 9, 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)/fs (11)。
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