CN104158559A - Long code fast-acquisition method on basis of direct spread system - Google Patents
Long code fast-acquisition method on basis of direct spread system Download PDFInfo
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Abstract
The invention provides a long code fast-acquisition method on the basis of a direct spread system. The method comprises the following steps: step S1, signals with the code length being L of input signals are subjected to carrier separation and then the carrier separated signals are subjected to FFT calculation; step S2, local pseudo codes with the lengths of the M segments being L are selected from local pseudo codes and are then stacked and then average calculated to obtain a new sequence with the length being L to be FFT conjugate calculated; step S3, the product of the FFT calculation result and the FFT conjugate calculation result is then IFFT calculated; step S4, the calculation result in the step S3 is then modulo calculated, the maximum value of related peak values is selected to be compared with a threshold value, if the maximum value is bigger than the preset threshold value, the step S5 is implemented, a preliminary pseudo code phase acquisition value range and a frequency acquisition value are obtained, as a result, a specific pseudo code phase acquisition value is further obtained through the deblurring calculation in terms of the preliminary pseudo code phase acquisition value range and the frequency acquisition value.
Description
Technical field
The present invention relates to the spread spectrum observation and control technology of space flight aerospace product, be specifically related to the signal capture application of space product observing and controlling class unit.
Background technology
In directly-enlarging system, with respect to short code spread spectrum, long code spread spectrum has better disguise, anti-intercepting and capturing and stronger anti-reconnaissance capability.Along with the further investigation to Aerospace Spread Spectrum observation and control technology, the selection of spreading code is not only confined to short pseudo noise code, and a lot of macrocyclic spreading codes are also applied in Practical Project.
Present conventional Fast and direct acquisition of long cycle code technology is mainly divided into catches and the large class of Direct Acquisition two indirectly.Capture technique typically refers to the capture technique of traditional short code guiding long code indirectly.And Direct Acquisition technology mainly contains parallel multi-channel long code Direct Acquisition method, expansion copies overlay method (XFAST, Extended Replica Folding Acquisition Search Technique), CCPAZP-FFT (Circular Correlation by partition and zero padding-FFT) the straight laws on arrests of long code etc.
More known by analyzing, the resource that parallel multi-channel long code Direct Acquisition method takies is maximum, and interference free performance is bad; The complex structure of the straight laws on arrests of CCPAZP-FFT long code, the storage resources taking is also more; Expansion copies the relatively simple for structure of overlay method, and interference free performance is better, and capture time is also fewer, but correlation is poor.
Generally speaking, long code spread spectrum means that system has the higher pseudo-code cycle, will increase by the impact of the characteristic of channel, system synchronously more difficult, and lock in time also can be longer.For the long code signal capture in directly-enlarging system, main problem is how to reduce the capture time of signal and improves acquisition performance.
Summary of the invention
The technical problem to be solved in the present invention is how to reduce the capture time of signal and improve acquisition performance.
In order to solve this technical problem, the invention provides a kind of Fast and direct acquisition of long cycle code method based on directly-enlarging system, it is characterized in that: comprise the steps:
Step S1: it carries out carrier separation to the signal that is L of code length in the signal of input, then it is carried out to FFT calculating;
Step S2: in the local pseudo-code producing at pn code generator, get M segment length for the local pseudo-code of L, to its average calculating that first superposes again, thereby obtain the new sequence that length is L, then it is carried out to the calculating of FFT conjugation;
Step S3: the product of the result that in the result that FFT in step S1 is calculated and step S2, FFT conjugation is calculated carries out IFFT calculating;
Step S4: ask mould to calculate to the result of calculation in step S3, select the maximum in correlation peak, by this maximum and threshold value comparison;
If be greater than the threshold value of setting, implement
Step S5: obtain the preliminary pseudo-code phase value of catching scope and frequency acquisition value, and then carry out the calculating of deblurring degree according to this preliminary pseudo-code phase value of catching scope and frequency acquisition value, and then obtain concrete pseudo-code phase value of catching;
In described step S4, if the maximum in correlation peak is not more than the threshold value of setting, implement
Step S6: change Doppler's frequency, repeating step S1, S2, S3 and S4, until searched for all Doppler frequency scopes; In the process of this step cycle, naturally also can comprise the corresponding interpolation extraction operation of local pseudo-code and intermediate-freuqncy signal.
If searched for all how general rate frequency ranges, the maximum of correlation peak is not more than the threshold value of setting all the time, implements
Step S7: separately get the local pseudo-code that a M segment length is L, repeating step S1, S2, S3 and S4,, until searched for all pseudo-code phase; In the process of this step cycle, naturally also can comprise the corresponding interpolation extraction operation of local pseudo-code and intermediate-freuqncy signal.
In described step S5, described deblurring degree calculates and comprises the steps:
S51: the input signal after carrier wave is peeled off carries out FFT calculating, this input signal is the signal of the frequency acquisition value substitution according to having obtained;
S52: get the subsequence that a segment length is L in the sequence that is L in this M segment length, carry out the calculating of FFT conjugate;
S53: the product of the result that in the result that FFT in step S51 is calculated and step S52, FFT conjugation is calculated carries out IFFT calculating;
S54: ask mould to calculate to the result of calculation in step S53, select the maximum in correlation peak, by this maximum and threshold value comparison;
If be greater than the threshold value of setting, obtained concrete pseudo-code phase value of catching;
In described step S54, if the maximum in correlation peak is not more than the threshold value of setting, implement
Step S56: in the sequence that is L in this M segment length, separately get one long be the local pseudo-code of L, repeating step S51, S52, S53, S54, until searched for all pseudo-code phase wherein.
In order to reduce capture time, improve signal to noise ratio, the present invention is directed to existing Fast and direct acquisition of long cycle code technology---expansion copies overlay method, has carried out design improvement.The present invention has got the long pseudo-code sequence of M section L in local pseudo-code, and superpose and average calculating, the sequence that formation length is L, carry out afterwards the computing of FFT conjugate, both results are multiplied each other, and carry out IFFT computing, by asking mould relatively to select large module, draw the rough pseudo-code phase value of catching scope and the value of catching of Doppler frequency, and then calculate concrete pseudo-code phase value of catching by deblurring degree.
Accompanying drawing explanation
Fig. 1 is the Fast and direct acquisition of long cycle code side's ratio juris composition frame chart based on directly-enlarging system that one embodiment of the invention provides.
Embodiment
Below with reference to Fig. 1, the Fast and direct acquisition of long cycle code method based on directly-enlarging system provided by the invention is described in detail, it is the present invention's one optional embodiment, can think, those skilled in the art can modify and polish it in the scope that does not change the present invention's spirit and content.
Please refer to Fig. 1, the present embodiment provides a kind of Fast and direct acquisition of long cycle code method based on directly-enlarging system, it is characterized in that: comprise the steps:
Step S1: it carries out carrier separation to the signal that is L of code length in the signal of input, then it is carried out to FFT calculating; In this step, also carry out the operations such as the buffer memory of sampled data and interpolation extraction after carrier wave is peeled off, this is operating as technological means conventional in field.
Step S2: in the local pseudo-code producing at pn code generator, get M segment length for the local pseudo-code of L, to its average calculating that first superposes again, thereby obtain the new sequence that length is L, then it is carried out to the calculating of FFT conjugation; In this step, before carrying out the calculating of FFT conjugation, also to carry out interpolation extraction operation.
Step S3: the product of the result that in the result that FFT in step S1 is calculated and step S2, FFT conjugation is calculated carries out IFFT calculating; Certainly, before IFFT calculates, also can carry out caching process to it;
Step S4: ask mould to calculate to the result of calculation in step S3, select the maximum in correlation peak, by this maximum and threshold value comparison;
If be greater than the threshold value of setting, implement
Step S5: obtain the preliminary pseudo-code phase value of catching scope and frequency acquisition value, and then carry out the calculating of deblurring degree according to this preliminary pseudo-code phase value of catching scope and frequency acquisition value, and then obtain concrete pseudo-code phase value of catching; Here the alleged pseudo-code phase value of catching scope also can be thought preliminary pseudo-code phase value of catching, and after deblurring degree calculates, just can obtain concrete pseudo-code phase value of catching.
In described step S4, if the maximum in correlation peak is not more than the threshold value of setting, implement
Step S6: change Doppler's frequency, repeating step S1S2, S3 and S4, until searched for all Doppler frequency scopes; In the present embodiment, can control the variation that realizes Doppler's frequency by frequency step, thereby realize the search to the frequency within the scope of all Doppler frequencies, its concrete means exist in field, so the present embodiment does not specifically describe.
If searched for all how general rate frequency ranges, the maximum of correlation peak is not more than the threshold value of setting all the time, implements
Step S7: separately get the local pseudo-code that a M segment length is L, repeating step S1, S2, S3 and S4, until searched for all pseudo-code phase.Specifically, be interpreted as until exhaust the local pseudo-code sequence combination that all M segment lengths are L.
In described step S5, described deblurring degree calculates and comprises the steps:
S51: the input signal after carrier wave is peeled off carries out FFT calculating, this input signal is the signal of the frequency acquisition value substitution according to having obtained; In this step, also carry out the operations such as the buffer memory of sampled data and interpolation extraction after carrier wave is peeled off, this is operating as technological means conventional in field.
S52: get the subsequence that a segment length is L in the sequence that is L in this M segment length, carry out the calculating of FFT conjugate;
S53: the product of the result that in the result that FFT in step S51 is calculated and step S52, FFT conjugation is calculated carries out IFFT calculating;
S54: ask mould to calculate to the result of calculation in step S53, select the maximum in correlation peak, by this maximum and threshold value comparison;
If be greater than the threshold value of setting, obtained concrete pseudo-code phase value of catching;
The same with S3, S4 with step S2, step S51, S52, S53, S54 also can carry out the processing such as corresponding interpolation extraction, buffer memory.
In described step S54, if the maximum in correlation peak is not more than the threshold value of setting, implement
Step S55: in the sequence that is L in this M segment length, separately get one long be the local pseudo-code of L, repeating step S51, S52, S53, S54, until searched for wherein all pseudo-code phase.
By above step, can realize the search that all pseudo-code phase and Duo Pu lead frequency range.
In sum, in order to reduce capture time, improving signal to noise ratio, the present invention is directed to existing Fast and direct acquisition of long cycle code technology---expansion copies overlay method, has carried out design improvement.The present invention has got the long pseudo-code sequence of M section L in local pseudo-code, and superpose and average calculating, the sequence that formation length is L, carry out afterwards the computing of FFT conjugate, both results are multiplied each other, and carry out IFFT computing, by asking mould relatively to select large module, draw the rough pseudo-code phase value of catching scope and the value of catching of Doppler frequency, and then calculate concrete pseudo-code phase value of catching by deblurring degree.The present invention has good versatility and good portability.The present invention can be applied to designing and developing of the similar unit product of aerospace model, reduces the capture time of unit, improves the signal to noise ratio of unit, improves the antijamming capability of unit, meets the mission requirements of operation on orbit.
Claims (4)
1. the Fast and direct acquisition of long cycle code method based on directly-enlarging system, is characterized in that: comprise the steps:
Step S1: it carries out carrier separation to the signal that is L of code length in the signal of input, then it is carried out to FFT calculating;
Step S2: in the local pseudo-code producing at pn code generator, get M segment length for the local pseudo-code of L, to its average calculating that first superposes again, thereby obtain the new sequence that length is L, then it is carried out to the calculating of FFT conjugation;
Step S3: the product of the result that in the result that FFT in step S1 is calculated and step S2, FFT conjugation is calculated carries out IFFT calculating;
Step S4: ask mould to calculate to the result of calculation in step S3, select the maximum in correlation peak, by this maximum and threshold value comparison;
If be greater than the threshold value of setting, implement
Step S5: obtain the preliminary pseudo-code phase value of catching scope and frequency acquisition value, and then carry out the calculating of deblurring degree according to this preliminary pseudo-code phase value of catching scope and frequency acquisition value, and then obtain concrete pseudo-code phase value of catching.
2. the Fast and direct acquisition of long cycle code method based on directly-enlarging system as claimed in claim 1, is characterized in that: in described step S4, if the maximum in correlation peak is not more than the threshold value of setting, implement
Step S6: change Doppler's frequency, repeating step S1, S2, S3 and S4, until searched for all Doppler frequency scopes;
If searched for all how general rate frequency ranges, the maximum of correlation peak is not more than the threshold value of setting all the time, implements
Step S7: separately get the local pseudo-code that a M segment length is L, repeating step S1, S2, S3 and S4, until searched for all pseudo-code phase.
3. a kind of Fast and direct acquisition of long cycle code method based on directly-enlarging system as claimed in claim 1, is characterized in that: in described step S5, described deblurring degree calculates and comprises the steps:
S51: the input signal after carrier wave is peeled off carries out FFT calculating, this input signal is the signal of the frequency acquisition value substitution according to having obtained;
S52: get the subsequence that a segment length is L in the sequence that is L in this M segment length, carry out the calculating of FFT conjugate;
S53: the product of the result that in the result that FFT in step S51 is calculated and step S52, FFT conjugation is calculated carries out IFFT calculating;
S54: ask mould to calculate to the result of calculation in step S53, select the maximum in correlation peak, by this maximum and threshold value comparison;
If be greater than the threshold value of setting, obtained concrete pseudo-code phase value of catching.
4. the Fast and direct acquisition of long cycle code method based on directly-enlarging system as claimed in claim 3, is characterized in that: in described step S54, if the maximum in correlation peak is not more than the threshold value of setting, implement
Step S55: in the sequence that is L in this M segment length, separately get one long be the local pseudo-code of L, repeating step S51, S52, S53, S54, until searched for wherein all pseudo-code phase.
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| CN110336583A (en) * | 2019-04-09 | 2019-10-15 | 中国科学院上海微***与信息技术研究所 | A kind of quick catching device and method of Direct Sequence Spread Spectrum Signal |
| CN111355514A (en) * | 2020-04-17 | 2020-06-30 | 南京中新赛克科技有限责任公司 | Spread spectrum detection method for direct spread spectrum signal |
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Application publication date: 20141119 |