CN110784245B - Spread spectrum code synchronization method and system based on cumulative power correlation - Google Patents
Spread spectrum code synchronization method and system based on cumulative power correlation Download PDFInfo
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- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
- H04B1/70751—Synchronisation aspects with code phase acquisition using partial detection
- H04B1/70752—Partial correlation
Abstract
The utility model discloses a spread spectrum code synchronization method and system based on cumulative power correlation, which preprocesses the collected signal sequence and PN code sequence to respectively obtain a signal power sequence and a PN code power sequence; grouping the signal power sequences according to the length of the PN code sequence, and performing power accumulation according to the corresponding position of each group of signal power sequences to obtain a signal accumulated power sequence; shifting the PN code power sequence, inputting the PN code power sequence into a correlator, and performing correlation operation on the PN code power sequence and the signal accumulated power sequence to obtain a correlation value; and detecting the maximum value in the correlation values, acquiring the position in the signal accumulated power sequence corresponding to the maximum correlation value, wherein the position is the position of phase synchronization, and completing the synchronization of the acquired signal sequence and the PN code sequence. Increasing data grouping and power accumulation operations reduces correlation times, reduces computation time, and improves synchronization efficiency.
Description
Technical Field
The present disclosure relates to the field of test technologies, and in particular, to a method and a system for synchronizing spreading codes based on cumulative power correlation.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
Spread spectrum communication is an information transmission system which spreads a transmitted information signal sequence and a spread spectrum code to a wide frequency band through spread spectrum modulation processing at a transmitting end and then demodulates a received signal sequence and a local spread spectrum code sequence at a receiving end, and has the characteristics of strong anti-interception capability, strong anti-interference performance and the like. The synchronization of the spread spectrum code has a crucial role in spread spectrum communication, the original information transmitted can be recovered only under the condition that the phases of the local spread spectrum code sequence and the received spread spectrum code sequence are strictly consistent, and the performance of the whole communication system is directly influenced by the quality of the synchronization performance. The conventional synchronization method mainly comprises a matched filter method, a sliding correlation method and the like, wherein the matched filter method is short in capture time, complex in structure, high in resource occupancy rate and less in application in engineering, and the sliding correlation method is long in capture time, simple in structure, easy to implement and low in cost, and is widely applied to actual engineering.
Compared with a matched filter method, the sliding correlation method has a simpler structure, but is influenced by signal symbols, positive correlation and negative correlation exist in correlation operation, so that multiple times of correlation operation are required to be carried out in each shift during synchronization, the influence of the symbols is removed, then correlation operation results are integrated to obtain correlation values, synchronization is completed through threshold judgment, the operation process is complex, and the synchronization efficiency is reduced; secondly, the sliding correlation method usually only carries out judgment through a threshold, and shifts according to a judgment result, each time only can carry out single shift, the shift times are more, the synchronization time is longer, and the problem is particularly prominent in long code spread spectrum communication.
Disclosure of Invention
In order to solve the above problems, the present disclosure provides a spreading code synchronization method and system based on accumulated power correlation, in which received signals are grouped according to the length of the spreading code, and power accumulation is performed on data at the same position in each group, then the method performs sliding correlation operation with the squared spreading code by using the characteristic of the autocorrelation function of the signals, and finds the data position corresponding to the maximum peak according to the operation result, thereby implementing synchronization of the spreading code.
In order to achieve the purpose, the following technical scheme is adopted in the disclosure:
in a first aspect, the present disclosure provides a method for synchronizing spreading codes based on cumulative power correlation, including:
acquiring a signal sequence to be synchronized and a PN code sequence, and preprocessing the signal sequence and the PN code sequence to respectively obtain a signal power sequence and a PN code power sequence;
grouping the signal power sequences according to the length of the PN code sequence, and performing power accumulation according to the corresponding position of each group of signal power sequences to obtain a signal accumulated power sequence;
shifting the PN code power sequence, inputting the PN code power sequence into a correlator, and performing correlation operation on the PN code power sequence and the signal accumulated power sequence to obtain a correlation value;
and detecting the maximum value in the correlation values, acquiring the position in the signal accumulated power sequence corresponding to the maximum correlation value, wherein the position is the position of phase synchronization, completing the synchronization of the signal sequence and the PN code sequence, and realizing the spread spectrum communication of the signal sequence.
The present disclosure increases data grouping and power accumulation operations to reduce the number of correlations, reduces the time complexity from O (N × L) to O (L), reduces the operation time, and improves the synchronization efficiency.
As some possible implementations, the preprocessing includes performing a square operation on the acquired signal sequence and the PN code sequence to remove the symbol influence.
The method and the device avoid the problem that correlation operation such as a sliding correlation method is influenced by signal symbols by preprocessing the acquired signal sequence and the PN code sequence, and avoid positive correlation and negative correlation.
As some possible implementation manners, the grouping the signal power sequences includes sequentially grouping the signal power sequences in segments according to the PN code sequence length L, where the length of each segment of the grouped signal power sequences is equal to the PN code sequence length, and discarding signal data of less than L sampling points at the tail of the signal.
As some possible implementation manners, the accumulating the grouped signal power sequences includes accumulating each segment of signal power sequence according to corresponding positions of 1 to L, and finally obtaining L power values to obtain a signal accumulated power sequence.
As some possible implementations, the shifting the PN code power sequence includes determining a phase offset between the signal power sequence and the PN code power sequence according to an autocorrelation function characteristic of the signal, and shifting the PN code power sequence according to the phase offset.
In a second aspect, the present disclosure provides a system for spreading code synchronization based on accumulated power correlation, comprising:
the device comprises a preprocessing module, a synchronization module and a synchronization module, wherein the preprocessing module is used for acquiring a signal sequence to be synchronized and a PN code sequence, and preprocessing the signal sequence to be synchronized and the PN code sequence to respectively obtain a signal power sequence and a PN code power sequence;
the grouping and accumulation module is used for grouping the signal power sequences according to the length of the PN code sequence and carrying out power accumulation according to the corresponding position of each group of signal power sequences to obtain a signal accumulated power sequence;
the correlation operation module is used for shifting the PN code power sequence, inputting the PN code power sequence into a correlator and performing correlation operation on the PN code power sequence and the signal accumulated power sequence to obtain a correlation value;
and the peak detection module is used for detecting the maximum value in the correlation values, acquiring the position in the signal accumulated power sequence corresponding to the maximum correlation value, wherein the position is the position of phase synchronization, completing the synchronization of the signal sequence and the PN code sequence and realizing the spread spectrum communication of the signal sequence.
Compared with the prior art, the beneficial effect of this disclosure is:
the method and the device have the advantages that received signals are grouped according to the length of a spread spectrum code, power accumulation is carried out on data at the same position in each group, data grouping and power accumulation operations are increased, correlation times are reduced, time complexity is reduced from O (N multiplied by L) to O (L), operation time is reduced, and meanwhile synchronization efficiency is improved;
and the characteristic of the autocorrelation function of the signal is utilized to perform sliding correlation operation with the spread spectrum code after being squared, and the data position corresponding to the maximum peak value is found according to the operation result, so that the synchronization of the spread spectrum code is realized.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
FIG. 1 is a schematic diagram of the characteristics of a signal autocorrelation function;
FIG. 2 is a schematic flow chart of a sliding correlation method;
fig. 3 is a schematic flow chart of a spreading code synchronization method based on cumulative power correlation according to the present disclosure.
The specific implementation mode is as follows:
the present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The sliding correlation method utilizes the autocorrelation characteristic of the signal, and under the condition of not considering noise, when the phase difference between the received signal sequence and the local PN code sequence is less than half a chip period, the correlation output of the sliding correlation method has an obvious peak value, and when the phase difference is larger, the correlation output is 0, as shown in fig. 1;
the functional block diagram of the sliding correlation method is shown in fig. 2, firstly, a received signal is multiplied by a pseudo-random code generated by a local PN code generator, then a correlation integrator is used for finishing correlation operation, then a result R of the correlation integration is sent to a threshold decision device (the threshold is set to be C) for decision, if R is less than C, a local VCO clock is controlled in sequence, the phase of the PN code generated by the PN code generator is changed, the decision is continued until the correlation value R is more than or equal to C, and the synchronization of the PN code is finished.
Example 1
As shown in fig. 3, the present disclosure provides a spreading code synchronization method based on accumulated power correlation, including:
(1) acquiring a signal sequence to be synchronized and a PN code sequence, and preprocessing the signal sequence and the PN code sequence to respectively obtain a signal power sequence and a PN code power sequence;
the preprocessing comprises the steps of carrying out square operation on the acquired signal sequence and the PN code sequence and removing the influence of symbols;
in this embodiment, the length of the local PN code sequence is set to L, and the length of the data of the acquired signal sequence is nxl.
(2) Grouping the signal power sequences according to the length of the PN code sequence, and performing power accumulation according to the corresponding position of each group of signal power sequences to obtain a signal accumulated power sequence;
the grouping of the signal power sequences comprises the steps of sequentially grouping the signal power sequences in sections according to the length L of a PN code sequence, wherein the length of each section of grouped signal power sequence is equal to the length of the PN code sequence and is divided into N sections of data, the length of each section of data is L, and signal data of less than L sampling points at the tail part of a signal are discarded;
accumulating the grouped signal power sequences, and accumulating each section of data according to the corresponding positions of 1-L, namely: and accumulating the nth value in the 1 st segment and the nth value in the 2 nd segment, wherein N is 1, 2.
(3) Shifting the PN code power sequence, inputting the PN code power sequence into a correlator, and performing correlation operation on the PN code power sequence and the signal accumulated power sequence to obtain a correlation value;
the shifting the PN code power sequence comprises the steps of judging the phase offset of the signal power sequence and the PN code power sequence according to the autocorrelation function characteristic of a signal, and shifting the PN code power sequence according to the phase offset;
according to the characteristics of the autocorrelation function of the signal, when the phase difference between the power sequence of the received signal and the power sequence of the local PN code is less than half a chip period, the correlation output will have a distinct peak, and when the phase difference is larger, the correlation output is smaller, as shown in fig. 1. According to the characteristics, the phase offset condition of the received signal power sequence and the local PN code power sequence can be judged;
after the PN code power sequence is shifted, the PN code power sequence is sent to a correlator to be correlated with the signal accumulated power sequence, L correlation values after each shift are calculated in sequence and recorded in a peak value detection module.
(4) Detecting the maximum value in the correlation values, acquiring the position in the signal accumulated power sequence corresponding to the maximum correlation value, wherein the position is the position of phase synchronization, completing the synchronization of the signal sequence and the PN code sequence, and realizing the spread spectrum communication of the signal sequence;
spread spectrum communication is a system in which the frequency spectrum of a baseband signal is spread to a wide frequency band by a pseudo-random sequence (PN code) and then transmitted; the peak value detection module finds the maximum value in the L correlation values, records the position n in the received signal accumulated power sequence corresponding to the maximum value, wherein the position is the position of phase synchronization, completes the synchronization of the acquired signal and the local PN code sequence, completes the acquisition and can enter a subsequent synchronous tracking link for subsequent processing.
The present disclosure provides a system for spreading code synchronization based on accumulated power correlation, comprising,
the device comprises a preprocessing module, a synchronization module and a synchronization module, wherein the preprocessing module is used for acquiring a signal sequence to be synchronized and a PN code sequence, and preprocessing the signal sequence to be synchronized and the PN code sequence to respectively obtain a signal power sequence and a PN code power sequence;
the grouping and accumulation module is used for grouping the signal power sequences according to the length of the PN code sequence and carrying out power accumulation according to the corresponding position of each group of signal power sequences to obtain a signal accumulated power sequence;
the correlation operation module is used for shifting the PN code power sequence, inputting the PN code power sequence into a correlator and performing correlation operation on the PN code power sequence and the signal accumulated power sequence to obtain a correlation value;
and the peak detection module is used for detecting the maximum value in the correlation values, acquiring the position in the signal accumulated power sequence corresponding to the maximum correlation value, wherein the position is the position of phase synchronization, completing the synchronization of the signal sequence and the PN code sequence and realizing the spread spectrum communication of the signal sequence.
The preprocessing module performs square operation on the acquired signal sequence and the PN code sequence to remove the influence of symbols.
The grouping and accumulation module comprises the steps of sequentially grouping the signal power sequences according to the length L of the PN code sequence, enabling the length of each grouped signal power sequence to be equal to the length of the PN code sequence, and discarding the signal data of which the tail part of the signal is less than L sampling points.
The grouping and accumulating module accumulates each section of signal power sequence according to the corresponding position of 1-L to finally obtain L power values and obtain the signal accumulated power sequence.
The correlation operation module judges the phase shift of the signal power sequence and the PN code power sequence according to the autocorrelation function characteristic of the signal, and shifts the PN code power sequence according to the phase shift.
The above is merely a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, which may be variously modified and varied by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (10)
1. A method for spreading code synchronization based on accumulated power correlation, comprising:
acquiring a signal sequence to be synchronized and a PN code sequence, and preprocessing the signal sequence and the PN code sequence to respectively obtain a signal power sequence and a PN code power sequence;
grouping the signal power sequences according to the length of the PN code sequence, and performing power accumulation according to the corresponding position of each group of signal power sequences to obtain a signal accumulated power sequence;
shifting the PN code power sequence, inputting the PN code power sequence into a correlator, and performing correlation operation on the PN code power sequence and the signal accumulated power sequence to obtain a correlation value;
and detecting the maximum value in the correlation values, acquiring the position in the signal accumulated power sequence corresponding to the maximum correlation value, wherein the position is the position of phase synchronization, completing the synchronization of the signal sequence and the PN code sequence, and realizing the spread spectrum communication of the signal sequence.
2. The method of claim 1, wherein the step of synchronizing the spreading codes based on the accumulated power correlation comprises the step of,
the preprocessing comprises the steps of carrying out square operation on the acquired signal sequence and the PN code sequence and removing the influence of symbols.
3. The method of claim 2, wherein the step of synchronizing the spreading codes based on the accumulated power correlation comprises the step of,
the grouping of the signal power sequences comprises the steps of sequentially grouping the signal power sequences according to the length L of a PN code sequence in sections, wherein the length of each section of grouped signal power sequence is equal to the length of the PN code sequence, and discarding signal data of which the tail part of a signal is less than L sampling points.
4. The method of claim 1, wherein the step of synchronizing the spreading codes based on the accumulated power correlation comprises the step of,
and accumulating the power according to the corresponding position of each group of signal power sequences, accumulating the signal power sequences of each section according to the corresponding positions of 1-L, and finally obtaining L power values to obtain a signal accumulated power sequence.
5. The method of claim 4, wherein the step of synchronizing the spreading codes based on the accumulated power correlation comprises the step of,
the shifting the PN code power sequence comprises the steps of judging the phase offset of the signal power sequence and the PN code power sequence according to the autocorrelation function characteristic of a signal, and shifting the PN code power sequence according to the phase offset.
6. A spread spectrum code synchronization system based on accumulated power correlation, comprising,
the device comprises a preprocessing module, a synchronization module and a synchronization module, wherein the preprocessing module is used for acquiring a signal sequence to be synchronized and a PN code sequence, and preprocessing the signal sequence to be synchronized and the PN code sequence to respectively obtain a signal power sequence and a PN code power sequence;
the grouping and accumulation module is used for grouping the signal power sequences according to the length of the PN code sequence and carrying out power accumulation according to the corresponding position of each group of signal power sequences to obtain a signal accumulated power sequence;
the correlation operation module is used for shifting the PN code power sequence, inputting the PN code power sequence into a correlator and performing correlation operation on the PN code power sequence and the signal accumulated power sequence to obtain a correlation value;
and the peak detection module is used for detecting the maximum value in the correlation values, acquiring the position in the signal accumulated power sequence corresponding to the maximum correlation value, wherein the position is the position of phase synchronization, completing the synchronization of the signal sequence and the PN code sequence and realizing the spread spectrum communication of the signal sequence.
7. A spread spectrum code synchronization system based on accumulated power correlation as recited in claim 6,
the preprocessing module performs square operation on the acquired signal sequence and the PN code sequence to remove the influence of symbols.
8. A spread spectrum code synchronization system based on accumulated power correlation as recited in claim 6,
the grouping and accumulation module comprises the steps of sequentially grouping the signal power sequences according to the length L of the PN code sequence, enabling the length of each grouped signal power sequence to be equal to the length of the PN code sequence, and discarding the signal data of which the tail part of the signal is less than L sampling points.
9. A spread spectrum code synchronization system based on accumulated power correlation as recited in claim 6,
the grouping and accumulating module accumulates each section of signal power sequence according to the corresponding position of 1-L to finally obtain L power values and obtain the signal accumulated power sequence.
10. A spread spectrum code synchronization system based on accumulated power correlation as recited in claim 6,
the correlation operation module judges the phase shift of the signal power sequence and the PN code power sequence according to the autocorrelation function characteristic of the signal, and shifts the PN code power sequence according to the phase shift.
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