CN117724121A - PN code capturing method and device, storage medium and electronic equipment - Google Patents
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Abstract
The application provides a PN code capturing method, a PN code capturing device, a storage medium and electronic equipment, wherein the PN code capturing method comprises the following steps: acquiring a window signal, wherein the window signal is a signal sent by a satellite terminal to a receiver, and comprises N symbols; taking a T-th group PN sequence from the PN code, wherein the T-th group PN sequence comprises PN sequences from a (T-1) K+1st phase to a T×K-th phase; acquiring a non-correlation peak value based on N symbols and a T group PN sequence; and under the condition that the non-correlation peak value meets the threshold requirement, determining the PN sequence corresponding to the non-correlation peak value as the captured target sequence. By introducing the method of non-correlation accumulation to obtain the non-correlation peak values belonging to N symbols and the T-th PN sequences, combining the self-adaptive threshold judgment and carrying out parallel search on the pseudo code phases, the problems of low gain, low acquisition probability and low acquisition speed of the traditional acquisition algorithm under the conditions of low signal-to-noise ratio, high dynamic and large Doppler can be solved.
Description
Technical Field
The present application relates to the field of satellite navigation technologies, and in particular, to a method and apparatus for capturing a PN code, a storage medium, and an electronic device.
Background
In a low-orbit satellite spread spectrum communication system, due to high-speed motion among satellites, a carrier wave when reaching a receiving end has large Doppler frequency offset, and great difficulty is brought to a receiver for signal acquisition. It has been difficult for a common one-dimensional search to meet the requirement for fast acquisition of Pseudo codes (also known as PN codes, all english called Pseudo-Noise codes), and how to achieve fast acquisition of PN codes has become a problem of concern to those skilled in the art.
Disclosure of Invention
An object of the present application is to provide a method, an apparatus, a storage medium and an electronic device for acquiring a PN code, so as to at least partially improve the above-mentioned problems.
In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:
in a first aspect, an embodiment of the present application provides a method for capturing a PN code, where the method includes:
acquiring a window signal, wherein the window signal is a signal sent by a satellite terminal to a receiver, and comprises N symbols;
taking a T-th group PN sequence from PN codes, wherein the T-th group PN sequence comprises PN sequences from (T-1) K+1 phases to T multiplied by K phases;
acquiring a non-correlation peak value based on the N symbols and the T-th group PN sequences;
and under the condition that the non-correlation peak value meets the threshold requirement, determining the PN sequence corresponding to the non-correlation peak value as a captured target sequence.
In a second aspect, an embodiment of the present application provides a PN code acquisition apparatus, including:
the information acquisition unit is used for acquiring window signals, wherein the window signals are signals sent to the receiver by the satellite terminal, and the window signals comprise N symbols;
a processing unit, configured to take a T-th group of PN sequences from a PN code, where the T-th group of PN sequences includes a (T-1) k+1-th phase PN sequence to a t×k-th phase PN sequence;
the processing unit is further configured to obtain a non-correlation peak value based on the N symbols and the T-th group PN sequence;
the processing unit is further configured to determine a PN sequence corresponding to the non-correlation peak as a captured target sequence if the non-correlation peak meets a threshold requirement.
In a third aspect, embodiments of the present application provide a storage medium having stored thereon a computer program which, when executed by a processor, implements the method described above.
In a fourth aspect, an embodiment of the present application provides an electronic device, including: a processor and a memory for storing one or more programs; the above-described method is implemented when the one or more programs are executed by the processor.
Compared with the prior art, the PN code capturing method, the PN code capturing device, the storage medium and the electronic equipment provided by the embodiment of the application comprise the following steps: acquiring a window signal, wherein the window signal is a signal sent by a satellite terminal to a receiver, and comprises N symbols; taking a T-th group PN sequence from the PN code, wherein the T-th group PN sequence comprises PN sequences from a (T-1) K+1st phase to a T×K-th phase; acquiring a non-correlation peak value based on N symbols and a T group PN sequence; and under the condition that the non-correlation peak value meets the threshold requirement, determining the PN sequence corresponding to the non-correlation peak value as the captured target sequence. By introducing the method of non-correlation accumulation to obtain the non-correlation peak values belonging to N symbols and the T-th PN sequences, combining the self-adaptive threshold judgment and carrying out parallel search on the pseudo code phases, the problems of low gain, low acquisition probability and low acquisition speed of the traditional acquisition algorithm under the conditions of low signal-to-noise ratio, high dynamic and large Doppler can be solved.
In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting in scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of an electronic device according to an embodiment of the present application;
fig. 2 is a schematic flow chart of a PN code acquisition method according to an embodiment of the present application;
fig. 3 is a second flowchart of a PN code acquisition method according to an embodiment of the present disclosure;
fig. 4 is a third flowchart of a PN code acquisition method according to an embodiment of the present disclosure;
FIG. 5 is a block diagram of an i-th target vector acquisition flow provided in an embodiment of the present application;
fig. 6 is a schematic unit diagram of a PN code acquisition apparatus according to an embodiment of the present application.
In the figure: 10-a processor; 11-memory; 12-bus; 13-a communication interface; 201-an information acquisition unit; 202-a processing unit.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present application, as provided in the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, in the description of the present application, the terms "first", "second", and the like are used only to distinguish the description, and are not to be construed as indicating or implying relative importance.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
In the description of the present application, it should be noted that, the terms "upper," "lower," "inner," "outer," and the like indicate an orientation or a positional relationship based on the orientation or the positional relationship shown in the drawings, or an orientation or a positional relationship conventionally put in use of the product of the application, merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application.
In the description of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.
Some embodiments of the present application are described in detail below with reference to the accompanying drawings. The following embodiments and features of the embodiments may be combined with each other without conflict.
For capturing the signal of the spread spectrum communication system, the method can be alternatively implemented by adopting a sliding correlator method, a matched filter method, a capturing algorithm based on fast fourier transform (Fast Fourier Transform, abbreviated as FFT) and the like.
The sliding correlator method adopts a serial search strategy to carry out two-dimensional acquisition on carrier Doppler and pseudo code phase, and has the defects of low acquisition speed and reduced output gain under large Doppler frequency shift. Similarly, although the matched filter method can achieve quick capture of pseudo codes, the matched filter method consumes large hardware resources, and is difficult to be applied to engineering in the satellite field. The fast acquisition algorithm based on the Fourier transform and the inverse Fourier transform converts the two-dimensional search of the carrier wave and the pseudo code into the one-dimensional search only aiming at the pseudo code, so that the acquisition time is reduced, however, in order to obtain more accurate Doppler frequency shift estimation, the calculation point number of the fast Fourier transform must be increased, and the acquisition time and the resource consumption of the system are increased.
In a low-orbit satellite spread spectrum communication system, due to high-speed motion among satellites, a carrier wave when reaching a receiving end has large Doppler frequency offset, which brings great difficulty to a receiver for signal acquisition. Conventional one-dimensional searches have had difficulty meeting the fast capture requirements for pseudo code.
In an alternative embodiment, a matched filter may be combined with an FFT to implement a fast acquisition PMF-FFT (PMF-FFT, part Matched Filtering-Fast Fourier Transformation) acquisition algorithm that combines the advantages of both the matched filter and the FFT algorithm, thereby enabling acquisition of signals with greater doppler shift while reducing acquisition time. Povey gives a mathematical model of the PMF-FFT algorithm at the same time, and analyzes capturing performances such as false alarm probability, capturing probability and the like of the algorithm under Gaussian noise. The PMF-FFT acquisition algorithm solves the difficult problems of pseudo code synchronous acquisition under low signal-to-noise ratio, high dynamic and large Doppler frequency offset.
However, there are still two problems with PMF-FFT acquisition algorithms: scallop loss problems and related loss problems. Through research on scallop loss problems and related loss problems, alternative improved methods are provided.
For example, two methods of zero padding and windowing of input data are provided for improving scallop loss; regarding the correlation loss, in the case of code pattern determination, the correlation loss depends on the size of the doppler shift and the length of the matched filter, and it is known that the smaller the length of the matched filter, the smaller the correlation loss, but the larger the correlator scale is, the greater the implementation complexity is, so that a suitable length of the matched filter can be selected as required.
When the signal-to-noise ratio is low and the Doppler frequency offset is particularly large, the correlation peak value obtained by the PMF-FFT acquisition algorithm is not obvious, and the PN code cannot be solved. In order to overcome the problem, the embodiment of the application also provides a PN code capturing method, and provides an improvement mode of incoherent accumulation aiming at the problem of unobvious correlation peak value, so that the problem can be overcome, and PN codes can be captured quickly.
The embodiment of the application provides electronic equipment which can be mobile phone equipment (such as a satellite phone), computer equipment and control equipment of a carrier. Referring to fig. 1, a schematic structure of an electronic device is shown. The electronic device comprises a processor 10, a memory 11, a bus 12. The processor 10 and the memory 11 are connected by a bus 12, the processor 10 being adapted to execute executable modules, such as computer programs, stored in the memory 11.
The processor 10 may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the PN code acquisition method may be accomplished by integrated logic circuitry of hardware or instructions in software form in the processor 10. The processor 10 may be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU for short), a network processor (Network Processor, NP for short), etc.; but also digital signal processors (Digital Signal Processor, DSP for short), application specific integrated circuits (Application Specific Integrated Circuit, ASIC for short), field-programmable gate arrays (Field-Programmable Gate Array, FPGA for short) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.
The memory 11 may comprise a high-speed random access memory (RAM: random Access Memory) and may also comprise a non-volatile memory (non-volatile memory), such as at least one disk memory.
Bus 12 may be a ISA (Industry Standard Architecture) bus, PCI (Peripheral Component Interconnect) bus, EISA (Extended Industry Standard Architecture) bus, or the like. Only one double-headed arrow is shown in fig. 1, but not only one bus 12 or one type of bus 12.
The memory 11 is used for storing programs, such as programs corresponding to the PN code acquisition means. The PN code acquisition means comprises at least one software function module which may be stored in the memory 11 in the form of software or firmware (firmware) or cured in the Operating System (OS) of the electronic device. The processor 10, upon receiving the execution instruction, executes the program to implement the PN code acquisition method.
Possibly, the electronic device provided in the embodiment of the present application further includes a communication interface 13. The communication interface 13 is connected to the processor 10 via a bus.
The electronic device is further provided with a receiver which can receive a continuous signal transmitted by the satellite terminal, and the continuous signal is a spread spectrum signal. The signal received by the receiver may be processed by the processor 10 to complete the acquisition of the PN code, which aims at aligning the spreading code phase, providing a basis for subsequent despreading.
It should be understood that the structure shown in fig. 1 is a schematic structural diagram of only a portion of an electronic device, which may also include more or fewer components than shown in fig. 1, or have a different configuration than shown in fig. 1. The components shown in fig. 1 may be implemented in hardware, software, or a combination thereof.
The method for capturing a PN code provided in the embodiment of the present application may be applied to, but not limited to, the electronic device shown in fig. 1, and referring to fig. 2, the method for capturing a PN code includes: s101, S103, S104, S105, and S106 are specifically described below.
S101, acquiring a window signal.
The window signal is a signal sent by the satellite terminal to the receiver, and the window signal comprises N symbols.
It should be noted that, the signal received by the receiver and transmitted by the satellite terminal is a continuous signal, which includes continuous symbols. Wherein, the symbols in the continuous signal are constellation mapped symbols. The satellite terminal can perform L-time spread spectrum on each symbol when transmitting signals, and the receiver extracts twice data, namely twice sampling data when receiving signals, wherein each symbol contains H sampling data, and h=2×l.
The window signal is a segment of the received continuous signal. Optionally, the continuous signal received by the receiver includes S symbols in total, S.gtoreq.N, the S-th window signal includes S-th symbol to s+N-1-th symbol, for example, the first window signal includes 1-th symbol to N-th symbol, the second window signal includes 2-th symbol to N+1-th symbol, s+N-1.ltoreq.S, s.gtoreq.1.
S103, taking the T-th group PN sequence from the PN codes.
Wherein the T-th PN sequence includes PN sequences of (T-1) K+1st phase to T×K-th phase.
Alternatively, the total length of the PN code is L, i.e., the total phase in the PN code is L, where L is the same as the spreading factor L in the foregoing.
Optionally, the initial value of T is 1, the 1 st group of PN sequences includes the 1 st phase PN sequence to the K th phase PN sequence, the 2 nd group of PN sequences includes the k+1st phase PN sequence to the 2K nd phase PN sequence, and so on.
S104, acquiring a non-correlation peak value based on the N symbols and the T group PN sequences.
Alternatively, the uncorrelated peaks belonging to the N symbols and T-th group of PN sequences are obtained by introducing uncorrelated accumulation.
S105, determining whether the non-correlation peak value meets the threshold requirement. If yes, executing S106; if not, executing other or ending.
It should be noted that, when the non-correlation peak value is greater than or equal to the preset threshold value, it is determined that the non-correlation peak value meets the threshold requirement, and S106 is executed. And when the non-correlation peak value is smaller than the preset threshold value, determining that the non-correlation peak value does not meet the threshold requirement, and executing other or ending.
S106, determining the PN sequence corresponding to the non-correlation peak value as the captured target sequence.
Optionally, when the non-correlation peak meets the threshold requirement, the non-correlation peak is a start peak, and the start peak confirmation mechanism confirms the PN phase corresponding to the start peak.
In the scheme, the problems of low gain, low capturing probability and low capturing speed of the traditional capturing algorithm under the conditions of low signal-to-noise ratio, high dynamic and large Doppler can be solved by introducing a method of non-correlation accumulation to acquire non-correlation peaks belonging to N symbols and T-th PN sequences, combining self-adaptive threshold judgment and carrying out parallel searching on pseudo code phases.
On the basis of fig. 2, regarding how to implement fast acquisition of the PN code in the case where the non-correlation peak does not meet the threshold requirement, the embodiment of the present application further provides an optional implementation, referring to fig. 3, where the method for acquiring the PN code further includes: s107 and S108 are specifically described below.
S107, determining whether T+1 is smaller than a first preset value. If yes, executing S108; if not, executing other or ending.
Alternatively, in the case where the execution result of S105 is no, that is, the non-correlation peak does not satisfy the threshold requirement, S107 is executed.
Wherein the first preset value is related to the value of L and the value of K, optionally, the first preset value=l/K.
It should be noted that, when t+1 is smaller than the first preset value, it is noted that the search of all PN codes is not yet completed, and S108 needs to be performed. Otherwise, the other or end is performed.
S108, let t=t+1.
Optionally, after S108, S103 is re-executed, where the T-th group of PN sequences is taken from the PN code until the non-correlation peak meets the threshold requirement or t+1 is equal to the first preset value.
It should be noted that, at the time of re-executing S103, since the value of T has already changed, the contents of the T-th group PN sequence will also change accordingly.
In order to solve the problem of doppler frequency offset on the basis of fig. 3, the present application further provides an optional implementation manner, referring to fig. 4, in S101, after acquiring the window signal, the PN code acquisition method further includes: s102, when T+1 is equal to a first preset value, the PN code capturing method further comprises the following steps: s109 and S110 are specifically described below.
S102, taking the R-th frequency point in a preset frequency offset range, and performing frequency offset compensation on N symbols.
Optionally, frequency scanning is performed first (frequency scanning is performed on a signal received by the receiver), an R-th frequency point is determined from a preset frequency offset range, and frequency offset compensation is performed on N symbols based on the R-th frequency point.
When the execution result of S107 is no, t+1 is equal to the first preset value, S109 is executed.
S109, determining whether R+1 is smaller than a second preset value. If yes, executing S110; if not, executing other or ending.
Optionally, the second preset value is the number of frequency points in the preset frequency offset range.
It should be noted that when r+1 is equal to the second preset value, it indicates that all frequency points are searched, but the threshold requirement is still not satisfied, and other operations need to be performed, which may be, but are not limited to, the next window signal. If r+1 is smaller than the second preset value, S110 is executed to continue searching.
S110, let r=r+1, t=1.
After executing S110, re-executing S102, re-fetching the R-th frequency point in the preset frequency offset range, performing frequency offset compensation on the N symbols, and fetching the T-th PN sequence from the PN code until the non-correlation peak value meets the threshold requirement or R+1 is equal to a second preset value.
On the basis of the foregoing, with regard to the content in S104, the embodiment of the present application further provides an optional implementation, please refer to the following, S104, the step of acquiring the non-correlation peak based on the N symbols and the T-th group PN sequence, which includes: s104-1, S104-2, S104-3, S104-4, S104-5 and S104-6 are described in detail below.
S104-1, dividing an nth symbol in the window signal into P segments of data sets, wherein N is more than or equal to 1 and less than or equal to N, each symbol comprises H pieces of sampling data, and each segment of data set comprises H/P pieces of sampling data.
S104-2, dividing the PN sequence of the ith phase in the T-th group PN sequence into P-segment subsequences, wherein i is more than or equal to 1 and less than or equal to K.
S104-3, carrying out correlation operation on the P-th sub-sequence in the PN sequence of the i-th phase and the P-th data set in the n-th symbol, and summing to obtain the P-th correlation sum value of the PN sequence of the i-th phase and the n-th symbol, wherein P is more than or equal to 1 and less than or equal to P.
S104-4, carrying out Fourier operation on the P correlation sum values of the PN sequence of the ith phase and the nth symbol to obtain a module value vector of the PN sequence of the ith phase and the nth symbol, wherein the module value vector comprises P module values.
Optionally, P-point fourier operation is performed on the P correlation sums, and each complex number in the operation result of the fourier operation is subjected to modulo value to obtain P modulo values, i.e. a modulo value vector is obtained. Optionally, the p-th modulus value corresponds to the p-th correlation sum value.
It should be noted that, the steps corresponding to S104-3 and S104-4 are performed on the PN sequence and the N symbols of the ith phase, so that N modulus vectors are obtained.
S104-5, performing uncorrelated accumulation on the PN sequence of the ith phase and N modular value vectors of the window signal to obtain a target vector.
It should be noted that, the correlation operation is performed on the PN sequence of the ith phase and the window signal (including N symbols), so as to obtain a module value vector of the PN sequence of the ith phase and the N symbols, and N module value vectors can be obtained in total, and the N module value vectors are subjected to uncorrelated accumulation, so as to obtain the target vector.
Assume that a total of 2 module vectors, (1, 2, 3) and (3, 5, 7), respectively, are uncorrelated accumulated, i.e., corresponding point added, resulting in a target vector of (1+3=4, 2+5=7, 3+7=10), which is illustrated herein.
It should be noted that, the T-th group of PN sequences has K phases, and each phase of the PN sequence corresponds to a target vector.
S104-6, determining a non-correlation peak value from K target vectors corresponding to the window signal, wherein the non-correlation peak value is the maximum value in the K target vectors.
Alternatively, when the non-correlation peak is the maximum value of the PN sequence of the ith phase and the target vector (i.e., the ith target vector) of the window signal, the PN sequence of the ith phase is the target sequence.
On the basis of the foregoing, regarding the content in S104-6, an alternative implementation manner is further provided in the embodiments of the present application, please refer to the following. S104-6, determining a non-correlation peak value from K target vectors corresponding to the window signal, wherein the step comprises the following steps: S104-6A and S104-6B are described in detail below.
S104-6A, determining the maximum value in each target vector as a waiting value.
Optionally, the maximum value in the ith target vector is Mi, i is more than or equal to 1 and less than or equal to K, and Mi is the waiting value.
With continued reference to the above example, the target vector is (4, 7, 10), then Mi is 10.
And S104-6B, determining the maximum one of the K waiting values as a non-correlation peak value.
Alternatively, the largest one is determined from the K waiting values (Mi) as the non-correlation peak.
On the basis of the foregoing, regarding the content in S104-3, an alternative implementation manner is further provided in the embodiments of the present application, please refer to the following. S104-3, carrying out correlation operation on a p-th sub-sequence in the PN sequence of the i-th phase and a p-th data set in the n-th symbol, and summing to obtain a p-th correlation sum value of the PN sequence of the i-th phase and the n-th symbol, wherein the step comprises the following steps: S104-3A and S104-3B are described in detail below.
S104-3A, inputting the p-th sub-sequence in the PN sequence of the i-th phase and the p-th data set in the n-th symbol into the p-th autocorrelator.
S104-3B, the p-th autocorrelator carries out correlation operation and summation, and outputs the p-th correlation summation value of the PN sequence of the i-th phase and the n-th symbol.
Referring to fig. 5, fig. 5 is a block diagram of an i-th target vector obtaining flow provided in an embodiment of the present application.
In a low-orbit satellite spread spectrum communication system, a satellite terminal performs 1024 times of spread spectrum, when EsN (Ratio of symbol energy to noise power spectral density) is-29 dB and frequency offset is set to 8 times of symbol rate (before spread spectrum), the difference between the result of comparing the result of non-coherent accumulation and the result of peak value comparison after non-coherent accumulation is obvious, the result of non-coherent accumulation is not used, no peak value exists, and the peak value is obvious after non-coherent accumulation.
Referring to fig. 6, fig. 6 is a schematic diagram illustrating an embodiment of a PN code acquisition apparatus, which is optionally applied to the electronic device described above.
The PN code acquisition device comprises: an information acquisition unit 201, and a processing unit 202.
An information obtaining unit 201, configured to obtain a window signal, where the window signal is a signal sent by a satellite terminal to a receiver, and the window signal includes N symbols;
a processing unit 202 for taking a T-th group PN sequence from the PN code, wherein the T-th group PN sequence includes a (T-1) k+1st phase PN sequence to a t×k th phase PN sequence;
the processing unit 202 is further configured to obtain a non-correlation peak value based on the N symbols and the T-th group PN sequence;
the processing unit 202 is further configured to determine a PN sequence corresponding to the non-correlation peak as the captured target sequence if the non-correlation peak meets a threshold requirement.
Alternatively, the information acquisition unit 201 may perform S101 described above, and the processing unit 202 may perform S102 to S110 described above.
Optionally, acquiring the non-correlation peak based on the N symbols and the T-th group PN sequence includes: dividing an nth symbol in the window signal into P segments of data sets, wherein N is more than or equal to 1 and less than or equal to N, each symbol comprises H pieces of sampling data, and each segment of data set comprises H/P pieces of sampling data; dividing the PN sequence of the ith phase in the PN sequence of the T group into P-segment subsequences, wherein i is more than or equal to 1 and less than or equal to K; carrying out correlation operation on a P-th sub-sequence in the PN sequence of the i-th phase and a P-th data set in the n-th symbol, and summing to obtain a P-th correlation sum value of the PN sequence of the i-th phase and the n-th symbol, wherein P is more than or equal to 1 and less than or equal to P; performing Fourier operation on the P correlation sum values of the PN sequence of the ith phase and the nth symbol to obtain a module value vector of the PN sequence of the ith phase and the nth symbol, wherein the module value vector comprises P module values; performing uncorrelated accumulation on the PN sequence of the ith phase and N modular value vectors of the window signal to obtain a target vector; and determining a non-correlation peak value from K target vectors corresponding to the window signal, wherein the non-correlation peak value is the maximum value in the K target vectors.
It should be noted that, the PN code acquisition apparatus provided in this embodiment may execute the method flow shown in the method flow embodiment to achieve the corresponding technical effects. For a brief description, reference is made to the corresponding parts of the above embodiments, where this embodiment is not mentioned.
The present application also provides a storage medium storing computer instructions, a program which when read and executed perform the PN code acquisition method of the above embodiments. The storage medium may include memory, flash memory, registers, combinations thereof, or the like.
An electronic device, such as a mobile phone device (for example, a satellite phone), a computer device, and a control device of a vehicle, is provided below, where the electronic device is shown in fig. 1, and the above-mentioned PN code acquisition method may be implemented; specifically, the electronic device includes: a processor 10, a memory 11, a bus 12. The processor 10 may be a CPU. The memory 11 is used to store one or more programs that, when executed by the processor 10, perform the PN code acquisition method of the above-described embodiments.
In summary, the method, the device, the storage medium and the electronic device for capturing the PN code provided in the embodiments of the present application include: acquiring a window signal, wherein the window signal is a signal sent by a satellite terminal to a receiver, and comprises N symbols; taking a T-th group PN sequence from the PN code, wherein the T-th group PN sequence comprises PN sequences from a (T-1) K+1st phase to a T×K-th phase; acquiring a non-correlation peak value based on N symbols and a T group PN sequence; and under the condition that the non-correlation peak value meets the threshold requirement, determining the PN sequence corresponding to the non-correlation peak value as the captured target sequence. By introducing the method of non-correlation accumulation to obtain the non-correlation peak values belonging to N symbols and the T-th PN sequences, combining the self-adaptive threshold judgment and carrying out parallel search on the pseudo code phases, the problems of low gain, low acquisition probability and low acquisition speed of the traditional acquisition algorithm under the conditions of low signal-to-noise ratio, high dynamic and large Doppler can be solved.
The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
It will be evident to those skilled in the art that the present application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Claims (10)
1. A method of acquiring a PN code, the method comprising:
acquiring a window signal, wherein the window signal is a signal sent by a satellite terminal to a receiver, and comprises N symbols;
taking a T-th group PN sequence from PN codes, wherein the T-th group PN sequence comprises PN sequences from (T-1) K+1 phases to T multiplied by K phases;
acquiring a non-correlation peak value based on the N symbols and the T-th group PN sequences;
and under the condition that the non-correlation peak value meets the threshold requirement, determining the PN sequence corresponding to the non-correlation peak value as a captured target sequence.
2. The PN code acquisition method of claim 1, further comprising:
under the condition that the non-correlation peak value does not meet the threshold requirement, determining whether T+1 is smaller than a first preset value;
if t+1 is smaller than the first preset value, t=t+1 is set, and the T-th group PN sequence is re-extracted from the PN code until the non-correlation peak satisfies the threshold requirement or t+1 is equal to the first preset value.
3. The PN code acquisition method of claim 2, further comprising, after said acquisition window signal:
taking an R-th frequency point in a preset frequency offset range, and performing frequency offset compensation on the N symbols;
when t+1 is equal to the first preset value, the method further comprises:
determining whether r+1 is less than a second preset value;
if r+1 is smaller than a second preset value, r=r+1 and t=1 are set, the R-th frequency point in the preset frequency offset range is re-fetched, frequency offset compensation is performed on the N symbols, and the T-th PN sequence is fetched from the PN code until the uncorrelated peak value meets a threshold requirement or r+1 is equal to the second preset value.
4. The PN code acquisition method of claim 1, wherein said step of acquiring a non-correlation peak based on said N symbols and said T-th set of PN sequences comprises:
dividing an nth symbol in the window signal into P segments of data sets, wherein N is more than or equal to 1 and less than or equal to N, each symbol comprises H pieces of sampling data, and each segment of data set comprises H/P pieces of sampling data;
dividing the PN sequence of the ith phase in the T-th PN sequence into P-segment subsequences, wherein i is more than or equal to 1 and less than or equal to K;
carrying out correlation operation on a P-th sub-sequence in the PN sequence of the i-th phase and a P-th data set in the n-th symbol, and summing to obtain a P-th correlation sum value of the PN sequence of the i-th phase and the n-th symbol, wherein P is more than or equal to 1 and less than or equal to P;
performing fourier operation on the P correlation sums of the PN sequence of the i-th phase and the n-th symbol to obtain a modulus vector of the PN sequence of the i-th phase and the n-th symbol, wherein the modulus vector comprises P modulus values;
performing uncorrelated accumulation on the PN sequence of the ith phase and N modular value vectors of the window signal to obtain a target vector;
and determining a non-correlation peak value from K target vectors corresponding to the window signal, wherein the non-correlation peak value is the maximum value in the K target vectors.
5. The PN code acquisition method of claim 4, wherein said step of determining a non-correlation peak from K of said target vectors corresponding to said window signal comprises:
determining the maximum value in each target vector as a to-be-determined value;
and determining the maximum one of the K waiting values as the non-correlation peak value.
6. The PN code acquisition method of claim 4 wherein said step of correlating and summing the p-th sub-sequence in the PN sequence of the i-th phase and the p-th data set in the n-th symbol to obtain the p-th correlation sum of the PN sequence of the i-th phase and the n-th symbol comprises:
inputting the p-th sub-sequence in the PN sequence of the i-th phase and the p-th data set in the n-th symbol into a p-th autocorrelator;
and the p-th autocorrelator carries out correlation operation and summation, and outputs the p-th correlation summation value of the PN sequence of the i-th phase and the n-th symbol.
7. A PN code acquisition apparatus, said apparatus comprising:
the information acquisition unit is used for acquiring window signals, wherein the window signals are signals sent to the receiver by the satellite terminal, and the window signals comprise N symbols;
a processing unit, configured to take a T-th group of PN sequences from a PN code, where the T-th group of PN sequences includes a (T-1) k+1-th phase PN sequence to a t×k-th phase PN sequence;
the processing unit is further configured to obtain a non-correlation peak value based on the N symbols and the T-th group PN sequence;
the processing unit is further configured to determine a PN sequence corresponding to the non-correlation peak as a captured target sequence if the non-correlation peak meets a threshold requirement.
8. The PN code acquisition apparatus of claim 7 wherein said obtaining non-correlation peaks based on said N symbols and said T-th set of PN sequences comprises:
dividing an nth symbol in the window signal into P segments of data sets, wherein N is more than or equal to 1 and less than or equal to N, each symbol comprises H pieces of sampling data, and each segment of data set comprises H/P pieces of sampling data;
dividing the PN sequence of the ith phase in the T-th PN sequence into P-segment subsequences, wherein i is more than or equal to 1 and less than or equal to K;
carrying out correlation operation on a P-th sub-sequence in the PN sequence of the i-th phase and a P-th data set in the n-th symbol, and summing to obtain a P-th correlation sum value of the PN sequence of the i-th phase and the n-th symbol, wherein P is more than or equal to 1 and less than or equal to P;
performing fourier operation on the P correlation sums of the PN sequence of the i-th phase and the n-th symbol to obtain a modulus vector of the PN sequence of the i-th phase and the n-th symbol, wherein the modulus vector comprises P modulus values;
performing uncorrelated accumulation on the PN sequence of the ith phase and N modular value vectors of the window signal to obtain a target vector;
and determining a non-correlation peak value from K target vectors corresponding to the window signal, wherein the non-correlation peak value is the maximum value in the K target vectors.
9. A computer readable storage medium, on which a computer program is stored, which computer program, when being executed by a processor, implements the method according to any of claims 1-6.
10. An electronic device, comprising: a processor and a memory for storing one or more programs; the method of any of claims 1-6 is implemented when the one or more programs are executed by the processor.
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