CN113589336B - BOC signal non-fuzzy capture method based on side peak elimination - Google Patents
BOC signal non-fuzzy capture method based on side peak elimination Download PDFInfo
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Abstract
The application relates to a BOC signal non-fuzzy capture method based on side peak elimination. The method comprises the steps of constructing a local waveform, generating a local code waveform signal, respectively carrying out correlation accumulation on I, Q branch signals of the local BOC signal and an input signal to obtain I, Q branch related signals of a BOC signal autocorrelation synthesis function and I, Q branch related signals of a BOC signal and local code waveform cross-correlation function, carrying out incoherent dot product detection processing on the four branch related signals to construct a nonlinear ambiguity-free captured decision synthesis function, and completing capture decision according to the ambiguity-free captured decision synthesis function and a preset capture threshold. The BOC capturing method provided by the invention can realize fuzzy-free capturing of the BOC signal, has small carrier-to-noise ratio attenuation, is suitable for BOC signals with different orders, and has capturing performance superior to that of the traditional capturing algorithm.
Description
Technical Field
The application relates to the technical field of satellite navigation signal receiving, in particular to a BOC signal non-fuzzy acquisition method based on side peak elimination.
Background
The global satellite navigation system is a technology integrating the aspects of traditional radio navigation, astronomical surveying and mapping and the like, provides global, all-weather, continuous and real-time positioning, navigation and time service for users, continuously develops along with the system and the technology, the number of the satellite systems is continuously increased, the frequency band is more and more crowded, the traditional BPSK modulation mode cannot meet all the requirements, and the BOC modulation signal can more fully utilize the frequency band resource and has better code tracking precision and anti-interference capability, so the existing satellite navigation system widely adopts the BOC modulation signal. The BOC modulation signal is modulated twice by using refuting subcarriers on the basis of the traditional BPSK modulation, so that spectrum splitting is realized, and an autocorrelation function of the BOC modulation signal is multimodal, so that difficulty is brought to capture and ambiguity is generated in capture, and thus a non-ambiguity capture technology of the BOC is widely concerned. At present, the main non-fuzzy capture methods comprise a Bump-Jump method, a BPSK-like method and a side peak elimination method, wherein the Bump-Jump method, the BPSK-like method and the side peak elimination method both need additional auxiliary means and need to consume additional resources when being realized. Another class of capture methods has emerged to overcome the previous few non-ambiguous capture methods: the method adopts a non-matched filtering method for receiving, locally generates a group of local codes, and performs related combination with a received signal to enable a combination function of the local codes to have no side peak, so that non-fuzzy capture is realized.
Disclosure of Invention
In view of the foregoing, it is necessary to provide a BOC signal unambiguous acquisition method based on side peak cancellation. According to the method, a local code waveform is constructed according to the condition of side peak elimination, and then the fuzzy capture of the BOC signal is realized with smaller capture performance loss by combining a detection method of incoherent dot product.
A BOC signal unambiguous acquisition method based on side-peak cancellation, the method comprising:
and receiving a BOC signal in a capture channel, and carrying out carrier stripping on the BOC signal.
A local code waveform and a local BOC signal are constructed from the spreading codes.
And respectively carrying out correlation accumulation on the BOC signal subjected to carrier stripping, the local code waveform and the local BOC signal to obtain I, Q branch correlation signals of an autocorrelation synthesis function of the BOC signal and I, Q branch correlation signals of a cross-correlation synthesis function of the BOC signal and the local code waveform.
And constructing a decision synthesis function without fuzzy capture for eliminating side peaks by adopting a non-coherent dot product detection method according to I, Q branch related signals of an autocorrelation synthesis function of the BOC signal and I, Q branch related signals of a cross-correlation synthesis function of the BOC signal and a local code waveform.
And completing the capturing judgment according to the judgment synthesis function of the fuzzy-free capturing and a preset capturing threshold.
In one embodiment, the BOC signal includes a sine BOC signal and a cosine BOC signal; constructing a local code waveform and a local BOC signal from a spreading code, comprising:
when the BOC signal is a sine BOC signal, constructing a local code waveform according to the spreading code; the local code waveform is:
wherein:represents the local code waveform of a sinusoidal BOC signal,T cis the chip period of the pseudo-random code,T sis the chip period of the square wave sub-carrier,Mdefined as the order of the received BOC signal;
when the BOC signal is a cosine BOC signal, constructing a local code waveform according to the spreading code; the local code waveform is:
whereinRespectively representing the local code waveforms of the cosine BOC signal at different time periods,T cis the chip period of the pseudo-random code,T sis the chip period of the square wave sub-carrier,Mdefined as the order in which the BOC signal is received.
In one embodiment, the stripped BOC signal includes two sets of stripped signals consisting of an in-phase signal and a quadrature signal;
respectively carrying out correlation accumulation on the BOC signal after carrier stripping, the local code waveform and the local BOC signal to obtain I, Q branch correlation signals of an autocorrelation synthesis function of the BOC signal and I, Q branch correlation signals of a cross-correlation synthesis function of the BOC signal and the local code waveform, wherein the correlation accumulation comprises the following steps:
carrying out correlation accumulation on the in-phase signals of the first group of stripping signals and the local code waveform to obtain I branch correlation signals of an autocorrelation synthesis function; carrying out correlation accumulation on the orthogonal signals of the first group of stripping signals and the local BOC signal to obtain Q branch correlation signals of the autocorrelation synthesis function;
carrying out correlation accumulation on the in-phase signals of the second group of stripped signals and the local code waveform to obtain I branch correlation signals of a cross-correlation synthesis function; and carrying out correlation accumulation on the orthogonal signals of the second group of stripping signals and the local BOC signals to obtain Q branch correlation signals of the cross-correlation synthesis function.
In one embodiment, when the BOC signal is a sinusoidal BOC signal:
expressions of an I branch related signal of the autocorrelation combining function, a Q branch related signal of the autocorrelation combining function, an I branch related signal of the cross-correlation combining function, and a Q branch related signal of the cross-correlation combining function are:
wherein,an I branch correlation signal representing an autocorrelation composition function,a Q branch correlation signal representing an autocorrelation composition function,representing local code waveformsThe I branch correlation signal of the synthesis function is cross-correlated with the sinusoidal BOC signal,representing local code waveformsThe Q branch correlation signal of the synthesis function is cross-correlated with the sinusoidal BOC signal,which represents the carrier-to-noise ratio of the received signal,which is indicative of the residual doppler frequency of the doppler,T p which represents the duration of the coherent integration,is expressed in chip periodsT c Is the code phase delay in units of a unit,represents the autocorrelation function of the BOC signal,representing sinusoidal BOC signals and local code waveformsCross correlation function of,Which is indicative of the phase error of the correlator output,、、、is the normalized noise term of the correlator output.
In one embodiment, when the BOC signal is a cosine BOC signal:
the expression of the I, Q branch correlation signal of the cross-correlation synthesis function is:
wherein,representing local codesThe I branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,representing local code waveformsThe Q branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,representing local codesWave formThe I branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,representing local code waveformsThe Q branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,ka sequence number representing the signal of interest is indicated,which represents the carrier-to-noise ratio of the received signal,which is indicative of the residual doppler frequency of the doppler,T p which represents the duration of the coherent integration,is expressed in chip periodsT c Is the code phase delay in units of a unit,、local code waveforms respectively representing cosine BOC signals and different time periods、The cross-correlation function of (a) is,、、、is the normalized noise term of the correlator output.
In one embodiment, a decision synthesis function without ambiguity acquisition for eliminating side peaks is constructed by a detection method of incoherent dot product according to I, Q branch correlation signals of an autocorrelation synthesis function of a BOC signal and I, Q branch correlation signals of a cross-correlation synthesis function of the BOC signal and a local code waveform, and the decision synthesis function comprises the following steps:
and respectively adopting a non-coherent dot product detection method for the I branch related signal of the autocorrelation synthesis function and the Q branch related signal of the cross-correlation synthesis function to obtain a first group of BOC signal autocorrelation functions and the cross-correlation functions of the BOC signals and local code waveforms.
And obtaining a first decision synthesis function according to the first group of BOC signal autocorrelation functions and the BOC signal and local code waveform cross-correlation functions.
And respectively adopting a non-coherent dot product detection method for the Q branch related signal of the autocorrelation synthesis function and the I branch related signal of the cross-correlation synthesis function to obtain a second group of BOC signal autocorrelation functions and the cross-correlation functions of the BOC signals and the local code waveforms.
And obtaining a second decision synthesis function according to the second group of BOC signal autocorrelation functions and the BOC signal and local code waveform cross-correlation functions.
Adding the first decision synthesis function and the second decision synthesis function to obtain a decision synthesis function without fuzzy capture, wherein the side peak is eliminated; the decision synthesis function expression of the fuzzy capture-free method is as follows:
wherein,as a cross-correlation function of the local BOC signal and the BOC signal, is the cross-correlation function of the local code waveform with the BOC signal.
In one embodiment, the stripped BOC signal includes: two groups of stripped signals consisting of in-phase signals and quadrature signals; i, Q branch correlation signals of the cross-correlation synthesis functions comprise I, Q branch correlation signals of two groups of cross-correlation synthesis functions; according to I, Q branch related signals of an autocorrelation synthesis function of a BOC signal and I, Q branch related signals of a cross-correlation synthesis function of the BOC signal and a local code waveform, a detection method of incoherent dot product is adopted to construct a decision synthesis function without ambiguity capture for eliminating side peaks, and the decision synthesis function comprises the following steps:
when the BOC signal is a cosine BOC signal:
respectively adopting a non-coherent dot product detection method for I, Q branch related signals of an autocorrelation synthesis function and I, Q branch related signals of two groups of cross-correlation synthesis functions, and carrying out non-linear combination processing on signals obtained after detection to obtain a decision synthesis function without fuzzy capture, wherein the side peaks of the decision synthesis function are eliminated; the expression of the decision synthesis function of the blur-free capture is:
wherein,for local code waveformsThe cross-correlation function with the BOC signal,for local code waveformsCross correlation function with BOC signal.
In one embodiment, the completing the capturing decision according to the decision combining function of the blur-free capturing and a preset capturing threshold includes:
acquiring an envelope value of a decision synthesis function without fuzzy capture; and (4) carrying out post-accumulation on the envelope value of the decision synthesis function without fuzzy capture, and comparing a post-accumulation result with a preset capture threshold to finish capture decision.
The above-mentioned BOC signal no-ambiguity capture method based on side peak elimination, the method generates local code waveform signal and I, Q branch signals of local BOC signal and input signal to respectively carry out correlation accumulation, gets I, Q branch correlation signal of BOC signal autocorrelation synthesis function and I, Q branch correlation signal of BOC signal and local code waveform cross-correlation function, carries out incoherent dot product detection processing on these four branch correlation signals, constructs nonlinear no-ambiguity capture decision synthesis function, and completes capture decision according to the no-ambiguity capture decision synthesis function and preset capture threshold. The BOC capturing method provided by the invention can realize fuzzy-free capturing of the BOC signal, has small carrier-to-noise ratio attenuation, is suitable for BOC signals with different orders, and has capturing performance superior to that of the traditional capturing algorithm.
Drawings
FIG. 1 is a schematic flow chart illustrating a BOC signal unambiguous acquisition method based on side-peak elimination in one embodiment;
FIG. 2 is a schematic diagram of a sinusoidal phase BOC signal acquisition method according to another embodiment;
FIG. 3 is a schematic diagram of a local code waveform of a modulated signal of BOCs (14,2) in another embodiment;
FIG. 4 is a schematic diagram of the synthesized correlation function of the modulated BOCs (14,2) signal in another embodiment;
FIG. 5 is a block diagram of a method for acquiring a BOC signal in cosine phase according to another embodiment;
fig. 6 is a schematic diagram of a local code waveform of a BOCc (15,2.5) modulation signal in another embodiment, where (a) is a local code 1 waveform and (b) is a local code 2 waveform;
fig. 7 is a schematic diagram of a synthesized correlation function of a BOCc (15,2.5) modulated signal in another embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
The square wave subcarrier frequency of the BOC (m, n) modulated signal is definedIs composed ofFrequency of pseudo-random codeIs composed ofThe order of the received BOC (M, n) modulation signal is M, and the sinusoidal BOC modulation signal is abbreviated as BOCS(m, n), cosine BOC modulated Signal abbreviated BOCC(m,n)。
In one embodiment, as shown in fig. 1, there is provided a BOC signal unambiguous acquisition method based on side-peak elimination, the method comprising the steps of:
step 100: and receiving the BOC signal in the capture channel, and carrying out carrier stripping on the BOC signal.
Step 102: a local code waveform and a local BOC signal are constructed from the spreading codes.
Step 104: and respectively carrying out correlation accumulation on the BOC signal subjected to carrier stripping, the local code waveform and the local BOC signal to obtain I, Q branch correlation signals of an autocorrelation synthesis function of the BOC signal and I, Q branch correlation signals of a cross-correlation synthesis function of the BOC signal and the local code waveform.
Step 106: and constructing a decision synthesis function without fuzzy capture for eliminating side peaks by adopting a non-coherent dot product detection method according to I, Q branch related signals of an autocorrelation synthesis function of the BOC signal and I, Q branch related signals of a cross-correlation synthesis function of the BOC signal and a local code waveform.
Step 108: and completing the capturing judgment according to the judgment synthesis function of the non-fuzzy capturing and a preset capturing threshold.
In the above BOC signal non-ambiguity capturing method based on side peak elimination, the method generates local code waveform signals and I, Q branch signals of the local BOC signals and input signals respectively for correlation accumulation by constructing local waveforms to obtain I, Q branch correlation signals of a BOC signal autocorrelation synthesis function and I, Q branch correlation signals of a BOC signal and local code waveform cross-correlation function, performs incoherent dot product detection on the four branch correlation signals to construct a nonlinear decision synthesis function without ambiguity capturing, and completes capturing decision according to the decision synthesis function without ambiguity capturing and a preset capturing threshold. The BOC capturing method provided by the invention can realize fuzzy-free capturing of the BOC signal, has small carrier-to-noise ratio attenuation, is suitable for BOC signals with different orders, and has capturing performance superior to that of the traditional capturing algorithm.
In one embodiment, the BOC signal includes a sine BOC signal and a cosine BOC signal; step 102 comprises: when the BOC signal is a sine BOC signal, constructing a local code waveform according to the spreading code; the local code waveform expression is:
wherein:represents the local code waveform of a sinusoidal BOC signal,T cas pseudo-random codesThe chip period of (a) is,T sis the chip period of the square wave sub-carrier,Mdefined as the order in which the BOC signal is received. The local code has a waveform period ofT c。
When the BOC signal is a cosine BOC signal, constructing a local code waveform according to the spreading code; the local code waveform expression is:
whereinRespectively representing the local code waveforms of the cosine BOC signal at different time periods,T cis the chip period of the pseudo-random code,T sis the chip period of the square wave sub-carrier,Mdefined as the order in which the BOC signal is received.
In one embodiment, the stripped BOC signal includes two sets of stripped signals consisting of an in-phase signal and a quadrature signal; step 104 comprises: carrying out correlation accumulation on the in-phase signals of the first group of stripping signals and the local code waveform to obtain I branch correlation signals of the autocorrelation synthesis function; carrying out correlation accumulation on the orthogonal signals of the first group of stripping signals and the local BOC signals to obtain Q branch correlation signals of the autocorrelation synthesis function; carrying out correlation accumulation on the in-phase signals of the second group of stripping signals and the local code waveform to obtain I branch correlation signals of a cross-correlation synthesis function; and carrying out correlation accumulation on the orthogonal signals of the second group of stripping signals and the local BOC signals to obtain Q branch correlation signals of the cross-correlation synthesis function.
In one embodiment, in step 104, when the BOC signal is a sinusoidal BOC signal: expressions of an I branch related signal of the autocorrelation combining function, a Q branch related signal of the autocorrelation combining function, an I branch related signal of the cross-correlation combining function, and a Q branch related signal of the cross-correlation combining function are:
wherein,an I branch correlation signal representing an autocorrelation composition function,a Q branch correlation signal representing an autocorrelation composition function,representing local code waveformsThe I branch correlation signal of the synthesis function is cross-correlated with the sinusoidal BOC signal,representing local code waveformsThe Q branch correlation signal of the synthesis function is cross-correlated with the sinusoidal BOC signal,which represents the carrier-to-noise ratio of the received signal,which is indicative of the residual doppler frequency of the doppler,T p which represents the duration of the coherent integration,is expressed in chip periodsT c Is the code phase delay in units of a unit,represents the autocorrelation function of the BOC signal,representing sinusoidal BOC signals and local code waveformsThe cross-correlation function of (a) is,which is indicative of the phase error of the correlator output,、、、is the normalized noise term of the correlator output.
In one embodiment, in step 104, when the BOC signal is a cosine BOC signal: the expression for the I, Q branch correlation signal of the cross-correlation synthesis function is:
wherein, among others,representing local codesThe I branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,representing local code waveformsCross correlation synthesis function with cosine BOC signalThe Q-branch correlation signal of (1),representing local code waveformsThe I branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,representing local code waveformsThe Q branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,ka sequence number representing the signal of interest is indicated,which represents the carrier-to-noise ratio of the received signal,which is indicative of the residual doppler frequency of the doppler,T p which represents the duration of the coherent integration,is expressed in chip periodsT c Is the code phase delay in units of a unit,、local code waveforms respectively representing cosine BOC signals and different time periods、The cross-correlation function of (a) is,、、、is the normalized noise term of the correlator output.
In one embodiment, step 106 includes: respectively adopting a non-coherent dot product detection method for an I branch related signal of an autocorrelation synthesis function and a Q branch related signal of a cross-correlation synthesis function to obtain a first group of BOC signal autocorrelation functions and a cross-correlation function of BOC signals and local code waveforms; obtaining a first decision synthesis function according to the first group of BOC signal autocorrelation functions and the cross-correlation functions of the BOC signals and the local code waveforms; respectively adopting a non-coherent dot product detection method for a Q branch related signal of the autocorrelation synthesis function and an I branch related signal of the cross-correlation synthesis function to obtain a second group of BOC signal autocorrelation functions and a cross-correlation function of the BOC signal and a local code waveform; obtaining a second decision synthesis function according to the second group of BOC signal autocorrelation functions and the cross-correlation function of the BOC signal and the local code waveform; adding the first decision synthesis function and the second decision synthesis function to obtain a decision synthesis function without fuzzy capture, wherein the side peak is eliminated; the decision synthesis function expression for blur-free capture is:
wherein,as a cross-correlation function of the local BOC signal and the BOC signal, is the cross-correlation function of the local code waveform with the BOC signal.
In one embodiment, the stripped BOC signal includes: two groups of stripped signals consisting of in-phase signals and quadrature signals; i, Q branch correlation signals of the cross-correlation synthesis functions comprise I, Q branch correlation signals of two groups of cross-correlation synthesis functions; step 106 comprises: when the BOC signal is a cosine BOC signal:
respectively adopting a non-coherent dot product detection method for I, Q branch related signals of an autocorrelation synthesis function and I, Q branch related signals of two groups of cross-correlation synthesis functions, and carrying out non-linear combination processing on signals obtained after detection to obtain a decision synthesis function without fuzzy capture, wherein the side peaks of the decision synthesis function are eliminated; the expression of the decision synthesis function without fuzzy capture is:
wherein,for local code waveformsThe cross-correlation function with the BOC signal,for local code waveformsCross correlation function with BOC signal.
In one embodiment, step 108 includes: acquiring an envelope value of a decision synthesis function without fuzzy capture; and (4) carrying out post-accumulation on the envelope value of the decision synthesis function without fuzzy capture, and comparing a post-accumulation result with a preset capture threshold to finish capture decision.
It should be understood that, although the steps in the flowchart of fig. 1 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 1 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.
In one embodiment, a BOC is providedS(14,2) acquisition procedure and BOC of modulated SignalC(15,2.5) a capturing process.
(1) Based on BOCS(14,2) modulating the signal to provide an embodiment of the sinusoidal phase BOC signal capturing method, and as shown in fig. 2, a schematic structural diagram of the sinusoidal phase BOC signal capturing method is shown. When the BOC signal is a sine phase BOC signal, the BOC unambiguous capturing method based on the side peak elimination in the figure 2 is further explained, and the main steps comprise:
step S1: constructing local waveforms
Constructing a BOC according to equation (2)S(14,2) modulating the local waveform of the signal, the generated local code waveform is shown in fig. 3.
Step S2: correlation accumulation processing
As shown in fig. 3, according to the requirement in step S1, local code waveform signals and local BOC signals are locally generated, and are correlated and accumulated with the I, Q branch signals of the input signal, respectively, to generate I, Q branch correlation signals of the autocorrelation synthesis function of the BOC signals and I, Q branch correlation signals of the cross-correlation synthesis function of the BOC signals and the local code waveform, and the expression of the generated four-way correlation signals is shown in expression (3).
Step S3: incoherent dot product detection
Performing incoherent dot product detectionAfter four paths of correlation signals are obtained through correlation accumulation in the step S2, incoherent dot product detection is carried out, a decision synthesis function without fuzzy capture for eliminating side peaks is constructed according to a formula (5), the decision synthesis function is substituted into a BOC signal autocorrelation synthesis function of a I, Q branch and a cross-correlation synthesis function of a BOC signal and a local code waveform, the obtained synthesis correlation function is shown in figure 4, and BOC can be seenSAnd (14,2) the signal only has a positive main peak, and the other peaks are negative peaks, and the envelope value of the decision synthesis function is taken as the detection decision value.
Step S4: post accumulation decision
And (4) performing post-accumulation on the envelope value of the decision synthesis function obtained in the step (S3) without fuzzy capture, and comparing the envelope value with a capture threshold to finish capture decision.
(2) Based on BOCC(15,2.5) modulating the signal, and providing an embodiment of capturing the cosine phase BOC signal, as shown in fig. 5, a schematic structural diagram of the method for capturing the cosine phase BOC signal according to the present invention is shown. The BOC unambiguous capturing method based on side peak elimination is further explained by combining with the method shown in FIG. 5, and the main steps comprise:
step P1: constructing local waveforms
Constructing a BOC according to equation (3)C(15,2.5) local waveforms of the modulated signals, and the generated local code waveforms are shown in fig. 6, where (a) in fig. 6 shows a waveform diagram of the local code waveform 1, and (b) shows a waveform diagram of the local code waveform 2.
Step P2: correlation accumulation processing
As shown in fig. 6, according to the requirement in step P1, two local code waveform signals are locally generated, and are respectively correlated and accumulated with the I, Q branch signal of the input signal, so as to obtain a I, Q branch correlation signal of the cross-correlation synthesis function of the input BOC signal and the two local code waveforms, and the expression of the generated four branch correlation signal is as shown in formula (4).
Step P3: incoherent dot product detection
Carrying out incoherent dot product detection, carrying out nonlinear combination processing after obtaining four paths of correlation signals by correlation accumulation in the step P2, and constructing a decision combination without fuzzy capture for eliminating side peaks according to a formula (6)Substituting the function into the cross-correlation synthesis function of the BOC signal of the I, Q branch and the two local code waveforms to obtain a synthesized correlation function as shown in FIG. 7, and observing that the BOC signal is correlated with the two local code waveformsCThe (15,2.5) signal has only one positive main peak, and the rest are negative peaks, and then the envelope value of the decision synthesis function is taken as the detection decision value.
Accumulating decisions after step P4
And (4) carrying out post-accumulation on the envelope value of the decision synthesis function obtained in the step P3 without fuzzy capture, and comparing the envelope value with a capture threshold to finish capture decision.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (4)
1. A BOC signal non-fuzzy capture method based on side peak elimination is characterized in that the method comprises the following steps:
receiving a BOC signal in a capture channel, and carrying out carrier stripping on the BOC signal;
constructing a local code waveform and a local BOC signal according to the spreading codes;
respectively carrying out correlation accumulation on the BOC signal subjected to carrier stripping and the local code waveform and the local BOC signal to obtain I, Q branch correlation signals of an autocorrelation synthesis function of the BOC signal and I, Q branch correlation signals of a cross-correlation synthesis function of the BOC signal and the local code waveform;
constructing a decision synthesis function without fuzzy capture for eliminating side peaks by adopting a non-coherent dot product detection method according to I, Q branch related signals of an autocorrelation synthesis function of a BOC signal and I, Q branch related signals of a cross-correlation synthesis function of the BOC signal and a local code waveform;
completing capture judgment according to the decision synthesis function of the fuzzy capture and a preset capture threshold; the BOC signals comprise sine BOC signals and cosine BOC signals;
constructing a local code waveform and a local BOC signal from a spreading code, comprising:
when the BOC signal is a sine BOC signal, constructing a local code waveform according to the spreading code; the expression of the local code waveform is as follows:
wherein:represents the local code waveform of a sinusoidal BOC signal,T cis the chip period of the pseudo-random code,T sis the chip period of the square wave sub-carrier,Mdefined as the order of the received BOC signal;
when the BOC signal is a cosine BOC signal, constructing a local code waveform according to the spreading code; the expression of the local code waveform is as follows:
whereinRespectively representing the local code waveforms of the cosine BOC signal at different time periods,T cis the chip period of the pseudo-random code,T sis the chip period of the square wave sub-carrier,Mdefined as the order of the received BOC signal; the stripped BOC signal comprises two groups of in-phase signals and positive signalsStripping signals consisting of cross signals;
respectively carrying out correlation accumulation on the BOC signal after carrier stripping, the local code waveform and the local BOC signal to obtain I, Q branch correlation signals of an autocorrelation synthesis function of the BOC signal and I, Q branch correlation signals of a cross-correlation synthesis function of the BOC signal and the local code waveform, wherein the correlation accumulation comprises the following steps:
carrying out correlation accumulation on the in-phase signals of the first group of stripping signals and the local BOC signals to obtain I branch correlation signals of the autocorrelation synthesis function; carrying out correlation accumulation on the orthogonal signals of the first group of stripping signals and the local BOC signal to obtain Q branch correlation signals of the autocorrelation synthesis function;
carrying out correlation accumulation on the in-phase signals of the second group of stripped signals and the local code waveform to obtain I branch correlation signals of a cross-correlation synthesis function; carrying out correlation accumulation on orthogonal signals of the second group of stripped signals and the local code waveform to obtain Q branch correlation signals of a cross-correlation synthesis function;
according to I, Q branch related signals of an autocorrelation synthesis function of a BOC signal and I, Q branch related signals of a cross-correlation synthesis function of the BOC signal and a local code waveform, a detection method of incoherent dot product is adopted to construct a decision synthesis function without ambiguity capture for eliminating side peaks, and the decision synthesis function comprises the following steps:
when the BOC signal is a sinusoidal BOC signal:
respectively adopting a non-coherent dot product detection method for an I branch related signal of an autocorrelation synthesis function and an I branch related signal of a cross-correlation synthesis function to obtain a first group of BOC signal autocorrelation functions and a cross-correlation function of BOC signals and local code waveforms;
obtaining a first decision synthesis function according to the first group of BOC signal autocorrelation functions and the cross-correlation functions of the BOC signals and the local code waveforms;
respectively adopting a non-coherent dot product detection method for a Q branch related signal of the autocorrelation synthesis function and a Q branch related signal of the cross-correlation synthesis function to obtain a second group of BOC signal autocorrelation functions and a cross-correlation function of the BOC signal and a local code waveform;
obtaining a second decision synthesis function according to the second group of BOC signal autocorrelation functions and the cross-correlation function of the BOC signal and the local code waveform;
adding the first decision synthesis function and the second decision synthesis function to obtain a decision synthesis function without fuzzy capture, wherein the side peak is eliminated; the stripped BOC signal includes: two groups of stripped signals consisting of in-phase signals and quadrature signals; i, Q branch correlation signals of the cross-correlation synthesis functions comprise I, Q branch correlation signals of two groups of cross-correlation synthesis functions;
according to I, Q branch related signals of an autocorrelation synthesis function of a BOC signal and I, Q branch related signals of a cross-correlation synthesis function of the BOC signal and a local code waveform, a detection method of incoherent dot product is adopted to construct a decision synthesis function without ambiguity capture for eliminating side peaks, and the decision synthesis function comprises the following steps:
when the BOC signal is a cosine BOC signal:
locally generating two local code waveform signals respectively, and performing correlation accumulation with I, Q branch signals of the input signal respectively to obtain I, Q branch correlation signals of a cross-correlation synthesis function of the input BOC signal and the two local code waveforms;
respectively adopting a non-coherent dot product detection method for I, Q branch related signals of the two groups of cross-correlation synthesis functions, and carrying out non-linear combination processing on signals obtained after detection to obtain a decision synthesis function without fuzzy capture for eliminating side peaks, wherein the decision synthesis function comprises the following steps:
adopting a non-coherent dot product detection method for the I branch related signal of the first path of cross-correlation synthesis function and the I branch related signal of the second path of cross-correlation synthesis function to obtain an I branch judgment synthesis function;
obtaining a Q branch judgment synthesis function by adopting a non-coherent dot product detection method for a Q branch related signal of a first path of cross-correlation synthesis function and a Q branch related signal of a second path of cross-correlation synthesis function;
and adding the I branch judgment synthesis function and the Q branch judgment synthesis function to obtain a judgment synthesis function without fuzzy capture, in which the side peak is eliminated.
2. The method of claim 1, wherein when the BOC signal is a sinusoidal BOC signal:
expressions of an I branch related signal of the autocorrelation combining function, a Q branch related signal of the autocorrelation combining function, an I branch related signal of the cross-correlation combining function, and a Q branch related signal of the cross-correlation combining function are:
wherein,an I branch correlation signal representing an autocorrelation composition function,a Q branch correlation signal representing an autocorrelation composition function,representing local code waveformsThe I branch correlation signal of the synthesis function is cross-correlated with the sinusoidal BOC signal,representing local code waveformsThe Q branch correlation signal of the synthesis function is cross-correlated with the sinusoidal BOC signal,which represents the carrier-to-noise ratio of the received signal,which is indicative of the residual doppler frequency of the doppler,T p which represents the duration of the coherent integration,is expressed in chip periodsT c Is the code phase delay in units of a unit,represents the autocorrelation function of the BOC signal,representing sinusoidal BOC signals and local code waveformsThe cross-correlation function of (a) is,which is indicative of the phase error of the correlator output,、、、is the normalized noise term of the correlator output.
3. The method of claim 1, wherein when the BOC signal is a cosine BOC signal:
the expression of the I, Q branch correlation signal of the cross-correlation synthesis function is:
wherein,representing local codesThe I branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,representing local code waveformsThe Q branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,representing local code waveformsThe I branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,representing local code waveformsThe Q branch correlation signal of the cross-correlation synthesis function with the cosine BOC signal,ka sequence number representing the signal of interest is indicated,which represents the carrier-to-noise ratio of the received signal,which is indicative of the residual doppler frequency of the doppler,T p which represents the duration of the coherent integration,is expressed in chip periodsT c Is the code phase delay in units of a unit,、local code waveforms respectively representing cosine BOC signals and different time periods、The cross-correlation function of (a) is,、、、is the normalized noise term of the correlator output.
4. The method of claim 1, wherein the performing the capturing decision according to the decision combining function of the blur-free capturing and a preset capturing threshold comprises:
acquiring an envelope value of a decision synthesis function without fuzzy capture;
and (4) carrying out post-accumulation on the envelope value of the decision synthesis function without fuzzy capture, and comparing a post-accumulation result with a preset capture threshold to finish capture decision.
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