CN111884675B - Method and system for tracking multi-system phase hopping spread spectrum modulation signal - Google Patents
Method and system for tracking multi-system phase hopping spread spectrum modulation signal Download PDFInfo
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- CN111884675B CN111884675B CN202010707176.6A CN202010707176A CN111884675B CN 111884675 B CN111884675 B CN 111884675B CN 202010707176 A CN202010707176 A CN 202010707176A CN 111884675 B CN111884675 B CN 111884675B
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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
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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
- H04B2001/70706—Spread spectrum techniques using direct sequence modulation using a code tracking loop, e.g. a delay locked loop
Abstract
The invention provides a method and a system for synchronizing a multi-system phase hopping spread spectrum modulation signal, which comprise the following steps: acquiring a phase hopping spread spectrum modulation signal sent by a sending end; the complex pseudo code sequence is determined by a first multilevel phase hopping sequence generated by a sending end; generating a second multilevel phase hopping sequence according to the mode of generating the first multilevel phase hopping sequence by the sending end, and mapping the second multilevel phase hopping sequence into a binary phase hopping sequence and a phase compensation sequence; generating a local reference carrier with a phase compensation function by combining a carrier determination mode and a phase compensation sequence in the hopping spread spectrum modulation signal; the receiving end strips the carrier in the phase-hopping spread spectrum modulation signal based on the local reference carrier with the phase compensation function and performs phase compensation on the complex pseudo code sequence to obtain a real pseudo code sequence and sending end data; and performing relevant operation on the binary phase hopping sequence, the real pseudo code sequence and the sending end data, and tracking to obtain the sending end data. The invention provides a low-complexity multi-system phase hopping spread spectrum modulation signal tracking method.
Description
Technical Field
The present invention belongs to the field of communication technology, and more particularly, to a method and a system for tracking a multilevel phase-hopping spread spectrum modulation signal.
Background
The second phase of the GNSS receiver synchronization is tracking, which is performed based on the acquired doppler frequency and pseudo code phase estimates. In the tracking process, the carrier frequency and the pseudo code phase of the local reference signal need to be highly synchronized with the received signal so as to achieve the two purposes of measuring the pseudo range and demodulating data. The tracking loop includes a carrier tracking loop and a code tracking loop. The purpose of the carrier tracking loop is to strip off the carrier in the received signal. The purpose of the code tracking loop is to strip off the pseudo-code and improve the signal-to-noise ratio of the navigation signal that would otherwise be drowned in noise. The carrier tracking loop and the code tracking loop are tightly combined together to jointly complete the tracking process of the signal.
The receiver performs signal tracking by good autocorrelation properties of the navigation signal, i.e. relying on equivalent pseudo-code sequences
The self-correlation performance is good, and the self-correlation performance is good,
indicating the phase jump offset of the k-th symbol. Therefore, the tracking loop of the hopping spread spectrum navigation signal can be designed by means of the tracking loop of the direct sequence spread spectrum navigation signal, only the real number correlation operation in the tracking loop needs to be changed into complex number correlation operation, the complex number correlation operation can depend on a flow chart of the multi-system hopping spread spectrum modulation signal tracking system shown in fig. 1 for calculating, and the complex number correlation operation depends on the phase compensator in fig. 1 for completing. Specifically, as shown in fig. 1, the input of the tracking loop is an intermediate frequency signal after down-conversion, the intermediate frequency signal is first mixed with a local reference carrier to strip a carrier in the signal, and the local reference carrier is generated by a carrier NCO; then, the mixed signal and the local reproduction pseudo code are subjected to complex correlation operation, and the local reproduction pseudo code is generated by a phase hopping sequence c generated by a phase hopping sequence generatorPH(k) The method is obtained by searching a phase hopping lookup table in a phase compensator, and after coherent integration and incoherent accumulation operations, on one hand, a pseudo code can be stripped to obtain a navigation message of a sending end, and on the other hand, a code tracking error can be obtained through a code loop discriminator; and finally, adjusting the local reference carrier frequency according to the carrier tracking error output by the carrier loop discriminator, and adjusting the phase of the local reproduction pseudo code according to the code tracking error to realize the closed loop feedback of the tracking loop. The tracking algorithm adopts complex correlation, and the complex correlation needs more multipliers and adders than real correlation, and the bit width of the used multipliers is large, and the implementation complexity is high, thus leading to the high implementation complexity of the tracking algorithm.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a method and a system for tracking a multi-system phase-hopping spread spectrum modulation signal, and aims to solve the problems of complex correlator structure in a tracking loop and high implementation complexity caused by large bit width of a multiplier used.
In order to achieve the above object, in a first aspect, the present invention provides a method for tracking a multilevel phase-hopping spread spectrum modulation signal, including the following steps:
a receiving end acquires a phase hopping spread spectrum modulation signal sent by a sending end; the hopping spread spectrum modulation signal comprises a carrier, a complex pseudo code sequence and sending end data; the complex pseudo code sequence is determined by a first multilevel phase hopping sequence generated by a sending end; the hopping sequence is a random sequence or a pseudo-random sequence and is used for controlling the hopping offset of the phase;
the receiving end generates a second multi-system phase hopping sequence according to the mode that the transmitting end generates the first multi-system phase hopping sequence, and the second multi-system phase hopping sequence is mapped into a binary phase hopping sequence and a phase compensation sequence based on a coding rule between the multi-system phase hopping sequence and the binary phase hopping sequence;
the receiving end combines the carrier determining mode in the hopping phase spread spectrum modulation signal and the phase compensation sequence to generate a local reference carrier with a phase compensation function;
the receiving end strips the carrier in the phase hopping spread spectrum modulation signal based on a local reference carrier with a phase compensation function and performs phase compensation on the complex pseudo code sequence to obtain a real pseudo code sequence and sending end data;
and the receiving end performs related operation on the binary phase hopping sequence, the real pseudo code sequence and the sending end data, and tracks to obtain the sending end data.
It will be appreciated that the complex pseudo-code sequence is a multilevel sequence and the real pseudo-code sequence is a binary sequence. And after the phase compensation operation is carried out on the complex number pseudo code sequence, a corresponding real number pseudo code sequence can be obtained.
It should be noted that "correlation" in the correlation operation is a related abbreviation, and the basic way of the correlation operation is: the object to be studied is first converted into a signal, which is then compared according to a mathematical formula having a correlation coefficient and a correlation function. In particular, the correlation coefficient is a number that represents the similarity between two equal length signals. The correlation functions are further divided into autocorrelation functions and cross-correlation functions. If the signals involved in the comparison are the same signal, the correlation function is called an autocorrelation function; if the signals involved in the comparison are different signals, the correlation function is called a cross-correlation function.
Specifically, the hopping sequence is used to control the hopping offset of the phase, which refers to the hopping offset of the phase of the control sequence symbol relative to the initial phase of the carrier.
In an alternative embodiment, the second multilevel phase-hopping sequence is cPH(k) (ii) a k represents the number of discrete symbols; subscript PH is an abbreviation for Phase Hopping (Phase Hopping);
c is determined based on the coding rule between the multi-system phase hopping sequence and the binary phase hopping sequencePH(k) Mapping to binary phase hopping sequence c1(k) And phase compensation sequence c2(k) Two sequences;
c1(k) the method is a binary sequence, and the level value of the binary sequence is { -1, +1 }; the specific value rule is as follows:
wherein, N represents the system of the multi-system phase hopping sequence; c in the mapping processPH(k) Residual part c ofΔ(k) Comprises the following steps: c. CΔ(k)＝cPH(k) Percent (N/2), wherein,% represents the remainder calculation;
where M represents the maximum value of the counter in the carrier digital oscillator.
In an alternative embodiment, the phase compensation sequence c2(k) As an incremental sequence of carrier digital oscillators to obtain a local reference carrier with phase compensation function.
In an optional embodiment, the receiving end generates a local reference carrier based on the count value of the carrier digital oscillator;
and increasing the count value of the carrier digital oscillator by a value corresponding to the phase compensation sequence on the basis of the current count so that the local reference carrier generated by the carrier digital oscillator has a phase compensation function.
In an optional embodiment, a real pseudo code sequence is obtained after phase compensation of the complex pseudo code sequence, so that a corresponding multi-system sequence is converted into a binary sequence, and a complex correlation operation step in the original signal tracking method is simplified into a real correlation step;
by controlling the counting of the carrier digital oscillator, the relevant parameters for carrying out the phase compensation operation on the complex pseudo code sequence are synchronously loaded in the carrier stripping step in advance, so that the operation of separately carrying out the phase compensation after the carrier is stripped is avoided, and the signal tracking step is simplified.
In a second aspect, the present invention provides a tracking system for a multilevel phase-hopping spread spectrum modulation signal, comprising:
the signal acquisition unit is used for acquiring a phase hopping spread spectrum modulation signal sent by a sending end; the hopping spread spectrum modulation signal comprises a carrier, a complex pseudo code sequence and sending end data; the complex pseudo code sequence is determined by a first multilevel phase hopping sequence generated by a sending end; the hopping sequence is a random sequence or a pseudo-random sequence and is used for controlling the hopping offset of the phase;
the sequence generating unit is used for generating a second multi-system phase hopping sequence according to the mode that the transmitting end generates the first multi-system phase hopping sequence, and mapping the second multi-system phase hopping sequence into a binary phase hopping sequence and a phase compensation sequence based on a coding rule between the multi-system phase hopping sequence and the binary phase hopping sequence;
the carrier generation unit is used for generating a local reference carrier with a phase compensation function by combining the determination mode of the carrier in the phase hopping spread spectrum modulation signal and the phase compensation sequence;
the phase compensation unit is used for stripping the carrier wave in the phase-hopping spread spectrum modulation signal based on a local reference carrier wave with a phase compensation function and performing phase compensation on the complex pseudo code sequence to obtain a real pseudo code sequence and sending end data;
and the data tracking unit is used for performing related operation on the binary phase hopping sequence, the real pseudo code sequence and the sending end data, and tracking to obtain the sending end data.
In an alternative embodiment, the second multilevel phase-hopping sequence generated by the sequence generation unit is cPH(k) (ii) a k represents the number of discrete symbols; subscript PH is abbreviation of phase jump; c is determined based on the coding rule between the multi-system phase hopping sequence and the binary phase hopping sequencePH(k) Mapping to binary phase hopping sequence c1(k) And phase compensation sequence c2(k) Two sequences; c. C1(k) The method is a binary sequence, and the level value of the binary sequence is { -1, +1 }; the specific value rule is as follows:
wherein, N represents the system of the multi-system phase jump sequence. C in the mapping processPH(k) Residual part c ofΔ(k) Comprises the following steps: c. CΔ(k)＝cPH(k) Percent (N/2), wherein,% represents the remainder calculation;
where M represents the maximum value of the counter in the carrier digital oscillator.
In an alternative embodiment, the carrier generation unit phase compensates the sequence c2(k) As an incremental sequence of carrier digital oscillators to obtain a local reference carrier with phase compensation function.
In an alternative embodiment, the carrier generation unit generates a local reference carrier based on a count value of the carrier digital oscillator; and increasing the count value of the carrier digital oscillator by a value corresponding to the phase compensation sequence on the basis of the current count so that the local reference carrier generated by the carrier digital oscillator has a phase compensation function.
In an optional embodiment, the phase compensation unit performs phase compensation on the complex pseudo code sequence to obtain a real pseudo code sequence, so that the corresponding multi-system sequence is converted into a binary sequence, and the complex correlation operation step in the original signal tracking method is simplified into a real correlation step;
the carrier generation unit synchronously loads relevant parameters for performing phase compensation operation on the complex pseudo code sequence into the carrier stripping step in advance through controlling the counting of the carrier digital oscillator, so that the operation of separately performing phase compensation after the carrier is stripped is avoided, and the signal tracking step is simplified.
Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
the invention provides a method and a system for tracking a multi-system phase-hopping spread spectrum modulation signal. The carrier ring has the function of adjusting the phase, so that the phase compensation operation can be completed by the carrier ring, only an adder needs to be additionally introduced into the carrier ring, and the complexity is far lower than that of a complex correlator. Meanwhile, since the autocorrelation main peak of the real pseudo code sequence is approximately the same as the complex pseudo code sequence, the invention can reduce the complexity of the realization of the tracking loop on the premise of ensuring that the positioning precision is not lost.
Drawings
FIG. 1 is a flow chart of a tracking system for a conventional multi-level phase-hopping spread spectrum modulated signal;
FIG. 2 is a flow chart of a method for tracking a multi-system phase-hopping spread spectrum modulation signal provided by the present invention;
FIG. 3 is a flow chart of a tracking loop for a multilevel phase-hopping spread spectrum modulated signal provided by the present invention;
FIG. 4 is an equivalent pseudo-code sequence obtained by simulation of the present invention
And an enantiomerShoot-derived binary phase hopping sequence c1(k) The main peak graph of the autocorrelation function;
FIG. 5 is a comparison graph of simulation results of code tracking accuracy of a pair of PH-BPSK (1) signals in the first tracking method and the second tracking method provided by the present invention;
FIG. 6 is a comparison graph of simulation results of code tracking accuracy of two pairs of PH-BOCs (10,5) signals in the first tracking method and the first tracking method provided by the present invention;
FIG. 7 is a comparison graph of simulation results of code tracking accuracy of a first tracking method and a second tracking method of two pairs of PH-BOCc (10,5) signals provided by the present invention;
fig. 8 is a diagram of a tracking system architecture for a multilevel phase-hopped spread spectrum modulated signal provided by the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention 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 invention and are not intended to limit the invention.
The invention provides a method for tracking a multi-system phase hopping spread spectrum modulation signal, which comprises the following steps as shown in figure 2:
s210, a receiving end acquires a phase hopping spread spectrum modulation signal sent by a sending end; the hopping spread spectrum modulation signal comprises a carrier, a complex pseudo code sequence and sending end data; the complex pseudo code sequence is determined by a first multilevel phase hopping sequence generated by a sending end; the hopping sequence is a random sequence or a pseudo-random sequence and is used for controlling the hopping offset of the phase;
s220, the receiving end generates a second multi-system phase hopping sequence according to the mode that the transmitting end generates the first multi-system phase hopping sequence, and the second multi-system phase hopping sequence is mapped into a binary phase hopping sequence and a phase compensation sequence based on the coding rule between the multi-system phase hopping sequence and the binary phase hopping sequence;
s230, the receiving end combines the carrier determining mode in the hopping spread spectrum modulation signal and the phase compensation sequence to generate a local reference carrier with a phase compensation function;
s240, the receiving end strips the carrier wave in the hopping spread spectrum modulation signal based on the local reference carrier wave with the phase compensation function and carries out phase compensation on the complex pseudo code sequence to obtain a real pseudo code sequence and sending end data; the real pseudo code sequence is a complex pseudo code sequence subjected to phase compensation;
and S250, the receiving end performs related operation on the binary phase hopping sequence, the real pseudo code sequence and the sending end data, and tracks the real pseudo code sequence and the sending end data to obtain the sending end data.
According to the invention, the multilevel sequence is mapped into the binary sequence, a phase compensator is not needed to perform complex correlation during correlation operation, and only a simple real number correlator is needed, so that the complexity of a tracking loop is reduced. In order not to lose the correlation performance of the signal, it is necessary to perform corresponding phase compensation on the received signal according to the mapping rule before correlation, and this phase compensation operation can be performed by using a phase compensator. However, to further reduce receiver complexity, this phase compensation operation may be performed in an NCO (numerically controlled oscillator). Fig. 3 shows a tracking loop based on carrier phase compensation assistance.
As shown in fig. 3, the received intermediate frequency signal is first mixed with a local reference carrier to strip the carrier in the signal, the local reference carrier being generated by a carrier NCO; at the same time, the phase compensation operation is performed based on the fact that the carrier loop can adjust the phase, and the phase compensation operation depends on the phase compensation sequence c2(k) The phase compensation sequence can be formed by a phase hopping sequence cPH(k) Obtained by looking up the phase mapping table. Then, the signal after mixing and phase compensation is mapped to obtain binary pseudo code c1(k) Performing real number correlation operation, the binary pseudo code can be formed by a phase hopping sequence cPH(k) The data is obtained by searching the phase mapping table, and after coherent integration and incoherent accumulation operations, on one hand, the pseudo code can be stripped to obtain the data of the sending end, for example, when the signal tracking method is applied to the navigation field, the data of the sending end can be a navigation message. On the other hand, the code ring discriminator can obtainTo code tracking error. And finally, adjusting the local reference carrier frequency according to the carrier tracking error output by the carrier loop discriminator, and adjusting the phase of the local reproduction pseudo code according to the code tracking error to realize the closed loop feedback of the tracking loop.
Further, in fig. 3, i and q are signals of an in-phase branch and a quadrature branch after frequency mixing and carrier phase compensation, respectively, where the purpose of frequency mixing is to strip a carrier. i.e. iE、iPAnd iLLeading branch signals, instant branch signals and lagging branch signals which are multiplied by local pseudo codes on the same-phase branch circuit respectively; i isE、IPAnd ILRespectively carrying out correlation and coherent integration on the same-phase branch and a local pseudo code to obtain leading branch signals, instant branch signals and lagging branch signals; q. q.sE、qPAnd q isLRespectively leading branch signals, instant branch signals and lagging branch signals after multiplication of local pseudo codes on the orthogonal branch; qE、QPAnd QLThe early, instantaneous and late branch signals after correlation and coherent integration with the local pseudo-code on the orthogonal branch, respectively.
As can be seen from FIG. 3, the phase hopping sequence c generated by the phase hopping sequence generatorPH(k) Mapped as c by looking up the phase mapping table1(k) And c2(k) Two sequences. c. C1(k) Is a binary sequence, and the level value of the binary sequence is { -1, +1 }. Because the phase hopping sequence is a pseudo-random sequence, the mapping from the multilevel sequence to the binary sequence can be completed by using the highest bit of the binary form of the phase hopping sequence, and the rule is as follows:
according to the above rules. C in the mapping processPH(k) A part c of the residueΔ(k) Comprises the following steps:
cΔ(k)＝cPH(k)％(N/2)
wherein,% represents the remainder operation.
From the point of view of the equivalent pseudo-code, i.e. will
Carrying out factorization:
therefore, in order not to degrade the correlation performance of the signal, some compensation of the received signal is required before the correlation. According to will
The formula after factorization and the definition of complex correlation are carried out, and the compensation is to multiply the received signal by
And (4) finishing. Therefore, the equivalent multi-system pseudo code sequence in the received signal is converted into a binary pseudo code sequence, and only real number correlation is needed during correlation operation, namely a simple multiplier can be used for replacing a phase compensator.
To further simplify the tracking loop, the phase compensation can be made on the basis of the fact that the carrier NCO can adjust the phase. The carrier NCO can be regarded as a counter, and the local copy sine and cosine carriers can be generated by looking up the lookup table according to the count value of the counter. When the counter overflows, the counter is cleared, so that one period of the carrier wave is equal to the time for the counter to count from 0 to the maximum value in the NCO, the increment of each counting of the counter is determined according to the output of the carrier wave loop filter, and the carrier frequency can be adjusted by adjusting the increment of the counter. The phase compensation operation can be seen as an increase of a value based on the current count value of the counter, thus obtaining another sequence c of phase map outputs2(k) Comprises the following steps:
where M represents the maximum value of the counter in the carrier NCO. C is to2(k) As an addition to the carrier NCOValue sequence, thus completing the phase compensation of the received signal, and the following operation is consistent with the direct sequence spread spectrum navigation signal.
In a specific embodiment, the invention performs simulation analysis on the code tracking performance of two designed tracking algorithms, the tracking algorithm based on matching correlation shown in fig. 1 is referred to as a first tracking method, and the tracking algorithm based on carrier phase compensation assistance shown in fig. 3 provided by the invention is referred to as a second tracking method.
In order to verify the feasibility of the tracking method two, an equivalent pseudo code sequence is firstly simulated
And by phase jump sequences cPH(k) Binary pseudo code sequence c obtained by mapping1(k) The autocorrelation property of. Fig. 4 shows the main peak of the autocorrelation function. As can be seen from fig. 4, the main peak of the autocorrelation function of the equivalent pseudo code and the binary pseudo code is almost the same, and the positioning accuracy of the navigation signal is mainly determined by the main peak of the autocorrelation function of the signal, so the tracking method is feasible, and the positioning accuracy of the phase-hopping spread spectrum navigation signal is not reduced.
Fig. 5, fig. 6 and fig. 7 simulate the code tracking accuracy of the first tracking method and the second tracking method for three modulation signals, namely PH-BPSK (1), PH-BOCs (10,5) and PH-BOCc (10,5), respectively. The three modulation signals respectively correspond to the commonly used BPSK (1), BOCs (10,5) and BOCc (10,5) signals, but the direct sequence spread spectrum modulation in the commonly used signal modulation flow is converted into phase hopping PH modulation. It can be seen from the three graphs that the code tracking accuracy of the first tracking method and the second tracking method is equivalent, and both the first tracking method and the second tracking method are well matched with the theoretical value, and the small deviation between the simulation result and the theoretical result in the graph is caused by the white gaussian noise in the simulation process.
From the simulation results, the tracking method one and the tracking method two can effectively track the phase-hopping spread spectrum navigation signal and have equivalent code tracking performance. However, the second tracking method is less complex in hardware to implement than the first tracking method. Table 1 lists the implementation complexity of the correlator part in both tracking loops. In the aspect of a lookup table, the lookup table is needed in the phase compensator of the tracking method one to complete the mapping from the phase hopping sequence to the equivalent pseudo code sequence, and three phase compensators can share one lookup table; and the second tracking method needs a phase mapping table to complete mapping from the phase hopping sequence to the binary pseudo code sequence and the phase compensation sequence. In the aspect of adders, 2 adders exist in each phase compensator, and 6 adders are needed in the tracking method one by one; and the second tracking method only needs 1 adder and is used at the output end of the carrier NCO to realize the phase compensation of the received signal. On the aspect of multipliers, 4 multipliers exist in each phase compensator, and a total of 12 multipliers are needed in the tracking method; the second tracking method requires 6 multipliers in total. Therefore, the tracking method two needs less than the tracking method 5 adders and 6 multipliers, the realization structure is simpler, and the corresponding operation complexity is lower. In addition, for the first tracking method, the multiplier needs to realize the product of the front-end data flow and the multi-system local pseudo code waveform, while the second tracking method only needs to realize the product of the front-end data flow and the binary local pseudo code waveform, and the complexity of multiplication is reduced by times. In summary, the implementation complexity of the tracking method two is significantly lower than that of the method one.
TABLE 1 implementation complexity table for correlator parts of two tracking methods
| Lookup table | Adder | Multiplier and method for generating a digital | |
| Tracking method | |||
| 1 | 1 | 6 | 12 |
| Tracking method two | 1 | 1 | 6 |
Specifically, the tracking method is based on the perfect matching correlation principle, and if a tracking loop is designed based on the perfect matching correlation principle, the loss of correlation performance is not caused, and the optimal code tracking precision can be theoretically achieved. However, for the phase-hopping spread spectrum navigation signal, the perfect matching correlation needs to be realized through complex correlation, and the complexity of realizing the complex correlation is high.
Accordingly, referring to table 1, the implementation complexity of the tracking method (tracking method two) provided by the present invention is lower than that of the tracking method one, that is, the present invention can reduce the complexity of the tracking algorithm without reducing the tracking accuracy compared with the prior art.
Fig. 8 is a diagram of the architecture of a tracking system for a multilevel phase-hopping spread spectrum modulated signal provided by the present invention, as shown in fig. 8, the system includes:
a signal obtaining unit 810, configured to obtain a phase hopping spread spectrum modulation signal sent by a sending end; the hopping spread spectrum modulation signal comprises a carrier, a complex pseudo code sequence and sending end data; the complex pseudo code sequence is determined by a first multilevel phase hopping sequence generated by a sending end; the hopping sequence is a random sequence or a pseudo-random sequence and is used for controlling the hopping offset of the phase;
a sequence generating unit 820, configured to generate a second multilevel jump phase sequence by referring to a manner in which a transmitting end generates a first multilevel jump phase sequence, and map the second multilevel jump phase sequence into a binary jump phase sequence and a phase compensation sequence based on a coding rule between the multilevel jump phase sequence and the binary jump phase sequence;
a carrier generation unit 830, configured to generate a local reference carrier with a phase compensation function by combining the determination manner of the carrier in the phase-hopping spread spectrum modulation signal and the phase compensation sequence;
a phase compensation unit 840, configured to strip a carrier in the phase-hopping spread spectrum modulation signal based on a local reference carrier with a phase compensation function and perform phase compensation on the complex pseudo code sequence to obtain a real pseudo code sequence and transmit end data; the real pseudo code sequence is a complex pseudo code sequence subjected to phase compensation;
and the data tracking unit 850 is configured to perform correlation operation on the binary phase hopping sequence, the real pseudo code sequence, and the sending end data, and track the sending end data.
It should be noted that specific functions of each unit in fig. 8 can be referred to the description in the foregoing method embodiment, and are not described herein again.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (8)
1. A method for tracking a multilevel phase-hopping spread spectrum modulation signal, comprising the steps of:
a receiving end acquires a phase hopping spread spectrum modulation signal sent by a sending end; the hopping spread spectrum modulation signal comprises a carrier, a complex pseudo code sequence and sending end data; the complex pseudo code sequence is determined by a first multilevel phase hopping sequence generated by a sending end; the hopping sequence is a random sequence or a pseudo-random sequence and is used for controlling the hopping offset of the phase;
the receiving end generates a second multi-system phase hopping sequence according to the mode that the transmitting end generates the first multi-system phase hopping sequence, and the second multi-system phase hopping sequence is mapped into a binary phase hopping sequence and a phase compensation sequence based on a coding rule between the multi-system phase hopping sequence and the binary phase hopping sequence; the second multilevel phase-hopping sequence is cPH(k)；k represents the number of discrete symbols; subscript PH is abbreviation of phase jump; c is determined based on the coding rule between the multi-system phase hopping sequence and the binary phase hopping sequencePH(k) Mapping to binary phase hopping sequence c1(k) And phase compensation sequence c2(k) Two sequences; c. C1(k) The method is a binary sequence, and the level value of the binary sequence is { -1, +1 }; the specific value rule is as follows:
wherein N represents the system of multi-system phase jump sequence, c in the mapping processPH(k) Residual part c ofΔ(k) Comprises the following steps: c. CΔ(k)＝cPH(k) Percent (N/2), wherein,% represents the remainder calculation;
the receiving end combines the carrier determining mode in the hopping phase spread spectrum modulation signal and the phase compensation sequence to generate a local reference carrier with a phase compensation function;
the receiving end strips the carrier in the phase hopping spread spectrum modulation signal based on a local reference carrier with a phase compensation function and performs phase compensation on the complex pseudo code sequence to obtain a real pseudo code sequence and sending end data;
and the receiving end performs related operation on the binary phase hopping sequence, the real pseudo code sequence and the sending end data, and tracks to obtain the sending end data.
2. The method of claim 1, wherein the phase compensation sequence c is a phase compensation sequence2(k) As an incremental sequence of carrier digital oscillators to obtain a local reference carrier with phase compensation function.
3. The method according to claim 2, wherein a receiving end generates a local reference carrier based on the count value of the carrier digital oscillator;
and increasing the count value of the carrier digital oscillator by a value corresponding to the phase compensation sequence on the basis of the current count so that the local reference carrier generated by the carrier digital oscillator has a phase compensation function.
4. The method according to any one of claims 1 to 3, wherein a real pseudo code sequence is obtained after phase compensation of a complex pseudo code sequence, so that the corresponding multilevel sequence is converted into a binary sequence, thereby simplifying the complex correlation operation step in the original signal tracking method to a real correlation operation step;
by controlling the counting of the carrier digital oscillator, the relevant parameters for carrying out the phase compensation operation on the complex pseudo code sequence are synchronously loaded in the carrier stripping step in advance, so that the operation of separately carrying out the phase compensation after the carrier is stripped is avoided, and the signal tracking step is simplified.
5. A system for tracking a multilevel phase hopped spread spectrum modulated signal, comprising:
the signal acquisition unit is used for acquiring a phase hopping spread spectrum modulation signal sent by a sending end; the hopping spread spectrum modulation signal comprises a carrier, a complex pseudo code sequence and sending end data; the complex pseudo code sequence is determined by a first multilevel phase hopping sequence generated by a sending end; the hopping sequence is a random sequence or a pseudo-random sequence and is used for controlling the hopping offset of the phase;
the sequence generating unit is used for generating a second multi-system phase hopping sequence according to the mode that the transmitting end generates the first multi-system phase hopping sequence, and mapping the second multi-system phase hopping sequence into a binary phase hopping sequence and a phase compensation sequence based on a coding rule between the multi-system phase hopping sequence and the binary phase hopping sequence; the second multilevel phase-hopping sequence is cPH(k) (ii) a k represents the number of discrete symbols; subscript PH is abbreviation of phase jump; based on between multi-system phase hopping sequence and binary phase hopping sequenceA coding rule ofPH(k) Mapping to binary phase hopping sequence c1(k) And phase compensation sequence c2(k) Two sequences; c. C1(k) The method is a binary sequence, and the level value of the binary sequence is { -1, +1 }; the specific value rule is as follows:
wherein N represents the system of multi-system phase jump sequence, c in the mapping processPH(k) Residual part c ofΔ(k) Comprises the following steps: c. CΔ(k)＝cPH(k) Percent (N/2), wherein,% represents the remainder calculation;
the carrier generation unit is used for generating a local reference carrier with a phase compensation function by combining the determination mode of the carrier in the phase hopping spread spectrum modulation signal and the phase compensation sequence;
the phase compensation unit is used for stripping the carrier wave in the phase-hopping spread spectrum modulation signal based on a local reference carrier wave with a phase compensation function and performing phase compensation on the complex pseudo code sequence to obtain a real pseudo code sequence and sending end data;
and the data tracking unit is used for performing related operation on the binary phase hopping sequence, the real pseudo code sequence and the sending end data, and tracking to obtain the sending end data.
6. The system for tracking a multilevel phase-hopped spread spectrum modulated signal of claim 5, wherein the carrier generation unit is configured to phase compensate the sequence c2(k) As an incremental sequence of carrier digital oscillators to obtain a local reference carrier with phase compensation function.
7. The tracking system for a multilevel phase-hopping spread spectrum modulation signal according to claim 6, wherein said carrier generation unit generates a local reference carrier based on a count value of said carrier digital oscillator; and increasing the count value of the carrier digital oscillator by a value corresponding to the phase compensation sequence on the basis of the current count so that the local reference carrier generated by the carrier digital oscillator has a phase compensation function.
8. The tracking system of the multilevel phase-hopping spread spectrum modulation signal according to any one of claims 5 to 7, wherein the phase compensation unit obtains a real number pseudo code sequence after performing phase compensation on the complex number pseudo code sequence, so that the corresponding multilevel sequence is converted into a binary sequence, thereby simplifying a complex number correlation operation step in an original signal tracking method into a real number correlation step;
the carrier generation unit synchronously loads relevant parameters for performing phase compensation operation on the complex pseudo code sequence into the carrier stripping step in advance through controlling the counting of the carrier digital oscillator, so that the operation of separately performing phase compensation after the carrier is stripped is avoided, and the signal tracking step is simplified.
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