CN111064494B - Demodulation and de-spreading method, system, medium and equipment for MSK spread spectrum receiver - Google Patents
Demodulation and de-spreading method, system, medium and equipment for MSK spread spectrum receiver Download PDFInfo
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Abstract
The present application relates to the field of despreading spread spectrum codes, and in particular, to a demodulation and despreading method, system, medium, and device for an MSK spread spectrum receiver. The application discloses determining a spread spectrum pulse position to be resolved; step 2: generating 4 paths of reference signals, N groups of reference code element sequences and corresponding code element initial phase sequences; based on the spread spectrum pulse position, carrying out signal sampling, and multiplying the sampled sampling signal by 4 paths of signals; performing intra-symbol accumulation integration on the 4 multiplication results to obtain a chip correlation value of each intra-symbol signal and 4 paths of reference signals; calculating I, Q two paths of correlation integral values of each group of whole spread spectrum signals through N groups of reference code elements and an initial phase sequence; performing modulus on the I, Q two paths of correlation values to obtain a final correlation integral value in the pulse; and comparing the magnitude of the related integral values in the N groups of pulses to determine a resolving result.
Description
Technical Field
The present application relates to the field of despreading spread spectrum codes, and in particular, to a demodulation and despreading method, system, medium, and device for an MSK spread spectrum receiver.
Background
The MSK spread spectrum receiver needs to despread the received spread spectrum signal to recover the original information. For burst data communication, information is discontinuous transmission, and synchronization is difficult to realize through a feedback loop, so a spread spectrum technology is generally adopted, a group of spread spectrum sequences are inserted in front of a transmitted data frame for system synchronization, a receiver determines the position of subsequent data information according to detection of the synchronization sequences, and then the data information is demodulated and despread. Since phase synchronization is difficult to achieve, the demodulation of data information generally adopts a non-coherent demodulation mode. .
In the traditional spread spectrum MSK receiver, the de-spreading processing of the MSK signal is to demodulate the received MSK signal firstly and then use the demodulation data and the spread spectrum code to carry out correlation operation to obtain a correlation peak.
In order to improve the error code performance of the system, an algorithm for simultaneously demodulating and despreading needs to be used, different spreading codes are firstly used for carrying out related despreading on a received MSK signal, and then the related peaks of the spreading codes are compared for carrying out demodulation judgment. Some existing similar algorithms have large calculation amount of related operation in despreading and demodulation, and occupy more system resources.
The traditional algorithm of demodulating before despreading loses precious spread spectrum gain, and the system error code performance is poor; the existing simultaneous demodulation and de-spreading algorithm has large calculation amount of correlation operation, occupies more system resources and generally has certain delay. If the method is based on a matched filter, the intermediate frequency sampling signal needs to be down-converted to a baseband first, and then is filtered by a digital filter, wherein the digital down-conversion and the digital filtering have certain processing delay and more resources such as multipliers need to be used; and as a joint demodulation and despreading method, the intermediate frequency sampling signals are directly processed, but the maximum likelihood is used for calculating a correlation value, so that the calculation amount is large.
Disclosure of Invention
The application provides a demodulation and de-spreading method, a system, a medium and equipment of an MSK spread spectrum receiver.
The embodiment of the application is realized by the following steps:
a demodulation and de-spreading method of an MSK spread spectrum receiver comprises the following steps:
step 1: determining the position of a spread spectrum pulse to be resolved;
step 2: generating 4 paths of reference signals, N groups of reference code element sequences and corresponding code element initial phase sequences;
and step 3: based on the spread spectrum pulse position, carrying out signal sampling, and multiplying the sampled sampling signal by 4 paths of signals;
and 4, step 4: respectively carrying out intra-code element accumulation integration on the 4 multiplication results to obtain intra-chip correlation integral values of each intra-code element signal and 4 paths of reference signals;
and 5: calculating I, Q two paths of correlation integral values of each group of whole spread spectrum signals through N groups of reference code elements and an initial phase sequence;
step 6: obtaining N correlation integral values in the final pulse according to the I, Q two paths of correlation integral values;
and 7: and 6, comparing the N correlation values obtained in the step 6, and taking K bit information x of the corresponding values of the M bit code element sequences corresponding to the maximum correlation value as the final original information after demodulation and despreading.
Preferably, the specific process of step 2 is as follows:
step 201: generating 2 pairs of 4 paths of intermediate frequency reference signals in real time;
step 202: generating or reading N groups of spreading code sequences to obtain a whole spreading code list matrix; the M bit code element of each row is one of spread spectrum information sequences, and the value of the code element is 0 or 1;
step 203: calculating a corresponding code element initial phase table according to the spread spectrum code table in S202 by using the characteristic of continuous MSK signal phase to obtain an initial phase sequence
The initial phase takes the value 0 pi or 1 pi.
Preferably, the expression of the 4 intermediate frequency reference signals is as follows:
a first pair of signals s0,I(t) and s0,Q(t); second pair of signals s1,I(t) and s1,Q(t); 2 paths of signals in the two pairs of signals are I, Q paths of signals with consistent frequency and 90-degree phase difference; the frequencies of the two pairs of reference signals are respectively f0＝fc-fw(ii) 4 and f1＝fc+fw/4, wherein f is usedcAt intermediate frequency of the signal, fwFor code rate, the symbol period is TsThe A/D sampling clock is fsIn total, N is 2KThe set of selectable spreading sequences.
Preferably, the specific process of step 5 is as follows:
step 501, determining a preliminary correlation integral value actually used by each group according to the correlation integral values of 4 chips in the mth code element calculated in step 4 and the mth code element value of the N groups of spread spectrum information sequences; when the code element is 0, the actual correlation values of the two paths I, Q in the code element are the intra-code-element correlation values of the 1 st local reference signal and the sampling signal in the S4; when the code element is 1, the code element is the code element inner correlation value of the 2 nd pair of local reference signals and the sampling signal;
step 502, determining a final symbol correlation integral value actually used by each group according to the initial phase value corresponding to the mth symbol in the N groups of spread spectrum information sequences calculated in step 203; if the initial phase is 0, the value obtained in step 501 is used as the final code element correlation integral value; if the initial phase is 1, the value obtained in step 501 needs to be subjected to sign negation operation to be used as a final code element correlation integral value;
step 503, accumulating the correlation integral values in the I, Q two paths of final code elements obtained in step 502 and the correlation integral values of the first m-1 code elements to obtain the correlation integral values of the first m code elements; when M is M-1, the symbol correlation integral value of the whole spread spectrum information sequence is obtained.
Preferably, in steps 501 and 502, the m-th intra-symbol correlation integral value is represented by the current symbol an,mAnd the initial phase of the current code element
Determining: when the code element an,m At 0, the two paths of correlation values in the symbol I, Q are
When the symbol an,m When 1, the intra-symbol correlation value is taken
The symbol-related integral value of the entire spreading information sequence in step 503 refers to:
accumulating the M code element inner correlation values in the whole symbol to calculate I, Q two paths of symbol inner correlation integral values I of N groups of sequencesn、QnThe specific calculation process is shown as the following formula:
preferably, the 4 reference signals are calculated by a numerically controlled oscillator, calculated by a direct digital frequency synthesizer (DDS), or pre-stored in a storage component.
Preferably, the N related integrated values in the pulse in step 6 are realized by one of the following three methods;
the method comprises the following steps: performing modular operation on I, Q two paths of correlation values to obtain final N sign internal correlation integral values En；
The method 2 comprises the following steps: the square sum of the I, Q two paths of correlation values is obtained to obtain the final N sign internal correlation integral value En；
The method 3 comprises the following steps: the absolute value of the I, Q two paths of correlation values is calculated to obtain the final correlation integral value E in the N symbolsn。
A demodulation and de-spreading system of an MSK spread spectrum receiver comprises: the spread spectrum correlation value calculation module is used for determining the position of a spread spectrum pulse to be resolved; generating 4 paths of reference signals, N groups of reference code element sequences and corresponding code element initial phase sequences; based on the spread spectrum pulse position, carrying out signal sampling, and multiplying the sampled sampling signal by 4 paths of signals; performing intra-symbol accumulation integration on the 4 multiplication results to obtain a correlation value of each intra-symbol signal and 4 paths of reference signals; calculating I, Q two paths of correlation integral values of each group of whole spread spectrum signals through N groups of reference code elements and an initial phase sequence; the pulse correlation value calculating module is used for obtaining N final correlation integral values in the pulse according to the I, Q two paths of correlation integral values; and the original demodulation and de-spreading module is used for comparing the N correlation values and taking K bit information x of the corresponding values of the M bit code element sequences corresponding to the maximum correlation value as the original information after final demodulation and de-spreading.
A computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of a method for demodulation and despreading by an MSK spread spectrum receiver as described in any one of the above.
An electromagnetic transient simulation algorithm device with multiple switching elements comprises: a memory for storing a computer program; a processor for implementing the steps of the demodulation and despreading method of the MSK spread spectrum receiver as described in any one of the above when the computer program is executed.
Has the advantages that:
the invention fully utilizes the characteristics of the intermediate frequency MSK signal and directly carries out demodulation and de-spread processing on the intermediate frequency MSK signal. The method has the advantages of excellent performance, low complexity, small calculation delay and the like, and the algorithm is still applicable when the sampling rate is under the condition of non-integral multiple of the code rate.
The demodulation despreading method provided by the invention can quickly calculate all possible correlation results by only 4 multipliers, and finally obtain the information after demodulation despreading. And is suitable for any type of spread spectrum system with any length, namely spreading the K bit original information into a group of M bit information in N groups during spreading, and the method is suitable for K, M, N with any positive integer value.
The method can be further expanded to coherent demodulation, if the initial phase of the signal is known, only 1 pair of 2 paths of reference signals in total need to be generated locally in S2, at this time, the correlation value calculated in S5 is the final correlation value, and the final comparison of S7 can be directly skipped over S6 to complete the demodulation.
The characteristics of continuous phase and fixed frequency hopping frequency of the intermediate frequency MSK signal are utilized to split the continuous intermediate frequency MSK signal into two single-frequency signal splicing forms. By combining the signal splicing method, the inter-symbol correlation integral is simply split into the sum of the combination of the intra-symbol signal determined by the symbol and the initial phase and the 4 paths of local reference signal correlation integrals in the MSK spread spectrum communication.
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In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
Fig. 1 is a schematic diagram of decomposing an MSK signal into two fixed frequency signals according to an embodiment of the present application;
FIG. 2 is a flow chart of a method provided by an embodiment of the present application;
fig. 3 is a schematic diagram of a demodulation despreading apparatus according to an embodiment of the present application.
Detailed Description
The technical solution in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
The working principle is as follows: the invention fully utilizes the characteristics of continuous phase and fixed frequency jump of the intermediate frequency MSK signal, greatly reduces the calculation amount required by calculation and the delay of operation processing while ensuring the error code performance of the system, and is still suitable when the sampling rate is non-integral multiple code rate. The invention provides possibility for realizing multi-channel signal processing on a single chip.
Referring to fig. 1, the bold type of the diagram is the selected splicing signal in each symbol. As can be seen from the figure, the intermediate frequency MSK signal can be split into two single frequency signals of fixed frequency.
Fig. 3 shows that when the transmitting end spreads the Kbit original symbol information x into Mbit information, the receiving end needs to solve the Kbit data by receiving the M-bit long signal. In the embodiment, assume that the intermediate frequency of the sampling signal is fcCode rate fwSymbol period of TsThe A/D sampling clock is fsIn total, N is 2KThe set of selectable spreading sequences.
The working process is as follows:
a demodulation and de-spreading method of an MSK spread spectrum receiver comprises the following steps:
step 1: determining the position of a spread spectrum pulse to be resolved;
step 2: generating 4 paths of reference signals, N groups of reference code element sequences and corresponding code element initial phase sequences;
and step 3: based on the spread spectrum pulse position, carrying out signal sampling, and multiplying the sampled sampling signal by 4 paths of signals;
and 4, step 4: respectively carrying out intra-code element accumulation integration on the 4 multiplication results to obtain intra-chip correlation integral values of each intra-code element signal and 4 paths of reference signals;
and 5: calculating I, Q two paths of correlation integral values of each group of whole spread spectrum signals through N groups of reference code elements and an initial phase sequence;
step 6: obtaining N correlation integral values in the final pulse according to the I, Q two paths of correlation integral values;
and 7: and comparing the N correlation values obtained in the S6, and taking K bit information x of the corresponding values of the M bit code element sequences corresponding to the maximum correlation value as the final original information after demodulation and despreading.
The first embodiment is as follows: the specific process of the step 2 is as follows:
step 201: locally generating 4 paths of intermediate frequency reference signals in 2 pairs in real time through a Numerically Controlled Oscillator (NCO) and a sine waveform lookup table, wherein 2 paths of signals in each 1 pair of signals are I, Q paths of signals with consistent frequency and 90-degree phase difference. The frequencies of the two pairs of reference signals are respectively f0＝fc-fw(ii) 4 and f1＝fc+fwAnd/4, and the 2 signals in each pair are I, Q signals with 90-degree phase difference. The expression of the 4-way signal is:
wherein use is made ofcAt intermediate frequency of the signal, fwIs the code rate;
step 202: generating or reading N groups of spread reference symbol sequences an,mObtaining the whole spread spectrum code table matrix; the M bit code element of each row is one of spread spectrum information sequences, and the value of the code element is 0 or 1; reference symbol sequence an,mThe code is a local spread spectrum code and is an N multiplied by M matrix, M code elements in each row are one group of spread spectrum code element sequences, and the value of the code element is 0 or 1; wherein N represents the nth spreading sequence, m represents the mth code element in the spreading sequence, N is more than or equal to 0 and less than N, and 0 is more than or equal to 0m＜M。
Step 203: by utilizing the characteristic of MSK signal phase continuity, according to the reference code element sequence an,mAnd the characteristic that the MSK signal phase is continuous, calculating an initial phase value corresponding to each code element in each group of locally generated spread spectrum code sequences to obtain an initial phase sequence of N groups of reference signals
Is an NxM matrix, the value of which is 0 pi or 1 pi, and the specific calculation process is as follows:
example two: in step 4, the 4 product results are subjected to intra-symbol accumulation integration to obtain a correlation value I of each intra-symbol signal and 4 reference signals0,m、Q0,m、I1,m、Q1,m. Where it is required to be based on the system sampling clock fsAnd code rate fwThe start and stop of the correlation integration in the chip are strictly controlled. With fs＝6.0fwFor example, from the first sampling point, the product value of the first 6 sampling points and the reference signal is accumulated to complete the integration in the first chip, and then the product value of the 7 th to 12 th sampling points and the reference signal is accumulated to complete the integration in the second chip, and the correlation calculation of the subsequent 3 rd to M th chips is sequentially realized according to the rule, and the specific calculation process of the mth chip under the condition is as follows:
in the above formula, ad (t) is a sampling signal, and the expression of the 4 intermediate frequency reference signals is:
wherein a first pair of signals s0,I(t) and s0,Q(t); second pair of signals s1,I(t) and s1,Q(t); 2 paths of signals in the two pairs of signals are I, Q paths of signals with consistent frequency and 90-degree phase difference; the frequencies of the two pairs of reference signals are respectively f0＝fc-fw(ii) 4 and f1＝fc+fw/4, wherein f is usedcAt intermediate frequency of the signal, fwFor code rate, the symbol period is TsThe A/D sampling clock is fsIn total, N is 2KThe set of selectable spreading sequences.
FIG. 3 is a schematic diagram of a processing structure according to an embodiment of the invention. In the embodiment, the (M, K) spreading is taken as an example, that is, the transmitting end spreads the Kbit original symbol information x into Mbit information during spreading, and the receiving end needs to solve the Kbit data by receiving the M-bit long signal. In the embodiment, assume that the intermediate frequency of the sampling signal is fcCode rate fwSymbol period of TsThe A/D sampling clock is fsIn total, N is 2KThe set of selectable spreading sequences.
Example three: the specific process of the step 5 is as follows:
step 501, determining a preliminary correlation integral value actually used by each group according to the correlation integral values of 4 chips in the mth code element calculated in step 4 and the mth code element value of the N groups of spread spectrum information sequences; when the code element is 0, the actual correlation values of the two paths I, Q in the code element are the intra-code-element correlation values of the 1 st local reference signal and the sampling signal in the S4; when the code element is 1, the code element is the code element inner correlation value of the 2 nd pair of local reference signals and the sampling signal;
step 502, determining a final symbol correlation integral value actually used by each group according to the initial phase value corresponding to the mth symbol in the N groups of spread spectrum information sequences calculated in step 203; if the initial phase is 0, the value obtained in step 501 is used as the final code element correlation integral value; if the initial phase is 1, the value obtained in step 501 needs to be subjected to sign negation operation to be used as a final code element correlation integral value;
step 503, accumulating the correlation integral values in the I, Q two paths of final code elements obtained in step 502 and the correlation integral values of the first m-1 code elements to obtain the correlation integral values of the first m code elements; when M is M, the symbol correlation integral value of the whole spread spectrum information sequence is obtained.
In step 501 and step 502, for example, the mth symbol is taken as an example, and the correlation integral value in the mth symbol is calculated from the current symbol an,mAnd the initial phase of the current code element
Determining: when the code element an,mAt 0, the two paths of correlation values in the symbol I, Q are
When the symbol an,mWhen 1, the intra-symbol correlation value is taken
Step 503 is to accumulate the M intra-symbol correlation values in the whole symbol according to the above rules, and calculate I, Q two-path intra-symbol correlation integral value I of the N-group sequencen、QnThe specific calculation process is shown as the following formula:
due to an,mAnd
the multiplication in the step can be replaced and realized by simple structures such as a selector, an adder-subtractor and the like, and a multiplier is not consumed actually.
Example four: the step 6 may specifically be: n related integral values in the pulse are realized by one of the following three methods;
the method comprises the following steps: performing modular operation on I, Q two paths of correlation values to obtain final N sign internal correlation integral values En；
Specifically, the correlation values of I, Q are subjected to modulo operation to obtain correlation integral values in the N final symbols. By carrying out I on I, Q two-way correlation valuen、QnPerforming modulus calculation, eliminating unknown initial phase of the sampling signal, and obtaining final correlation integral values in N symbols
The method 2 comprises the following steps: the square sum of the I, Q two paths of correlation values is obtained to obtain the final N sign internal correlation integral value En；
Specifically, the square sum of the I, Q two paths of correlation values is obtained to obtain N final intra-symbol correlation integral values. By carrying out I on I, Q two-way correlation valuen、QnThe square sum is calculated, the unknown initial phase of the sampling signal is eliminated, and the final N sign internal correlation integral value E is obtainedn＝In 2+Qn 2。
The method 3 comprises the following steps: the absolute value of the I, Q two paths of correlation values is calculated to obtain the final correlation integral value E in the N symbolsn。
Specifically, the absolute value of the I, Q two paths of correlation values is calculated to obtain the correlation integral values in the N final symbols. By carrying out I on I, Q two-way correlation valuen、QnCalculating absolute value, eliminating unknown initial phase of sampling signal to obtain final N-symbol internal correlation integral value En＝abs(In+jQn)。
Example five: the specific mode of the step 7 is as follows: and comparing the correlation integral values in the N symbols to determine the final demodulation and despreading symbols. And comparing the N correlation values obtained in the S6, and taking the K bit information x of the value corresponding to the M bit code element sequence corresponding to the maximum correlation value as the original information after final demodulation and despreading.
Example six: the 4 paths of reference signals are obtained by calculation of a numerical control oscillator, direct digital frequency synthesizer (DDS) or stored in a storage component in advance.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other ways. The apparatus embodiments described above are merely illustrative, and for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, functional modules in the embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.
The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
It is noted that, herein, relational terms such as first and second, and the like may be 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. Also, 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 an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (10)
1. A demodulation and de-spreading method for an MSK spread spectrum receiver is characterized by comprising the following steps:
step 1: determining the position of a spread spectrum pulse to be resolved;
step 2: generating 4 paths of reference signals, N groups of reference code element sequences and corresponding code element initial phase sequences;
and step 3: based on the spread spectrum pulse position, carrying out signal sampling, and multiplying the sampled sampling signal by 4 paths of reference signals;
and 4, step 4: respectively carrying out intra-code element accumulation integration on the 4 multiplication results to obtain intra-chip correlation integral values of each intra-code element signal and 4 paths of reference signals;
and 5: calculating I, Q two paths of correlation integral values of each group of whole spread spectrum signals through N groups of reference code elements and an initial phase sequence;
step 6: obtaining N correlation integral values in the final pulse according to the I, Q two paths of correlation integral values;
and 7: and 6, comparing the N correlation values obtained in the step 6, and taking K bit information x of the corresponding values of the M bit code element sequences corresponding to the maximum correlation value as the final original information after demodulation and despreading.
2. The method of claim 1, wherein said step 2: the specific process is as follows:
step 201: generating 2 pairs of 4 paths of intermediate frequency reference signals in real time;
step 202: generating or reading N groups of spreading code sequences to obtain a whole spreading code list matrix; the M bit code element of each row is one of spread spectrum information sequences, and the value of the code element is 0 or 1;
step 203: calculating a corresponding code element initial phase table according to the spread spectrum code table in step 202 by using the characteristic of MSK signal phase continuity to obtain an initial phase sequence
The initial phase takes the value 0 pi or 1 pi.
3. The method of claim 2, wherein the 4 if reference signals are expressed as:
a first pair of signals s0,I(t) and s0,Q(t); second pair of signals s1,I(t) and s1,Q(t); 2 paths of signals in the two pairs of signals are I, Q paths of signals with consistent frequency and 90-degree phase difference; the frequencies of the two pairs of reference signals are respectively f0＝fc-fw(ii) 4 and f1＝fc+fw/4, wherein f is usedcAt intermediate frequency of the signal, fwFor code rate, the symbol period is TsThe A/D sampling clock is fsIn total, N is 2KThe set of selectable spreading sequences.
4. The method according to claim 2 or 3, wherein the step 5 is implemented by the following steps:
step 501, determining a preliminary correlation integral value actually used by each group according to the correlation integral values of 4 chips in the mth code element calculated in step 4 and the mth code element value of the N groups of spread spectrum information sequences; when the code element is 0, the actual correlation values of the I, Q paths in the code element are the intra-code-element correlation values of the 1 st local reference signal and the sampling signal in the step 4; when the code element is 1, the code element is the code element inner correlation value of the 2 nd pair of local reference signals and the sampling signal;
step 502, determining a final symbol correlation integral value actually used by each group according to the initial phase value corresponding to the mth symbol in the N groups of spread spectrum information sequences calculated in step 203; if the initial phase is 0, the value obtained in step 501 is used as the final code element correlation integral value; if the initial phase is 1, the value obtained in step 501 needs to be subjected to sign negation operation to be used as a final code element correlation integral value;
step 503, accumulating the correlation integral values in the I, Q two paths of final code elements obtained in step 502 and the correlation integral values of the first m-1 code elements to obtain the correlation integral values of the first m code elements; when M is M-1, the symbol correlation integral value of the whole spread spectrum information sequence is obtained.
5. The method of claim 4, wherein in steps 501 and 502, the associated integration values in the mth symbol are calculated fromFront code element an,mAnd the initial phase of the current code element
Determining: when the code element an,mAt 0, the two paths of correlation values in the symbol I, Q are
When the symbol an,mWhen 1, the intra-symbol correlation value is taken
The symbol-related integral value of the entire spreading information sequence in step 503 refers to:
accumulating the M code element inner correlation values in the whole symbol to calculate I, Q two paths of symbol inner correlation integral values I of N groups of sequencesn、QnThe specific calculation process is shown as the following formula:
6. the method according to claims 1, 2, 3 and 5, wherein the 4 reference signals are calculated by a numerically controlled oscillator, calculated by a direct digital frequency synthesizer or pre-stored in a storage component.
7. The method of claim 6, wherein the N associated integration values in the pulse of step 6 are achieved by one of three methods;
the method comprises the following steps: performing modular operation on I, Q two paths of correlation values to obtain final N sign internal correlation integral values En；
The method 2 comprises the following steps: the square sum of the I, Q two paths of correlation values is obtained to obtain the final N sign internal correlation integral value En；
The method 3 comprises the following steps: the absolute value of the I, Q two paths of correlation values is calculated to obtain the final N symbol internal phasesOff integral value En。
8. A demodulation despreading system for an MSK spread spectrum receiver, comprising:
the spread spectrum correlation value calculation module is used for determining the position of a spread spectrum pulse to be resolved; generating 4 paths of reference signals, N groups of reference code element sequences and corresponding code element initial phase sequences; based on the spread spectrum pulse position, carrying out signal sampling, and multiplying the sampled sampling signal by 4 paths of signals; performing intra-symbol accumulation integration on the 4 multiplication results to obtain a correlation value of each intra-symbol signal and 4 paths of reference signals; calculating I, Q two paths of correlation integral values of each group of whole spread spectrum signals through N groups of reference code elements and an initial phase sequence;
the pulse correlation value calculating module is used for obtaining N final correlation integral values in the pulse according to the I, Q two paths of correlation integral values;
and the original demodulation and de-spreading module is used for comparing the N correlation values and taking K bit information x of the corresponding values of the M bit code element sequences corresponding to the maximum correlation value as the original information after final demodulation and de-spreading.
9. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a computer program which, when being executed by a processor, carries out the steps of the method for demodulating and despreading an MSK spread spectrum receiver according to any one of claims 1 to 7.
10. An electromagnetic transient simulation algorithm device comprising a plurality of switching elements, comprising: a memory for storing a computer program; a processor for implementing the steps of the method for demodulating and despreading an MSK spread spectrum receiver according to any one of claims 1 to 7 when executing said computer program.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1181165A (en) * | 1995-12-29 | 1998-05-06 | 诺基亚电信公司 | Multi-branch frequency-hopping receiver |
| AU2006340851A1 (en) * | 2005-07-28 | 2007-10-04 | Harris Global Communications, Inc. | Adaptive synchronization enhancement technique for serial modulated waveforms |
| CN101309253A (en) * | 2007-06-11 | 2008-11-19 | 杭州中科微电子有限公司 | Non-coherent frequency compensation and modulation method and demodulating apparatus |
| US8948230B1 (en) * | 2013-11-28 | 2015-02-03 | Uniband Electronic Corp. | Multi-rate coexistence scheme in DSSS O-QPSK network |
| CN104486275A (en) * | 2014-12-11 | 2015-04-01 | 中国电子科技集团公司第二十研究所 | Data chain intermediate-frequency signal processing method |
| CN207070050U (en) * | 2017-06-20 | 2018-03-02 | 深圳市科立讯数据技术有限公司 | A kind of number passes spread-spectrum signal decoding control equipment |
| CN108347259A (en) * | 2018-02-07 | 2018-07-31 | 成都泰格微电子研究所有限责任公司 | A kind of MSK demodulation methods based on matched filter |
-
2019
- 2019-12-11 CN CN201911264277.4A patent/CN111064494B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1181165A (en) * | 1995-12-29 | 1998-05-06 | 诺基亚电信公司 | Multi-branch frequency-hopping receiver |
| AU2006340851A1 (en) * | 2005-07-28 | 2007-10-04 | Harris Global Communications, Inc. | Adaptive synchronization enhancement technique for serial modulated waveforms |
| CN101309253A (en) * | 2007-06-11 | 2008-11-19 | 杭州中科微电子有限公司 | Non-coherent frequency compensation and modulation method and demodulating apparatus |
| US8948230B1 (en) * | 2013-11-28 | 2015-02-03 | Uniband Electronic Corp. | Multi-rate coexistence scheme in DSSS O-QPSK network |
| CN104486275A (en) * | 2014-12-11 | 2015-04-01 | 中国电子科技集团公司第二十研究所 | Data chain intermediate-frequency signal processing method |
| CN207070050U (en) * | 2017-06-20 | 2018-03-02 | 深圳市科立讯数据技术有限公司 | A kind of number passes spread-spectrum signal decoding control equipment |
| CN108347259A (en) * | 2018-02-07 | 2018-07-31 | 成都泰格微电子研究所有限责任公司 | A kind of MSK demodulation methods based on matched filter |
Non-Patent Citations (2)
| Title |
|---|
| A low complexity MSK-based M-ary cyclic shift keying transceiver for direct sequence spread spectrum system over multipath fading channels;Juinn-Horng Deng et al;《2009 11th International Conference on Advanced Communication Technology》;20090218;全部 * |
| 西方体制敌我识别器基带信号处理算法研究及实现;欧阳超;《中国优秀硕士学位论文全文数据库 工程科技II辑》;20160315(第03期);全部 * |
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