CN108471392B - A method and system for demodulating MSK signals based on pre-decision - Google Patents

Abstract

The present invention provides a kind of based on the msk signal demodulation method adjudicated in advance and system, which comprises obtains the pre- court verdict of msk signal to be demodulated；According to the pre- judgement as a result, filtering out multiple local template signals；Based on the multiple local template signals filtered out, the final judging result of the msk signal to be demodulated is obtained.It is provided by the invention based on the msk signal demodulation method adjudicated in advance and system, by being adjudicated in advance msk signal, and suitable local template signal is selected according to pre- court verdict, msk signal is demodulated based on multiple symbol differential detection algorithm again, improve bit error rate performance, its resource occupation of multiple symbol differential detection is reduced, the complexity of system is reduced.

Description

A method and system for demodulating MSK signals based on pre-decision

technical field

The invention relates to the technical field of digital signal processing, in particular to a pre-decision-based MSK signal demodulation method and system.

Background technique

The minimum frequency shift keying (MSK) signal demodulation algorithm is the core component in the wireless communication system using MSK modulation, and the detection ability of the MSK demodulation algorithm directly determines the performance of the system.

In the prior art, for the demodulation of the MSK signal, in consideration of the implementation complexity, a non-coherent demodulation method that does not require high carrier synchronization is usually adopted. Existing non-coherent demodulation algorithms can generally be divided into symbol-by-symbol demodulation algorithms and multi-symbol demodulation algorithms. The symbol-by-symbol demodulation algorithm is simple to implement. Commonly used symbol-by-symbol demodulation algorithms include non-coherent envelope detection and 1-bit differential demodulation. The multi-symbol demodulation algorithm has better bit error rate performance, and the commonly used multi-symbol demodulation algorithm includes the multi-symbol differential detection (Multiple-symbol differential detection, MSDD) algorithm and the like.

However, the bit error rate performance of the symbol-by-symbol demodulation algorithm in the prior art is relatively poor; since the multi-symbol demodulation algorithm needs to search 2 ^N templates for each decision, it has high requirements for the implementation complexity of the system. unacceptable in practical applications.

Contents of the invention

The purpose of the present invention is to provide a pre-judgment-based MSK signal demodulation method and system, which solves the technical problems of high bit error rate and complex system of MSK demodulation in the prior art.

In order to solve the above technical problems, on the one hand, the present invention provides a method for demodulating MSK signals based on pre-decision, including:

Obtain the pre-judgment result of the MSK signal to be demodulated;

Screening out multiple local template signals according to the pre-judgment result;

Based on the screened multiple local template signals, the final decision result of the MSK signal to be demodulated is obtained.

Further, the acquisition of the final decision result of the MSK signal to be demodulated based on the selected multiple local template signals is specifically:

Multiplying each local template signal with the MSK signal to be demodulated after a preset time delay to obtain multiple multiplication results;

Integrate each multiplication result to obtain multiple integral results;

performing envelope detection on each integration result to obtain multiple envelope detection values;

The final judgment result of the MSK signal to be demodulated is determined according to the local template signal corresponding to the maximum envelope detection value.

Further, the acquisition of the pre-decision result of the MSK signal to be demodulated is specifically:

The pre-decision result of the MSK signal to be demodulated is obtained based on a symbol-by-symbol demodulation algorithm.

Further, the acquisition of the pre-decision result of the MSK signal to be demodulated is specifically:

The pre-decision result of the MSK signal to be demodulated is obtained based on a one-bit differential demodulation algorithm.

Further, before obtaining the pre-decision result of the MSK signal to be demodulated, it also includes:

Divide the MSK signal to be demodulated into two paths, perform pre-judgment on one path, and delay the other path.

On the other hand, the present invention provides a pre-decision-based MSK signal demodulation system, including:

Pre-judgment module, used to obtain the pre-judgment result of the MSK signal to be demodulated;

A template filter module, configured to filter out a plurality of local template signals according to the pre-judgment result;

The multi-symbol differential detector module is configured to obtain the final decision result of the MSK signal to be demodulated based on the filtered multiple local template signals.

Further, the multi-symbol differential detection module includes:

A delayer submodule, configured to delay the MSK signal to be demodulated according to a preset time

The multiplier sub-module is used to multiply each local template signal with the delayed MSK signal to be demodulated to obtain multiple multiplication results;

The integrator sub-module is used to integrate each multiplication result to obtain multiple integration results;

The envelope detector sub-module is used to perform envelope detection on each integration result to obtain multiple envelope detection values;

The decision sub-module is configured to determine the final decision result of the MSK signal to be demodulated according to the local template signal corresponding to the maximum envelope detection value.

In another aspect, the present invention provides an electronic device for MSK signal demodulation, including:

A memory and a processor, the processor and the memory communicate with each other through a bus; the memory stores program instructions that can be executed by the processor, and the processor invokes the program instructions to perform the above-mentioned method.

In yet another aspect, the present invention provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions, when the program instructions are executed by a computer , make the computer execute the above-mentioned method.

In another aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the above-mentioned method is realized.

The MSK signal demodulation method and system based on pre-judgment provided by the present invention, by pre-judging the MSK signal, selecting a suitable local template signal according to the pre-judgment result, and demodulating the MSK signal based on the multi-symbol differential detection algorithm, improving The bit error rate performance is improved, the resource occupation of multi-symbol differential detection is reduced, and the complexity of the system is reduced.

Description of drawings

1 is a schematic diagram of a pre-decision-based MSK signal demodulation method according to an embodiment of the present invention;

2 is a schematic diagram of a pre-decision-based MSK signal demodulation system according to an embodiment of the present invention;

Fig. 3 is a schematic structural diagram of an electronic device for MSK signal demodulation provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

FIG. 1 is a schematic diagram of a pre-decision-based MSK signal demodulation method according to an embodiment of the present invention. As shown in FIG. 1 , an embodiment of the present invention provides a pre-decision-based MSK signal demodulation method, including:

Step S10, obtaining the pre-decision result of the MSK signal to be demodulated;

Step S20, screening out a plurality of local template signals according to the pre-judgment result;

Step S30, based on the selected multiple local template signals, obtain the final decision result of the MSK signal to be demodulated.

Specifically, firstly, the MSK signal to be demodulated is divided into two paths, and a pre-judgment is performed on the first path of the MSK signal to be demodulated to obtain a set of pre-judgment results of the transmitted information. For example, in a system with an observation window of 7 bits, a group of pre-judgment results remembered are b _pre , b _pre = [b ₁ b ₂ b ₃ b ₄ b ₅ b ₆ b ₇ ], where b ₄ is For the symbols to be decided in subsequent calculations, it is assumed that there are only misjudgments less than or equal to 1 symbol in other results of this group of pre-decisions.

Then, according to the pre-judgment result, multiple local template signals are screened out. Select a group of local template signals that are similar to the pre-judgment results as the output of the screening module. According to the group of pre-judgment results b _pre obtained in the above example, 14 local template signals are obtained after screening, which are as follows:

s ₀ (1)=[b ₁ b ₂ b ₃ 0 b ₅ b ₆ b ₇ ]

s ₁ (1)=[b ₁ b ₂ b ₃ 1 b ₅ b ₆ b ₇ ]

Finally, based on the screened multiple local template signals, a multi-symbol differential detection algorithm is used to obtain the final decision result of the MSK signal to be demodulated.

Taking the MSDD algorithm as an example, in a system with an observation window of ⁷ bits, 27 local template signals need to be selected to adopt the MSDD algorithm. Compared with the prior art, the demodulation method provided by the embodiment of the present invention can effectively reduce the use of local template signals, thereby reducing the complexity of the system. According to the pre-judgment result, only 14 local template signals can be screened out to complete the demodulation of the MSK signal.

The MSK signal demodulation method based on pre-judgment provided by the present invention performs pre-judgment on the MSK signal, selects a suitable local template signal according to the pre-judgment result, and then demodulates the MSK signal based on a multi-symbol differential detection algorithm, thereby improving the error rate. The code rate performance reduces the resource occupation of multi-symbol differential detection and reduces the complexity of the system.

On the basis of the above embodiments, further, the final judgment result of the MSK signal to be demodulated is obtained based on the multiple local template signals screened out, specifically:

Multiplying each local template signal with the MSK signal to be demodulated after a preset time delay to obtain multiple multiplication results;

Integrate each multiplication result to obtain multiple integral results;

performing envelope detection on each integration result to obtain multiple envelope detection values;

The final judgment result of the MSK signal to be demodulated is determined according to the local template signal corresponding to the maximum envelope detection value.

Specifically, the detailed process of obtaining the final decision result of the MSK signal to be demodulated is as follows:

In order to reserve enough calculation time for screening the local template signal, it is necessary to perform delay processing on the second MSK signal to be demodulated. The preset delay time is determined according to the actual situation of the system.

After the filtered local template signals are obtained, the time-delayed second MSK signal to be demodulated is multiplied by each local template signal to obtain multiple multiplication results. Here, the same number of multipliers as the number of filtered local template signals is required, and the step after the multiplication calculation also needs multiple parallel calculations.

Then, each multiplication result is integrated to obtain multiple integration results. The integration time is an integer multiple of the symbol period, and the integration start and end time here needs to be determined according to the bit synchronization information. In the process of implementing the algorithm, the integral operation will be transformed into a summation, that is, to accumulate the multiplication results. Taking the example in the foregoing embodiment as an example, in a system with a 7-bit observation window, the accumulation time is 7 symbol periods.

Then, envelope detection is performed on each integral result, that is, each integral result is modulo squared, and the real part and the imaginary part of the integrated output signal are squared and added to obtain a plurality of envelope detection values. Taking the example in the above embodiment as an example, in a system with an observation window of 7 bits, 14 local template signals are obtained, and in this step, a total of 14 envelope detection values are obtained.

Finally, according to the local template signal corresponding to the maximum envelope detection value, the final decision result of the MSK signal to be demodulated is determined. All the envelope detection values obtained from multiple channels are compared and judged. After the decision unit determines the channel where the maximum value is located, it will determine the judgment result of the current symbol according to the local template signal corresponding to this channel. Taking the example in the above embodiment as an example, in a system with an observation window of 7 bits, a maximum value is selected from the obtained 14 envelope detection values, and the intermediate symbol value of the local template signal corresponding to the maximum envelope detection value is final verdict.

The MSK signal demodulation method based on pre-judgment provided by the present invention performs pre-judgment on the MSK signal, selects a suitable local template signal according to the pre-judgment result, and then demodulates the MSK signal based on a multi-symbol differential detection algorithm, thereby improving the error rate. The code rate performance reduces the resource occupation of multi-symbol differential detection and reduces the complexity of the system.

On the basis of the above embodiments, further, the acquisition of the pre-decision result of the MSK signal to be demodulated is specifically:

The pre-decision result of the MSK signal to be demodulated is obtained based on a symbol-by-symbol demodulation algorithm.

Specifically, when pre-judging the first MSK signal to be demodulated, since the performance of the pre-judgment will not significantly affect the bit error rate performance of the demodulation method in the embodiment of the present invention, it is possible to use a method with low implementation complexity. The symbol-by-symbol demodulation method obtains the pre-judgment result, thereby reducing the complexity of the whole system.

The MSK signal demodulation method based on pre-judgment provided by the present invention performs pre-judgment on the MSK signal, selects a suitable local template signal according to the pre-judgment result, and then demodulates the MSK signal based on a multi-symbol differential detection algorithm, thereby improving the error rate. The code rate performance reduces the resource occupation of multi-symbol differential detection and reduces the complexity of the system.

On the basis of the above embodiments, further, the acquisition of the pre-decision result of the MSK signal to be demodulated is specifically:

The pre-decision result of the MSK signal to be demodulated is obtained based on a one-bit differential demodulation algorithm.

Specifically, when pre-judging the first MSK signal to be demodulated, since the performance of the pre-judgment will not significantly affect the bit error rate performance of the demodulation method in the embodiment of the present invention, it is possible to use a method with low implementation complexity. The 1bit differential demodulation method obtains the pre-judgment result, thereby reducing the complexity of the entire system.

The MSK signal demodulation method based on pre-judgment provided by the present invention performs pre-judgment on the MSK signal, selects a suitable local template signal according to the pre-judgment result, and then demodulates the MSK signal based on a multi-symbol differential detection algorithm, thereby improving the error rate. The code rate performance reduces the resource occupation of multi-symbol differential detection and reduces the complexity of the system.

FIG. 2 is a schematic diagram of a pre-decision-based MSK signal demodulation system according to an embodiment of the present invention. As shown in FIG. 2 , an embodiment of the present invention provides a pre-decision-based MSK signal demodulation system, including a pre-decision module 10, The template filter module 20 and the multi-symbol differential detector module 30, wherein the pre-decision module 10 is used to obtain the pre-decision result of the MSK signal to be demodulated.

The template filter module 20 is configured to filter out multiple local template signals according to the pre-judgment result.

The multi-symbol differential detector module 30 is configured to obtain a final decision result of the MSK signal to be demodulated based on the filtered multiple local template signals.

Specifically, an embodiment of the present invention provides a pre-decision-based MSK signal demodulation system, which is used to complete the method described in the above embodiment, and complete the method described in the above embodiment through the demodulation system provided in this embodiment The specific steps are the same as those in the above embodiment, and will not be repeated here.

The MSK signal demodulation system based on pre-judgment provided by the present invention performs pre-judgment on the MSK signal, selects a suitable local template signal according to the pre-judgment result, and then demodulates the MSK signal based on a multi-symbol differential detection algorithm, thereby improving the error rate. The code rate performance reduces the resource occupation of multi-symbol differential detection and reduces the complexity of the system.

On the basis of the above embodiments, further, the multi-symbol differential detection module includes:

A delayer submodule, configured to delay the MSK signal to be demodulated according to a preset time

The multiplier sub-module is used to multiply each local template signal with the delayed MSK signal to be demodulated to obtain multiple multiplication results;

The integrator sub-module is used to integrate each multiplication result to obtain multiple integration results;

The envelope detector sub-module is used to perform envelope detection on each integration result to obtain multiple envelope detection values;

The decision sub-module is configured to determine the final decision result of the MSK signal to be demodulated according to the local template signal corresponding to the maximum envelope detection value.

Specifically, an embodiment of the present invention provides a pre-decision-based MSK signal demodulation system, which is used to complete the method described in the above embodiment, and complete the method described in the above embodiment through the demodulation system provided in this embodiment The specific steps are the same as those in the above embodiment, and will not be repeated here.

The MSK signal demodulation system based on pre-judgment provided by the present invention performs pre-judgment on the MSK signal, selects a suitable local template signal according to the pre-judgment result, and then demodulates the MSK signal based on a multi-symbol differential detection algorithm, thereby improving the error rate. The code rate performance reduces the resource occupation of multi-symbol differential detection and reduces the complexity of the system.

FIG. 3 is a schematic structural diagram of an electronic device for MSK signal demodulation provided by an embodiment of the present invention. As shown in FIG. 3 , the device includes: a processor 801, a memory 802, and a bus 803;

Wherein, the processor 801 and the memory 802 complete mutual communication through the bus 803;

The processor 801 is used to call the program instructions in the memory 802 to execute the methods provided by the above method embodiments, including, for example:

Obtain the pre-judgment result of the MSK signal to be demodulated;

Screening out multiple local template signals according to the pre-judgment result;

Based on the screened multiple local template signals, the final decision result of the MSK signal to be demodulated is obtained.

An embodiment of the present invention discloses a computer program product, the computer program product includes a computer program stored on a non-transitory computer-readable storage medium, the computer program includes program instructions, and when the program instructions are executed by a computer, The computer can execute the methods provided by the above method embodiments, including, for example:

Obtain the pre-judgment result of the MSK signal to be demodulated;

Screening out multiple local template signals according to the pre-judgment result;

Based on the screened multiple local template signals, the final decision result of the MSK signal to be demodulated is obtained.

An embodiment of the present invention provides a non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the methods provided in the above method embodiments, for example include:

Obtain the pre-judgment result of the MSK signal to be demodulated;

Screening out multiple local template signals according to the pre-judgment result;

Based on the screened multiple local template signals, the final decision result of the MSK signal to be demodulated is obtained.

Those of ordinary skill in the art can understand that all or part of the steps for realizing the above-mentioned method embodiments can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the It includes the steps of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other various media that can store program codes.

The above-described embodiments of devices and equipment are merely illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, That is, it can be located in one place, or it can also be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without any creative effort.

Through the above description of the implementations, those skilled in the art can clearly understand that each implementation can be implemented by means of software plus a necessary general hardware platform, and of course also by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the prior art can be embodied in the form of software products, and the computer software products can be stored in computer-readable storage media, such as ROM/RAM, magnetic discs, optical discs, etc., including several instructions to make a computer device (which may be a personal computer, server, or network device, etc.) execute the methods described in various embodiments or some parts of the embodiments.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (7)

1. a kind of MSK signal demodulation method based on pre-decision, it is characterized in that, comprising: Obtaining a pre-judgment result of the MSK signal to be demodulated, the pre-judgment result being a binary sequence of a set of preset digits; According to the pre-judgment result, a plurality of local template signals are screened out, and each local template signal is a binary sequence of a set of preset digits pre-stored locally; Obtaining the final judgment result of the MSK signal to be demodulated based on the screened multiple local template signals; The final judgment result of the MSK signal to be demodulated is obtained based on the screened multiple local template signals, specifically: Multiplying each local template signal with the MSK signal to be demodulated after a preset time delay to obtain multiple multiplication results; Integrate each multiplication result to obtain multiple integral results; performing envelope detection on each integration result to obtain multiple envelope detection values; The final judgment result of the MSK signal to be demodulated is determined according to the local template signal corresponding to the maximum envelope detection value. 2. The method according to claim 1, characterized in that said obtaining the pre-judgment result of the MSK signal to be demodulated is specifically: The pre-decision result of the MSK signal to be demodulated is obtained based on a symbol-by-symbol demodulation algorithm. 3. The method according to claim 1, wherein the pre-judgment result of the MSK signal to be demodulated is obtained, specifically: The pre-decision result of the MSK signal to be demodulated is obtained based on a one-bit differential demodulation algorithm. 4. The method according to claim 1, characterized in that, before obtaining the pre-decision result of the MSK signal to be demodulated, further comprising: Divide the MSK signal to be demodulated into two paths, perform pre-judgment on one path, and delay the other path. 5. A kind of MSK signal demodulation system based on pre-decision, it is characterized in that, comprising: Pre-judgment module, used to obtain the pre-judgment result of the MSK signal to be demodulated, the pre-judgment result is a binary sequence of a set of preset digits; A template filter module, configured to filter out a plurality of local template signals according to the pre-judgment result, each local template signal is a binary sequence of a set of preset digits pre-stored locally; A multi-symbol differential detector module, configured to obtain the final decision result of the MSK signal to be demodulated based on a plurality of local template signals screened out; The multi-symbol differential detector module includes: A delayer submodule, configured to delay the MSK signal to be demodulated according to a preset time The multiplier sub-module is used to multiply each local template signal with the delayed MSK signal to be demodulated to obtain multiple multiplication results; The integrator sub-module is used to integrate each multiplication result to obtain multiple integration results; The envelope detector sub-module is used to perform envelope detection on each integration result to obtain multiple envelope detection values; The decision sub-module is configured to determine the final decision result of the MSK signal to be demodulated according to the local template signal corresponding to the maximum envelope detection value. 6. An electronic device for MSK signal demodulation, characterized in that, comprising: A memory and a processor, the processor and the memory communicate with each other through a bus; the memory stores program instructions executable by the processor, and the processor invokes the program instructions to execute the The method described in any one of 1 to 4 is required. 7. A computer-readable storage medium, on which a computer program is stored, wherein the computer program implements the method according to any one of claims 1 to 4 when executed by a processor.