A method and apparatus for non-coherent demodulation of a GMSK signal

Abstract

The present disclosure relates to a GMSK signal non-coherent demodulation method and device. The method comprises: obtaining a state grid map by multi-symbol detection; obtaining a matched filter according to the state grid map; passing a received baseband signal through the matched filter to obtain a signal correlation value; obtaining a branch metric value of each state node in the baseband signal according to the signal correlation value; updating a path metric value of each state node according to the branch metric value; retaining a path corresponding to the maximum path metric value of each state node and taking the path as a survivor path of each state node; and backtracking the survivor path of each state node to obtain demodulation data of the baseband signal. The method provided by the present disclosure obtains a state grid by multi-symbol detection, combines multiple symbol information, solves the problem of insufficient memory length in the related art, avoids the spread of false edges in the grid, and reduces the error probability of symbol judgment during demodulation.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of communication technology, and in particular, to a GMSK signal non-coherent demodulation method and device. BACKGROUND

[0002] Gaussian Filtered Minimum Shift Keying (GMSK) as a constant envelope continuous phase modulation (CPM) technology, with its high spectral efficiency and anti-nonlinear distortion ability, is widely used in GSM, Bluetooth, satellite communication and other systems.

[0003] In the related art, the demodulation of the GMSK signal is divided into coherent demodulation and non-coherent demodulation. Among them, non-coherent demodulation does not need to perform carrier synchronization, making the receiver design structure simpler and having a wide range of application scenarios. In the related art, GMSK non-coherent demodulation usually uses differential phase detection, but its performance is greatly lost compared to coherent demodulation. Although differential detection can avoid carrier phase synchronization, it has two defects: one is the noise amplification effect: differential operation converts additive noise into multiplicative noise, which has poor anti-noise ability and is limited in application scenarios; the other is the insufficient memory length: the introduction of the GMSK Gaussian pre-filter makes the energy of a single symbol spread to adjacent symbols, forming inherent ISI (Inter-Symbol Interference), which only uses the information of adjacent symbols, and a single symbol error will lead to subsequent continuous decision errors; differential demodulation only uses the correlation of adjacent symbols and cannot resist deep ISI. Moreover, with the increase of the partial response length of the signal, the performance of the differential detection will become worse and worse. SUMMARY

[0004] To solve the above technical problems, the present disclosure provides a GMSK signal non-coherent demodulation method and device.

[0005] The present disclosure provides a GMSK signal non-coherent demodulation method, comprising: obtaining a state grid graph by using multi-symbol detection; obtaining a matched filter according to the state grid graph; passing a received baseband signal through the matched filter to obtain a signal correlation value; obtaining a branch metric value of each state node in the baseband signal according to the signal correlation value; updating a path metric value of each state node according to the branch metric value; retaining a path corresponding to the maximum path metric value of each state node and taking the path as a survivor path of each state node; backtracking the survivor path of each state node to obtain demodulation data of the baseband signal.

[0006] Optionally, the state trellis diagram obtained by the multi-symbol detection comprises: setting a window length of the multi-symbol detection as N to obtain the state trellis diagram, wherein a state number of the state trellis diagram is a state of the state trellis diagram is an input of the state trellis diagram is a next time state of the state trellis diagram is L is a preset partial response length, n is a positive integer, is a symbol period.

[0007] Optionally, the matched filter obtained according to the state trellis diagram comprises: obtaining an instantaneous phase according to the state trellis diagram and a phase response function of the GMSK signal wherein ; obtaining a phase function in a time interval (n-N+1)T≤t≤(n+1)T according to the instantaneous phase wherein , ; obtaining the matched filter according to the phase function wherein j is an imaginary unit.

[0008] Optionally, the signal correlation value wherein is a received baseband signal, and * represents a conjugate.

[0009] Optionally, the branch metric value is a complex envelope of the signal correlation value, and the branch metric value .

[0010] Optionally, the branch metric value of each state node in the baseband signal is obtained according to the signal correlation value, comprising: substituting and into the branch metric value respectively to obtain two branch metric values of each state node.

[0011] Optionally, after obtaining the survivor path of each state node, further comprising: obtaining a survivor path value of each state node, and determining a minimum survivor path value in the survivor path value of each state node; subtracting the minimum survivor path value from the survivor path value of each state node.

[0012] ​​Based on the same inventive concept, the disclosure further provides a GMSK signal non-coherent demodulation device, comprising: a multi-symbol detection module for obtaining a state grid map by multi-symbol detection; a first calculation module for obtaining a matched filter according to the state grid map; a matched filter module for passing a received baseband signal through the matched filter to obtain a signal correlation value; a second calculation module for obtaining a branch metric value of each state node in the baseband signal according to the signal correlation value; a path update module for updating a path metric value of each state node according to the branch metric value; a path selection module for retaining a path corresponding to the maximum path metric value of each state node and taking the path as a survivor path of each state node; and a demodulation module for backtracking the survivor path of each state node to obtain demodulation data of the baseband signal.

[0013] Based on the same inventive concept, the disclosure further provides an electronic device, comprising: a processor; a memory for storing executable instructions; wherein the processor is configured to read the executable instructions from the memory and execute the executable instructions to implement any one of the methods.

[0014] Based on the same inventive concept, the disclosure further provides a computer-readable storage medium having a computer program stored thereon, characterized in that the storage medium stores a computer program, and when the computer program is executed by a processor, the processor implements any one of the methods.

[0015] The technical solution provided by the disclosure has the following advantages compared with the prior art: the disclosure provides a non-coherent demodulation method for GMSK signals, which does not require carrier phase recovery and does not use differential detection, thereby improving the anti-noise capability during signal demodulation. At the same time, the method provided by the disclosure obtains a state grid through multi-symbol detection, combines multiple symbol information, solves the problem of insufficient memory length in related technologies, and the error of a single symbol can be compensated by other symbols within the multi-symbol detection window, thereby avoiding the error from spreading along the grid and reducing the error probability of the symbol decision during demodulation. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the disclosure and, together with the specification, serve to explain the principles of the disclosure.

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the disclosure or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0018] Figure 1 A flowchart of a GMSK signal non-coherent demodulation method provided by an embodiment of the present disclosure is shown in FIG. 1.

[0019] Figure 2 A flowchart of another GMSK signal non-coherent demodulation method provided by an embodiment of the present disclosure is shown in FIG. 2.

[0020] Figure 3 A simulation test result diagram of a method provided by an embodiment of the present disclosure is shown in FIG. 3.

[0021] Figure 4 A simulation test result diagram of another method provided by an embodiment of the present disclosure is shown in FIG. 4.

[0022] Figure 5 A structural diagram of a GMSK signal non-coherent demodulation device provided by an embodiment of the present disclosure is shown in FIG. 5.

[0023] Figure 6 An electronic device hardware structure diagram provided by an embodiment of the present disclosure is shown in FIG. 6. DETAILED DESCRIPTION

[0024] In order to more clearly understand the above-mentioned purposes, features and advantages of the embodiments of the present disclosure, the schemes of the embodiments of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0025] In the following description, many specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure, but the embodiments of the present disclosure can also be implemented in other ways different from those described herein; obviously, the embodiments described in the specification are only some of the embodiments of the present disclosure, not all the embodiments.

[0026] First, a GMSK signal is simply introduced, and the technical solutions related to the nature of the GMSK signal described below in the embodiments of the present disclosure can refer to this.

[0027] The general form of the baseband signal of the GMSK signal is as follows:

[0028] 。

[0029] In the formula, φ(t) is a time-varying phase function, and the modulation information of the GMSK signal is carried on the function; is a transmitted symbol information vector, and the elements in the vector take values in {-1, +1}.

[0030] The expression of φ(t) is as follows:

[0031] The expression of φ(t) is as follows: .

[0032] wherein, is a modulation coefficient, is a symbol period, is a phase response function, at , is an integral of a pulse shaping function , specifically,

[0033] .

[0034] wherein, is a partial response length of a signal, indicating a time duration length of a pulse shaping function .

[0035] For a GMSK signal, is a response of a Gaussian filter to a rectangular pulse:

[0036] .

[0037] wherein, is a 3dB bandwidth of a filter, BT is a normalized 3dB bandwidth of a Gaussian filter. Q(t) is a complementary cumulative distribution function, used to describe a shaping effect of a Gaussian filter to a rectangular pulse. In the above expression of , two terms Q(·) are subtracted, the essence is to calculate an integral of a Gaussian distribution function within a time window [-T / 2, T / 2].

[0038] Within a time interval , a phase function of a GMSK signal can be further expressed as:

[0039] .

[0040] wherein, is an accumulated phase, indicating a constant part in a total additional phase within an interval ; is an instantaneous phase, indicating a changing part in the total additional phase within the interval .

[0041] Embodiments of the present disclosure provide a GMSK signal non-coherent demodulation method, as shown in Figure 1 , comprising:

[0042] S1, obtaining a state trellis diagram by using multi-symbol detection.

[0043] S2, obtaining a matched filter according to the state trellis diagram.

[0044] ​S3, passing the received baseband signal through a matched filter to obtain a signal correlation value.

[0045] S4, obtaining a branch metric value of each state node in the baseband signal according to the signal correlation value.

[0046] S5, updating a path metric value of each state node according to the branch metric value.

[0047] S6, reserving a path corresponding to a maximum path metric value of each state node, and taking the path as a survivor path of each state node.

[0048] S7, backtracking the survivor path of each state node to obtain demodulation data of the baseband signal.

[0049] Embodiments of the present disclosure provide a non-coherent demodulation method of a GMSK signal, which does not need to perform carrier phase recovery and does not use differential detection, and improves the anti-noise capability during signal demodulation. Meanwhile, the method provided by the embodiments of the present disclosure obtains a state grid through multi-symbol detection, combines multiple symbol information, solves the problem of insufficient memory length in the related art, and the error of a single symbol can be compensated by other symbols within a multi-symbol detection window, so that the error is prevented from spreading along the grid, and the error probability of the symbol decision during demodulation is reduced.

[0050] Specifically, the overall flow of the method provided by the embodiments of the present disclosure is shown in Figure 2 First, a state grid and a matched filter are obtained by using multi-symbol detection (S1 and S2 described above), then the received signal is passed through the matched filter (S3 described above), non-coherent detection quantity decision is performed (S4 described above), and finally, a Viterbi calculation method is performed (S5 to S7 described above) to obtain demodulation data.

[0051] In some embodiments, S1 described above includes:

[0052] The window length of the multi-symbol detection is set to N to obtain a state grid graph, wherein in a time interval (n-N+1)T≤t≤(n+1)T, the number of states of the state grid graph is the current state of the state grid graph is the input of the state grid graph is the next time state of the state grid graph is a transmitted bit sequence related to the instantaneous phase (i.e., used to obtain the instantaneous phase) is a sequence of the current state of the state grid graph plus the input of the state grid graph is L is a preset partial response length, and n is a positive integer.

[0053] Specifically, the multi-symbol detection can detect multiple states in the state grid map through a window, such as the state sequence in the above embodiment, thereby solving the problem of insufficient memory length in the related art, and a single symbol error can be compensated by other symbols in the multi-symbol detection window, so as to avoid error diffusion along the grid and reduce the error probability of the symbol decision in the demodulation.

[0054] The partial response length L is the truncation length of the pulse shaping function The Gaussian pulse is theoretically infinite in length, but needs to be truncated to a finite length LT in engineering, that is, g(t) is a Gaussian pulse function in the time interval of 0≤t≤LT, and is 0 outside the interval. In a specific implementation, the partial response length L is a parameter of modulation, which needs to be comprehensively evaluated in the design of modulation in combination with the value, performance and complexity of BT. In a specific embodiment, under the GSM standard, L=3 (BT=0.3). The partial response length L is the same in modulation and demodulation.

[0055] In some embodiments, S2 includes:

[0056] S21, obtaining an instantaneous phase according to the state grid map and a phase response function of the GMSK signal S21, obtaining an instantaneous phase according to the state grid map and a phase response function of the GMSK signal S21, obtaining an instantaneous phase according to the state grid map and a phase response function of the GMSK signal .

[0057] S22, obtaining a phase function in the time interval (n-N+1)T≤t≤(n+1)T according to the instantaneous phase S22, obtaining a phase function in the time interval (n-N+1)T≤t≤(n+1)T according to the instantaneous phase S22, obtaining a phase function in the time interval (n-N+1)T≤t≤(n+1)T according to the instantaneous phase , .

[0058] S23, obtaining a matched filter according to the phase function S23, obtaining a matched filter according to the phase function S23, obtaining a matched filter according to the phase function , j is an imaginary unit. The function of the matched filter is similar to the expression of the general form of the baseband signal , because the matched filter needs to contain the waveform of all possible transmitted baseband signals, so that the received baseband signal can pass through the matched filter, specifically, the received signal is multiplied by the matched filter .

[0059] Specifically, the calculation process of the phase function refers to the following formula:

[0060] .

[0061] In some embodiments, the signal correlation value , wherein, For the received baseband signal, the conjugate is denoted as

[0062] In implementation, S3 includes:

[0063] The received signal is subjected to a matched filter to obtain the correlation value of the received signal and all possible transmitted signal waveforms in the time interval (n-N+1)T≤t≤(n+1)T, and the signal length used for correlation is the window length N, so as to obtain the signal correlation value.

[0064] In some embodiments, the branch metric value is a complex envelope of the signal correlation value, and the branch metric value .

[0065] In some embodiments, S4 includes:

[0066] In each state node, the and are substituted into the branch metric value to obtain two branch metric values of each state node.

[0067] In implementation, at the time of (n+1)T, for each state node, there are two choices of input and , so that each state node can obtain the non-coherent branch metric values of the two branches entering the node.

[0068] In some embodiments, S5 includes:

[0069] At the time of (n+1)T, the two branch metric values obtained by each state node are accumulated with one surviving path value of each state node at the time of nT to obtain two path metric values of each state node at the time of (n+1)T.

[0070] In some embodiments, S6 includes:

[0071] The two path metric values in each state node are compared, and the path corresponding to the maximum path metric value is retained, and the other path is discarded. After each state node completes the above operation, there will be only one surviving path. The surviving path and the corresponding path metric value are retained, and the length of the memorized path is .

[0072] In some embodiments, after S6, the method provided by the embodiments of the present disclosure further includes:

[0073] The surviving path value of each state node is obtained, and the minimum surviving path value is determined in the surviving path value of each state node. The surviving path value of each state node is subtracted by the minimum surviving path value to avoid data overflow and achieve the purpose of normalization.

[0074] In some embodiments, S7 comprises:

[0075] Steps S4 to S6 are repeated for each symbol (each symbol comprises a state node), After that, starting from each symbol, the demodulation value of the symbol before the symbol is outputted, then the survivor path with the largest path metric is selected, the data saved by the path is traced back, the information at the moment is demodulated, and the process returns to the beginning, and the next loop is continued until all symbol sequences in the received signal complete the above steps, and finally the demodulated data is obtained.

[0076] The embodiments of the present disclosure also provide two simulation test results, as shown in Figure 3 and Figure 4 , wherein, Figure 3 and Figure 4 , the horizontal coordinate is Eb / N0, Eb represents the energy of each bit, N0 represents the noise power in a unit bandwidth, Eb / N0 represents the ratio of the energy of each bit to the noise power in a unit bandwidth, and the vertical coordinate is the bit error rate BER.

[0077] Figure 3 The non-coherent demodulation performance of the method provided by the embodiments of the present disclosure for GMSK signal multi-symbol joint detection is simulated, wherein, , , It can be seen from the figure that the performance of is 1 dB better than that of , and the performance of differs from the performance of the theoretical coherent demodulation by only 1 dB, because the larger the window length is, the more symbols and information can be used, the better the demodulation performance is, and the better the noise suppression effect is.

[0078] Figure 4 The anti-frequency offset performance of the method provided by the embodiments of the present disclosure is simulated, wherein, , , It can be seen from the figure that the normalized frequency offset less than has little effect on the demodulation performance of the method provided by the embodiments of the present disclosure.

[0079] It should be noted that the method of the embodiments of the present disclosure can be executed by a single device, such as a computer or a server. The method of the embodiments of the present disclosure can also be applied to a distributed scenario and completed by multiple devices in cooperation. In the distributed scenario, one of the multiple devices can only execute one or more steps in the method of the embodiments of the present disclosure, and the multiple devices can interact with each other to complete the above method. ​​

[0080] It should be noted that the above description describes some embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0081] Based on the same inventive concept, corresponding to any of the methods in the above embodiments, this application also provides a non-coherent demodulation device for GMSK signals, such as... Figure 5 As shown, it includes:

[0082] The multi-symbol detection module 10 is used to obtain a state mesh diagram using multi-symbol detection.

[0083] The first calculation module 20 is used to obtain the matched filter based on the state grid diagram.

[0084] The matched filter module 30 is used to pass the received baseband signal through the matched filter to obtain the signal correlation value.

[0085] The second calculation module 40 is used to obtain the branch metric value of each state node in the baseband signal based on the signal correlation value.

[0086] The path update module 50 is used to update the path metric value of each state node based on the branch metric value.

[0087] The path selection module 60 is used to retain the path corresponding to the largest path metric value of each state node and use that path as the surviving path of each state node.

[0088] The demodulation module 70 is used to trace back the surviving path of each state node to obtain the demodulated data of the baseband signal.

[0089] This disclosure provides a noncoherent demodulation apparatus for GMSK signals that eliminates the need for carrier phase recovery and differential detection, thereby improving noise immunity during demodulation. Furthermore, the apparatus obtains a state grid through multi-symbol detection, combining information from multiple symbols to address the insufficient memory length issue in related technologies. Additionally, errors in a single symbol can be compensated for by other symbols within the multi-symbol detection window, preventing errors from spreading along the grid and reducing the probability of incorrect symbol decisions during demodulation.

[0090] For ease of description, the above devices are described in terms of function, divided into various modules. Of course, in implementing this application, the functions of each module can be implemented in one or more software and / or hardware.

[0091] The apparatus of the above embodiments is used to implement the corresponding GMSK signal non-coherent demodulation method of any one of the preceding embodiments, and has the beneficial effects of the corresponding method embodiments, which are not repeated here.

[0092] Figure 6 A structural schematic diagram of an electronic device provided by an embodiment of the present disclosure is shown.

[0093] As shown in Figure 6 The electronic device can include a processor 1101 and a memory 1102 storing computer program instructions.

[0094] Specifically, the processor 1101 can include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present disclosure.

[0095] The memory 1102 can include a mass storage for information or instructions. By way of example and not limitation, the memory 1102 can include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive, or a combination of two or more of these. The memory 1102 can include removable or non-removable (or fixed) media, as appropriate. The memory 1102 can be internal or external to the integrated gateway device, as appropriate. In particular embodiments, the memory 1102 is a non-volatile solid-state memory. In particular embodiments, the memory 1102 includes read-only memory (ROM). The ROM can be mask-programmed ROM, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM), or flash memory, or a combination of two or more of these, as appropriate.

[0096] The processor 1101 reads and executes the computer program instructions stored in the memory 1102 to perform the steps of the GMSK signal non-coherent demodulation method provided by the embodiments of the present disclosure.

[0097] In one example, the electronic device can further include a transceiver 1103 and a bus 1104. As shown in Figure 6 the processor 1101, the memory 1102, and the transceiver 1103 are connected and communicate with each other through the bus 1104.

[0098] The bus 1104 includes hardware, software, or both. By way of example and not limitation, the bus can include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side BUS (FSB), a Hyper Transport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a memory bus, a MicroChannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VLB) bus, or another suitable bus or a combination of two or more of these. Where appropriate, the bus 1104 can include one or more buses. Although this application describes and shows a particular bus, this application contemplates any suitable bus or interconnect.

[0099] The following is an embodiment of a computer-readable storage medium provided by the embodiments of the present disclosure, which belongs to the same inventive concept as the GMSK signal non-coherent demodulation method of the above-mentioned embodiments. Details not described in the embodiment of the computer-readable storage medium can be referred to the embodiments of the GMSK signal non-coherent demodulation method.

[0100] The embodiment provides a storage medium containing computer executable instructions, which when executed by a computer processor, are used to perform a GMSK signal non-coherent demodulation method.

[0101] Of course, the storage medium provided by the embodiments of the present disclosure includes computer executable instructions, which are not limited to the method operations as above, but can also perform related operations in the GMSK signal non-coherent demodulation method provided by any embodiment of the present disclosure.

[0102] Through the above description of the embodiments, those skilled in the art can clearly understand that the present disclosure can be realized by software and necessary general hardware, and of course can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present disclosure can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a floppy disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a FLASH, a hard disk, or an optical disc, etc., including a plurality of instructions to make a computer cloud platform (which can be a personal computer, a server, or a network cloud platform, etc.) execute the GMSK signal non-coherent demodulation method provided by each embodiment of the present disclosure.

[0103] It should be noted that in this paper, relationship terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the term "includes", "contains" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the above element.

[0104] The above is only a specific embodiment of the present disclosure, which enables those skilled in the art to understand or implement the present disclosure. Various modifications of these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the above embodiments, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of non-coherent demodulation of a GMSK signal, characterized in that, The method comprises the following steps: obtaining a state trellis diagram by using multi-symbol detection; obtaining a matched filter according to the state trellis diagram; passing a received baseband signal through the matched filter to obtain a signal correlation value; obtaining a branch metric value of each state node in the baseband signal according to the signal correlation value; updating a path metric value of each state node according to the branch metric value; retaining a path corresponding to a maximum path metric value of each state node as a survivor path of each state node; backtracking the survivor path of each state node to obtain demodulation data of the baseband signal; the step of obtaining the state trellis diagram by using multi-symbol detection comprises the following steps: Setting a window length of multi-symbol detection as N obtains the state grid map, wherein a state number of the state grid map is , a state of the state grid map is , an input of the state grid map is , a next time state of the state grid map is , L is a preset partial response length, n is a positive integer, is a symbol period; the step of obtaining the matched filter according to the state trellis diagram comprises the following steps: According to the state grid map and a phase response function of the GMSK signal Obtaining the instantaneous phase wherein , is a modulation coefficient; According to the instantaneous phase The phase function is obtained in the time interval (n-N+1)T≤t≤(n+1)T wherein, , ; According to the phase function Obtaining the matched filter wherein, j is the imaginary unit; after obtaining the survivor path of each state node, the method further comprises the following steps: obtaining a survivor path value of each state node, and determining a minimum survivor path value in the survivor path value of each state node; subtracting the minimum survivor path value from the survivor path value of each state node.

2. The method of claim 1, wherein, the signal correlation value wherein is the received baseband signal, and * denotes the conjugate.

3. The method of claim 1, wherein, The branch metric values are complex envelopes of the signal correlation values, the branch metric values .

4. The method of claim 3, wherein, the step of obtaining the branch metric value of each state node in the baseband signal according to the signal correlation value comprises the following steps: Substitute the values of the state node and the branch metric value into the state transition function to obtain the state node of the next state. Substitute the values of the state node and the branch metric value into the state transition function to obtain the state node of the next state. Substitute the values of the state node and the branch metric value into the state transition function to obtain the state node of the next state. Sub 5. A GMSK signal non-coherent demodulation apparatus based on the GMSK signal non-coherent demodulation method of claim 1, characterized in that, The method comprises the following steps: a multi-symbol detection module is configured to obtain a state trellis diagram by using multi-symbol detection; a first calculation module is configured to obtain a matched filter according to the state trellis diagram; a matched filtering module is configured to pass a received baseband signal through the matched filter to obtain a signal correlation value; a second calculation module is configured to obtain a branch metric value of each state node in the baseband signal according to the signal correlation value; a path updating module is configured to update a path metric value of each state node according to the branch metric value; a path selection module is configured to retain a path corresponding to a maximum path metric value of each state node as a survivor path of each state node; a demodulation module is configured to backtrack the survivor path of each state node to obtain demodulation data of the baseband signal.

6. An electronic device, comprising: The method comprises the following steps: a processor; a memory configured to store executable instructions; wherein the processor is configured to read the executable instructions from the memory and execute the executable instructions to implement the method of any one of claims 1 to 4.

7. A computer readable storage medium having stored thereon a computer program, characterized in that, The storage medium stores a computer program, and when the computer program is executed by the processor, the processor implements the method of any one of claims 1 to 4.

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