CN118764153A - Multiframe synchronization method, device, equipment and storage medium of GSM system - Google Patents

Abstract

The present invention relates to the field of communication technology, and provides a multi-frame synchronization method, device, equipment and storage medium of a GSM system, the method comprising: receiving a communication signal sent by a base station, and acquiring a baseband signal of the communication signal; performing a coarse synchronization search on the baseband signal based on a peak ratio algorithm, detecting the position of a frequency correction burst to determine a coarse synchronization point; performing a fine synchronization search on the baseband signal based on an energy ratio algorithm and the coarse synchronization point, detecting the position of a synchronization burst to determine a fine synchronization point; performing multi-frame synchronization on the baseband signal according to the fine synchronization point. Based on the characteristics of the GSM frame structure, the detection accuracy of the frequency correction burst is improved by the peak ratio algorithm, and the detection accuracy of the synchronization burst is improved by the energy ratio algorithm, and a fine synchronization search is performed on the basis of the coarse synchronization search to determine the multi-frame synchronization position, thereby ensuring the accuracy of the multi-frame synchronization.

Description

Multiframe synchronization method, device, equipment and storage medium of GSM system

Technical Field

The present invention relates to the field of communication technology, and in particular to a multiframe synchronization method, device, equipment and storage medium of a GSM system.

Background Art

GSM (Global System for Mobile Communications) belongs to the second generation of mobile communications and is widely used in communications of mobile terminals around the world. The GSM system adopts GMSK (Gaussian Filtered Minimum Shift Keying) modulation, and its frame structure includes five levels: ultra-high frame, superframe, multiframe, TDMA (Time Division Multiple Access) frame and time slot. Among them, TDMA frame is the basic unit in communication technology, consisting of multiple time slots, each of which is allocated to a user for communication. This frame structure ensures that the data of different users will not overlap in time, thereby avoiding signal interference, and the design of TDMA frame takes into account the synchronization and timing of the GSM system to ensure that each user transmits data within the specified time slot.

Currently, the synchronization of the GSM system is performed by listening to the air interface data of the nearby base station, capturing the FB and SB sequences or demodulating to obtain the time slot synchronization point, and performing time slot synchronization, but the multiframe synchronization of the GSM system cannot be achieved.

Summary of the invention

The present invention provides a multiframe synchronization method, device, equipment and storage medium of a GSM system, which are used to solve the defect that the prior art cannot realize multiframe synchronization of the GSM system and realize multiframe synchronization of the GSM system.

The present invention provides a multiframe synchronization method for a GSM system, comprising:

Receiving a communication signal sent by a base station and acquiring a baseband signal of the communication signal;

Performing a coarse synchronization search on the baseband signal based on a peak ratio algorithm to detect the position of a frequency correction burst to determine a coarse synchronization point;

Based on the energy ratio algorithm and the coarse synchronization point, the baseband signal is subjected to a fine synchronization search to detect the position of the synchronization burst to determine the fine synchronization point;

The baseband signal is multi-frame synchronized according to the fine synchronization point.

According to the multiframe synchronization method of the GSM system provided by the present invention, the baseband signal is subjected to a coarse synchronization search based on a peak ratio algorithm, and the position of the frequency correction burst is detected to determine the coarse synchronization point, including:

Acquire a sampling rate of the baseband signal, and determine a first window size according to the sampling rate; the first window size corresponds to a first number of sampling points;

Performing sliding window processing on the baseband signal based on the first window size, and performing fast Fourier transform processing on the first target sampling point in the current window based on a peak ratio algorithm to calculate the peak energy of the first target sampling point;

Calculating a ratio of the peak energy to the total energy of the baseband signal to obtain a peak ratio of the first target sampling point;

determining, according to the peak ratio, whether a first signal segment corresponding to the first target sampling point includes a frequency correction burst;

If not included, the current window is slid based on a preset first sliding step size to perform a coarse synchronization search on the baseband signal, and the step of performing a fast Fourier transform process on the first target sampling point in the current window based on the peak ratio algorithm to calculate the peak energy of the first target sampling point is returned and executed, until the first signal segment corresponding to the first target sampling point contains a frequency correction burst, and the coarse synchronization point is determined according to the position of the frequency correction burst.

According to the multiframe synchronization method of the GSM system provided by the present invention, determining whether the first signal segment corresponding to the first target sampling point contains a frequency correction burst according to the peak ratio includes:

Comparing the peak value ratio with a preset first threshold value;

Determining whether the first signal segment corresponding to the first target sampling point contains a frequency correction burst according to the comparison result;

Among them, if the peak ratio is greater than the first threshold value, the first signal segment corresponding to the first target sampling point contains a frequency correction burst; if the peak ratio is less than or equal to the first threshold value, the first signal segment corresponding to the first target sampling point does not contain a frequency correction burst.

According to the multiframe synchronization method of the GSM system provided by the present invention, the baseband signal is subjected to a fine synchronization search based on the energy ratio algorithm and the coarse synchronization point, and the position of the synchronization burst is detected to determine the fine synchronization point, including:

Determine a second window size according to the sampling rate; the second window size corresponds to a second number of sampling points;

Taking the coarse synchronization point as a starting point for fine synchronization search, and performing sliding window processing on the baseband signal based on the second window size to perform fine synchronization search on the baseband signal;

During the sliding window processing, a correlation operation is performed on the second target sampling point in the current window based on an energy ratio algorithm to calculate a correlation energy value of the second target sampling point;

Calculating a ratio of the correlation energy value to a total energy value of the baseband signal to obtain an energy ratio of the second target sampling point;

The position of the synchronization burst is detected according to the energy ratio to determine a fine synchronization point.

According to the multiframe synchronization method of the GSM system provided by the present invention, the detecting the position of the synchronization burst according to the energy ratio to determine the fine synchronization point includes:

comparing the energy ratio with a preset second threshold value;

Determine whether the second signal segment corresponding to the second target sampling point contains a synchronization burst according to the comparison result;

If the second signal segment does not include a synchronization burst, returning to and executing the step of performing sliding window processing on the baseband signal based on the second window size to perform fine synchronization search on the baseband signal, until the second signal segment includes a synchronization burst, and determining a fine synchronization point according to the position of the synchronization burst;

Among them, if the energy ratio is greater than a preset second threshold value, the second signal segment corresponding to the second target sampling point contains a synchronization burst; if the energy ratio is less than or equal to the preset second threshold value, the second signal segment corresponding to the second target sampling point does not contain a synchronization burst.

According to the multiframe synchronization method of the GSM system provided by the present invention, the determining of the fine synchronization point according to the position of the synchronization burst comprises:

Determine a first candidate synchronization point according to the position of the synchronization burst; the synchronization burst includes a plurality of synchronization bursts, and the position of any synchronization burst corresponds to a candidate synchronization point;

Calculating a position difference between the first candidate synchronization point and a second candidate synchronization point; wherein the second candidate synchronization point is a candidate synchronization point adjacent to the first candidate synchronization point and before the first candidate synchronization point; the position difference corresponds to a first preset number of time division multiple access frames, or the position difference corresponds to a second preset number of time division multiple access frames;

If the position difference corresponds to a first preset number of time division multiple access frames, return to and execute the step of performing sliding window processing on the baseband signal based on the second window size to perform a fine synchronization search on the baseband signal, until the position difference corresponds to a second preset number of time division multiple access frames, and determine the fine synchronization point according to the position of the first candidate synchronization point.

According to the multiframe synchronization method of the GSM system provided by the present invention, the baseband signal of the communication signal is obtained, including:

Digitally process the communication signal to obtain a digital intermediate frequency signal; the digital processing includes filtering, mixing and intermediate frequency analog signal;

Performing digital mixing processing on the digital intermediate frequency signal to obtain a zero intermediate frequency digital signal;

Based on a preset sampling rate, the zero intermediate frequency digital signal is sampled to obtain a baseband signal.

The present invention also provides a multiframe synchronization device for a GSM system, comprising:

A signal acquisition module, used to receive a communication signal sent by a base station and acquire a baseband signal of the communication signal;

A coarse synchronization search module, used for performing a coarse synchronization search on the baseband signal based on a peak ratio algorithm, detecting the position of the frequency correction burst, so as to determine a coarse synchronization point;

A fine synchronization search module, configured to perform a fine synchronization search on the baseband signal based on an energy ratio algorithm and the coarse synchronization point, detect the position of the synchronization burst, and determine the fine synchronization point;

The multi-frame synchronization module is used to perform multi-frame synchronization on the baseband signal according to the fine synchronization point.

The present invention also provides an electronic device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the multi-frame synchronization method of the GSM system as described above are implemented.

The present invention also provides a non-transitory computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the multi-frame synchronization method of the GSM system as described in any one of the above are implemented.

The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the steps of the multi-frame synchronization method of the GSM system as described above are implemented.

The multi-frame synchronization method, device, equipment, and storage medium of the GSM system provided by the present invention detect the position of the frequency correction burst through the peak ratio algorithm, perform a coarse synchronization search on the baseband signal, determine the coarse synchronization point, and on this basis, detect the synchronization burst position based on the energy ratio algorithm, determine the fine synchronization point through fine synchronization search, obtain the position of the multi-frame synchronization point, and realize multi-frame synchronization. Based on the characteristics of the GSM frame structure, the detection accuracy of the frequency correction burst is improved through the peak ratio algorithm, and the detection accuracy of the synchronization burst is improved through the energy ratio algorithm. On the basis of the coarse synchronization search, a fine synchronization search is performed to determine the multi-frame synchronization position, thereby ensuring the accuracy of the multi-frame synchronization.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic flow chart of a multiframe synchronization method for a GSM system provided by the present invention.

FIG. 2 is a schematic diagram of a synchronous burst sequence provided by the present invention.

FIG3 is a schematic diagram of a rough synchronization search process provided by the present invention.

FIG. 4 is one of the schematic diagrams of the precise synchronization search process provided by the present invention.

FIG. 5 is a second schematic diagram of the precise synchronization search process provided by the present invention.

FIG6 is a schematic diagram of the structure of the multiframe synchronization device of the GSM system provided by the present invention.

FIG. 7 is a schematic diagram of the structure of an electronic device provided by the present invention.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

It should be noted that in the five-level frame structure of the GSM system, each superframe consists of 2715648 consecutive TDMA frames. At the same time, each superframe consists of 2048 consecutive superframes, and each superframe consists of 51 consecutive 26-multiframes or 26 consecutive 51-multiframes. The two multiframe settings are designed to meet the information transmission requirements of different rates. Among them, the 26-multiframe consists of 26 consecutive TDMA frames with a time interval of 120ms, which is mainly used for TCH (Traffic Channel), SACCH (Slow Associated Control Channel) and FACCH (Fast Associated Control Channel); the common 51-multiframe consists of 51 TDMA frames with a time interval of 235.385ms, which is mainly used for BCCH (Broadcast Control Channel) and CCCH (Common Control Channel). 120ms is 26 TDMA frames, one TDMA frame is 4.616ms, there are 8 time slots TS0 to TS7, each time slot is 0.577ms, each time slot corresponds to 156.25 bits, then the code rate is 156.25/(120/26/8)=270.8333KB, when there is no oversampling, one TDMA frame is 156.25 8=1250 points.

Furthermore, in the GSM system, the pulse of FCCH (Frequency Correction Channel) is the FB (Frequency Correction Burst) sequence, which is used for frequency synchronization; the pulse of SCH (Synchronization Channel) is the SB (Synchronization Burst) sequence, which is used to decode the TDMA frame number and BSIC (Base Station Identity Code) code; the pulse of BCCH and CCCH is the NB (Normal Burst) sequence, which is used to decode the general information of the cell and receive paging and access; IDLE is an idle frame that does not contain useful information, and its pulse is the DB (Dummy Burst) sequence.

Based on the above frame structure of the GSM system, an embodiment of the present invention provides a multi-frame synchronization method of the GSM system, which is based on an FPGA (Field Programmable Gate Array) architecture to achieve multi-frame synchronization of the GSM system. Specifically, FIG1 is a flow chart of the multi-frame synchronization method of the GSM system provided by the present invention. As shown in FIG1, the method includes the following steps:

Step 100, receiving a communication signal sent by a base station, and acquiring a baseband signal of the communication signal;

Step 200, performing a coarse synchronization search on the baseband signal based on a peak ratio algorithm, detecting the position of the frequency correction burst to determine a coarse synchronization point;

Step 300, based on the energy ratio algorithm and the coarse synchronization point, perform a fine synchronization search on the baseband signal, detect the position of the synchronization burst, and determine the fine synchronization point;

Step 400: Perform multi-frame synchronization on the baseband signal according to the fine synchronization point.

Receive a communication signal sent by a base station, the communication signal being a GSM signal, and obtain a baseband signal of the GSM signal. Optionally, obtain the baseband signal of the GSM signal by filtering and frequency conversion.

A coarse synchronization search is performed on the baseband signal based on a peak ratio algorithm to detect the position of the frequency correction burst (the pulse sequence of the FCCH frame) to determine the coarse synchronization point, which represents the approximate position of the multiframe synchronization.

On the basis of the coarse synchronization search, a fine synchronization search is performed on the baseband signal based on the energy ratio algorithm to detect the position of the synchronization burst (the pulse sequence of the SCH frame) to determine the fine synchronization point, which is the multiframe synchronization point, that is, the multiframe synchronization position.

According to the position of the fine synchronization point, the baseband signal is synchronized with the multiframe. In the present embodiment, the multiframe synchronization is mainly used for the 51 multiframe synchronization, and the multiframe synchronization point is the 51 multiframe synchronization point. Optionally, the multiframe synchronization is intended to solve the problem of misrouting of the flag signals of each channel, and is achieved by ensuring that each flag signal in the accompanying signal has its own determined position on TS16 of a multiframe. If the multiframe is not synchronized, the flag signal will be misrouted, resulting in the inability to communicate. Multiframe synchronization effectively avoids communication interruptions by ensuring that each flag signal is in a specific position in the multiframe, ensures the continuity and reliability of communication, and ensures that the receiving end can accurately identify and demultiplex digital signals, thereby maintaining the quality and efficiency of communication.

Optionally, the FCCH frame is a sequence of all zeros, and the signal after GMSK modulation is a standard sine wave at a specific frequency, and its spectrum has a sharp single-peak characteristic. Therefore, the coarse synchronization search based on the peak ratio algorithm detects the burst sequence of the FCCH frame by detecting the single peak value, thereby determining the coarse synchronization point.

Optionally, the burst sequence of the SCH frame carries the message of the SCH channel, which is used for the synchronization of the terminal and the base station. The SCH burst sequence contains a 64-bit training sequence. The training sequences of all SCH burst sequences are the same, that is, {101110010110001000000100000011110010110101000101010111011000011011}. The composition of the burst sequence of the SCH frame is shown in FIG2, including two 3 tail bits, two 39 information bits, a 64 training sequence and an 8.25 protection bit. Among them, the two 39 information bits include information such as the TDMA frame number, which is the basis for terminal synchronization. Therefore, it is the first burst sequence that needs to be demodulated after the terminal is turned on. The training sequence in the SCH channel has the characteristic of good correlation to determine the precise synchronization point.

In this embodiment, the position of the frequency correction burst is detected by the peak ratio algorithm, the baseband signal is subjected to a coarse synchronization search, the coarse synchronization point is determined, and on this basis, the synchronization burst position is detected based on the energy ratio algorithm, the fine synchronization point is determined through a fine synchronization search, the position of the multi-frame synchronization point is obtained, and multi-frame synchronization is achieved. Based on the characteristics of the GSM frame structure, the detection accuracy of the frequency correction burst is improved by the peak ratio algorithm, and the detection accuracy of the synchronization burst is improved by the energy ratio algorithm. On the basis of the coarse synchronization search, a fine synchronization search is performed to determine the multi-frame synchronization position, thereby ensuring the accuracy of the multi-frame synchronization.

In one embodiment, the baseband signal of the GSM signal is obtained by digital processing and mixing processing. Specifically, in step 100, the baseband signal of the communication signal is obtained, including:

Step 110, digitally process the communication signal to obtain a digital intermediate frequency signal; the digital processing includes filtering, mixing and intermediate frequency analog signal;

Step 120, performing digital mixing processing on the digital intermediate frequency signal to obtain a zero intermediate frequency digital signal;

Step 130: sampling the zero intermediate frequency digital signal based on a preset sampling rate to obtain a baseband signal.

The received GSM signal is digitized to convert the communication signal of the GSM system into a digital intermediate frequency signal, wherein the digital processing at least includes filtering, mixing and intermediate frequency analog signal processing. Then the digital intermediate frequency signal is further digitally mixed to obtain a zero intermediate frequency digital signal, and finally, based on a preset sampling rate, the zero intermediate frequency digital signal is sampled to obtain a baseband signal.

In one embodiment, both the coarse synchronization search and the fine synchronization search are implemented based on the sliding window processing of the baseband signal. Specifically, in step 200, the baseband signal is subjected to a coarse synchronization search based on a peak ratio algorithm, and the position of the frequency correction burst is detected to determine the coarse synchronization point, including:

Step 210, obtaining a sampling rate of the baseband signal, and determining a first window size according to the sampling rate; the first window size corresponds to a first number of sampling points;

Step 220, performing sliding window processing on the baseband signal based on the first window size, and performing fast Fourier transform processing on the first target sampling point in the current window based on a peak ratio algorithm to calculate the peak energy of the first target sampling point;

Step 230, calculating the ratio of the peak energy to the total energy of the baseband signal to obtain the peak ratio of the first target sampling point;

Step 240, determining whether a first signal segment corresponding to the first target sampling point contains a frequency correction burst according to the peak ratio;

Step 250, if not included, then the current window is slid based on a preset first sliding step size to perform a coarse synchronization search on the baseband signal, and the step of performing a fast Fourier transform process on the first target sampling point in the current window based on the peak ratio algorithm to calculate the peak energy of the first target sampling point is returned and executed, until the first signal segment corresponding to the first target sampling point contains a frequency correction burst, and the coarse synchronization point is determined according to the position of the frequency correction burst.

First, the sampling rate of the baseband signal is obtained, and a first window size is determined according to the sampling rate, the first window size corresponding to a first number of sampling points. The baseband signal is subjected to sliding window processing based on the first window size, and a plurality of first target sampling points in the current window are subjected to fast Fourier transform (FFT) processing based on a peak ratio algorithm, so as to calculate the peak energy of the first target sampling point in the window.

Furthermore, according to the calculated peak energy, the ratio of the peak energy to the total energy of the baseband signal is further calculated to obtain the peak ratio of the first target sampling point, thereby determining whether the first signal segment corresponding to the first target sampling point contains a frequency correction burst, i.e., an FCCH burst, according to the calculated peak ratio. If the first signal segment does not contain a frequency correction burst, the current window is subjected to sliding processing based on a preset first sliding compensation, thereby performing a coarse synchronization search on the baseband signal, and recalculating the peak energy of the first target sampling point in the current window, until it is determined according to the calculated peak ratio that the first signal segment corresponding to the first target sampling point contains an FCCH burst, and the coarse synchronization point is determined according to the position of the detected FCCH burst.

Further, when determining whether the first signal segment contains an FCCH burst according to the peak ratio, the calculated peak ratio is compared with a preset first threshold value and the determination is made according to the comparison result. Therefore, step 240 further includes:

Step 241, comparing the peak ratio with a preset first threshold value;

Step 242, determining whether the first signal segment corresponding to the first target sampling point contains a frequency correction burst according to the comparison result;

Among them, if the peak ratio is greater than the first threshold value, the first signal segment corresponding to the first target sampling point contains a frequency correction burst; if the peak ratio is less than or equal to the first threshold value, the first signal segment corresponding to the first target sampling point does not contain a frequency correction burst.

The calculated peak ratio is compared with a preset first threshold value, and it is determined whether the first signal segment corresponding to the first target sampling point includes an FCCH burst according to the comparison result. If the calculated peak ratio is greater than the preset first threshold value, the first signal segment corresponding to the first target sampling point includes an FCCH burst; otherwise, if the calculated peak ratio is less than or equal to the preset first threshold value, the first signal segment corresponding to the first target sampling point does not include an FCCH burst.

In one embodiment, referring to the rough synchronization search process described in FIG3 , the FCCH frame is a pulse burst sequence of all zeros, and the signal after GMSK modulation is a standard sine wave of a specific frequency, and its spectrum has a sharp single peak characteristic. Therefore, the existence of the FCCH burst sequence can be detected by detecting the single peak value, and the position of the rough synchronization point can be determined. For example, if the baseband signal of the received GSM signal is 4 times oversampled, the sampling rate is 1.0833MHz, and the FCCH signal length is 625 (4 156.25) sampling points, during the sliding window processing, the 512 sampling points in the window are subjected to FFT processing. It can be seen that the single peak corresponding to the FCCH frequency domain generally appears near the N=33rd sampling point, and 10 sampling points (a total of 21 sampling points) are taken around the 33rd sampling point (i.e. the peak point) as the range for calculating the peak ratio. Then the peak ratio is compared with the preset first threshold value G0. If the peak ratio is greater than G0, it can be determined that the FCCH burst sequence is detected in the window of the current sliding window processing. Otherwise, the sampling points in the next sliding window are continued to be detected until the FCCH burst sequence is detected.

Optionally, under the FPGA architecture, the first sliding step size of the coarse synchronization search stage is set to 256 sample points, and the first threshold value G0 is configured to be set to 0.75. If the number of sampling points corresponding to the first window size is 512, FFT processing is performed on 512 sampling points in the window each time, and the frequency resolution is approximately 2115 Hz. The actual device generally does not have such a large frequency deviation. Therefore, the value of the 33rd sampling point is taken as the peak value. In theory, the coarse synchronization point can be searched using 12 frames of data. According to the sliding step size of 256 sampling points, the window can be slid up to 234 times.

As shown in FIG3 , in the coarse synchronization search stage, the sliding window processing is provided with a maximum window sliding number, which is a preset value, such as 234. When the calculated peak ratio is less than or equal to the preset first threshold value G0, the window sliding number N is obtained. If N is less than or equal to the first preset value corresponding to the maximum sliding number, the window is slid to obtain the next group of 512 sampling points for FFT operation. The coarse synchronization search is completed until the window sliding number is greater than the first preset value corresponding to the maximum sliding number, or when the calculated peak ratio is greater than the preset first threshold value G0, the position of the coarse synchronization point is determined according to the position of the detected FCCH burst sequence, and the coarse synchronization search is completed.

In one embodiment, a fine synchronization search is performed based on the search results of the coarse synchronization search, and the fine synchronization search also adopts a sliding window processing method. Specifically, step 300 may also include:

Step 310, determining a second window size according to the sampling rate; the second window size corresponds to a second number of sampling points;

Step 320, taking the coarse synchronization point as the starting point of fine synchronization search, and performing sliding window processing on the baseband signal based on the second window size to perform fine synchronization search on the baseband signal;

Step 330, during the sliding window processing, performing a correlation operation on the second target sampling point in the current window based on an energy ratio algorithm to calculate a correlation energy value of the second target sampling point;

Step 340, calculating the ratio of the correlation energy value to the total energy value of the baseband signal to obtain the energy ratio of the second target sampling point;

Step 350: Detect the position of the synchronization burst according to the energy ratio to determine a fine synchronization point.

Similarly, the second window size is determined according to the sampling rate of the baseband signal, and the second window size corresponds to the second number of sampling points. The coarse synchronization point obtained by the coarse synchronization search is used as the starting point of the fine synchronization search. The baseband signal is subjected to sliding window processing based on the second window size, thereby performing fine synchronization search on the baseband signal. During the sliding window processing, based on the energy ratio algorithm, a correlation operation is performed on multiple second target sampling points in the current window to calculate the correlation energy value of the second target sampling point. Based on the calculated correlation energy value, the ratio of the correlation energy value to the total energy value of the baseband signal is further calculated to obtain the energy ratio of the second target sampling point. The position of the synchronization burst sequence is detected based on the energy ratio, thereby determining the fine synchronization point.

Further, when detecting the position of the synchronization burst sequence according to the calculated energy ratio, the calculated energy ratio is specifically compared with a preset second threshold value. Therefore, step 350 may also include:

Step 351, comparing the energy ratio with a preset second threshold value;

Step 352, determining whether the second signal segment corresponding to the second target sampling point contains a synchronization burst according to the comparison result, returning to and executing the step of performing sliding window processing on the baseband signal based on the second window size to perform precise synchronization search on the baseband signal;

Step 353: if the second signal segment includes a synchronization burst, determine a precise synchronization point according to the position of the synchronization burst;

Among them, if the energy ratio is greater than a preset second threshold value, the second signal segment corresponding to the second target sampling point contains a synchronization burst; if the energy ratio is less than or equal to the preset second threshold value, the second signal segment corresponding to the second target sampling point does not contain a synchronization burst.

After the energy ratio is calculated, the energy ratio is compared with a preset second threshold value, and it is determined whether the second signal segment corresponding to the second target sampling point in the current window contains a synchronization burst sequence according to the comparison result. If the calculated energy ratio is greater than the preset second threshold value, the second signal segment corresponding to the second target sampling point in the current window contains the synchronization burst sequence; otherwise, if the calculated energy ratio is less than or equal to the preset second threshold value, the second signal segment corresponding to the second target sampling point in the current window does not contain the synchronization burst sequence.

Further, if the second signal segment includes a synchronization burst, the fine synchronization point is determined according to the position of the synchronization burst.

After determining whether the second signal segment corresponding to the second target sampling point contains a synchronization burst, the current window is slid based on a preset second sliding step size, thereby performing a precise synchronization search on the baseband signal.

In one embodiment, during the fine synchronization search process, multiple synchronization burst sequences may be detected through sliding window processing, and it is necessary to determine the fine synchronization point according to the positions of the multiple synchronization burst sequences. Therefore, step 353 may also include:

Step 3531, determining a first candidate synchronization point according to the position of the synchronization burst; the synchronization burst includes multiple ones, and the position of any synchronization burst corresponds to a candidate synchronization point;

Step 3532, calculating a position difference between the first candidate synchronization point and a second candidate synchronization point; wherein the second candidate synchronization point is a candidate synchronization point adjacent to the first candidate synchronization point and before the first candidate synchronization point; the position difference corresponds to a first preset number of time division multiple access frames, or the position difference corresponds to a second preset number of time division multiple access frames;

Step 3533: if the position difference corresponds to a first preset number of time division multiple access frames, return and execute the step of performing sliding window processing on the baseband signal based on the second window size to perform a precise synchronization search on the baseband signal, until the position difference corresponds to a second preset number of time division multiple access frames, and determine the precise synchronization point according to the position of the first candidate synchronization point.

Through fine synchronization search, the position of one or more synchronization burst sequences can be detected. When a synchronization burst is detected in the current window, it is determined whether the position of the synchronization burst is a fine synchronization point. Specifically, when determining the fine synchronization point according to the position of the synchronization burst, the first candidate synchronization point is determined according to the position of the synchronization burst in the current window. When the synchronization burst includes multiple synchronization bursts, the position of any synchronization burst corresponds to a candidate synchronization point, that is, the position of each synchronization burst is used as a candidate for a fine synchronization point.

Further, the position difference between the first candidate synchronization point and the second candidate synchronization point is calculated, wherein the second candidate synchronization point is a candidate synchronization point adjacent to the first candidate synchronization point and before the first candidate synchronization point, and the position difference between the first candidate synchronization point and the second candidate synchronization point corresponds to a first preset number of time division multiple access TDMA frames, or corresponds to a second preset number of TDMA frames.

If the position difference between the first candidate synchronization point and the second candidate synchronization point corresponds to a first preset number of TDMA frames, return to and execute step 320, perform sliding window processing on the baseband signal based on the second window size to perform a precise synchronization search on the baseband signal, and continue searching for the next candidate synchronization point until the position difference between the searched first candidate synchronization point and its previous second candidate synchronization point corresponds to a second preset number of TDMA frames.

If the position difference between the first candidate synchronization point and the second candidate synchronization point corresponds to a second preset number of TDMA frames, the fine synchronization point is determined according to the position of the first candidate synchronization point. In this case, the position of the first candidate synchronization point is the fine synchronization point.

Optionally, based on the sliding window processing of the baseband signal, one or more fine synchronization searches may be performed on the baseband signal. Optionally, one fine synchronization search detects a synchronization burst position, that is, obtains a candidate synchronization point. Optionally, one fine synchronization search detects the positions of multiple synchronization bursts, and obtains multiple candidate synchronization points.

In one embodiment, referring to the fine synchronization search process shown in FIG4 , during the fine synchronization search process, the baseband signal is subjected to sliding window processing, and the sampling points in the current window are subjected to correlation operation, so as to calculate the correlation energy value of the sampling points in the window. Then, the ratio of the correlation energy value to the total energy of the baseband signal is calculated to obtain the energy ratio of the sampling points in the window, and the presence of a synchronization burst sequence in the current window is detected based on the energy ratio.

Furthermore, the calculated energy ratio is compared with a preset second threshold value G1. If the calculated energy ratio is greater than the preset second threshold value G1, a synchronous burst sequence exists in the current window. Otherwise, if the calculated energy ratio is less than the preset second threshold value G1, no synchronous burst sequence exists in the current window.

Further, if there is a synchronization burst in the current window, the position of the fine synchronization point is determined, otherwise, if there is no synchronization burst in the current window, the number of sliding times M of the current window is obtained, and if the number of sliding times M of the current window is greater than a second preset value, the fine synchronization search is completed, and if the current window sliding number is less than or equal to the second preset value, the window is slid to continue to perform fine synchronization search on the baseband signal. The second preset value is the maximum number of window sliding times of the sliding window processing of the fine synchronization search, and the second preset value may be the same as or different from the first preset value of the sliding window processing in the coarse synchronization search stage.

Among them, when determining the fine synchronization point according to the position of the synchronization burst in the current window, the position of the synchronization burst is specifically used as a candidate synchronization point, and the position difference between it and the previous candidate synchronization point is calculated. If the position difference corresponds to a specific frame number of TDMA, the position of the synchronization burst in the current window is the position of the fine synchronization point.

For example, taking the baseband signal with 4 times oversampling as an example, according to the characteristics of the GSM frame structure, the position of the SCH burst sequence and the FCCH burst sequence differ by 1 TDMA frame. Therefore, after obtaining the coarse synchronization point, the approximate position of the fine synchronization can be determined according to the coarse synchronization point, and then 256+336 sampling point data are taken out as the range of the fine synchronization search. The second window size corresponds to 256 sampling points. During the sliding window processing, 256 sampling points are selected in turn for correlation operation, and the ratio of their correlation energy value to the total energy value of the input baseband signal is calculated to obtain the energy ratio of the sampling points in the window. Then the calculated energy ratio is compared with the preset second threshold value G1. If the energy ratio is greater than G1, there is an SCH sequence in the current window. Otherwise, the sliding window continues to detect the sampling points in the next window until the SCH sequence is detected. In particular, if there are multiple energy ratios greater than G1, the sampling point corresponding to the maximum correlation energy value is used as the candidate position of the fine synchronization point.

Under the FPGA architecture, the sliding step size of the correlation operation of 256 sampling points can be 1 sampling point, and the second threshold value G1 is configured to be set to 0.3. In theory, 256+336 sampling points can be used to search for the candidate position of the precise synchronization point. According to the sliding step size of 1 sampling point, the maximum sliding time is 337 times.

In another embodiment, referring to the fine synchronization search process shown in FIG5 , the fine synchronization search is provided with a maximum number of searches. In each fine synchronization search, a sliding window processing method is used to detect whether the second signal segment corresponding to the sampling point in the window contains a synchronization burst sequence. When detecting the existence of a synchronization burst, specifically based on an energy ratio algorithm, the relevant energy value of the sampling point in the window is calculated, and then the ratio of the relevant energy value to the total energy of the baseband signal is calculated to obtain the energy ratio of the sampling point in the window, and whether there is a synchronization burst in the window is detected based on the energy ratio. Further, if the calculated energy ratio is greater than a preset second threshold value G1, there is a synchronization burst sequence in the window, otherwise, if the calculated energy ratio is less than the preset second threshold value G1, there is no synchronization burst sequence in the window.

Furthermore, according to the characteristics of the GSM frame structure, except for the position difference of 11 TDMA frames between the SCH synchronization burst sequence of the IDLE frame and the next SCH synchronization burst sequence, the positions of the other adjacent SCH synchronization burst sequences differ by 10 TDMA frames. Based on this, as long as the candidate synchronization points of the two fine synchronization points are detected, and the position difference between the latter candidate synchronization point and the former candidate synchronization point is 11 TDMA frames, it can be determined that the latter of the two candidate synchronization points is the fine synchronization point, that is, the 51 multiframe synchronization point.

Therefore, if a synchronization burst is detected, the position of the corresponding candidate synchronization point is determined, a fine synchronization search is completed, and the position difference between the current candidate synchronization point and the previous candidate synchronization point is calculated. If the position difference is 11 TDMA frames, the currently detected candidate synchronization point is the fine synchronization point, thereby determining the position of the fine synchronization point. Otherwise, if the position difference between the current candidate synchronization point and the previous candidate synchronization point is 10 TDMA frames, the current fine synchronization search number K is obtained. If K is less than or equal to the preset maximum search number, the baseband signal is continuously subjected to sliding window processing, and the next fine synchronization search is performed until the detected candidate synchronization point is a fine synchronization point, or the current fine synchronization search number K is greater than the preset maximum search number, and the fine synchronization search is completed.

In some embodiments, the multiframe synchronization method of the GSM system provided in the embodiments of the present invention is applied to the GSM multiframe synchronization system, which includes a radio frequency subsystem, a down-conversion subsystem, a coarse synchronization subsystem, a fine synchronization subsystem, a multiframe synchronization subsystem and a configuration management subsystem. Among them, the down-conversion subsystem, the coarse synchronization subsystem, the fine synchronization subsystem and the multiframe synchronization subsystem are all implemented based on the FPGA architecture, and the configuration management subsystem can be implemented based on the ARM (Acorn RISC (Reduced Instruction Set Computer, Reduced Instruction Set Computer) Machine, Advanced Reduced Instruction Set Machine) architecture.

During multi-frame synchronization, the RF subsystem receives the GSM signal sent by the base station through the antenna, completes the GSM frequency signal filtering, mixing and digital processing of the intermediate frequency analog signal, and finally transmits the obtained digital intermediate frequency signal to the down-conversion subsystem. The down-conversion subsystem implemented based on the FPGA architecture first performs digital mixing processing on the digital intermediate frequency signal according to the GSM frequency information preset by the configuration management subsystem to obtain a zero intermediate frequency digital signal; secondly, according to the pre-planned GSM baseband signal sampling rate (assuming 4 times oversampling, the GSM baseband sampling rate is 1.0833M), the digital down-conversion function is completed, and finally a GSM baseband signal with a given sampling rate is obtained.

The coarse synchronization subsystem implemented based on FPGA architecture is used to perform coarse synchronization search on the baseband signal and determine the coarse synchronization point. Specifically, since the burst sequence of the FCCH frame is a sequence of all zeros, the signal after GMSK modulation is a standard sine wave with a frequency of 67.708KHz, and its spectrum has a sharp single peak characteristic. Therefore, the coarse synchronization subsystem detects the existence of the FCCH frame burst by detecting the single peak value and determines the coarse synchronization point.

The fine synchronization subsystem implemented based on FPGA performs fine synchronization search on the basis of the coarse synchronization point determined by the coarse synchronization subsystem to determine the fine synchronization point. Since the SCH sequence carries the message of the SCH channel, it is used for the synchronization of the terminal and the base station. The fine synchronization subsystem uses the characteristic that the training sequence in the SCH channel has good correlation to determine the candidate synchronization points of the fine synchronization point. According to the characteristics of the GSM frame structure, the multiframe synchronization subsystem determines that the positions of the adjacent SCH burst sequences differ by 10 TDMA frames, except for the position difference of 11 TDMA frames between the SCH burst sequence of the IDLE frame and the next SCH burst sequence. Based on this, as long as two fine synchronization candidate synchronization points are detected, and the position difference between the latter candidate synchronization point and the former candidate synchronization point is 11 TDMA frames, the latter candidate synchronization point can be determined as the multiframe synchronization point. Therefore, the multiframe synchronization subsystem finds the fine synchronization point of multiframe synchronization based on the candidate synchronization points searched by the fine synchronization subsystem and the characteristics of the GSM frame structure.

The configuration management subsystem implemented based on the ARM architecture serves as the control center to manage and control the entire GSM multiframe synchronization system, including but not limited to sending GSM frequency information, monitoring the synchronization completion status of each subsystem, etc.

In this embodiment, the position of the coarse synchronization point is determined based on the peak ratio, thereby improving the detection accuracy of the FCCH burst sequence; the position of the fine synchronization point is determined based on the energy ratio, thereby improving the detection accuracy of the SCH burst sequence. During the fine synchronization search, the position of the multi-frame synchronization point is determined based on the position difference between two candidate synchronization points in combination with the characteristics of the GSM frame structure, thereby ensuring the accuracy of the multi-frame synchronization.

Furthermore, the multi-frame synchronization is realized based on FPGA, which has high speed, low energy consumption, and small hardware resource occupation, thereby improving the efficiency of the multi-frame synchronization.

The multiframe synchronization device of the GSM system provided by the present invention is described below. The multiframe synchronization device of the GSM system described below and the multiframe synchronization method of the GSM system described above can be referred to each other.

6, the multiframe synchronization device of the GSM system provided by the embodiment of the present invention includes:

The signal acquisition module 10 is used to receive the communication signal sent by the base station and obtain the baseband signal of the communication signal;

A coarse synchronization search module 20, configured to perform a coarse synchronization search on the baseband signal based on a peak ratio algorithm, detect the position of the frequency correction burst, and determine a coarse synchronization point;

A fine synchronization search module 30, configured to perform a fine synchronization search on the baseband signal based on an energy ratio algorithm and the coarse synchronization point, detect the position of the synchronization burst, and determine the fine synchronization point;

The multi-frame synchronization module 40 is used to perform multi-frame synchronization on the baseband signal according to the fine synchronization point.

In one embodiment, the coarse synchronization search module 20 is further used for:

Acquire a sampling rate of the baseband signal, and determine a first window size according to the sampling rate; the first window size corresponds to a first number of sampling points;

Performing sliding window processing on the baseband signal based on the first window size, and performing fast Fourier transform processing on the first target sampling point in the current window based on a peak ratio algorithm to calculate the peak energy of the first target sampling point;

Calculating a ratio of the peak energy to the total energy of the baseband signal to obtain a peak ratio of the first target sampling point;

determining, according to the peak ratio, whether a first signal segment corresponding to the first target sampling point includes a frequency correction burst;

If not included, the current window is slid based on a preset first sliding step size to perform a coarse synchronization search on the baseband signal, and the step of performing a fast Fourier transform process on the first target sampling point in the current window based on the peak ratio algorithm to calculate the peak energy of the first target sampling point is returned and executed, until the first signal segment corresponding to the first target sampling point contains a frequency correction burst, and the coarse synchronization point is determined according to the position of the frequency correction burst.

In one embodiment, the coarse synchronization search module 20 is further used for:

Comparing the peak value ratio with a preset first threshold value;

Determining whether the first signal segment corresponding to the first target sampling point contains a frequency correction burst according to the comparison result;

Among them, if the peak ratio is greater than the first threshold value, the first signal segment corresponding to the first target sampling point contains a frequency correction burst; if the peak ratio is less than or equal to the first threshold value, the first signal segment corresponding to the first target sampling point does not contain a frequency correction burst.

In one embodiment, the fine synchronization search module 30 is further used to:

Determine a second window size according to the sampling rate; the second window size corresponds to a second number of sampling points;

Taking the coarse synchronization point as a starting point for fine synchronization search, and performing sliding window processing on the baseband signal based on the second window size to perform fine synchronization search on the baseband signal;

During the sliding window processing, a correlation operation is performed on the second target sampling point in the current window based on an energy ratio algorithm to calculate a correlation energy value of the second target sampling point;

Calculating a ratio of the correlation energy value to a total energy value of the baseband signal to obtain an energy ratio of the second target sampling point;

The position of the synchronization burst is detected according to the energy ratio to determine a fine synchronization point.

In one embodiment, the fine synchronization search module 30 is further used to:

comparing the energy ratio with a preset second threshold value;

Determine whether the second signal segment corresponding to the second target sampling point contains a synchronization burst according to the comparison result;

If the second signal segment does not include a synchronization burst, returning to and executing the step of performing sliding window processing on the baseband signal based on the second window size to perform fine synchronization search on the baseband signal, until the second signal segment includes a synchronization burst, and determining a fine synchronization point according to the position of the synchronization burst;

Among them, if the energy ratio is greater than a preset second threshold value, the second signal segment corresponding to the second target sampling point contains a synchronization burst; if the energy ratio is less than or equal to the preset second threshold value, the second signal segment corresponding to the second target sampling point does not contain a synchronization burst.

In one embodiment, the fine synchronization search module 30 is further used to:

Determine a first candidate synchronization point according to the position of the synchronization burst; the synchronization burst includes a plurality of synchronization bursts, and the position of any synchronization burst corresponds to a candidate synchronization point;

Calculating a position difference between the first candidate synchronization point and a second candidate synchronization point; wherein the second candidate synchronization point is a candidate synchronization point adjacent to the first candidate synchronization point and before the first candidate synchronization point; the position difference corresponds to a first preset number of time division multiple access frames, or the position difference corresponds to a second preset number of time division multiple access frames;

If the position difference corresponds to a first preset number of time division multiple access frames, return to and execute the step of performing sliding window processing on the baseband signal based on the second window size to perform a fine synchronization search on the baseband signal, until the position difference corresponds to a second preset number of time division multiple access frames, and determine the fine synchronization point according to the position of the first candidate synchronization point.

In one embodiment, the signal acquisition module 10 is further used for:

Digitally process the communication signal to obtain a digital intermediate frequency signal; the digital processing includes filtering, mixing and intermediate frequency analog signal;

Performing digital mixing processing on the digital intermediate frequency signal to obtain a zero intermediate frequency digital signal;

Based on a preset sampling rate, the zero intermediate frequency digital signal is sampled to obtain a baseband signal.

FIG7 illustrates a schematic diagram of a physical structure of an electronic device. As shown in FIG7 , the electronic device may include: a processor 710, a communications interface 720, a memory 730, and a communication bus 740, wherein the processor 710, the communications interface 720, and the memory 730 communicate with each other through the communication bus 740. The processor 710 may call the logic instructions in the memory 730 to execute the steps of the multiframe synchronization method of the GSM system, for example, including:

Receiving a communication signal sent by a base station and acquiring a baseband signal of the communication signal;

Performing a coarse synchronization search on the baseband signal based on a peak ratio algorithm to detect the position of a frequency correction burst to determine a coarse synchronization point;

Based on the energy ratio algorithm and the coarse synchronization point, the baseband signal is subjected to a fine synchronization search to detect the position of the synchronization burst to determine the fine synchronization point;

The baseband signal is multi-frame synchronized according to the fine synchronization point.

In addition, the logic instructions in the above-mentioned memory 730 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

On the other hand, the present invention further provides a computer program product, the computer program product comprising a computer program, the computer program may be stored on a non-transitory computer-readable storage medium, and when the computer program is executed by a processor, the computer can execute the steps of the multiframe synchronization method of the GSM system provided in the above embodiments, for example, including:

Receiving a communication signal sent by a base station and acquiring a baseband signal of the communication signal;

Performing a coarse synchronization search on the baseband signal based on a peak ratio algorithm to detect the position of a frequency correction burst to determine a coarse synchronization point;

Based on the energy ratio algorithm and the coarse synchronization point, the baseband signal is subjected to a fine synchronization search to detect the position of the synchronization burst to determine the fine synchronization point;

The baseband signal is multi-frame synchronized according to the fine synchronization point.

In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the computer program is executed by a processor to perform the steps of the multiframe synchronization method of the GSM system provided in the above embodiments, for example, including:

Receiving a communication signal sent by a base station and acquiring a baseband signal of the communication signal;

Performing a coarse synchronization search on the baseband signal based on a peak ratio algorithm to detect the position of a frequency correction burst to determine a coarse synchronization point;

Based on the energy ratio algorithm and the coarse synchronization point, the baseband signal is subjected to a fine synchronization search to detect the position of the synchronization burst to determine the fine synchronization point;

The baseband signal is multi-frame synchronized according to the fine synchronization point.

The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, or of course by hardware. Based on this understanding, the above technical solution can essentially or in other words be embodied in the form of a software product that contributes to the prior art. The computer software product can be stored in a computer-readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A multiframe synchronization method for a GSM system, comprising: Receiving a communication signal sent by a base station and acquiring a baseband signal of the communication signal; Performing a coarse synchronization search on the baseband signal based on a peak ratio algorithm to detect the position of a frequency correction burst to determine a coarse synchronization point; Based on the energy ratio algorithm and the coarse synchronization point, the baseband signal is subjected to a fine synchronization search to detect the position of the synchronization burst to determine the fine synchronization point; The baseband signal is multi-frame synchronized according to the fine synchronization point. 2. The multiframe synchronization method of the GSM system according to claim 1, characterized in that the baseband signal is subjected to a coarse synchronization search based on a peak ratio algorithm to detect the position of a frequency correction burst to determine a coarse synchronization point, comprising: Acquire a sampling rate of the baseband signal, and determine a first window size according to the sampling rate; the first window size corresponds to a first number of sampling points; Performing sliding window processing on the baseband signal based on the first window size, and performing fast Fourier transform processing on the first target sampling point in the current window based on a peak ratio algorithm to calculate the peak energy of the first target sampling point; Calculating a ratio of the peak energy to the total energy of the baseband signal to obtain a peak ratio of the first target sampling point; determining, according to the peak ratio, whether a first signal segment corresponding to the first target sampling point includes a frequency correction burst; If not included, the current window is slid based on a preset first sliding step size to perform a coarse synchronization search on the baseband signal, and the step of performing a fast Fourier transform process on the first target sampling point in the current window based on the peak ratio algorithm to calculate the peak energy of the first target sampling point is returned and executed, until the first signal segment corresponding to the first target sampling point contains a frequency correction burst, and the coarse synchronization point is determined according to the position of the frequency correction burst. 3. The multiframe synchronization method of the GSM system according to claim 2, characterized in that the step of determining whether the first signal segment corresponding to the first target sampling point contains a frequency correction burst according to the peak ratio comprises: Comparing the peak value ratio with a preset first threshold value; Determining whether the first signal segment corresponding to the first target sampling point contains a frequency correction burst according to the comparison result; Among them, if the peak ratio is greater than the first threshold value, the first signal segment corresponding to the first target sampling point contains a frequency correction burst; if the peak ratio is less than or equal to the first threshold value, the first signal segment corresponding to the first target sampling point does not contain a frequency correction burst. 4. The multiframe synchronization method of the GSM system according to claim 2, characterized in that the baseband signal is subjected to a fine synchronization search based on an energy ratio algorithm and the coarse synchronization point, and the position of the synchronization burst is detected to determine the fine synchronization point, comprising: Determine a second window size according to the sampling rate; the second window size corresponds to a second number of sampling points; Taking the coarse synchronization point as a starting point for fine synchronization search, and performing sliding window processing on the baseband signal based on the second window size to perform fine synchronization search on the baseband signal; During the sliding window processing, a correlation operation is performed on the second target sampling point in the current window based on an energy ratio algorithm to calculate a correlation energy value of the second target sampling point; Calculating a ratio of the correlation energy value to a total energy value of the baseband signal to obtain an energy ratio of the second target sampling point; The position of the synchronization burst is detected according to the energy ratio to determine a fine synchronization point. 5. The multiframe synchronization method of the GSM system according to claim 4, characterized in that the detecting the position of the synchronization burst according to the energy ratio to determine the precise synchronization point comprises: comparing the energy ratio with a preset second threshold value; Determine whether the second signal segment corresponding to the second target sampling point contains a synchronization burst according to the comparison result; If the second signal segment does not include a synchronization burst, returning to and executing the step of performing sliding window processing on the baseband signal based on the second window size to perform fine synchronization search on the baseband signal, until the second signal segment includes a synchronization burst, and determining a fine synchronization point according to the position of the synchronization burst; Among them, if the energy ratio is greater than a preset second threshold value, the second signal segment corresponding to the second target sampling point contains a synchronization burst; if the energy ratio is less than or equal to the preset second threshold value, the second signal segment corresponding to the second target sampling point does not contain a synchronization burst. 6. The multiframe synchronization method of the GSM system according to claim 5, characterized in that the step of determining the precise synchronization point according to the position of the synchronization burst comprises: Determine a first candidate synchronization point according to the position of the synchronization burst; the synchronization burst includes a plurality of synchronization bursts, and the position of any synchronization burst corresponds to a candidate synchronization point; Calculating a position difference between the first candidate synchronization point and a second candidate synchronization point; wherein the second candidate synchronization point is a candidate synchronization point adjacent to the first candidate synchronization point and before the first candidate synchronization point; the position difference corresponds to a first preset number of time division multiple access frames, or the position difference corresponds to a second preset number of time division multiple access frames; If the position difference corresponds to a first preset number of time division multiple access frames, return to and execute the step of performing sliding window processing on the baseband signal based on the second window size to perform a fine synchronization search on the baseband signal, until the position difference corresponds to a second preset number of time division multiple access frames, and determine the fine synchronization point according to the position of the first candidate synchronization point. 7. The multiframe synchronization method of the GSM system according to claim 1, characterized in that the acquiring of the baseband signal of the communication signal comprises: Digitally process the communication signal to obtain a digital intermediate frequency signal; the digital processing includes filtering, mixing and intermediate frequency analog signal; Performing digital mixing processing on the digital intermediate frequency signal to obtain a zero intermediate frequency digital signal; Based on a preset sampling rate, the zero intermediate frequency digital signal is sampled to obtain a baseband signal. 8. A multiframe synchronization device for a GSM system, comprising: A signal acquisition module, used to receive a communication signal sent by a base station and acquire a baseband signal of the communication signal; A coarse synchronization search module, used for performing a coarse synchronization search on the baseband signal based on a peak ratio algorithm, detecting the position of the frequency correction burst, so as to determine a coarse synchronization point; A fine synchronization search module, configured to perform a fine synchronization search on the baseband signal based on an energy ratio algorithm and the coarse synchronization point, detect the position of the synchronization burst, and determine the fine synchronization point; The multi-frame synchronization module is used to perform multi-frame synchronization on the baseband signal according to the fine synchronization point. 9. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the processor implements the steps of the multi-frame synchronization method of the GSM system as described in any one of claims 1 to 7. 10. A non-transitory computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps of the multiframe synchronization method of the GSM system as claimed in any one of claims 1 to 7 are implemented.