CN115086126B - GMSK signal-based synchronization method, device and computer-readable storage medium - Google Patents
GMSK signal-based synchronization method, device and computer-readable storage medium Download PDFInfo
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- H04L27/2007—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained
- H04L27/2017—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained in which the phase changes are non-linear, e.g. generalized and Gaussian minimum shift keying, tamed frequency modulation
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Abstract
The application discloses a synchronization method, a synchronization device and a computer readable storage medium based on GMSK signals, wherein the method comprises the following steps: receiving a GMSK signal to construct a buffer queue to be demodulated, wherein the buffer queue to be demodulated comprises a differential phase signal generated by processing the GMSK signal; when the buffer queue to be demodulated reaches a preset length, calculating an optimal sampling point based on the buffer queue to be demodulated; taking out part of differential phase signals from a to-be-demodulated buffer queue, and demodulating part of differential phase signals to obtain first demodulation signals; when the first demodulation signal comprises a preset training sequence, constructing a demodulated buffer queue, and calculating an optimal sampling point based on the demodulated buffer queue, wherein the demodulated buffer queue comprises differential phase signals participating in demodulation; the position of the optimal sampling point is taken as the synchronous position. By means of the method, the calculation accuracy of the synchronous position can be improved, and the demodulation performance of the GMSK signal is improved.
Description
Technical Field
The present application relates to the field of communications technologies, and in particular, to a GMSK signal-based synchronization method, apparatus, and computer-readable storage medium.
Background
The Gaussian minimum shift keying (Gaussian Filtered Minimum Shift Keying, GMSK) modulation and demodulation scheme has the characteristics of constant envelope, compact frequency spectrum, small out-of-band radiation and the like, and becomes one of the more mature modulation and demodulation technical schemes in the digital trunking communication technology; for GMSK signals, a differential phase demodulation algorithm is generally adopted, an optimal sampling point is required to be calculated according to the prior data in the demodulation process, and frequency offset correction and Viterbi demodulation are required to be carried out according to the optimal sampling point after the prior data. However, in an actual application scenario, signal sources may be frequently switched, positions of optimal sampling points corresponding to GMSK signals generated by different signal sources may be different, even the same signal source may also switch receiving frequency points at any time according to service requirements, so as to change the optimal sampling points, and in addition, even if the same signal source does not perform any manual operation, the optimal sampling points also show long-range instability. Therefore, for the GMSK burst signal received in the carrier-free state, the best sampling point obtained by calculating according to the preamble noise signal has no reference value for demodulation of the subsequent effective carrier data, and at this time, if the demodulation parameters are used strongly or reset, the demodulation performance of the GMSK burst signal is affected, so that the demodulation performance is poor.
Disclosure of Invention
The application provides a synchronization method, a synchronization device and a computer readable storage medium based on GMSK signals, which can improve the calculation accuracy of synchronization positions and the demodulation performance of the GMSK signals.
In order to solve the technical problems, the technical scheme adopted by the application is as follows: there is provided a GMSK signal-based synchronization method comprising: receiving a GMSK signal to construct a buffer queue to be demodulated, wherein the buffer queue to be demodulated comprises a differential phase signal generated by processing the GMSK signal; when the buffer queue to be demodulated reaches a preset length, calculating an optimal sampling point based on the buffer queue to be demodulated; taking out part of differential phase signals from a to-be-demodulated buffer queue, and demodulating part of differential phase signals to obtain first demodulation signals; when the first demodulation signal comprises a preset training sequence, constructing a demodulated buffer queue, and calculating an optimal sampling point based on the demodulated buffer queue, wherein the demodulated buffer queue comprises differential phase signals participating in demodulation; the position of the optimal sampling point is taken as the synchronous position.
In order to solve the technical problems, another technical scheme adopted by the application is as follows: there is provided a synchronisation device comprising a memory and a processor, which are interconnected, wherein the memory is adapted to store a computer program which, when executed by the processor, is adapted to carry out the GMSK signal based synchronisation method of the above-mentioned kind.
In order to solve the technical problems, another technical scheme adopted by the application is as follows: there is provided a computer readable storage medium for storing a computer program for implementing the GMSK signal-based synchronization method of the above-mentioned aspects when the computer program is executed by a processor.
Through above-mentioned scheme, the beneficial effect of this application is: generating a differential phase signal by processing a received GMSK signal, and then storing the differential phase signal to establish a buffer queue to be demodulated; when the length of the to-be-demodulated buffer queue reaches a preset length, calculating an optimal sampling point based on the to-be-demodulated buffer queue; demodulating part of the differential phase signals in the buffer queue to be demodulated to generate a first demodulation signal; and then detecting the first demodulation signal, if the first demodulation signal contains the preset training sequence, constructing a demodulated buffer queue by using the first demodulation signal, and calculating an optimal sampling point by using the demodulated buffer queue, wherein the position corresponding to the optimal sampling point is the synchronous position. The method and the device have the advantages that whether the effectiveness of the received GMSK signals is distinguished by detecting the training sequence or not, a to-be-demodulated buffer queue and a demodulated buffer queue are respectively constructed to calculate the most suitable position for signal synchronization, the signal is utilized to calculate the optimal sampling point, the optimal sampling point can be applied to the GMSK demodulation process of the signal, the limitation that the post-sequence data demodulation process in the GMSK demodulation process completely depends on the synchronization position of the preamble data is effectively overcome, and the demodulation performance of the GMSK signals is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:
fig. 1 is a flow chart of an embodiment of a GMSK signal-based synchronization method provided in the present application;
fig. 2 is a flow chart of another embodiment of the GMSK signal-based synchronization method provided in the present application;
fig. 3 is a schematic diagram of a to-be-demodulated buffer queue provided in the present application;
FIG. 4 is a schematic diagram of a demodulated cache queue provided herein;
FIG. 5 is a schematic structural diagram of an embodiment of a synchronization device provided in the present application;
fig. 6 is a schematic structural diagram of an embodiment of a computer-readable storage medium provided in the present application.
Detailed Description
The following description of the technical solutions in the embodiments of the present application will be made clearly and completely with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
Referring to fig. 1, fig. 1 is a flowchart of an embodiment of a GMSK signal-based synchronization method provided in the present application, where the method includes:
step 11: and receiving the GMSK signal to construct a buffer queue to be demodulated.
After the receiving equipment is started, the receiving equipment is in an unloaded front transition state by default, the GMSK signal is continuously received in the unloaded front transition state, and meanwhile, differential phase discrimination processing is carried out on the received GMSK signal, so that a differential phase signal is generated. Specifically, 1-bit delay processing is performed on two paths of received I, Q GMSK signals respectively, multiplication operation is performed on an I path of GMSK original signal and a Q path of GMSK delay signal to obtain a first multiplication operation signal, multiplication operation is performed on the Q path of GMSK original signal and the I path of GMSK delay signal to obtain a second multiplication operation signal, and finally phase difference is obtained by subtracting the first multiplication operation signal from the second multiplication operation signal, namely, a differential phase signal, and further, the differential phase signal can be processed to fall in intervals of [ -pi/2, pi/2 ] through an inverse trigonometric function.
And storing the generated differential phase signals into a to-be-demodulated buffer queue until the to-be-demodulated buffer queue reaches a preset length, wherein the to-be-demodulated buffer queue comprises differential phase signals generated by processing GMSK signals.
Step 12: and when the buffer queue to be demodulated reaches a preset length, calculating an optimal sampling point based on the buffer queue to be demodulated.
Because the demodulation signal of each bit is obtained through the participation of the differential phase signals of the preset number of sampling points in the demodulation operation, the sampling point which is the closest to the real demodulation signal can be obtained through participation in the calculation in the preset number of sampling points, namely the optimal sampling point. When calculating the optimal sampling point by using the to-be-demodulated buffer queue, firstly sequencing all differential phase signals in the to-be-demodulated buffer queue by taking a preset number as a group according to a time sequence to be divided into a plurality of groups, namely, each group of differential phase signals comprises differential phase signals with the preset number of sampling points, and labeling each group of differential phase signals to generate a preset number of serial numbers; and accumulating algebraic sums of differential phase signals of sampling points with the same serial numbers in all differential phase signals to obtain differential phase algebraic sum accumulated values of the differential phase signals with preset numbers, and marking the sampling point corresponding to the serial number with the largest differential phase algebraic sum accumulated value as the optimal sampling point.
Step 13: and taking out part of the differential phase signals from the buffer queue to be demodulated, and demodulating part of the differential phase signals to obtain first demodulation signals.
After a buffer queue to be demodulated is constructed, part of differential phase signals are sequentially taken out from the buffer queue to be demodulated according to a storage sequence, and then the differential phase signals are demodulated to obtain a first demodulation signal; specifically, in order to maintain stability of the buffer queue to be demodulated, each time a 1-bit differential phase signal is stored, the 1-bit differential phase signal can be sequentially taken out from the buffer queue to be demodulated for GMSK demodulation.
Step 14: and when the first demodulation signal comprises a preset training sequence, constructing a demodulated buffer queue.
If a preset training sequence is detected in the sequence of the demodulation output of the differential phase signal, entering a carrier pre-transition state; in the carrier pre-transition state, carrying out differential phase discrimination operation on the received GMSK signals, storing the generated differential phase signals into a buffer queue to be demodulated, and taking the buffer queue to be demodulated as input to calculate an optimal sampling point; and demodulating and outputting all signals in the buffer queue to be demodulated, and entering a carrier state.
And in the carrier state, storing all differential phase signals participating in the demodulation process of the first demodulation signal to construct a demodulated buffer queue, wherein the demodulated buffer queue can store differential phase signals with specified lengths at most.
Step 15: the optimal sampling point is calculated based on the demodulated buffer queue.
The demodulated buffer queue comprises differential phase signals participating in demodulation, all differential phases in the demodulated buffer queue can be divided into a plurality of groups according to time by taking a preset number of sampling points as a group, each group comprises the differential phases of the preset number of sampling points, a preset number of serial numbers are marked respectively, differential phase algebra and accumulation operation is carried out on the sampling points with the same serial numbers in all differential phase signals, algebra and accumulation values of the preset number of differential phases are obtained, and the sampling point corresponding to the serial number with the largest differential phase algebra sum is marked as the optimal sampling point.
Step 16: the position of the optimal sampling point is taken as the synchronous position.
After the optimal sampling point is calculated, the position of the optimal sampling point can be used as a synchronization position, and the transmission and reception with the transmitting device can be synchronized by using the synchronization position.
The scheme of the embodiment can be applied to private network equipment and public network equipment adopting a GMSK scheme, and provides a method for calculating a synchronous position in a digital trunking wireless communication technology, and the method can calculate an optimal sampling point according to a signal and is applied to the GMSK demodulation process of the signal. Compared with the mode that the subsequent signal demodulation in the traditional technology completely depends on the preamble signal, the method can be used for respectively solving the optimal sampling points by identifying the GMSK signal characteristics, so that the introduction of interference signals can be avoided, higher synchronization precision can be obtained, and the demodulation performance of the GMSK signal can be improved.
Referring to fig. 2, fig. 2 is a flow chart of another embodiment of a GMSK signal-based synchronization method provided in the present application, where the method includes:
step 201: and receiving the GMSK signal of the first bit, performing differential phase discrimination operation on the GMSK signal of the first bit to obtain a differential phase signal, and storing the differential phase signal into a buffer queue to be demodulated.
The first bit is denoted as X bits, which may be 1 bit or 2 bits; and after the receiving equipment is started, in an unloaded front transition state, the receiving equipment can receive the GMSK signal with X bits, then carries out differential phase discrimination operation on the GMSK signal, stores the calculated differential phase signal into a buffer queue to be demodulated, does not calculate an optimal sampling point at the moment, and outputs an unloading GMSK demodulation signal.
Step 202: judging whether the length of the buffer queue to be demodulated reaches a preset length.
Recording the preset length as N (N > 0) bits, if the length of the buffer queue to be demodulated reaches N bits, entering a stable carrier-free state, and executing step 203; if the length of the buffer queue to be demodulated is smaller than N bits, returning to receive the GMSK signal of the first bit, and performing differential phase discrimination operation on the GMSK signal of the first bit to obtain a differential phase signal, that is, returning to execute step 201 until the length of the buffer queue to be demodulated reaches the preset length. Further, the specific value of N may be determined according to the physical layer burst structure feature, where the physical layer includes, but is not limited to, a preset training sequence and an effective sequence located after the preset training sequence, and N is not greater than the difference between the length of the effective sequence after the training sequence and the length of the preset training sequence.
Step 203: and calculating an optimal sampling point based on the differential phase signals in the buffer queue to be demodulated.
Taking a buffer queue to be demodulated of (n+x) bits as input to calculate an optimal sampling point, which can provide a reference for this demodulation process; specifically, all differential phase signals are sorted in a time sequence in a group with a preset number, each group of differential phase signals comprises differential phase signals with a preset number of sampling points, each group of differential phase signals is marked to generate a preset number of serial numbers, algebraic sums of differential phase signals with the same serial number in all differential phase signals are accumulated, and differential phase algebraic sum accumulated values of the preset number of sampling points are obtained; and marking the sampling point corresponding to the serial number with the largest differential phase algebra and accumulated value as the optimal sampling point, and taking the optimal sampling point as the optimal sampling point capable of participating in the demodulation process.
Step 204: and receiving the GMSK signal of the second bit, performing differential phase discrimination operation on the GMSK signal of the second bit to obtain a differential phase signal, and storing the differential phase signal into a buffer queue to be demodulated.
At this time, the equipment is in a stable carrier-free state, can receive the GMSK signal of X bits, carries out differential phase discrimination operation on the GMSK signal to obtain a differential phase signal, and stores the differential phase signal into a buffer queue to be demodulated; specifically, the differential phase signal of each bit includes a differential phase of a preset number of sampling points.
Step 205: and sequentially taking out the differential phase signals from the buffer queue to be demodulated as signals to be demodulated, and demodulating the signals to be demodulated to obtain first demodulation signals.
In the stable carrier-free stage, in order to maintain the stability of the N-bit buffer queue to be demodulated, each time the differential phase signal of the X bits is stored, the differential phase signal of the X bits can be sequentially taken out from the buffer queue to be demodulated to carry out GMSK demodulation, and the first demodulation signal of each bit comprises differential phase signals of a preset number of sampling points.
Step 206: judging whether the first demodulation signal contains a preset training sequence or not.
If a valid training sequence is detected in the demodulated output sequence, entering a pre-carrier transition state, and executing step 207; if no effective training sequence is detected in the demodulated output sequence, the step of sequentially taking out the differential phase signals from the buffer queue to be demodulated as the signals to be demodulated is returned, namely, step 205 is executed.
It will be appreciated that when the device is in a steady carrier-free state, if the preset training sequence is detected for the first time, the timing is started, and if the preset training sequence is detected again later, the timing needs to be reset.
Step 207: if the first demodulation signal contains a preset training sequence, resetting the timing time, receiving a GMSK signal of a third bit, performing differential phase discrimination operation on the GMSK signal of the third bit to obtain a differential phase signal, and storing the differential phase signal into a to-be-demodulated buffer queue; and demodulating all the differential phase signals in the buffer queue to be demodulated to obtain a second demodulation signal so as to construct a demodulated buffer queue.
When the equipment is in a carrier pre-transition state, receiving an X-bit GMSK signal, performing differential phase discrimination operation on the received X-bit GMSK signal, and storing the generated differential phase signal into a to-be-demodulated buffer queue; taking a buffer queue to be demodulated of (N+X) bits as an input to calculate an optimal sampling point; in order to release the time delay, all the (N+X) bits of the buffer queue to be demodulated are demodulated and output to obtain a second demodulation signal, and then the second demodulation signal enters a carrier state; in the carrier state, all differential phase signals participating in the demodulation process of the second demodulation signal are stored in a demodulated buffer queue, namely the demodulated buffer queue comprises all differential phase signals participating in the demodulation of the second demodulation signal, so as to establish an M-bit demodulated buffer queue, wherein M can be 3-4 times of the length of a physical layer burst sequence.
Step 208: and receiving the fourth bit GMSK signal, and performing differential phase discrimination operation on the fourth bit GMSK signal to obtain a differential phase signal.
The device is in a stable carrier state, receives the X-bit GMSK signal, and performs differential phase discrimination operation on the X-bit GMSK signal to generate a corresponding differential phase signal.
Step 209: and judging whether the differential phase signal and the second demodulation signal are effective signals or not.
And calculating the distance between the differential phase signal generated by using the currently received fourth-bit GMSK signal and the preset training sequence, and if the differential phase signal generated by using the fourth-bit GMSK signal and the corresponding differential phase signal in the demodulated buffer queue are in the N-bit continuous sequence range after the preset training sequence, the effective signal is obtained.
Step 210: if the differential phase signal and the second demodulation signal are effective signals, an optimal sampling point is calculated based on the differential phase signal corresponding to the differential phase signal and the second demodulation signal.
If the differential phase signal corresponding to the fourth bit of the X-bit GMSK signal and the M-bit demodulated buffer queue of the preamble thereof are valid signals, the differential phase signal corresponding to the X-bit GMSK signal and the M-bit demodulated buffer queue are used as inputs to calculate an optimal sampling point.
Step 211: if the differential phase signal or the second demodulation signal is not the effective signal, the last optimal sampling point is taken as the optimal sampling point.
If the differential phase signal corresponding to the fourth bit X-bit GMSK signal and the M-bit demodulated buffer queue of the preamble thereof are not valid signals, they may be noise signals, and thus cannot participate in the calculation of the optimal sampling point, otherwise noise interference may be introduced, and since the optimal sampling point has no significant change in the short range, the calculation result of the last optimal sampling point may be used as the optimal sampling point applied to the demodulation process.
Step 212: the position of the optimal sampling point is taken as the synchronous position.
After the optimal sampling point is calculated, the position of the optimal sampling point can be used as a synchronization position, and the transmission and reception with the transmitting device can be synchronized by using the synchronization position.
Step 213: and demodulating the differential phase signal generated by the fourth bit GMSK signal to obtain a third demodulation signal.
In order to maintain the stability of the M-bit demodulated buffer queue, the newly received fourth bit GMSK signal of the X bits needs to be immediately GMSK demodulated to prevent delay; specifically, demodulating the fourth bit GMSK signal to obtain a third demodulated signal; then judging whether the third demodulation signal contains a preset training sequence or not; if the third demodulation signal contains the preset training sequence, resetting the timing time and returning to the step of receiving the fourth bit GMSK signal; if the third demodulation signal does not contain the preset training sequence, judging whether the current statistical time exceeds the preset time; if the current statistical time exceeds the preset time, namely the preset training sequence cannot be detected for a long time, executing the step of constructing a to-be-demodulated buffer queue; and if the current statistical time does not exceed the preset time, returning to the step of receiving the GMSK signal of the fourth bit.
The embodiment provides a calculation method suitable for a synchronous position of a GMSK signal, which can be applied to an interphone, and can distinguish a carrier-free state, a carrier-free state and a conversion state between the carrier-free state and the carrier-free state by identifying a demodulation output sequence in the process of receiving the GMSK signal by equipment; under the no-load state, realizing fixed delay in the receiving and demodulating process by constructing a buffer queue to be demodulated, and taking the GMSK signal of X bits to be demodulated and the buffer queue to be demodulated of N bits behind the GMSK signal as input to calculate an optimal sampling point; under the carrier state, releasing fixed time delay between the receiving and demodulating processes, constructing a demodulated buffer queue, and under the condition that the differential phase signal of X bits to be demodulated and the M-bit demodulated buffer queue of the preamble of the differential phase signal are determined to be effective signals, taking the differential phase signal and the M-bit demodulated buffer queue of the preamble of the differential phase signal as inputs to calculate an optimal sampling point; specifically, taking X as 1 and N as 128 as an example, the calculation of the synchronization position of the receiving device in the carrier-free state, the carrier-present state and the transition state therebetween includes the following steps:
(1) And (3) after the receiving device is started, defaulting to be in an unloaded front transition state, and executing the step (2).
(2) In the no-load front transition state, receiving a 1-bit GMSK signal, performing differential phase discrimination operation, and storing the generated differential phase signal into a to-be-demodulated buffer queue, as shown in figure 3; if the length of the buffer queue to be demodulated does not reach 128 bits, calculating an optimal sampling point, outputting a GMSK-free demodulation signal, and continuously executing the step (2); if the length of the buffer queue to be demodulated reaches 128 bits, entering a stable carrier-free state, and executing the step (3).
(3) And in a stable carrier-free state, receiving a 1-bit GMSK signal, performing differential phase discrimination operation, storing the generated differential phase signal into a buffer queue to be demodulated, and calculating the differential phase algebraic sum of all sampling points by taking the 129-bit buffer queue to be demodulated as input, wherein the sampling point corresponding to the algebraic sum maximum value is the optimal sampling point.
In order to maintain the stability of the N-bit buffer queue to be demodulated, taking out a 1-bit GMSK signal from the head of the buffer queue to be demodulated to perform GMSK demodulation; if the effective training sequence is detected in the demodulated output sequence, entering a carrier pre-transition state, executing the step (4), otherwise executing the step (3); further, the differential phase signal calculated by using the newly received GMSK signal with X bits is denoted as a newly stored signal, the differential phase signal to be demodulated currently in the buffer queue to be demodulated is denoted as a signal to be demodulated, and as can be seen from fig. 3, the newly stored signal is separated from the signal to be demodulated by (N-X) bits, that is, there is a delay between the received GMSK signal and the GMSK signal to be demodulated.
(4) In the carrier pre-transition state, a 1-bit GMSK signal is received, differential phase discrimination operation is carried out, the generated differential phase signal is stored in a buffer queue to be demodulated, the buffer queue to be demodulated with 129 bits is used as input to calculate algebraic sum of differential phases of sampling points, and the sampling point corresponding to the maximum value of the algebraic sum is the optimal sampling point.
In order to release the time delay, all signals in the 129-bit buffer queue to be demodulated need to be demodulated and output, and then the signals enter a stable carrier state, and the step (5) is executed.
(5) In the stable carrier state, the demodulated signal generated in the step (4) is stored, and a demodulated buffer queue is established for storing the demodulated effective differential phase signal, as shown in fig. 4, where M may be 1536. And receiving a 1-bit GMSK signal, performing differential phase discrimination operation, judging that the 1-bit differential phase signal to be demodulated and the signal in the demodulated buffer queue of 1536 bits of the preamble fall within a 128-bit range after a preset training sequence, taking the 1-bit differential phase signal to be demodulated and the signal in the demodulated buffer queue as effective signals, taking the effective signals as algebraic sums of differential phases of sampling points to be calculated, wherein the sampling point corresponding to the algebraic sum maximum value is the optimal sampling point, otherwise, using the optimal sampling point calculated last time, the mode can obtain an accurate optimal sampling point without introducing noise signals in a carrier-free state.
Since the fixed delay is completely released, the newly received 1-bit differential phase signal needs to be immediately GMSK demodulated, i.e. the newly stored signal and the signal to be demodulated are the same signal, as shown in fig. 4; if the effective training sequence is detected in the demodulated output sequence, resetting the timing time, and executing the step (5); if the effective training sequence is not detected in the demodulated output sequence, accumulating and timing; if the accumulated timing time does not exceed the preset time (such as 96 ms), executing step (5); if the accumulated timing time exceeds the preset time, entering an unloaded wave front transition state, namely executing the step (2).
In the scheme provided by the application, the receiving equipment distinguishes the no-carrier front transition state, the no-carrier state, the carrier front transition state and the carrier state by identifying the training sequence in the demodulation output in the process of receiving the GMSK signal; in the no-load front transition state, the fixed delay of the receiving and demodulating process is realized by constructing a buffer queue to be demodulated, and the optimal sampling point is not calculated; under the no-load state, taking the differential phase signal of X bits to be demodulated and the buffer queue of N bits to be demodulated behind the differential phase signal as inputs to calculate an optimal sampling point; under the carrier pre-transition state, taking the differential phase signal of X bits to be demodulated and the N-bit buffer queue to be demodulated behind the differential phase signal as inputs to calculate an optimal sampling point, fully demodulating and outputting the signals in the buffer queue to be demodulated, and releasing the fixed delay between the receiving and demodulating processes; under the carrier state, constructing a demodulated buffer queue, and under the condition that the differential phase signal of X bits to be demodulated and the demodulated buffer queue of M bits of the preamble of the differential phase signal are determined to be effective signals, taking the differential phase signal and the demodulated buffer queue of M bits as inputs to calculate an optimal sampling point; the scheme provided by the application can effectively identify the GMSK signal in the carrier-free state, calculates the optimal sampling point according to the signal to be demodulated, and is applied to the GMSK demodulation process of the application, so that interference signals are prevented from being introduced, and the demodulation performance of the GMSK signal is improved; in addition, compared with the existing scheme, the scheme provided by the application takes the fixed X bits as the minimum demodulation unit, only one detection process is needed, related operation is not involved, the operation amount is small, the operation time can be reduced, and the requirement on a processor is reduced.
Referring to fig. 5, fig. 5 is a schematic structural diagram of an embodiment of a synchronization device provided in the present application, where the synchronization device 50 includes a memory 51 and a processor 52 connected to each other, and the memory 51 is used to store a computer program, where the computer program, when executed by the processor 52, is used to implement the GMSK signal-based synchronization method in the above embodiment; the synchronization device 50 may be a receiver, a part of a component in a receiver, or other apparatus having a synchronous receiving function.
Referring to fig. 6, fig. 6 is a schematic structural diagram of an embodiment of a computer readable storage medium provided in the present application, where the computer readable storage medium 60 is used to store a computer program 61, and the computer program 61, when executed by a processor, is used to implement the GMSK signal-based synchronization method in the above embodiment.
The computer readable storage medium 60 may be a server, a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, etc. various media capable of storing program codes.
In the several embodiments provided in the present application, it should be understood that the disclosed methods and apparatuses may be implemented in other manners. For example, the above-described device embodiments are merely illustrative, e.g., the division of modules or units is merely a logical functional division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, each unit may exist alone physically, or two or more units may be integrated into one unit. The integrated units may be implemented in hardware or in software functional units.
The foregoing description is only exemplary embodiments of the present application and is not intended to limit the scope of the present application, and all equivalent structures or equivalent processes using the descriptions and the drawings of the present application, or direct or indirect application in other related technical fields are included in the scope of the present application.
Claims (8)
1. A GMSK signal-based synchronization method, comprising:
receiving a GMSK signal to construct a buffer queue to be demodulated, wherein the buffer queue to be demodulated comprises a differential phase signal generated by processing the GMSK signal;
when the to-be-demodulated buffer queue reaches a preset length, calculating an optimal sampling point based on the to-be-demodulated buffer queue;
taking out part of differential phase signals from the buffer queue to be demodulated, and demodulating the part of differential phase signals to obtain first demodulation signals;
when the first demodulation signal comprises a preset training sequence, constructing a demodulated buffer queue, and calculating an optimal sampling point based on the demodulated buffer queue, wherein the demodulated buffer queue comprises differential phase signals participating in demodulation;
taking the position of the optimal sampling point as a synchronous position;
the differential phase signal of each bit comprises a differential phase of a preset number of sampling points, and the step of constructing a demodulated buffer queue comprises the following steps:
receiving a GMSK signal of a third bit, and performing differential phase discrimination operation on the GMSK signal of the third bit to obtain a differential phase signal;
storing the differential phase signals into the to-be-demodulated cache queue;
demodulating all the differential phase signals in the buffer queue to be demodulated to obtain a second demodulation signal so as to construct a demodulated buffer queue;
wherein the demodulated buffer queue includes all of the differential phase signals that are involved in demodulation of the second demodulation signal;
the step of calculating the optimal sampling point based on the demodulated buffer queue comprises the following steps:
receiving a fourth bit GMSK signal, and performing differential phase discrimination operation on the fourth bit GMSK signal to obtain a differential phase signal;
judging whether the differential phase signal and the second demodulation signal are effective signals or not, wherein the distance between the differential phase signal and the preset training sequence is calculated, and if the differential phase signal and the corresponding differential phase signal in the demodulated buffer queue are in an N-bit continuous sequence range behind the preset training sequence, the differential phase signal is the effective signal;
if yes, calculating the optimal sampling point based on the differential phase signal corresponding to the differential phase signal and the second demodulation signal;
if not, the last optimal sampling point is taken as the optimal sampling point.
2. The GMSK signal-based synchronization method of claim 1, wherein the step of receiving the GMSK signal to construct a buffer queue to be demodulated comprises:
receiving a GMSK signal of a first bit, and performing differential phase discrimination operation on the GMSK signal of the first bit to obtain the differential phase signal;
storing the differential phase signals into the to-be-demodulated cache queue;
judging whether the length of the buffer queue to be demodulated reaches the preset length;
and if not, returning to the GMSK signal receiving the first bit, and performing differential phase discrimination operation on the GMSK signal receiving the first bit to obtain the differential phase signal until the length of the buffer queue to be demodulated reaches the preset length.
3. The GMSK signal-based synchronization method of claim 1, wherein the first demodulation signal of each bit includes a differential phase signal of a preset number of sampling points, the step of taking out a part of the differential phase signal from the buffer queue to be demodulated, and demodulating the part of the differential phase signal to obtain a first demodulation signal includes:
receiving a GMSK signal of a second bit, and performing differential phase discrimination operation on the GMSK signal of the second bit to obtain a differential phase signal;
storing the differential phase signals into the to-be-demodulated cache queue;
taking out differential phase signals from the buffer queue to be demodulated in sequence to serve as signals to be demodulated;
demodulating the signal to be demodulated to obtain the first demodulated signal;
judging whether the first demodulation signal contains the preset training sequence or not;
if yes, resetting the timing time;
and if not, returning to the step of receiving the GMSK signal of the second bit, and carrying out differential phase discrimination operation on the GMSK signal of the second bit to obtain a differential phase signal.
4. A GMSK signal-based synchronization method according to claim 1, characterized in that the method further comprises:
demodulating the fourth bit GMSK signal to obtain a third demodulation signal;
judging whether the third demodulation signal contains the preset training sequence or not;
if yes, resetting the timing time, and returning to the step of receiving the fourth bit GMSK signal.
5. The GMSK signal-based synchronization method of claim 4, further comprising:
when the third demodulation signal does not contain the preset training sequence, judging whether the current statistical time exceeds the preset time or not;
if yes, executing the step of constructing a to-be-demodulated cache queue;
if not, returning to the step of receiving the fourth bit GMSK signal.
6. The GMSK signal-based synchronization method of claim 1, wherein the step of calculating the optimal sampling point comprises:
sequencing all differential phase signals according to a time sequence in a group of preset quantity, and marking;
accumulating algebraic sums of differential phase signals of sampling points with the same serial numbers in all the differential phase signals to obtain differential phase algebraic sum accumulated values of a preset number of sampling points;
and marking the sampling point corresponding to the serial number with the largest differential phase algebra and accumulated value as the optimal sampling point.
7. A synchronization device comprising a memory and a processor connected to each other, wherein the memory is adapted to store a computer program for implementing the GMSK signal-based synchronization method of any one of claims 1-6 when executed by the processor.
8. A computer readable storage medium storing a computer program, which, when being executed by a processor, is adapted to carry out the GMSK signal-based synchronization method of any one of claims 1-6.
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