CN113824662A - Carrier synchronization method and device, electronic equipment and computer readable medium - Google Patents
Carrier synchronization method and device, electronic equipment and computer readable medium Download PDFInfo
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Abstract
The application relates to a carrier synchronization method and device for a high-dynamic burst signal, electronic equipment and a computer readable medium. The method comprises the following steps: converting the high dynamic burst signal from the low earth orbit satellite mobile communication channel into at least one short frame data; generating at least one doppler first order rate of change based on the at least one short frame data; respectively eliminating the influence of the corresponding Doppler first-order change rate in the at least one short frame data to generate at least one integrated data; generating a Doppler frequency offset estimate based on the at least one consolidated data; and carrying out carrier synchronization of the high-dynamic burst signal based on the Doppler first-order change rate and the Doppler frequency offset estimation value. The method has wide applicability for burst frame signals, reduces the data processing amount of the algorithm on the premise of ensuring the Doppler change rate and the Doppler frequency estimation precision, greatly reduces the calculated amount, and provides a new thought for the carrier synchronization algorithm in the field of software radio.
Description
Technical Field
The present disclosure relates to the field of satellite signal processing, and in particular, to a method and an apparatus for carrier synchronization of a high dynamic burst signal, an electronic device, and a computer readable medium.
Background
In low-orbit satellite communication, a low-orbit satellite performs high-speed relative motion relative to a ground terminal, so that a large doppler frequency shift exists in a received signal, the doppler frequency shift changes along with motion time, the dynamic property is high, a first-order frequency change rate and even a high-order frequency change rate exist, and a challenge is brought to carrier parameter estimation.
If the phase-locked loop technology is adopted to capture the high-dynamic burst signal, when the Doppler frequency shift range in the received signal is large, the synchronization time is long, and the situation that the loop is not converged yet and the burst signal is already finished is likely to occur, so that the carrier parameter estimation cannot be completed. If the Doppler change rate estimation algorithm based on the maximum likelihood criterion is adopted, although the performance is better, the realization complexity is extremely high, and the engineering application is difficult.
The existing scheme or the calculated data amount is large, the short frame data burst structure is not suitable, or the existing scheme is only suitable for the special structure of the known sequence existing at the frame head and the frame tail, and the universality is not high.
Therefore, a new method, apparatus, electronic device and computer readable medium for carrier synchronization of high dynamic burst signals are needed.
The above information disclosed in this background section is only for enhancement of understanding of the background of the application and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
In view of this, the present application provides a method, an apparatus, an electronic device and a computer readable medium for carrier synchronization of a high dynamic burst signal, which have wide applicability for burst frame signals, reduce data processing amount of an algorithm on the premise of ensuring doppler change rate and doppler frequency estimation accuracy, are easier for engineering implementation, greatly reduce computation amount, and provide a new idea for a carrier synchronization algorithm in the field of software radio.
Other features and advantages of the present application will be apparent from the following detailed description, or may be learned by practice of the application.
According to an aspect of the present application, a method for carrier synchronization of a high dynamic burst signal is provided, where the method includes: converting the high dynamic burst signal from the low earth orbit satellite mobile communication channel into at least one short frame data; generating at least one doppler first order rate of change based on the at least one short frame data; respectively eliminating the influence of the corresponding Doppler first-order change rate in the at least one short frame data to generate at least one integrated data; generating a Doppler frequency offset estimate based on the at least one consolidated data; and carrying out carrier synchronization of the high-dynamic burst signal based on the Doppler first-order change rate and the Doppler frequency offset estimation value.
In an exemplary embodiment of the present application, includes: when the frame length of the high dynamic burst signal is larger than a threshold value, cutting off the high dynamic burst signal into a plurality of short frame data; and when the frame length of the high dynamic burst signal is less than or equal to a threshold value, taking the high dynamic burst signal as short frame data.
In an exemplary embodiment of the present application, truncating the high dynamic burst signal into a plurality of short frame data includes: and truncating the high dynamic burst signal into a plurality of short frame data based on a sliding window method.
In an exemplary embodiment of the present application, generating at least one doppler first order rate of change based on the at least one short frame data comprises: carrying out frame head and tail nonlinear de-modulation and fast Fourier transform on short frame data; generating a first-order temporal rate of change of Doppler based on the fast Fourier transform result; and generating a first-order Doppler change rate of the short frame data based on the three-division fast approximation algorithm and the first-order Doppler temporary change rate.
In an exemplary embodiment of the present application, fast fourier transforming the head and the tail of the short frame data frame respectively includes: obtaining a plurality of symbols of a frame head and a frame tail of the intra-frame data of the at least one short frame data to perform nonlinear de-modulation operation; and performing fast Fourier transform on data obtained after the frame head and the frame tail are subjected to nonlinear de-modulation.
In an exemplary embodiment of the present application, generating a doppler first order temporal rate of change based on a fast fourier transform result includes: acquiring a frequency point corresponding to the maximum value of the spectrum energy obtained by the frame header data through fast Fourier transform; acquiring a frequency point corresponding to the maximum value of the spectrum energy obtained by fast Fourier transform of frame tail data; and generating the Doppler first-order temporary change rate based on the frequency point corresponding to the maximum frame head spectrum energy value, the frequency point corresponding to the maximum frame tail spectrum energy value, the frame length of the short frame data, the number of symbols and a single symbol period.
In an exemplary embodiment of the present application, generating the doppler first order change rate based on the three-division fast approximation algorithm and the doppler first order temporal change rate includes: determining a transformation interval based on the Doppler first order temporal rate of change; and searching and determining the Doppler first-order change rate based on the three-division fast approximation algorithm in the transformation interval.
In an exemplary embodiment of the present application, determining the doppler first order rate of change based on the three-division fast approximation algorithm search within the transformation interval comprises: and searching and determining the Doppler first-order change rate in the transformation interval based on the three-division fast approximation algorithm and a quadratic interpolation mode.
In an exemplary embodiment of the present application, generating doppler frequency offset estimates based on the at least one consolidated datum comprises: performing a fast fourier transform on the at least one consolidated data; determining a frequency point and an adjacent frequency point corresponding to the maximum value of the spectrum energy based on the result of the fast Fourier transform; and generating the Doppler frequency offset estimation value based on the frequency point and the adjacent frequency points.
In an exemplary embodiment of the present application, generating the doppler frequency offset estimation value based on the frequency point and the adjacent frequency point includes: and generating the Doppler frequency offset estimation value by utilizing a quadratic interpolation method based on the frequency point and the adjacent frequency points.
According to an aspect of the present application, a carrier synchronization apparatus for a high dynamic burst signal is provided, the apparatus including: the short frame module is used for converting the high dynamic burst signal from the low orbit satellite mobile communication channel into at least one short frame data; a rate of change module to generate at least one first-order rate of change of doppler based on the at least one short frame data; an integration module for eliminating the influence of the first-order Doppler change rate in the at least one short frame data to generate at least one integrated data; an estimate module to generate a doppler frequency offset estimate based on the at least one integration data; and the synchronization module is used for carrying out carrier synchronization on the high-dynamic burst signal based on the Doppler first-order change rate and the Doppler frequency offset estimation value.
According to an aspect of the present application, an electronic device is provided, the electronic device including: one or more processors; storage means for storing one or more programs; when executed by one or more processors, cause the one or more processors to implement a method as above.
According to an aspect of the application, a computer-readable medium is proposed, on which a computer program is stored, which program, when being executed by a processor, carries out the method as above.
According to the carrier synchronization method, the device, the electronic equipment and the computer readable medium of the high dynamic burst signal, the high dynamic burst signal from the low earth orbit satellite mobile communication channel is converted into at least one short frame data; generating at least one doppler first order rate of change based on the at least one short frame data; respectively eliminating the influence of the corresponding Doppler first-order change rate in the at least one short frame data to generate at least one integrated data; generating a Doppler frequency offset estimate based on the at least one consolidated data; the carrier synchronization method based on the Doppler first-order change rate and the Doppler frequency offset estimation value for the high-dynamic burst signal has wide applicability for burst frame signals, reduces the data processing amount of the algorithm on the premise of ensuring the Doppler change rate and the Doppler frequency estimation precision, is easier for engineering realization, greatly reduces the calculated amount, and provides a new idea for the carrier synchronization algorithm in the field of software radio.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings. The drawings described below are only some embodiments of the present application, and other drawings may be derived from those drawings by those skilled in the art without inventive effort.
Fig. 1 is a flowchart illustrating a carrier synchronization method for a high dynamic burst signal according to an exemplary embodiment.
Fig. 2 is a flowchart illustrating a carrier synchronization method for a high dynamic burst signal according to an exemplary embodiment.
Fig. 3 is a flowchart illustrating a carrier synchronization method for a high dynamic burst signal according to another exemplary embodiment.
Fig. 4 is a diagram illustrating a carrier synchronization method for a high dynamic burst signal according to another exemplary embodiment.
Fig. 5 is a block diagram illustrating a carrier synchronization apparatus for high dynamic burst signals according to an exemplary embodiment.
FIG. 6 is a block diagram illustrating an electronic device in accordance with an example embodiment.
FIG. 7 is a block diagram illustrating a computer-readable medium in accordance with an example embodiment.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals denote the same or similar parts in the drawings, and thus, a repetitive description thereof will be omitted.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the subject matter of the present application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the application.
The block diagrams shown in the figures are functional entities only and do not necessarily correspond to physically separate entities. I.e. these functional entities may be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and/or processor means and/or microcontroller means.
The flow charts shown in the drawings are merely illustrative and do not necessarily include all of the contents and operations/steps, nor do they necessarily have to be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.
It will be understood that, although the terms first, second, third, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first component discussed below may be termed a second component without departing from the teachings of the present concepts. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be appreciated by those skilled in the art that the drawings are merely schematic representations of exemplary embodiments, and that the blocks or processes shown in the drawings are not necessarily required to practice the present application and are, therefore, not intended to limit the scope of the present application.
The technical terms involved in the present application are as follows:
doppler shift: it is referred to that when a mobile station moves in a certain direction at a constant rate, a change in phase and frequency due to a propagation path difference is caused, and such a change is generally referred to as doppler shift.
Carrier synchronization: also known as carrier recovery, i.e. a local oscillation is generated in the receiving device which is co-frequency and in phase with the carrier of the received signal and supplied to the demodulator for coherent demodulation.
The inventors of the present application found that, in the prior art, there is a carrier synchronization method as follows:
the first scheme is as follows: performing parameter estimation by converting NLFM signal parameter estimation into an LFM signal, intercepting data by adopting a sliding window, sequentially performing frequency modulation rate elimination, FFT (fast Fourier transform) conversion and amplitude-frequency response and variable peak-to-average ratio maximum value (the energy is fixed, the energy peak value is high when the width is small, the corresponding peak spectral line position is a first-stage frequency estimation value) on the intercepted N point signals one by step delta within a frequency modulation range, and calculating the first-stage frequency modulation rate estimation value; in the same method, the second-stage frequency estimation is carried out in the range of the residual frequency modulation (the first stepping is the range of the residual frequency modulation), so that the estimation precision is improved; sliding the sliding window backwards for a certain length, and performing the two-step frequency estimation aiming at the intercepted data of the new sliding window; according to the two-window frequency estimation result, the high-order frequency change rate can be calculated, so that carrier synchronization is realized. The amount of calculated data is large and is not suitable for short data frame burst structures.
Scheme II: the frequency modulation rate approximation is carried out by adopting a trisection method, namely, the frequency change is trisected, and the maximum value is successively approximated by utilizing the convex function property, so that the FFT operation times are reduced.
The third scheme is as follows: the frequency estimation precision is improved by combining FFT (frame header and frame tail are respectively conjugated to remove modulation, FFT conversion, frequency deviation change rate calculation and first-order correction, nonlinear conversion and FFT conversion are carried out on corrected data, frequency deviation calculation is carried out, and therefore carrier parameter estimation is completed).
The existing scheme or the calculation data amount is large, the short data burst structure is not suitable, or the existing scheme is only suitable for the special structure of the known sequence existing at the frame head and the frame tail, and the universality is not high. In view of the technical problems in the prior art, the present application provides a carrier synchronization method for a high dynamic burst signal, which reduces the amount of calculation data when the high dynamic burst signal is carrier synchronized, and has wide applicability when the high dynamic burst signal is carrier synchronized with a general format data frame.
The inventor of the present application believes that, for low-orbit satellite communication, the signal modulation type is generally MPSK, and the channel condition is good, and is approximately gaussian white noise channel, and the received signal is as follows:
in the above formula
、
Is the intermediate frequency carrier frequency and the initial phase of the transmitting end,
、
is the actual carrier frequency of the signalThe deviation of the frequency and the phase from the local carrier frequency and the phase of the receiving end,
representing the corresponding function of the impulse of the transmitted signal into the shaping filter, k being an integer, T representing the symbol period,
the phase of the symbol is represented by,
represents complex white gaussian noise, the mean of which is 0.
Sampling the received intermediate frequency signal to obtain:
down-converting it:
the formula is carried into:
wherein the content of the first and second substances,
，
expansion is performed with a taylor series:
in the formula
Representing the carrier frequency offset of the received signal,
representing the rate of change of the first order frequency offset of the received signal,
representing the rate of change of the second order frequency offset of the received signal. Generally, the change rate of more than the second order is small, the present application mainly studies the carrier frequency offset and the first order change rate, and ignores the second order change. Assuming that the received signal is matched and filtered to achieve ideal bit timing synchronization and frame synchronization, the received signal can be expressed as:
where n =0, 1, 2, …, L.
L is the number of symbols of the frame data,
for the amplitude normalized BPSK baseband modulation symbols,
in order to be a doppler frequency offset,
in the form of a symbol period, the symbol period,
is the rate of change of the doppler frequency,
is the initial phase of the carrier wave,
representing complex white gaussian noise.
Based on the above theoretical analysis, the present application proposes a carrier synchronization method for high dynamic burst signals, and the following is described in detail with the aid of specific embodiments.
Fig. 1 is a flowchart illustrating a carrier synchronization method for a high dynamic burst signal according to an exemplary embodiment. The method 10 for carrier synchronization of high dynamic burst signals at least includes steps S102 to S110.
As shown in fig. 1, in S102, a high dynamic burst signal from a low earth orbit satellite mobile communication channel is converted into at least one short frame data.
In one embodiment, the high dynamic burst signal may be truncated into a plurality of short frames of data when a frame length of the high dynamic burst signal is greater than a threshold; more specifically, the high dynamic burst signal is truncated into a plurality of short frames of data based on a sliding window method, and more specifically, the length of the last window data frame may be appropriately adjusted according to the frame length.
In one embodiment, the high dynamic burst signal may be regarded as a short frame when the frame length of the high dynamic burst signal is less than or equal to the threshold L.
In one embodiment, it may be equivalent to baseband
Judging the length of a short frame by the signal, and directly carrying out subsequent step processing when the actual frame length is less than or equal to L if the length of the short frame is L; when the actual frame length is larger than L, the whole frame data is intercepted, the window width is L, and the data in each window is processed as a frame of short frame data (the length of the last window data frame can be properly adjusted according to the frame length, and the length of the last window data frame should be smaller than 2L).
In a specific embodiment, the short frame data length may be 128 to 384 symbols, i.e., L may have any value from 128 to 384. Preferably, the threshold L may be set to 256.
Wherein the content of the first and second substances,
the expression of (c) may be:
where n =0, 1, 2, …, L.
Wherein L is the number of symbols of the frame data,
for the amplitude normalized BPSK baseband modulation symbols,
in order to be a doppler frequency offset,
in the form of a symbol period, the symbol period,
is the rate of change of the doppler frequency,
is the initial phase of the carrier wave,
representing complex white gaussian noise.
At S104, at least one doppler first order rate of change is generated based on the at least one short frame data. The method comprises the following steps: respectively carrying out nonlinear de-modulation and fast Fourier transform on the head and the tail of the short frame data frame; generating a first-order temporal rate of change of Doppler based on the fast Fourier transform result; and generating a first-order Doppler change rate of the short frame data based on the three-division fast approximation algorithm and the first-order Doppler temporary change rate.
In S106, the influence of the corresponding doppler first order change rate is respectively eliminated from the at least one short frame data, and at least one integrated data is generated. Each frame of the short frame data may be separately subjected to a doppler first order rate of change cancellation operation.
In S108, a doppler frequency offset estimate is generated based on the at least one ensemble of data. The method comprises the following steps: performing a fast fourier transform on the at least one consolidated data; determining a frequency point and an adjacent frequency point corresponding to the maximum value of the spectrum energy based on the result of the fast Fourier transform; and generating the Doppler frequency offset estimation value based on the frequency point and the adjacent frequency points.
More specifically, the doppler frequency offset estimation value may be generated by using a quadratic interpolation method based on the frequency point and the adjacent frequency points.
Integrated data for eliminating first order rate of change of doppler
(only including Doppler frequency offset at this moment) do FFT to get the frequency point corresponding to the maximum value of the frequency spectrum energy and the frequency point corresponding to the adjacent spectral line, and similarly, the quadratic interpolation method is used to improve the estimation precision of the Doppler frequency offset, and the final accurate estimation of the Doppler frequency offset is obtained as follows:
wherein in the formula
For FFT operation resolution, the frequency point corresponding to the maximum value of the spectrum energy in the last calculation is (f)J,zJ) The two end points adjacent to the maximum value of the spectral energy in the last calculation are (f)J-1,zJ-1)、(fJ+1,zJ+1)。
In S110, carrier synchronization of the high dynamic burst signal is performed based on the doppler first order change rate and the doppler frequency offset estimation value.
In one embodiment, may be for a signal
And (3) Doppler frequency offset elimination:
according to the carrier synchronization method of the high dynamic burst signal, the high dynamic burst signal from the low orbit satellite mobile communication channel is converted into at least one short frame data; generating at least one doppler first order rate of change based on the at least one short frame data; respectively eliminating the influence of the corresponding Doppler first-order change rate in the at least one short frame data to generate at least one integrated data; generating a Doppler frequency offset estimate based on the at least one consolidated data; the carrier synchronization method based on the Doppler first-order change rate and the Doppler frequency offset estimation value for the high-dynamic burst signal has wide applicability for burst frame signals, reduces the data processing amount of the algorithm on the premise of ensuring the Doppler change rate and the Doppler frequency estimation precision, is easier for engineering realization, greatly reduces the calculated amount, and provides a new idea for the carrier synchronization algorithm in the field of software radio.
It should be noted that the high-order change rate estimation performed after the doppler change rate estimation is performed based on the present algorithm should be included in the protection scope of the present algorithm.
According to the carrier synchronization method of the high dynamic burst signal, the method has wide applicability for the burst frame signal, reduces the data processing amount of the algorithm on the premise of ensuring the Doppler change rate and the Doppler frequency estimation precision, and is easier to implement in engineering.
The concrete embodiment is as follows:
(1) the short frame signal can directly use an algorithm to carry out carrier synchronization;
(2) converting the long frame signal into a short frame signal by adopting a capture window function mode and processing the short frame signal;
(3) the frame signal does not require frame header and tail specific known pilot symbols.
According to the carrier synchronization method for the high-dynamic burst signals, three methods of Doppler frequency change rate estimation, trisection method fast approximation and quadratic interpolation are combined by using the head sequence and the tail sequence in the frame, so that the estimation precision is not reduced while the algorithm data processing amount is reduced.
According to the carrier synchronization method of the high dynamic burst signal, the data processing amount can be reduced: the required FFT conversion times = two-time FFT at the tail of the frame header and the three-section fast approximation method and a plurality of times of FFT + two-time interpolation FFT, and the calculated amount is greatly reduced.
The carrier synchronization method of the high dynamic burst signal can be completely realized based on software, does not need complex hardware for adaptation and is suitable, and a new thought is provided for a carrier synchronization algorithm in the field of software radio.
It should be clearly understood that this application describes how to make and use particular examples, but the principles of this application are not limited to any details of these examples. Rather, these principles can be applied to many other embodiments based on the teachings of the present disclosure.
Fig. 2 is a flowchart illustrating a carrier synchronization method for a high dynamic burst signal according to another exemplary embodiment. The process 20 shown in fig. 2 is a detailed description of the process S104 "generating at least one doppler first order rate of change based on the at least one short frame data" in the process shown in fig. 1.
As shown in fig. 2, in S202, the at least one short frame data is subjected to fast fourier transform. The method comprises the following steps: obtaining a plurality of symbols of a frame head and a frame tail of the intra-frame data of the at least one short frame data to perform nonlinear de-modulation operation; and respectively carrying out fast Fourier transform on the head and the tail of the short frame data after the demodulation operation.
More specifically, a frequency point corresponding to the maximum value of the spectrum energy obtained by performing fast fourier transform on frame header data can be obtained; acquiring a frequency point corresponding to the maximum value of the spectrum energy obtained by fast Fourier transform of frame tail data; and generating the Doppler first-order temporary change rate based on the frequency point corresponding to the maximum frame head spectrum energy value, the frequency point corresponding to the maximum frame tail spectrum energy value, the frame length of the short frame data, the number of symbols and a single symbol period.
Within short frame data, equivalent signal to baseband
Respectively intercepting N symbols (N far) at frame head and frame tailLess than L), the squaring operation is performed separately, i.e.:
wherein
Receiving a signal
Is a belt with noise
Of a Doppler frequency shift of
First order rate of change of
。
In S204, a doppler first order temporal rate of change is generated based on the fast fourier transform result. And performing FFT (fast Fourier transform) on the square data of the frame head and the frame tail of the frame head, solving the maximum value of the spectrum energy, wherein the corresponding frequency point is the Doppler frequency offset rough estimation which ignores the first-order change rate, and the occupied time of the difference value of the Doppler frequency offset of the frame tail and the Doppler frequency offset of the frame head divided by the number of corresponding symbols is the first-order change rate of the Doppler frequency which is roughly estimated.
(the maximum value of the FFT at the frame end corresponds to the frequency point/2-the maximum value of the FFT at the frame head corresponds to the frequency point/2)/((the frame length L-sign number N) × the symbol period) = the first-order temporal doppler change rate a.
In S206, the doppler first order change rate is generated based on the three-division fast approximation algorithm and the doppler first order temporal change rate. Aiming at the Doppler first-order temporary change rate a, a three-division fast approximation algorithm is carried out in the adjacent interval [ a-a/2, a + a/2] to improve the estimation precision.
In the prior art, the method is adopted to intercept N point signals one by one according to the step length delta 1Eliminating frequency modulation rate, FFT transforming, solving the peak-to-average ratio maximum value of amplitude-frequency response and variable, and estimating the frequency modulation rate of second-stage stepping length delta 2 within the frequency change rate range (kmin, kmax)
The second FFT transformation has high arithmetic operation complexity.
The three-division fast approximation algorithm in the application can effectively reduce the number of loop iteration and accelerate the convergence process, but the three-division fast approximation algorithm is slow in convergence speed in a small precision range, so that after a specific precision is reached, the convergence is accelerated by adopting a secondary interpolation mode.
Fig. 3 is a flowchart illustrating a carrier synchronization method for a high dynamic burst signal according to another exemplary embodiment. The flow 30 shown in fig. 3 is a detailed description of S206 "generating the doppler first-order change rate based on the three-division fast approximation algorithm and the doppler first-order temporal change rate" in the flow shown in fig. 2.
As shown in fig. 3, in S302, a transition region is determined based on the doppler first order temporal rate of change. The Doppler first order temporal change rate is a, and the transformation interval is determined as follows: [ a-a/2, a + a/2 ].
In S304, a search is performed based on the three-division fast approximation algorithm within the transformation interval.
Aiming at a signal model with first-order Doppler change rate, the function model has convex function property, so that a ternary approximation algorithm is adopted to search for the maximum value. The basic idea is as follows:
using two points
,
A function of
Is evenly divided into three segments as shown in FIG. 4, and compared
And
size:
if it is not
Then the right interval is changed to
The search interval is changed from (XL, XR) to (XL, X2), wherein XL represents the minimum value of the search interval and XR represents the maximum value of the search interval; in one embodiment, XL has an initial value of a-a/2 and XR has an initial value of a + a/2.
If it is not
If the left interval is changed to
I.e. the search space is changed from (XL, XR) to (X1, XR).
The searching range is narrowed according to the method for approximation until the left and right intervals are within a certain allowable range, and the interval searching is finished to obtain the maximum value of the function.
In a specific embodiment, the doppler rate range (kmin, kmax) may be trisected (kmin = a-a/2, kmax = a + a/2), with k1= kmin + (kmax-kmin)/3, and k2= kmax- (kmax-kmin)/3.
Completion signals using k1, k2, respectively
The first order rate of change process of (a):
for the above
，
Respectively performing FFT operation, and recording two groups of spectrum peaks A1 and A2 under FFT and corresponding frequencies f1,f2;
Comparing a1, a2 size, if a1 > a2, update kmax = k 2; if A1 ≦ A2, update kmin = k 1.
In S306, when the maximum value reaches a preset precision, the doppler first-order change rate is determined based on a quadratic interpolation mode.
More specifically, the determination
If the frequency points are not satisfied, the steps of comparing the sizes of A1 and A2 are repeated until the frequency points are not satisfied, and the frequency points (f) corresponding to the maximum value of the frequency spectrum energy in the last calculation are calculatedJ,zJ) And the last calculation of two end-point values (f) adjacent to the maximum value of the spectral energyJ-1,zJ-1)、(fJ+1,zJ+1) Using these 3 points, a quadratic curve z (z ═ Af) is constructed2+ Bf + C), the 3 points are substituted into a quadratic curve to obtain a coefficient A, B, C, and finally, an accurate estimation of the doppler first-order rate of change a is obtained as follows:
in the formula
One third of the error interval (e/3).
First order rate of change cancellation:
。
those skilled in the art will appreciate that all or part of the steps implementing the above embodiments are implemented as computer programs executed by a CPU. When executed by the CPU, performs the functions defined by the methods provided herein. The program may be stored in a computer readable storage medium, which may be a read-only memory, a magnetic or optical disk, or the like.
Furthermore, it should be noted that the above-mentioned figures are only schematic illustrations of the processes involved in the method according to exemplary embodiments of the present application, and are not intended to be limiting. It will be readily understood that the processes shown in the above figures are not intended to indicate or limit the chronological order of the processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, e.g., in multiple modules.
The following are embodiments of the apparatus of the present application that may be used to perform embodiments of the method of the present application. For details which are not disclosed in the embodiments of the apparatus of the present application, reference is made to the embodiments of the method of the present application.
Fig. 5 is a block diagram illustrating a carrier synchronization apparatus for high dynamic burst signals according to an exemplary embodiment. As shown in fig. 5, the carrier synchronization apparatus 50 for high dynamic burst signals includes: a short frame module 502, a change rate module 504, an integration module 506, an estimation module 508, and a synchronization module 510.
The short frame module 502 is used for converting the high dynamic burst signal from the low earth orbit satellite mobile communication channel into at least one short frame data;
the rate of change module 504 is configured to generate at least one doppler first order rate of change based on the at least one short frame data;
the integration module 506 is configured to eliminate the influence of the doppler first order change rate in the at least one short frame data, and generate at least one integrated data;
an estimate module 508 is configured to generate a doppler frequency offset estimate based on the at least one integration datum;
the synchronization module 510 is configured to perform carrier synchronization of the high dynamic burst signal based on the doppler first order change rate and the doppler frequency offset estimation value.
According to the carrier synchronization device of the high dynamic burst signal, the high dynamic burst signal from the low orbit satellite mobile communication channel is converted into at least one short frame data; generating at least one doppler first order rate of change based on the at least one short frame data; respectively eliminating the influence of the corresponding Doppler first-order change rate in the at least one short frame data to generate at least one integrated data; generating a Doppler frequency offset estimate based on the at least one consolidated data; the carrier synchronization method based on the Doppler first-order change rate and the Doppler frequency offset estimation value for the high-dynamic burst signal has wide applicability for burst frame signals, reduces the data processing amount of the algorithm on the premise of ensuring the Doppler change rate and the Doppler frequency estimation precision, is easier for engineering realization, greatly reduces the calculated amount, and provides a new idea for the carrier synchronization algorithm in the field of software radio.
FIG. 6 is a block diagram illustrating an electronic device in accordance with an example embodiment.
An electronic device 600 according to this embodiment of the present application is described below with reference to fig. 6. The electronic device 600 shown in fig. 6 is only an example, and should not bring any limitation to the functions and the scope of use of the embodiments of the present application.
As shown in fig. 6, the electronic device 600 is embodied in the form of a general purpose computing device. The components of the electronic device 600 may include, but are not limited to: at least one processing unit 610, at least one storage unit 620, a bus 630 that connects the various system components (including the storage unit 620 and the processing unit 610), a display unit 640, and the like.
Wherein the storage unit stores program code executable by the processing unit 610 to cause the processing unit 610 to perform steps according to various exemplary embodiments of the present application described in the present specification. For example, the processing unit 610 may perform the steps as shown in fig. 1, 2, 3.
The storage unit 620 may include readable media in the form of volatile memory units, such as a random access memory unit (RAM) 6201 and/or a cache memory unit 6202, and may further include a read-only memory unit (ROM) 6203.
The memory unit 620 may also include a program/utility 6204 having a set (at least one) of program modules 6205, such program modules 6205 including, but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which, or some combination thereof, may comprise an implementation of a network environment.
The electronic device 600 may also communicate with one or more external devices 600' (e.g., keyboard, pointing device, bluetooth device, etc.), such that a user can communicate with devices with which the electronic device 600 interacts, and/or any device (e.g., router, modem, etc.) with which the electronic device 600 can communicate with one or more other computing devices. Such communication may occur via an input/output (I/O) interface 650. Also, the electronic device 600 may communicate with one or more networks (e.g., a Local Area Network (LAN), a Wide Area Network (WAN), and/or a public network such as the Internet) via the network adapter 660. The network adapter 660 may communicate with other modules of the electronic device 600 via the bus 630. It should be appreciated that although not shown in the figures, other hardware and/or software modules may be used in conjunction with the electronic device 600, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, among others.
Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein may be implemented by software, or by software in combination with necessary hardware. Therefore, as shown in fig. 7, the technical solution according to the embodiment of the present application may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (which may be a CD-ROM, a usb disk, a removable hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which may be a personal computer, a server, or a network device, etc.) to execute the above method according to the embodiment of the present application.
The software product may employ any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
The computer readable storage medium may include a propagated data signal with readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A readable storage medium may also be any readable medium that is not a readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a readable storage medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
Program code for carrying out operations of the present application may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., through the internet using an internet service provider).
The computer readable medium carries one or more programs which, when executed by a device, cause the computer readable medium to perform the functions of: converting the high dynamic burst signal from the low earth orbit satellite mobile communication channel into at least one short frame data; generating at least one doppler first order rate of change based on the at least one short frame data; eliminating the influence of the Doppler first order change rate in the at least one short frame data to generate at least one integrated data; generating a Doppler frequency offset estimate based on the at least one consolidated data; and carrying out carrier synchronization of the high-dynamic burst signal based on the Doppler first-order change rate and the Doppler frequency offset estimation value.
Those skilled in the art will appreciate that the modules described above may be distributed in the apparatus according to the description of the embodiments, or may be modified accordingly in one or more apparatuses unique from the embodiments. The modules of the above embodiments may be combined into one module, or further split into multiple sub-modules.
Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein may be implemented by software, or by software in combination with necessary hardware. Therefore, the technical solution according to the embodiment of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a usb disk, a removable hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which can be a personal computer, a server, a mobile terminal, or a network device, etc.) to execute the method according to the embodiment of the present application.
Exemplary embodiments of the present application are specifically illustrated and described above. It is to be understood that the application is not limited to the details of construction, arrangement, or method of implementation described herein; on the contrary, the intention is to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (13)
1. A carrier synchronization method for a high dynamic burst signal, comprising:
converting the high dynamic burst signal from the low earth orbit satellite mobile communication channel into at least one short frame data;
generating at least one doppler first order rate of change based on the at least one short frame data;
respectively eliminating the influence of the corresponding Doppler first-order change rate in the at least one short frame data to generate at least one integrated data;
generating a Doppler frequency offset estimate based on the at least one consolidated data;
and carrying out carrier synchronization of the high-dynamic burst signal based on the Doppler first-order change rate and the Doppler frequency offset estimation value.
2. The method of claim 1, wherein converting high dynamic burst signals from a low earth orbit satellite mobile communications channel into at least one short frame of data comprises:
when the frame length of the high dynamic burst signal is larger than a threshold value, cutting off the high dynamic burst signal into a plurality of short frame data;
and when the frame length of the high dynamic burst signal is less than or equal to a threshold value, taking the high dynamic burst signal as short frame data.
3. The method of claim 2, wherein truncating the high dynamic burst into a plurality of short frames of data comprises:
and truncating the high dynamic burst signal into a plurality of short frame data based on a sliding window method.
4. The method of claim 1, wherein generating at least one doppler first order rate of change based on the at least one short frame of data comprises:
respectively carrying out de-modulation and fast Fourier transform on the head and the tail of the short frame data frame;
generating a first-order temporal rate of change of Doppler based on the fast Fourier transform result;
and generating the Doppler first-order change rate of the short frame data based on a three-division fast approximation algorithm and the Doppler first-order temporary change rate.
5. The method of claim 4, wherein the step of performing de-modulation and fast fourier transform on the end of the short frame data frame comprises:
acquiring a plurality of symbols of a frame head and a frame tail of the intra-frame data of the at least one short frame data and respectively carrying out nonlinear de-modulation operation;
and performing fast Fourier transform on data obtained after the frame head and the frame tail are subjected to nonlinear de-modulation.
6. The method of claim 5, wherein generating a first order temporal rate of change of doppler based on fast fourier transform results comprises:
acquiring a frequency point corresponding to the maximum value of the spectrum energy obtained by the frame header data through fast Fourier transform;
acquiring a frequency point corresponding to the maximum value of the spectrum energy obtained by fast Fourier transform of frame tail data;
and generating the Doppler first-order temporary change rate based on the frequency point corresponding to the maximum frame head spectrum energy value, the frequency point corresponding to the maximum frame tail spectrum energy value, the frame length of the short frame data, the number of symbols and a single symbol period.
7. The method of claim 5, wherein generating the Doppler first order rate of change based on the three-division fast approximation algorithm and the Doppler first order temporal rate of change comprises:
determining a transformation interval based on the Doppler first order temporal rate of change;
and searching and determining the Doppler first-order change rate based on the three-division fast approximation algorithm in the transformation interval.
8. The method of claim 7, wherein determining the first-order rate of change of doppler based on the three-division fast approximation algorithm search within the transition interval comprises:
and searching and determining the Doppler first-order change rate in the transformation interval based on the three-division fast approximation algorithm and a quadratic interpolation mode.
9. The method of claim 1, wherein generating doppler frequency offset estimates based on the at least one integrated datum comprises:
performing a fast fourier transform on the at least one consolidated data;
determining a frequency point and an adjacent frequency point corresponding to the maximum value of the spectrum energy based on the result of the fast Fourier transform;
and generating the Doppler frequency offset estimation value based on the frequency point and the adjacent frequency points.
10. The method of claim 9, wherein generating the doppler frequency offset estimate based on the frequency bins and adjacent frequency bins comprises:
and generating the Doppler frequency offset estimation value by utilizing a quadratic interpolation method based on the frequency point and the adjacent frequency points.
11. A carrier synchronization apparatus for a high dynamic burst signal, comprising:
the short frame module is used for converting the high dynamic burst signal from the low orbit satellite mobile communication channel into at least one short frame data;
a rate of change module to generate at least one first-order rate of change of doppler based on the at least one short frame data;
an integration module for eliminating the influence of the first-order Doppler change rate in the at least one short frame data to generate at least one integrated data;
an estimate module to generate a doppler frequency offset estimate based on the at least one integration data;
and the synchronization module is used for carrying out carrier synchronization on the high-dynamic burst signal based on the Doppler first-order change rate and the Doppler frequency offset estimation value.
12. An electronic device, comprising:
one or more processors;
storage means for storing one or more programs;
when executed by the one or more processors, cause the one or more processors to implement the method of any one of claims 1-10.
13. A computer-readable medium, on which a computer program is stored, which, when being executed by a processor, carries out the method according to any one of claims 1-10.
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