CN118174992B - Delay-Doppler joint estimation method and device based on low-rail short burst signal - Google Patents
Delay-Doppler joint estimation method and device based on low-rail short burst signal Download PDFInfo
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Abstract
The application relates to a delay-Doppler joint estimation method and device based on a low-rail short burst signal. The method comprises the following steps: and constructing a red-blue frequency estimator by using the Doppler estimation initial value of the baseband receiving signal and the single carrier signal which is approximately unsigned and modulated, constructing a early-delay symbol phase estimator by using the delay estimation initial value of the baseband receiving signal and the symbol signal which is approximately unsigned and modulated, estimating a carrier Doppler frequency residual error estimated value and a delay residual error estimated value of the baseband receiving signal according to the red-blue frequency estimator and the early-delay symbol phase estimator, and realizing delay Doppler joint estimation and carrier Doppler frequency residual error estimation according to a preset carrier Doppler frequency residual error threshold and a preset delay residual error threshold. By adopting the method, the estimation accuracy of time delay and Doppler can be improved.
Description
Technical Field
The application relates to the technical field of space-sky-land-sea integrated lead-through fusion, in particular to a delay-Doppler joint estimation method and device based on a low-rail short burst signal.
Background
The air, ground and sea integrated communication and conduction fusion information system has wide application prospect, can realize global coverage, high-speed communication interconnection, accurate navigation time service, supports applications such as smart city, intelligent transportation, unmanned agriculture, military combat and the like, can provide high-speed, low-delay, high-precision, high-reliability and high-safety communication transmission and navigation positioning time service for users in different fields, and has wide application prospect. The low-orbit constellation is an important component of an air-sky-sea integrated lead-through fusion information system. The low-orbit satellite system generally adopts a short burst Time Division Multiplexing (TDM) signal system, and transmits a plurality of signals in the same channel, so that more information can be transmitted in a shorter time, and the channel utilization efficiency is improved. However, compared with the ground network system, the low-orbit satellite information system has the characteristics of high-speed satellite motion, large uncertainty of signal transmission delay and the like, and in order to realize high-efficiency communication and high-precision positioning time service, accurate estimation of the signal transmission delay and Doppler shift is required.
The communication and navigation signals of the traditional continuous system usually adopt modes such as a pseudo code tracking loop, a carrier tracking loop and the like to continuously estimate the time delay and the Doppler frequency shift of the received signals. However, for the low-rail short burst signal, because the duration time of the single signal is short and the dynamic change is large, the traditional loop tracking method for the continuous signal is difficult to converge, the estimation accuracy of delay and Doppler is insufficient, and the user communication speed and the positioning time service accuracy are affected.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a delay-doppler joint estimation method and apparatus based on a low-rail short burst signal, which can improve the estimation accuracy of delay and doppler.
A delay-doppler joint estimation method based on a low-rail short burst signal, the method comprising:
Acquiring a baseband receiving signal; recovering the modulation information symbol on the baseband receiving signal according to the time delay estimation initial value of the baseband receiving signal, and stripping the modulation information symbol on the baseband receiving signal in a signal combination mode to obtain a single carrier signal which is approximately modulated without symbol; constructing a red-blue frequency estimator by using Doppler estimation initial value of a baseband receiving signal and an approximate unsigned single carrier signal;
Recovering carrier residues on the baseband received signals according to the initial carrier Doppler frequency estimation value of the baseband received signals, and stripping residual carriers on the baseband received signals in a signal combination mode to obtain symbol signals approximate to carrier modulation; constructing an early-late symbol phase estimator by utilizing a delay estimation initial value of a baseband receiving signal and a symbol signal which is approximately without carrier modulation;
And according to the carrier Doppler frequency residual estimation value and the delay residual estimation value of the baseband receiving signal estimated by the red-blue frequency estimator and the early-delay symbol phase estimator, if the carrier Doppler frequency residual estimation value and the delay residual estimation value are smaller than a preset carrier Doppler frequency residual threshold and a preset delay residual threshold, directly outputting the corresponding carrier Doppler frequency estimation value and the corresponding delay estimation value, and if the carrier Doppler frequency residual estimation value and the delay residual estimation value are not smaller than the preset carrier Doppler frequency residual threshold and the delay residual threshold, updating the modulation information symbol on the baseband receiving signal and the carrier residual on the baseband receiving signal to reconstruct the red-blue frequency estimator and the early-delay symbol phase estimator until the carrier Doppler frequency residual estimation value and the delay residual estimation value are smaller than the preset carrier Doppler frequency residual threshold and the delay residual threshold, and outputting the final carrier Doppler frequency estimation value and the final delay estimation value.
In one embodiment, recovering a modulation information symbol on a baseband received signal according to an initial value of delay estimation of the baseband received signal, and stripping the modulation information symbol on the baseband received signal by a signal combination mode to obtain a single carrier signal with approximate unsigned modulation, which comprises:
recovering modulation information symbols of the baseband receiving signals according to the initial time delay estimation values of the baseband receiving signals, and stripping the modulation information symbols on the baseband receiving signals in a signal combination mode to obtain single carrier signals which are approximately modulated without symbols as
；
Wherein,Representing the baseband received signal and,Representing the initial value of the delay estimate of the baseband received signal,Representing the modulated information symbols on the baseband received signal,Representing the signal time of the baseband received signal.
In one embodiment, the red-blue frequency estimator comprises a red-shift correlator and a blue-shift correlator; a method for constructing a red-blue frequency estimator using an initial doppler estimate of a baseband received signal and an approximately unsigned modulated single carrier signal, comprising:
Frequency conversion operation is carried out on the single carrier signal which is approximately unsigned and modulated by utilizing Doppler estimation initial value of the baseband receiving signal, and a red shift correlator is obtained
；
Wherein,The accumulation time is integrated for the correlator,For the red-blue frequency shift correlation interval,As an approximation of an unsigned modulated single carrier signal,For the initial value of the doppler estimation,Signal time representing the baseband received signal;
Frequency conversion operation is carried out on the single carrier signal which is approximately unsigned and modulated by utilizing Doppler estimation initial value of baseband receiving signal, and a blue phase shifter is obtained
。
In one embodiment, the red-blue frequency estimator is constructed from a red-shift correlator and a blue-shift correlator
；
Wherein,Is the carrier doppler frequency residual estimate.
In one embodiment, recovering carrier residues on the baseband received signal according to an initial value of carrier doppler frequency estimation of the baseband received signal, and stripping residual carriers on the baseband received signal by a signal combining manner to obtain a symbol signal with approximate no carrier modulation, including:
Recovering carrier residues on the baseband received signals according to the initial value of the carrier Doppler frequency estimation of the baseband received signals, and stripping residual carriers on the baseband received signals in a signal combination mode to obtain symbol signals which are approximate to no carrier modulation
；
Wherein,Representing the baseband received signal and,Representing the initial value of the carrier doppler frequency estimate of the baseband received signal,Representing the carrier residual on the baseband received signal.
In one embodiment, the early-late symbol phase estimator comprises an early-code phase correlator and a late-code phase correlator; an early-late symbol phase estimator constructed using an initial delay estimate of a baseband received signal and an approximately carrierless modulated symbol signal, comprising:
Performing a de-symbol operation on the symbol signal without the approximate carrier modulation by using the initial value of the time delay estimation of the baseband received signal to obtain an advanced code phase correlator as
；
Wherein,For the early-late code phase correlation interval,The accumulation time is integrated for the correlator,To approximate a symbol signal without carrier modulation,Representing the initial value of the delay estimate of the baseband received signal,Signal time representing the baseband received signal;
Performing a de-sign operation on the symbol signal without the approximate carrier modulation by using the initial value of the delay estimation of the baseband received signal to obtain a lag code phase correlator as
。
In one embodiment, the early-late symbol phase estimator is constructed from an early code phase correlator and a late code phase correlator
；
Wherein,Is the delay residual error estimated value.
In one embodiment, the updating method of the modulation information symbol on the baseband receiving signal and the carrier residual on the baseband receiving signal includes:
the modulation information symbol on the baseband received signal is updated in the following way Wherein, the method comprises the steps of, wherein,For the time delay residual estimate value,Estimating an initial value for the time delay of the baseband receiving signal;
the carrier residual on the baseband received signal is updated by Wherein, the method comprises the steps of, wherein,Representing the initial value of the carrier doppler frequency estimate of the baseband received signal,Is an estimated value of the carrier doppler frequency residual,Representing the signal time of the baseband received signal.
A delay-doppler joint estimation device based on a low-rail short burst signal, the device comprising:
The red-blue frequency estimator construction module is used for acquiring a baseband receiving signal; recovering the modulation information symbol on the baseband receiving signal according to the time delay estimation initial value of the baseband receiving signal, and stripping the modulation information symbol on the baseband receiving signal in a signal combination mode to obtain a single carrier signal which is approximately modulated without symbol; constructing a red-blue frequency estimator by using Doppler estimation initial value of a baseband receiving signal and an approximate unsigned single carrier signal;
The early-late symbol phase estimator construction module is used for recovering carrier residues on the baseband receiving signals according to the carrier Doppler frequency estimation initial value of the baseband receiving signals, and stripping residual carriers on the baseband receiving signals in a signal compounding mode to obtain symbol signals without approximate carrier modulation; constructing an early-late symbol phase estimator by utilizing a delay estimation initial value of a baseband receiving signal and a symbol signal which is approximately without carrier modulation;
And the delay-Doppler joint estimation module is used for estimating a carrier Doppler frequency residual estimation value and a delay residual estimation value of a baseband receiving signal according to the red-blue frequency estimator and the early-delay symbol phase estimator, directly outputting the corresponding carrier Doppler frequency estimation value and the delay estimation value if the carrier Doppler frequency residual estimation value and the delay residual estimation value are smaller than a preset carrier Doppler frequency residual threshold and a preset delay residual threshold, and updating a modulation information symbol on the baseband receiving signal and a carrier residual on the baseband receiving signal to reconstruct the red-blue frequency estimator and the early-delay symbol phase estimator until the carrier Doppler frequency residual estimation value and the delay residual estimation value are smaller than the preset carrier Doppler frequency residual threshold and the delay residual threshold, and outputting the final carrier Doppler frequency estimation value and the final delay estimation value.
According to the delay-Doppler joint estimation method and device based on the low-rail short burst signal, the red-blue frequency estimator is designed in a signal combination mode to strip modulation information symbols on the baseband receiving signal to accurately estimate carrier Doppler frequency residual errors of the baseband receiving signal, the early-late symbol phase estimator is designed in a signal combination mode to strip residual carriers on the baseband receiving signal to accurately estimate delay residual errors of the baseband receiving signal, then the carrier Doppler frequency residual error estimation value and the delay residual error estimation value of the baseband receiving signal carry out residual error judgment and then iterate to estimate delay Doppler, and operations such as stripping information symbols and carrier signals modulated on the baseband receiving signal, relevant integral accumulation, designing normalization estimation functions, developing delay-Doppler joint estimation, iterating feedback and the like can be carried out, so that rapid accurate estimation of delay and Doppler of the short burst signal can be realized, and the problem of overlong convergence time of a traditional loop tracking method is solved. And the estimation accuracy of the time delay and the frequency is not affected. Simulation results show that the method can approach the theoretical limit of delay and Doppler frequency measurement under the condition of not obviously increasing the computational complexity. The method can effectively improve the communication transmission rate and the navigation positioning time service precision, and eliminates the problem of overlong convergence time of the traditional loop tracking method.
Drawings
FIG. 1 is a flow chart of a delay-Doppler joint estimation method based on a low-rail short burst signal in an embodiment;
FIG. 2 is a schematic diagram of a delay-Doppler joint estimator based on a low-rail short burst signal in one embodiment;
FIG. 3 is a graph of delay estimation truth versus estimate in one embodiment;
FIG. 4 is a graph of the carrier-to-noise ratio of an input signal versus the accuracy of a delay measurement in another embodiment;
FIG. 5 is a graph of input signal duration versus delay measurement accuracy in one embodiment;
FIG. 6 is a graph of true and estimated values of carrier Doppler frequency estimation in one embodiment;
FIG. 7 is a graph of input signal carrier-to-noise ratio versus carrier Doppler frequency accuracy in one embodiment;
FIG. 8 is a graph of input signal duration versus carrier Doppler frequency measurement accuracy in one embodiment;
fig. 9 is a block diagram of a delay-doppler joint estimation device based on a low-rail short burst signal in one embodiment.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
In one embodiment, as shown in fig. 1, a delay-doppler joint estimation method based on a low-rail short burst signal is provided, which includes the following steps:
102, obtaining a baseband receiving signal; recovering the modulation information symbol on the baseband receiving signal according to the time delay estimation initial value of the baseband receiving signal, and stripping the modulation information symbol on the baseband receiving signal in a signal combination mode to obtain a single carrier signal which is approximately modulated without symbol; a red-blue frequency estimator is constructed using the Doppler estimated initial value of the baseband received signal and the approximately unsigned modulated single carrier signal.
Input the baseband received signal after down-conversion, filtering and extractionEstimating initial value according to time delay of received signalRecovering a received signal modulation information symbol waveformThe red and blue frequency estimator designed in a mode of stripping modulation information symbols on the baseband receiving signal in a signal compounding mode can accurately estimate carrier Doppler frequency residual errors of the baseband receiving signal.
104, Recovering carrier residues on the baseband received signals according to the initial value of the carrier Doppler frequency estimation of the baseband received signals, and stripping residual carriers on the baseband received signals in a signal combination mode to obtain symbol signals without carrier modulation approximately; an early-late symbol phase estimator is constructed using the initial delay estimate of the baseband received signal and the symbol signal that is approximately carrier-free modulated.
Estimating initial value according to carrier Doppler frequency of received signalRecovering carrier residual of received signalThe residual carrier wave on the baseband receiving signal is stripped by a signal compounding mode to obtain a symbol signal which is approximate to no carrier wave modulation, and the delay residual error of the baseband receiving signal can be accurately estimated by the early-late symbol phase estimator designed by the signal compounding mode to strip the residual carrier wave on the baseband receiving signal.
Step 106, estimating the carrier Doppler frequency residual estimation value and the delay residual estimation value of the baseband receiving signal according to the red-blue frequency estimator and the early-delay symbol phase estimator, if the carrier Doppler frequency residual estimation value and the delay residual estimation value are smaller than the preset carrier Doppler frequency residual threshold and the delay residual threshold, directly outputting the corresponding carrier Doppler frequency estimation value and the delay estimation value, if the carrier Doppler frequency residual estimation value and the delay residual estimation value are not smaller than the preset carrier Doppler frequency residual threshold and the delay residual threshold, updating the modulation information symbol on the baseband receiving signal and the carrier residual on the baseband receiving signal to reconstruct the red-blue frequency estimator and the early-delay symbol phase estimator until the carrier Doppler frequency residual estimation value and the delay residual estimation value are smaller than the preset carrier Doppler frequency residual threshold and the delay residual threshold, and outputting the final carrier Doppler frequency estimation value and the final delay estimation value.
Constructing a delay-doppler joint estimator from a red-blue frequency estimator and an early-late symbol phase estimator, the structure of the delay-doppler joint estimator being as shown in fig. 2, in which the signal is receivedAfter stripping the information symbols modulated on the signal, a signal is obtainedAfter stripping the carrier signal modulated on the signal, a signal is obtainedLocal carrier wave respectively generating red shift frequencyAnd blue shift frequencyAnd receiving signalsThe correlation value is obtained after operations such as multiplication, integral accumulation and the likeAndThe local symbols respectively generate advanced phasesAnd lag phaseAnd receiving signalsThe correlation value is obtained after operations such as multiplication, integral accumulation and the likeAndObtaining carrier Doppler frequency residual errors through frequency and time delay estimation respectivelyAnd delay residualThe carrier Doppler frequency estimation value and the time delay estimation value of the signal can be further updated at the momentAndAnd when the Doppler frequency and the delay estimation residual error judgment of the received signal carrier wave are not expected, carrying out iterative estimation processing on the same signal.
According to the estimated value of carrier Doppler frequency residual error and the estimated value of delay residual error of the baseband receiving signal estimated by the red-blue frequency estimator and the early-late symbol phase estimator, respectively judging the estimated value of carrier Doppler frequency residual error of the baseband receiving signalAnd a delay residual estimateWhether or not they are all smaller than a preset thresholdAnd. When the judgment condition is met, the corresponding carrier Doppler frequency estimated value is directly outputAnd delay estimate; Otherwise, the same baseband receiving signal is subjected to iterative estimation processing, and the initial time delay estimation value of the baseband receiving signal is updated asSupport generating the modulation information symbol waveform of the received signal, update the initial value of carrier Doppler frequency estimation of the baseband received signal toSupport for generating carrier residuals for received signalsThe red-blue frequency estimator and the early-late symbol phase estimator are reconstructed, and the delay-Doppler joint estimation and iterative feedback are carried out by designing a direct estimator of the pseudo code phase and the carrier Doppler frequency, so that the rapid and accurate estimation of the delay and the Doppler of the short burst signal can be realized.
In the delay-doppler joint estimation method based on the low-rail short burst signal, the red-blue frequency estimator is designed in a signal combination mode to strip modulation information symbols on the baseband receiving signal to accurately estimate carrier wave doppler frequency residual errors of the baseband receiving signal, the early-late symbol phase estimator is designed in a signal combination mode to strip residual carriers on the baseband receiving signal to accurately estimate delay residual errors of the baseband receiving signal, then the carrier wave doppler frequency residual error estimation value and the delay residual error estimation value of the baseband receiving signal carry out residual error judgment and then iterate to estimate delay-doppler, and operations such as stripping information symbols modulated on the baseband receiving signal and the carrier signal, relevant integral accumulation, designing a normalization estimation function, developing delay-doppler joint estimation and iterate feedback are carried out, so that quick accurate estimation of delay and doppler of the short burst signal can be realized, and the problem of overlong convergence time of the traditional loop tracking method is solved. And the estimation accuracy of the time delay and the frequency is not affected. Simulation results show that the method can approach the theoretical limit of delay and Doppler frequency measurement under the condition of not obviously increasing the computational complexity. The method can effectively improve the communication transmission rate and the navigation positioning time service precision, and eliminates the problem of overlong convergence time of the traditional loop tracking method.
In one embodiment, recovering a modulation information symbol on a baseband received signal according to an initial value of delay estimation of the baseband received signal, and stripping the modulation information symbol on the baseband received signal by a signal combination mode to obtain a single carrier signal with approximate unsigned modulation, which comprises:
recovering modulation information symbols of the baseband receiving signals according to the initial time delay estimation values of the baseband receiving signals, and stripping the modulation information symbols on the baseband receiving signals in a signal combination mode to obtain single carrier signals which are approximately modulated without symbols as
；
Wherein,Representing the baseband received signal and,Representing the initial value of the delay estimate of the baseband received signal,Representing the modulated information symbols on the baseband received signal,Representing the signal time of the baseband received signal.
In one embodiment, the red-blue frequency estimator comprises a red-shift correlator and a blue-shift correlator; a method for constructing a red-blue frequency estimator using an initial doppler estimate of a baseband received signal and an approximately unsigned modulated single carrier signal, comprising:
Frequency conversion operation is carried out on the single carrier signal which is approximately unsigned and modulated by utilizing Doppler estimation initial value of the baseband receiving signal, and a red shift correlator is obtained
；
Wherein,The accumulation time is integrated for the correlator,For the red-blue frequency shift correlation interval,As an approximation of an unsigned modulated single carrier signal,For the initial value of the doppler estimation,Signal time representing the baseband received signal;
Frequency conversion operation is carried out on the single carrier signal which is approximately unsigned and modulated by utilizing Doppler estimation initial value of baseband receiving signal, and a blue phase shifter is obtained
。
In one embodiment, the red-blue frequency estimator is constructed from a red-shift correlator and a blue-shift correlator
；
Wherein,Is the carrier doppler frequency residual estimate.
In one embodiment, recovering carrier residues on the baseband received signal according to an initial value of carrier doppler frequency estimation of the baseband received signal, and stripping residual carriers on the baseband received signal by a signal combining manner to obtain a symbol signal with approximate no carrier modulation, including:
Recovering carrier residues on the baseband received signals according to the initial value of the carrier Doppler frequency estimation of the baseband received signals, and stripping residual carriers on the baseband received signals in a signal combination mode to obtain symbol signals which are approximate to no carrier modulation
；
Wherein,Representing the baseband received signal and,Representing the initial value of the carrier doppler frequency estimate of the baseband received signal,Representing the carrier residual on the baseband received signal.
In one embodiment, the early-late symbol phase estimator comprises an early-code phase correlator and a late-code phase correlator; an early-late symbol phase estimator constructed using an initial delay estimate of a baseband received signal and an approximately carrierless modulated symbol signal, comprising:
Performing a de-symbol operation on the symbol signal without the approximate carrier modulation by using the initial value of the time delay estimation of the baseband received signal to obtain an advanced code phase correlator as
；
Wherein,For the early-late code phase correlation interval,The accumulation time is integrated for the correlator,To approximate a symbol signal without carrier modulation,Representing the initial value of the delay estimate of the baseband received signal,Signal time representing the baseband received signal;
Performing a de-sign operation on the symbol signal without the approximate carrier modulation by using the initial value of the delay estimation of the baseband received signal to obtain a lag code phase correlator as
。
In one embodiment, the early-late symbol phase estimator is constructed from an early code phase correlator and a late code phase correlator
；
Wherein,Is the delay residual error estimated value.
In one embodiment, the updating method of the modulation information symbol on the baseband receiving signal and the carrier residual on the baseband receiving signal includes:
the modulation information symbol on the baseband received signal is updated in the following way Wherein, the method comprises the steps of, wherein,For the time delay residual estimate value,Estimating an initial value for the time delay of the baseband receiving signal;
the carrier residual on the baseband received signal is updated by Wherein, the method comprises the steps of, wherein,Representing the initial value of the carrier doppler frequency estimate of the baseband received signal,Is an estimated value of the carrier doppler frequency residual,Representing the signal time of the baseband received signal.
In one embodiment, fig. 3 is a graph of the relationship between the true value and the estimated value of the delay-doppler joint estimation method based on the low-rail short burst signal, and in this embodiment, the simulation considers the pure signal of the noiseless and carrierless doppler modulation, taking the early-late code phase correlation interval to be 0.25 chip, and the approximate linear unbiased estimation curve of the estimator is about [ -0.25, 0.25] chip. When the signal delay true value is 0 chip, the estimated value is about 0.002 chip; when the signal delay true value is 0.25 chip, the estimated value is about 0.26 chip; when the signal delay value is-0.25 chip, the estimated value is about-0.26 chip. It can be seen that, when the delay value of the signal to be estimated is smaller, the deviation of the delay estimation is smaller, so that the estimation deviation can be effectively reduced through multiple iterative estimation.
In one embodiment, fig. 4 is a graph of the relationship between the carrier-to-noise ratio of the input signal and the delay measurement accuracy of the delay-doppler joint estimation method based on the low-rail short burst signal, in this embodiment, the simulation considers the ideal signal with white gaussian noise and no carrier doppler modulation, the integration and accumulation time of the correlator is 12 ms, the early-late code phase correlation interval is 0.125 chip, and the monte carlo simulation number is 1000.
For the early-late code phase estimator, the lower limit of the delay measurement accuracy is that under the condition of infinite bandwidth of a received signalWhereinIn order to identify the relevant interval of the device,For the signal-to-carrier-noise ratio,The accumulation time is integrated for the correlator.
Simulation results show that the simulation value of the delay estimation precision of the received signal is similar to the theoretical value, and when the carrier-to-noise ratio of the received signal is 50 dB-Hz, the delay measurement precision is about 67.6 m; when the carrier-to-noise ratio of the received signal is 55 dB-Hz, the time delay measurement precision is about 38.0 m; the accuracy of the delay measurement is approximately 21.4 m when the carrier-to-noise ratio of the received signal is 60 dB-Hz.
In one embodiment, fig. 5 is a graph of the relationship between the input signal duration and the delay measurement accuracy of a delay-doppler joint estimation method based on a low-rail short burst signal, and in this embodiment, simulation considers an ideal signal with gaussian white noise and no carrier doppler modulation, where the signal-to-noise ratio is 55 dB-Hz, the early-late code phase correlation interval is 0.125 chip, and the monte carlo simulation number is 1000. Simulation results show that the simulation value of the time delay estimation precision of the received signal is similar to the theoretical value, and when the duration of the received signal is 6 ms, the time delay measurement precision is about 54.2 m; when the received signal duration is 12 ms, the delay measurement accuracy is about 38.0 m; the accuracy of the delay measurement is approximately 17.0 m when the received signal duration is 60 ms.
In one embodiment, fig. 6 is a graph of the relationship between the true value and the estimated value of the carrier doppler frequency estimation based on the delay-doppler joint estimation method of the low-rail short burst signal, in this embodiment, the simulation considers the pure signal with no noise and no symbol modulation, the coherent integration time is 1 ms, the correlation interval of red-blue frequency shift is 500Hz, and the approximate linear unbiased estimation curve of the estimator is about [ -500, 500] Hz. When the signal frequency deviation true value is 0Hz, the estimated value is about 0Hz; when the signal frequency deviation true value is 500Hz, the estimated value is about 500Hz; when the signal frequency deviation is true at-500 Hz, the estimated value is about-500 Hz. It can be seen that there is little error in the frequency deviation estimation over the active interval for an ideal received signal.
In one embodiment, fig. 7 is a graph of the relationship between the carrier-to-noise ratio of the input signal and the carrier doppler frequency accuracy of the delay-doppler joint estimation method based on the low-rail short burst signal, in this embodiment, the simulation considers the ideal signal with white gaussian noise and unsigned modulation, the integration and accumulation time of the correlator is 6 ms, the correlation interval of red and blue frequency shift is 250/3 Hz, and the simulation number of monte carlo is 1000.
For the red-blue frequency shift estimator, the lower limit of the Kramer of the Doppler frequency measurement accuracy under the condition of the infinite bandwidth of the received signal isWhereinFor the signal-to-carrier-noise ratio,The accumulation time is integrated for the correlator.
Simulation results show that the simulation value of the carrier Doppler frequency estimation precision is similar to the theoretical value, and when the carrier-to-noise ratio of the received signal is 50 dB-Hz, the carrier Doppler frequency measurement precision is about 0.9 Hz; when the carrier-to-noise ratio of the received signal is 55 dB-Hz, the carrier Doppler frequency measurement accuracy is about 0.5 Hz; the carrier doppler frequency measurement accuracy is about 0.3 Hz when the received signal carrier-to-noise ratio is 60 dB-Hz.
In one embodiment, fig. 8 is a graph of the relationship between the input signal duration and the carrier doppler frequency measurement accuracy of a delay-doppler joint estimation method based on a low-rail short burst signal, and in this embodiment, the simulation considers an ideal signal with white gaussian noise and unsigned modulation, the signal-to-noise ratio is 55 dB-Hz, the correlation interval of red and blue frequency shift is 250/3 Hz, and the monte carlo simulation number is 1000. Simulation results show that the simulation value of the carrier Doppler frequency estimation precision is similar to the theoretical value, and when the duration of a received signal is 6 ms, the carrier Doppler frequency measurement precision is about 1.5 Hz; the carrier doppler frequency measurement accuracy is about 0.5 Hz when the received signal duration is 12 ms; the carrier doppler frequency measurement accuracy is about 0.05 Hz when the received signal duration is 60 ms.
It should be understood that, although the steps in the flowchart of fig. 1 are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in fig. 1 may include multiple sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, nor do the order in which the sub-steps or stages are performed necessarily performed in sequence, but may be performed alternately or alternately with at least a portion of other steps or sub-steps of other steps.
In one embodiment, as shown in fig. 9, there is provided a delay-doppler joint estimation device based on a low-rail short burst signal, including: a red-blue frequency estimator construction module 902, an early-late symbol phase estimator construction module 904, and a delay-doppler joint estimation module 906, wherein:
A red-blue frequency estimator construction module 902, configured to obtain a baseband received signal; recovering the modulation information symbol on the baseband receiving signal according to the time delay estimation initial value of the baseband receiving signal, and stripping the modulation information symbol on the baseband receiving signal in a signal combination mode to obtain a single carrier signal which is approximately modulated without symbol; constructing a red-blue frequency estimator by using Doppler estimation initial value of a baseband receiving signal and an approximate unsigned single carrier signal;
The early-late symbol phase estimator construction module 904 is configured to recover carrier residues on the baseband received signal according to an initial value of carrier doppler frequency estimation of the baseband received signal, and strip residual carriers on the baseband received signal in a signal combining manner to obtain a symbol signal with no approximate carrier modulation; constructing an early-late symbol phase estimator by utilizing a delay estimation initial value of a baseband receiving signal and a symbol signal which is approximately without carrier modulation;
The delay-doppler joint estimation module 906 is configured to estimate a carrier-doppler frequency residual estimation value and a delay-residual estimation value of a baseband received signal according to the red-blue frequency estimator and the early-delay symbol phase estimator, directly output a corresponding carrier-doppler frequency estimation value and a delay-doppler estimation value if the carrier-doppler frequency residual estimation value and the delay-residual estimation value are both smaller than a preset carrier-doppler frequency residual threshold and a delay-residual threshold, and update a modulation information symbol on the baseband received signal and a carrier residual on the baseband received signal to reconstruct the red-blue frequency estimator and the early-delay symbol phase estimator until the carrier-doppler frequency residual estimation value and the delay-residual estimation value are both smaller than the preset carrier-doppler frequency residual threshold and the delay-residual threshold, and output a final carrier-doppler frequency estimation value and a final delay-doppler estimation value.
For specific limitations regarding the delay-doppler joint estimation device based on the low-rail short burst signal, reference may be made to the above limitation regarding the delay-doppler joint estimation method based on the low-rail short burst signal, which is not described herein. The above-mentioned delay-doppler joint estimation device based on the low-rail short burst signal may be implemented in whole or in part by software, hardware, or a combination thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (9)
1. A delay-doppler joint estimation method based on a low-rail short burst signal, the method comprising:
Acquiring a baseband receiving signal; recovering modulation information symbols on the baseband received signal according to the initial time delay estimation value of the baseband received signal, and stripping the modulation information symbols on the baseband received signal in a signal combination mode to obtain a single carrier signal which is approximately modulated without symbols; constructing a red-blue frequency estimator by using the Doppler estimation initial value of the baseband receiving signal and the single carrier signal which is approximately unsigned and modulated;
Recovering carrier residues on the baseband received signals according to the initial carrier Doppler frequency estimation value of the baseband received signals, and stripping residual carriers on the baseband received signals in a signal combination mode to obtain symbol signals without carrier modulation approximately; constructing an early-late symbol phase estimator by utilizing the time delay estimation initial value of the baseband receiving signal and the symbol signal which is approximately carrier-free to modulate;
and according to the carrier Doppler frequency residual error estimation value and the delay residual error estimation value of the baseband receiving signal estimated by the red-blue frequency estimator and the early-delay symbol phase estimator, if the carrier Doppler frequency residual error estimation value and the delay residual error estimation value are smaller than a preset carrier Doppler frequency residual error threshold and a preset delay residual error threshold, directly outputting the corresponding carrier Doppler frequency estimation value and the corresponding delay estimation value, and if the carrier Doppler frequency residual error estimation value and the delay residual error estimation value are not smaller than the preset carrier Doppler frequency residual error threshold and the preset delay residual error threshold, updating the modulation information symbol on the baseband receiving signal and the carrier residual on the baseband receiving signal to reconstruct the red-blue frequency estimator and the early-delay symbol phase estimator until the carrier Doppler frequency residual error estimation value and the delay residual error estimation value are smaller than the preset carrier Doppler frequency residual error threshold and the preset delay residual error threshold, and outputting the final carrier Doppler frequency estimation value and the final delay estimation value.
2. The method of claim 1, wherein recovering the modulation information symbols on the baseband received signal based on the initial delay estimate of the baseband received signal, and stripping the modulation information symbols on the baseband received signal by signal combining to obtain the single carrier signal with approximately no symbol modulation, comprises:
Recovering modulation information symbols of the baseband receiving signals according to the initial time delay estimation values of the baseband receiving signals, and stripping the modulation information symbols on the baseband receiving signals in a signal combination mode to obtain single carrier signals which are approximately unsigned and modulated
；
Wherein,Representing the baseband received signal and,Representing the initial value of the delay estimate of the baseband received signal,Representing the modulated information symbols on the baseband received signal,Representing the signal time of the baseband received signal.
3. The method of claim 1, wherein the red-blue frequency estimator comprises a red-shift correlator and a blue-shift correlator; constructing a red-blue frequency estimator using the Doppler estimated initial value of the baseband received signal and the approximately unsigned modulated single carrier signal, comprising:
performing frequency conversion operation on the single carrier signal with the approximate unsigned modulation by using the Doppler estimation initial value of the baseband receiving signal to obtain a red shift correlator as
；
Wherein,The accumulation time is integrated for the correlator,For the red-blue frequency shift correlation interval,As an approximation of an unsigned modulated single carrier signal,For the initial value of the doppler estimation,Signal time representing the baseband received signal;
performing frequency conversion operation on the single carrier signal with the approximate unsigned modulation by using the Doppler estimation initial value of the baseband receiving signal to obtain a blue phase shifter
。
4. A method according to claim 3, characterized in that the method further comprises:
Constructing a red-blue frequency estimator according to the red-shift correlator and the blue-shift correlator as
；
Wherein,Is the carrier doppler frequency residual estimate.
5. The method according to any one of claims 1 to 4, wherein recovering carrier residues on the baseband received signal according to the initial value of the carrier doppler frequency estimation of the baseband received signal, and stripping the residual carriers on the baseband received signal by signal combining to obtain a symbol signal with approximately no carrier modulation, comprises:
Recovering carrier residues on the baseband received signals according to the initial value of the carrier Doppler frequency estimation of the baseband received signals, and stripping residual carriers on the baseband received signals in a signal combination mode to obtain symbol signals without approximate carrier modulation as
；
Wherein,Representing the baseband received signal and,Representing the initial value of the carrier doppler frequency estimate of the baseband received signal,Representing the carrier residual on the baseband received signal.
6. The method of claim 1 wherein the early-late symbol phase estimator comprises an early-code phase correlator and a late-code phase correlator; constructing an early-late symbol phase estimator using the initial delay estimate of the baseband received signal and the approximately carrier-free modulated symbol signal, comprising:
performing a de-symbol operation on the symbol signal with the approximate carrier-free modulation by using the initial value of the delay estimation of the baseband received signal to obtain an advanced code phase correlator as
；
Wherein,For the early-late code phase correlation interval,The accumulation time is integrated for the correlator,To approximate a symbol signal without carrier modulation,Representing the initial value of the delay estimate of the baseband received signal,Signal time representing the baseband received signal;
Performing a de-sign operation on the symbol signal without carrier modulation by using the initial value of the delay estimation of the baseband received signal to obtain a delayed code phase correlator as
。
7. The method of claim 6, wherein the method further comprises:
Constructing an early-late symbol phase estimator based on the early and late code phase correlators
；
Wherein,Is the delay residual error estimated value.
8. The method of claim 1, wherein the updating of the modulation information symbols on the baseband received signal and the carrier residual on the baseband received signal comprises:
the updating mode of the modulation information symbol on the baseband receiving signal is as follows Wherein, the method comprises the steps of, wherein,For the time delay residual estimate value,Estimating an initial value for the time delay of the baseband receiving signal;
The updating mode of the carrier wave residue on the baseband receiving signal is as follows Wherein, the method comprises the steps of, wherein,Representing the initial value of the carrier doppler frequency estimate of the baseband received signal,Is an estimated value of the carrier doppler frequency residual,Representing the signal time of the baseband received signal.
9. A delay-doppler joint estimation device based on a low-rail short burst signal, the device comprising:
The red-blue frequency estimator construction module is used for acquiring a baseband receiving signal; recovering modulation information symbols on the baseband received signal according to the initial time delay estimation value of the baseband received signal, and stripping the modulation information symbols on the baseband received signal in a signal combination mode to obtain a single carrier signal which is approximately modulated without symbols; constructing a red-blue frequency estimator by using the Doppler estimation initial value of the baseband receiving signal and the single carrier signal which is approximately unsigned and modulated;
The early-late symbol phase estimator construction module is used for recovering carrier residues on the baseband receiving signals according to the carrier Doppler frequency estimation initial value of the baseband receiving signals, and stripping residual carriers on the baseband receiving signals in a signal combination mode to obtain symbol signals without approximate carrier modulation; constructing an early-late symbol phase estimator by utilizing the time delay estimation initial value of the baseband receiving signal and the symbol signal which is approximately carrier-free to modulate;
And the delay-Doppler joint estimation module is used for estimating a carrier Doppler frequency residual estimation value and a delay residual estimation value of a baseband receiving signal according to the red-blue frequency estimator and the early-delay symbol phase estimator, directly outputting a corresponding carrier Doppler frequency estimation value and a delay estimation value if the carrier Doppler frequency residual estimation value and the delay residual estimation value are smaller than a preset carrier Doppler frequency residual threshold and a preset delay residual threshold, and updating a modulation information symbol on the baseband receiving signal and a carrier residual on the baseband receiving signal to reconstruct the red-blue frequency estimator and the early-delay symbol phase estimator until the carrier Doppler frequency residual estimation value and the delay residual estimation value are smaller than the preset carrier Doppler frequency residual threshold and the delay residual threshold, and outputting a final carrier Doppler frequency estimation value and a final delay estimation value.
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