CN111245476A - Low-orbit satellite deep spread spectrum low-complexity pseudo code capturing method - Google Patents
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
- H04B1/7077—Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
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- H04L27/266—Fine or fractional frequency offset determination and synchronisation
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Abstract
The invention discloses a pseudo code capturing method of low orbit satellite deep spread spectrum low complexity, which relates to the technical field of space, sky, ground and sea integrated communication, in particular to a pseudo code rapid capturing method combined with FFT frequency domain parallel capturing algorithm under the condition of deep spread spectrum, firstly averaging every M points of received signals and local pseudo random sequences respectively to obtain two new sequences, respectively carrying out FFT operation, carrying out FFT displacement according to the predicted frequency offset range to obtain N frequency offset searching channels, carrying out conjugate multiplication of signal FFT and new local pseudo code sequence FFT on each searching channel to obtain a correlation value, calculating the peak-to-average ratio, determining the frequency offset searching channel and the code offset position according to the position of the maximum peak value when the peak-to-average ratio is more than the capturing threshold, thereby completing capturing and effectively reducing the algorithm complexity of pseudo code capturing, meanwhile, the consumption of resources is greatly saved.
Description
Technical Field
The invention belongs to the technical field of aerospace, geodetic and sea integrated communication, and particularly relates to a low-orbit satellite depth spread spectrum low-complexity pseudo code capturing method.
Background
The core of the air-ground integrated information network is a satellite communication network. In the constellation network, the satellite network is used as a hub for the combination of the air, sea and air information platforms, so that the information platforms are combined into an organic whole from relative dispersion. The low earth orbit satellite system becomes an important supplement of the ground mobile communication system, and makes up the disadvantages of natural geographical obstacles and limited coverage area of the ground mobile communication system. Meanwhile, the low-orbit satellite has the unique advantages of low operation orbit, short transmission delay, flexible networking, wide coverage range and the like, and can meet the access requirements of users at any time and any place.
In low-earth-orbit satellite communication, the ground mobile terminal is convenient to disguise in special occasions, the anti-interception capability of the system is improved, information is intercepted and interfered during communication, and the emission power spectral density of the ground mobile terminal is often required to be extremely low in covert communication. The direct sequence spread spectrum system has the advantages of good confidentiality, low interception probability, strong anti-interference capability and the like and is generally applied to low-orbit satellite communication. In order to improve the security of a communication system, it is often necessary to deeply spread a transmission signal and spread the frequency spectrum of the transmission signal to a wide frequency band. However, since the angular velocity of the low earth orbit satellite is large, the radial velocity and acceleration relative to the ground are also high, and these factors make it difficult to communicate with the ground mobile terminal. Firstly, because the low-earth orbit satellite moves relative to the ground continuously, the signal received by the spread spectrum receiver has carrier Doppler frequency offset which is up to dozens of KHz or even hundreds of KHz relative to the local pseudo code; secondly, because the low earth orbit satellite often has a covert requirement when communicating with the ground mobile terminal, the principle of the direct sequence spread spectrum technology can know that the deep spread spectrum is needed to be carried out on the sending signal; in addition, due to the trend of miniaturization of low-earth orbit satellites, hardware resources and power resources available for on-satellite signal processing are increasingly limited.
However, the conventional pseudo code acquisition technology is adopted to acquire the received signal, if the sampling serial search method is adopted, the acquisition time is very long due to the very large code phase and frequency offset range to be searched, and the visible time of the low-orbit satellite moving around the earth is very short relative to the ground mobile terminal, so that the system requirement is difficult to achieve in the past; if the traditional parallel search method is adopted, although the acquisition time is shortened, the large-range frequency offset search consumes a large amount of hardware resources.
Disclosure of Invention
The invention aims to solve the technical problem of providing a low-orbit satellite deep spread spectrum low-complexity pseudo code capturing method, which is a pseudo code rapid capturing method combined with an FFT frequency domain parallel capturing algorithm under the condition of deep spread spectrum, can effectively reduce the algorithm complexity of pseudo code capturing, and simultaneously greatly saves the consumption of resources.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention adopts the following technical scheme for solving the technical problems: a low orbit satellite depth spread spectrum low complexity pseudo code capture method, said method is a pseudo code fast capture method combined with FFT (fast Fourier transform) frequency domain parallel capture algorithm under the condition of the depth spread spectrum, average every M point to receive signal and local pseudo random sequence separately at first, get two new sequences and do FFT operation separately, and shift FFT according to frequency deviation scope predicted, get N frequency deviation search channels, multiply the conjugation of signal FFT and new local pseudo code sequence FFT on each search channel and get the correlation value, and calculate its peak-to-average ratio, when the peak-to-average ratio is greater than and catches the threshold, can confirm frequency deviation search channel and code offset position according to the position of the maximum peak value, thus finish catching; the low-orbit satellite deep spread spectrum low-complexity pseudo code capturing method comprises the following steps:
s1, initializing and setting the frequency of a digital oscillator as the frequency f of receiving an analog intermediate frequency signal0The predicted frequency offset range is [ -f [)d，fd]；
S2, the received analog intermediate frequency signal s (t) has a sampling rate fsThe ADC module performs sampling to form a digital intermediate frequency signal x (n), wherein the sampling rate of the ADC module is greater than 2 times of the bandwidth of the analog intermediate frequency signal, and then the step S3 is performed;
s3, obtaining I-path digital zero-frequency signals by digital down-conversion processing of the digital intermediate-frequency signals x (n)
And Q-path digital zero-frequency signal
Then proceed to S4;
s4.I path digital zero frequencySignal
And Q-path digital zero-frequency signal
Respectively processed by a low pass filter to obtain signals x'I(n) and x'Q(n), then proceed to S5;
s5, for line I signal x'I(n) and Q-line signal x'Q(n) averaging every M points to obtain an average signal
And
the complex symbol of the signal is
Then proceed to S6;
s6, pair signal
Performing FFT operation, and estimating the frequency deviation range [ -f ]d，fd]Shifting the FFT to obtain N frequency offset search channel values [ Y ]1，Y2，…，Yk，…，YN]Then, proceed to S7;
s7, obtaining the local PN code after BPSK modulation and average processing of every M points
Performing conjugate operation of FFT to obtain [ C1，C2，…，Ck，…，CN]In which C is1，C2，…，Ck，…，CNIs equal to the N frequency offset search channel values [ Y ]1，Y2，…，Yk，…，YN]Multiplying and IFFT (inverse fast Fourier transform) to obtain a correlation value R, calculating the peak-to-average ratio S, and when the obtained peak-to-average ratio is larger than a capture threshold, obtaining the maximum peak according to the maximum peakThe position of the value determines a frequency offset search channel and a code offset position, thereby completing the acquisition.
As a preferred technical scheme of the invention, the digital intermediate frequency signal is processed into a digital zero-frequency signal through digital down-conversion to form an I-path digital zero-frequency signal
And Q-path digital zero-frequency signal
The expression of (c) is as follows:
wherein, Ts＝1/fs，fsThe sampling rate of the received analog if signal s (t), x (n) is the digital if signal, and n is the time instant of the digital if signal, i.e. the discrete value of time t in the analog if signal s (t) is n.
As a preferred technical scheme of the invention: the digital low-pass filter is used for filtering stray generated in the down-conversion process to obtain a line I signal x'I(n) and Q-line signal x'QThe computational expression of (n) is as follows:
wherein the content of the first and second substances,
in order to be the convolution operator, the convolution operation,
is a line-I digital zero-frequency signal, x'Q(n) is Q digital zero frequency signals, n is the time of the digital intermediate frequency signal, namely the discrete value of time t in the analog intermediate frequency signal s (t) is n;
wherein α is 0.25.
As a preferred technical scheme of the invention: for the signal
Performing FFT operation, and shifting FFT according to the predicted frequency offset range to obtain N frequency offset search channel values [ Y ]1，Y2，…，Yk，…，YN]The calculation expression is as follows:
wherein f isdFor the estimation of the frequency offset, exp (×) is an exponential function, N is the number of frequency offset search channel values, k is one of N, Ts＝1/fs，fsIs the sampling rate of the received analog intermediate frequency signal s (t).
As a preferred technical scheme of the invention: the local PN code is obtained after BPSK modulation and average processing of every M points
Performing conjugate operation of FFT to obtain [ C1，C2，…，Ck，…，CN]And C is1， C2，…，Ck，…，CNEqual in value, the calculation expression is as follows:
wherein, FFT*For the conjugate operation of the FFT, n is the time instant of the digital intermediate frequency signal, i.e. the discrete value of time t in the analog intermediate frequency signal s (t) is n.
As a preferred technical scheme of the invention: said [ C1，C2，…，Ck，…，CN]And N frequency offset search channel values [ Y1，Y2，…，Yk，…，YN]The multiplication is carried out by IFFT (inverse Fourier transform) to obtain a correlation value R, and the calculation expression is as follows:
as a preferred technical scheme of the invention: the method for capturing the pseudo code with low complexity by the low-orbit satellite deep spread spectrum is characterized by comprising the following steps: the BPSK modulation maps 0,1 of the PN code into a symbol in the following manner:
compared with the prior art, the low-complexity pseudo code capturing method for the low-orbit satellite deep spread spectrum has the following technical effects:
1) the invention relates to a low-complexity pseudo code capturing method for deep spread spectrum of a low-orbit satellite, which is characterized in that every M points of a received signal and a local pseudo random sequence are respectively averaged, so that the number of points of FFT (fast Fourier transform) and IFFT (inverse fast Fourier transform) operation is reduced to 1/M of the original number, and hardware resources and power resources for on-satellite signal processing are greatly saved;
2) according to the low-complexity pseudo code capturing method for the low-orbit satellite deep spread spectrum, due to the fact that M-point averaging is needed, the signal rate entering an FFT operation unit is reduced to 1/M, and therefore IFFT operation can be conducted by using the remaining M-1 time gaps, which is equivalent to M parallel operation channels in FFT capturing;
3) the low-complexity pseudo code capturing method for the low-orbit satellite deep spread spectrum can realize rapid capturing under carrier Doppler frequency offset of dozens of KHz or even hundreds of KHz and lower resources thereof;
4) compared with the traditional algorithm, the low-complexity pseudo code capturing method for the low-orbit satellite deep spread spectrum has the advantages of low algorithm complexity, obvious advantages of preventing information from being intercepted and interfered during communication, and suitability for capturing the low-complexity pseudo code of the low-orbit satellite deep spread spectrum;
the invention relates to the technical field of space, sky, land and sea integrated communication, in particular to a pseudo code capturing method with low complexity of low-orbit satellite deep spread spectrum, which is a pseudo code rapid capturing method combined with an FFT frequency domain parallel capturing algorithm under the condition of deep spread spectrum, firstly, averaging every M points of a received signal and a local pseudo random sequence respectively to obtain two new sequences, respectively carrying out FFT operation, carrying out FFT displacement according to a predicted frequency offset range to obtain N frequency offset searching channels, carrying out conjugate multiplication on the signal FFT and the new local pseudo code sequence FFT on each searching channel to obtain a correlation value, calculating the peak-to-average ratio of the correlation value, and determining the frequency offset searching channel and the code offset position according to the position of the maximum peak value when the peak-to-average ratio is larger than a capturing threshold so as to finish capturing and effectively reduce the algorithm complexity of pseudo code capturing, meanwhile, the consumption of resources is greatly saved.
Drawings
FIG. 1 is a diagram of an application model of a low-orbit satellite deep spread spectrum low-complexity pseudo code capturing method according to the present invention;
FIG. 2 is a flow chart of a low-complexity pseudo code capturing method of the invention with deep spread spectrum of a low-earth orbit satellite;
fig. 3 is a diagram of simulation results of the effect of the frequency offset on the correlation peak of the present invention.
Detailed Description
Referring to fig. 1-3, a method for capturing a low-complexity pseudo code by low-orbit satellite deep spread spectrum is a pseudo code rapid capture method combined with an FFT frequency domain parallel capture algorithm under a deep spread spectrum condition, and includes averaging each M points of a received signal and a local pseudo random sequence to obtain two new sequences, performing FFT operation on the two new sequences, shifting the FFT according to a predicted frequency offset range to obtain N frequency offset search channels, multiplying the signal FFT with a new local pseudo code sequence FFT in a conjugate manner on each search channel to obtain a correlation value, calculating a peak-to-average ratio of the correlation value, and determining a frequency offset search channel and a code offset position according to a maximum peak position when the peak-to-average ratio is greater than a capture threshold, thereby completing capture.
The acquisition threshold may be preset empirically.
As shown in fig. 2, the method for acquiring low-complexity pseudo code by low-earth-orbit satellite deep spreading includes the following steps:
s1, initializing and setting the frequency of a digital oscillator as the frequency f of receiving an analog intermediate frequency signal0The predicted frequency offset range is [ -f [)d，fd](ii) a The predicted frequency offset range can be obtained empirically or by calculation, and during communication, the signal frequencies of the ground mobile terminal and the satellite receiving terminal change, which is called doppler effect, and the frequency shift caused by doppler effect is called doppler shift, and the calculation formula is as follows:
the theta is an included angle between the moving direction of the ground mobile terminal and the incident wave direction; v is the moving speed of the ground mobile terminal, and c is the propagation speed of the electromagnetic wave c-3 x 105Km/s, f is the carrier frequency.
S2, the received analog intermediate frequency signal s (t) has a sampling rate fsThe ADC module performs sampling to form a digital intermediate frequency signal x (n), wherein the sampling rate of the ADC module is greater than 2 times of the bandwidth of the analog intermediate frequency signal, and then the step S3 is performed;
s3, obtaining I-path digital zero-frequency signals by digital down-conversion processing of the digital intermediate-frequency signals x (n)
And Q-path digital zero-frequency signal
Then proceed to S4;
s4.I path digital zero frequency signal
And Q-path digital zero-frequency signal
Respectively processed by a low pass filter to obtain signals x'I(n) and x'Q(n), then proceed to S5;
s5, for line I signal x'I(n) and Q-line signal x'Q(n) averaging every M points to obtain an average signal
And
the complex symbol of the signal is
Then proceed to S6;
s6, pair signal
Performing FFT operation, and estimating the frequency deviation range [ -f ]d，fd]Shifting the FFT to obtain N frequency offset search channel values [ Y ]1，Y2，…，Yk，…，YN]Then, proceed to S7;
s7, obtaining the local PN code after BPSK modulation and average processing of every M points
Performing conjugate operation of FFT to obtain [ C1，C2，…，Ck，…，CN]In which C is1，C2，…，Ck，…，CNIs equal to the N frequency offset search channel values [ Y ]1，Y2，…，Yk，…，YN]And multiplying and carrying out IFFT to obtain a correlation value R, calculating the peak-to-average ratio S of the correlation value R, and determining a frequency offset search channel and a code offset position according to the position of the maximum peak value when the obtained peak-to-average ratio is greater than a capture threshold, thereby completing capture.
The peak-to-average ratio is the maximum value and the average value on each frequency point, and the ratio is calculated, wherein the calculation formula of the peak-to-average ratio S is as follows:
where N is the time of the digital if signal, i.e. the dispersion value of time t in the analog if signal s (t) is N, N is the numerical value of the frequency offset search channel value, and R is the correlation value.
In this embodiment, the digital if signal is processed into a digital zero-frequency signal through digital down-conversion to form an I-channel digital zero-frequency signal
And Q-path digital zero-frequency signal
The calculation expression of (a) is as follows:
wherein, Ts＝1/fs，fsThe sampling rate of the received analog if signal s (t), x (n) is the digital if signal, and n is the time instant of the digital if signal, i.e. the discrete value of time t in the analog if signal s (t) is n.
In this embodiment, the digital low-pass filter filters out spurious signals generated during down-conversion to obtain the I-path signal x'I(n) and Q-line signal x'QThe computational expression of (n) is as follows:
wherein the content of the first and second substances,
in order to be the convolution operator, the convolution operation,
is a line-I digital zero-frequency signal, x'Q(n) is Q digital zero frequency signals, n is the time of the digital intermediate frequency signal, namely the discrete value of time t in the analog intermediate frequency signal s (t) is n;
wherein α is 0.25.
In this embodiment, the signals are processed
Performing FFT operation, and shifting FFT according to the predicted frequency offset range to obtain N frequency offset search channel values [ Y ]1，Y2，…，Yk，…，YN]The formula is as follows:
wherein f isdFor the estimation of the frequency offset, exp (×) is an exponential function, N is the number of frequency offset search channel values, k is one of N, Ts＝1/fs，fsIs the sampling rate of the received analog intermediate frequency signal s (t).
In this embodiment, the local PN code is obtained by BPSK modulation and averaging every M points
Performing conjugate operation of FFT to obtain [ C1，C2，…，Ck，…，CN]And C is1，C2，…，Ck，…，CNEqual in value, the calculation expression is as follows:
wherein, FFT*For the conjugate operation of the FFT, n is the time instant of the digital intermediate frequency signal, i.e. the discrete value of time t in the analog intermediate frequency signal s (t) is n.
In this example, [ C ] is as defined above1，C2，…，Ck，…，CN]And N frequency offset search channel values [ Y1， Y2，…，Yk，…，YN]The multiplication is performed by IFFT (inverse fourier transform) to obtain a correlation value R, and the calculation expression is as follows:
in this embodiment, the BPSK modulation maps 0,1 of the PN code into a symbol in the following manner:
the designed low-orbit satellite deep spread spectrum low-complexity pseudo code capturing method is applied to practice, the spreading ratio is 8192, the average point number is 8, the code phase difference is 0, the frequency offset is 20KHz, the EbN0 is 0, and the simulation result of the influence of the frequency offset on the correlation peak is shown in figure 3. It can be seen from the figure that the acquisition performance is better when frequency offset exists.
The invention relates to the technical field of space, sky, land and sea integrated communication, in particular to a pseudo code capturing method with low complexity of low-orbit satellite deep spread spectrum, which is a pseudo code rapid capturing method combined with an FFT frequency domain parallel capturing algorithm under the condition of deep spread spectrum, firstly, averaging every M points of a received signal and a local pseudo random sequence respectively to obtain two new sequences, respectively carrying out FFT operation, carrying out FFT displacement according to a predicted frequency offset range to obtain N frequency offset searching channels, carrying out conjugate multiplication on the signal FFT and the new local pseudo code sequence FFT on each searching channel to obtain a correlation value, calculating the peak-to-average ratio of the correlation value, and determining the frequency offset searching channel and the code offset position according to the position of the maximum peak value when the peak-to-average ratio is larger than a capturing threshold so as to finish capturing and effectively reduce the algorithm complexity of pseudo code capturing, meanwhile, the consumption of resources is greatly saved.
The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.
Finally, it should be noted that: various modifications and alterations of this invention may be made by those skilled in the art without departing from the spirit and scope of this invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Claims (7)
1. A low-orbit satellite deep spread spectrum low-complexity pseudo code capturing method is characterized by comprising the following steps:
s1, initializing and setting the frequency of a digital oscillator as the frequency f of receiving an analog intermediate frequency signal0Predicted frequency offset range is [ -fd，fd]；
S2, the received analog intermediate frequency signal s (t) has a sampling rate fsThe ADC module performs sampling to form a digital intermediate frequency signal x (n), wherein the sampling rate of the ADC module is greater than 2 times of the bandwidth of the analog intermediate frequency signal, and then the step S3 is performed;
s3, obtaining I-path digital zero-frequency signals by digital down-conversion processing of the digital intermediate-frequency signals x (n)
And Q-path digital zero-frequency signal
Then proceed to S4;
s4.I path digital zero frequency signal
And Q-path digital zero-frequency signal
Respectively processed by a low pass filter to obtain signals x'I(n) and x'Q(n), then proceed to S5;
s5, for line I signal x'I(n) and Q-line signal x'Q(n) averaging every M points to obtain an average signal
And
the complex symbol of the signal is
Then proceed to S6;
s6, pair signal
Performing FFT operation, and estimating the frequency deviation range [ -f ]d，fd]Shifting the FFT to obtain N frequency offset search channel values [ Y ]1，Y2，…，Yk，…，YN]Then, proceed to S7;
s7, obtaining the local PN code after BPSK modulation and average processing of every M points
Performing conjugate operation of FFT to obtain [ C1，C2，…，Ck，…，CN]In which C is1，C2，…，Ck，…，CNAre equal in value and then search for a channel value Y with N frequency offsets1，Y2，…，Yk，…，YN]And multiplying and carrying out IFFT to obtain a correlation value R, calculating the peak-to-average ratio S of the correlation value R, and determining a frequency offset search channel and a code offset position according to the position of the maximum peak value when the obtained peak-to-average ratio is larger than a capture threshold, thereby completing capture.
2. The method as claimed in claim 1, wherein the digital if signal is processed by digital down-conversion to be a digital zero-frequency signal to form an I-channel digital zero-frequency signal
And Q-way digitalZero frequency signal
The calculation expression of (a) is as follows:
wherein, Ts＝1/fs，fsThe sampling rate of the received analog if signal s (t), x (n) is the digital if signal, and n is the time instant of the digital if signal, i.e. the discrete value of time t in the analog if signal s (t) is n.
3. The method of claim 1, wherein the digital low pass filter filters out spurious signals generated during down-conversion to obtain line-I signal x'I(n) and Q-line signal x'QThe computational expression of (n) is as follows:
wherein the content of the first and second substances,
in order to be the convolution operator, the convolution operation,
is a line-I digital zero-frequency signal, x'Q(n) is Q digital zero frequency signals, n is the time of the digital intermediate frequency signal, namely the discrete value of time t in the analog intermediate frequency signal s (t) is n;
wherein α is 0.25.
4. The low earth orbit satellite depth of claim 1Method for low complexity pseudocode acquisition in spread spectrum, characterized in that said signal is acquired
Performing FFT operation, and shifting FFT according to the predicted frequency offset range to obtain N frequency offset search channel values [ Y ]1，Y2，…，Yk，…，YN]The calculation expression is as follows:
wherein f isdFor the estimation of the frequency offset, exp (×) is an exponential function, N is the number of frequency offset search channel values, k is one of N, Ts＝1/fs，fsIs the sampling rate of the received analog intermediate frequency signal s (t).
5. The method as claimed in claim 1, wherein the local PN code is obtained by BPSK modulation and averaging every M points
Performing conjugate operation of FFT to obtain [ C1，C2，…，Ck，…，CN]And C is1，C2，…，Ck，…，CNEqual in value, the calculation expression is as follows:
wherein, FFT*For the conjugate operation of the FFT, n is the time instant of the digital intermediate frequency signal, i.e. the discrete value of time t in the analog intermediate frequency signal s (t) is n.
6. The method as claimed in claim 1, wherein the method comprises deep-spread low-complexity pseudo code acquisitionIn the above-mentioned [ C ]1，C2，…，Ck，…，CN]And N frequency offset search channel values [ Y1，Y2，…，Yk，…，YN]The multiplication is carried out by IFFT (inverse Fourier transform) to obtain a correlation value R, and the calculation expression is as follows:
7. the method as claimed in claim 1, wherein the BPSK modulation maps 0,1 of the PN code into symbols by the following mapping method:
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| CN111835381A (en) * | 2020-06-16 | 2020-10-27 | 西安空间无线电技术研究所 | Low signal-to-noise ratio spread spectrum signal capturing method with variable symbol rate |
| CN111917460A (en) * | 2020-08-14 | 2020-11-10 | 东方红卫星移动通信有限公司 | Low-earth-orbit satellite high-speed signal capturing method based on FPGA |
| CN112118196A (en) * | 2020-09-07 | 2020-12-22 | 北京航宇星通科技有限公司 | Signal acquisition method and system |
| CN113872909A (en) * | 2021-09-28 | 2021-12-31 | 东方红卫星移动通信有限公司 | Low-earth-orbit satellite Internet of things short-time burst carrier capturing method and system |
| CN114221674A (en) * | 2021-12-06 | 2022-03-22 | 西北工业大学 | Spread spectrum signal rate self-adaptive capturing method |
| CN117060985A (en) * | 2023-10-10 | 2023-11-14 | 南京控维通信科技有限公司 | Shipborne dual-antenna PCMA system signal recapturing method and device |
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| CN112118196B (en) * | 2020-09-07 | 2023-03-10 | 北京航宇星通科技有限公司 | Signal acquisition method and system |
| CN113872909A (en) * | 2021-09-28 | 2021-12-31 | 东方红卫星移动通信有限公司 | Low-earth-orbit satellite Internet of things short-time burst carrier capturing method and system |
| CN113872909B (en) * | 2021-09-28 | 2023-09-01 | 东方红卫星移动通信有限公司 | Short-time burst carrier capturing method and system for low-orbit satellite Internet of things |
| CN114221674A (en) * | 2021-12-06 | 2022-03-22 | 西北工业大学 | Spread spectrum signal rate self-adaptive capturing method |
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