CN105721041B - Satellite communication based on signal cross ambiguity function is same to be multiplexed small signal detecting method frequently - Google Patents
Satellite communication based on signal cross ambiguity function is same to be multiplexed small signal detecting method frequently Download PDFInfo
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- CN105721041B CN105721041B CN201610051299.2A CN201610051299A CN105721041B CN 105721041 B CN105721041 B CN 105721041B CN 201610051299 A CN201610051299 A CN 201610051299A CN 105721041 B CN105721041 B CN 105721041B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/18578—Satellite systems for providing broadband data service to individual earth stations
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
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Abstract
The present invention discloses a kind of satellite communication based on signal cross ambiguity function with being multiplexed small signal detecting method frequently, include the following steps: that (10) forward signal obtains: from received modulated signal data, obtaining this wave beam forward signal and with frequency multiplexing wave beam forward signal；(20) cross ambiguity function calculates: using the related cumulative method of segmentation, calculating this wave beam forward signal and is multiplexed the second order cross ambiguity function of wave beam forward signal with frequency；(30) peak value searching: search second order cross ambiguity function obtains peak value；(40) small signal detection: by peak value compared with detection threshold, if peak value is greater than detection threshold, judgement is detected with being multiplexed small signal frequently, is otherwise judged to being not detected with being multiplexed small signal frequently.Using small signal detecting method of the invention, known signal can make full use of, it is easy to accomplish, in low signal-to-noise ratio, accuracy rate is high.
Description
Technical field
The invention belongs to satellite communications and digital signal processing technique field, especially a kind of to be based on signal cross ambiguity function
Satellite communication with being multiplexed small signal detecting method frequently.
Background technique
Signal detection technique uses electronics, information theory and physics method, analyzes noise Producing reason and rule, grinds
The statistical property and its difference for studying carefully measured signal and noise detect to be covered by ambient noise using a series of signal processing method
The signal of lid.
Detection to signal of communication is the precondition for carrying out parameter identification, DF and location to signal and detecing receipts demodulation etc.,
It only detects signal, is possible to the signal processing for carrying out next step.It therefore, is communication and communication to the detection of signal of communication
One of hot issue in confrontation research.Since satellite communication system is usually a power constrained system, and signal is propagated
Apart from remote, cause the received signal to noise ratio of satellite-signal lower, be a kind of typical weak signal scene.
In the document for the related signal detection delivered both at home and abroad at present, signal detecting method can substantially be divided into: with line
Normal signal detection method based on property method, and the novel signal detection method based on nonlinear method.Based on linear
Signal detecting method specifically includes that tim e- domain detection method, frequency domain detection method and Time-frequency Analysis etc., is based on nonlinear signal detection
Method specifically includes that stochastic resonance method, chaology detection method and Artificial Neural Network etc..Satellite communication is multiplexed with frequency
The detection needs of small signal have preferable detection performance compared with low signal-to-noise ratio, can use this wave beam forward signal
Feature auxiliary carries out signal detection, specifically for satellite communication be frequently multiplexed the detection method of small signal almost without.
For this specific communication scene of satellite communication, there is also some shortcomings for these methods: 1, algorithm is complicated, realizes tired
It is difficult, it is difficult to accomplish real-time signal detection；2, affected by noise larger, detection performance is poor in the environment of low signal-to-noise ratio, no
It is able to satisfy the lower weak signal scene of snr of received signal in satellite communication；3, although nonlinear analysis method is current signal inspection
One of the hot spot of research is surveyed, but there are limitation, using also immature, at present also in theory stage, such as chaology detection
Method, still in simulation stage, application range has limitation, and adiabatic approximation theory and the linear response theory requirement such as accidental resonance are defeated
Enter the frequency f of signal < < 1 to meet assumed condition.But signal frequency in practical applications often has very big difference with this requirement
It not, is even more far beyond the frequency range for meeting Stochastic Resonance Theory requirement in satellite communication system.
In short, problem of the existing technology is: to satellite communication with the detection for being multiplexed small signal frequently, cannot make full use of
The feature of known signal, noise resisting ability is poor, and in low signal-to-noise ratio, detection performance is poor, and calculates complicated, realization difficulty.
Summary of the invention
The purpose of the present invention is to provide a kind of satellite communications based on signal cross ambiguity function to examine with small signal is multiplexed frequently
Survey method, can make full use of known signal, it is easy to accomplish, in low signal-to-noise ratio, accuracy rate is high.
The technical solution for realizing the aim of the invention is as follows:
A kind of satellite communication based on signal cross ambiguity function is same to be multiplexed small signal detecting method frequently, which is characterized in that packet
Include following steps:
(10) forward signal obtains: from received modulated signal data, obtaining this wave beam forward signal and is multiplexed with frequency
Wave beam forward signal；
(20) cross ambiguity function calculates: utilizing the related cumulative method of segmentation, calculates this wave beam forward signal and with frequently multiple
With the second order cross ambiguity function of wave beam forward signal；
(30) peak value searching: search second order cross ambiguity function obtains peak value；
(40) small signal detection: by peak value compared with detection threshold, if peak value is greater than detection threshold, judgement detects same
Frequency is multiplexed small signal, is otherwise judged to being not detected with being multiplexed small signal frequently.
Compared with prior art, the present invention its remarkable advantage:
1, adaptable: this method can adapt to various sophisticated signals, noise circumstance；
2, noise resisting ability is strong: this method noise resisting ability is strong, and in low signal-to-noise ratio, accuracy rate is high, can be preferably
Meet the lower weak signal scene of snr of received signal in satellite communication；
3, computation complexity is low: this method proposes a kind of method for being segmented related accumulation calculating second order cross ambiguity function, point
Ambiguity function is not calculated on day part, and proposes to take some reasonable approximations in terms of being further reduced in subsection fuzzy function
Subsection fuzzy functional dependence is finally added up and obtains a total cross ambiguity function, greatly reduces computation complexity by calculation amount；
4, be suitble to satellite communication channel feature: satellite communication channel is awgn channel, and signal shaping generally uses more than liter
The characteristics of string forming, suitable satellite communication channel.
The present invention is done with reference to the accompanying drawings and detailed description and is further illustrated.
Detailed description of the invention
Fig. 1 is application scenarios schematic diagram of the invention.
Fig. 2 is that the present invention is based on the satellite communications of signal cross ambiguity function with the process for being multiplexed small signal detecting method frequently
Figure.
Fig. 3 is the flow chart that cross ambiguity function calculates step in Fig. 2.
Fig. 4 is the flow chart of peak value searching step in Fig. 2.
Fig. 5 is the bpsk signal detection accuracy based on second order cross ambiguity function.
Fig. 6 is the bpsk signal detection false alarm rate based on second order cross ambiguity function.
Fig. 7 is the QPSK signal detection accuracy based on second order cross ambiguity function.
Fig. 8 is the QPSK signal detection false alarm rate based on second order cross ambiguity function.
Specific embodiment
It is related to as shown in Figure 1, being multiplexed small signal detecting method frequently together the present invention is based on the satellite communication of signal cross ambiguity function
And a multi-beam satellite and an earth station, the multiplexing of seven wave beam of earth coverage area, wave beam A, B are with frequency multiplexing wave beam, if wave
Beam A is this wave beam, then the signal of A wave beam forwarding, and adjacent same frequency multiplexing wave beam B may also be forwarded, and the present invention is used for known A
When the feature of wave beam forward signal, the lesser signal of signal strength of detection B wave beam forwarding.
As shown in Fig. 2, a kind of satellite communication based on signal cross ambiguity function of the present invention is same to be multiplexed small signal detection side frequently
Method, which comprises the steps of:
(10) forward signal obtains: from received modulated signal data, obtaining this wave beam forward signal and is multiplexed with frequency
Wave beam forward signal；
(20) cross ambiguity function calculates: utilizing the related cumulative method of segmentation, calculates this wave beam forward signal and with frequently multiple
With the second order cross ambiguity function of wave beam forward signal；
As shown in figure 3, (20) the cross ambiguity function calculating step includes:
(21) signal subsection: set earth station transmitting signal as s (t), r1(t) and r2It (t) is that grounded receiving station receives respectively
The forward signal that wave beam is multiplexed from this wave beam and with frequency, by when a length of T sampling point be equally divided into K sections, then every section when it is a length of
T1=T/K, the signal of kth section are as follows:
r1k(t)=r1(t+kT1),t∈[0,T1),
r2k(t)=r2(t+kT1),t∈[0,T1)；
(22) cross ambiguity function is sought in segmentation: calculating cross ambiguity function, the cross ambiguity function of kth section on day part respectively
Are as follows:
Wherein, D is signal arrival time difference, and Δ f is that signal arrival rate is poor, φk=-2 π Δ fkT1For to each segmentation CAF
Carry out the phase correction terms of phase compensation；
Cross ambiguity function step is sought in described (22) segmentation specifically:
The cross ambiguity function of kth section is expressed as discrete form, is shown below,
Wherein, r1k(nTs) and r2k(nTs) be sampling after signal, N be kth segment data sampling point number, TsFor sampling week
Phase, time delay D=mTs, Fs=1/TsFor sample frequency, Fs/ Q is frequency displacement resolution cell, frequency displacement Δ f=p (Fs/ Q),
Such as lower aprons are carried out to above formula,
Wherein,
I.e. by N point instantaneous correlation functionIt is divided into N2Section, to N in every section1Point calculates mean value, then only
N need to be calculated2The cross ambiguity function of point.
(23) related cumulative: subsection fuzzy functional dependence is added up, total cross ambiguity function is obtained, is shown below,
(30) peak value searching: search second order cross ambiguity function obtains peak value；
As shown in figure 4, (30) the peak value searching step includes:
(31) it searches for maximum value: searching for the maximum value of cross ambiguity function in detection bandwidth；
(32) spy of spectral peak setting search thresholding: is occurred at signal arrival time difference, difference on the frequency according to cross ambiguity function
Point, setting search thresholding；
(33) determine peak value: calculating the ratio of maximum value and mean value, if the ratio great-than search thresholding, judgement is to search
Rope is to peak value, and otherwise judgement is not search peak value.
(40) small signal detection: by peak value compared with detection threshold, if peak value is greater than detection threshold, judgement detects same
Frequency is multiplexed small signal, is otherwise judged to being not detected with being multiplexed small signal frequently.
Small signal detection (40) step specifically:
Determine whether to detect according to the following formula and be multiplexed small signal frequently together,
The present invention is directed to this application scenarios of satellite communication, fully considers satellite channel feature, proposes a kind of based on signal
The satellite communication of cross ambiguity function makes full use of known signal characteristics with small signal detecting method is multiplexed frequently, adaptable strong,
The advantages such as noise resisting ability is strong, and computation complexity is low.
It is 5dB, 10dB, 15dB that Fig. 5 and Fig. 6, which is set forth when the forward signal of this wave beam is respectively Signal to Noise Ratio (SNR) 1,
When bpsk signal, signal detection accuracy and false alarm rate simulation result based on second order cross ambiguity function.
It is 5dB, 10dB, 15dB that Fig. 7 and Fig. 8, which is set forth when the forward signal of this wave beam is respectively Signal to Noise Ratio (SNR) 1,
When QPSK signal, signal detection accuracy and false alarm rate simulation result based on second order cross ambiguity function.
As it can be seen that when modulation system is BPSK, when being greater than -15dB with frequency multiplexing wave beam forward signal Signal to Noise Ratio (SNR) 2, this wave
Signal detection accuracy when beam forward signal signal-to-noise ratio is 5dB, 10dB, 15dB is both greater than 95%.This wave beam forward signal letter
It makes an uproar than higher, signal detection accuracy is also higher.Detection accuracy when modulation system is QPSK is slightly below bpsk signal.Two kinds
The signal detection false alarm rate of modulation system is below 2%.
The present invention provides a kind of satellite communications based on signal cross ambiguity function with small signal detecting method is multiplexed frequently, answers
When pointing out, for those skilled in the art, without departing from the principle of the present invention, can also make
Several improvements and modifications, these modifications and embellishments should also be considered as the scope of protection of the present invention.In addition, be not known in the present embodiment
The available prior art of each component part is realized.
Claims (2)
1. a kind of satellite communication based on signal cross ambiguity function is same to be multiplexed small signal detecting method frequently, which is characterized in that including
Following steps:
(10) forward signal obtains: from received modulated signal data, obtaining this wave beam forward signal and with frequency multiplexing wave beam
Forward signal；
(20) cross ambiguity function calculates: using the related cumulative method of segmentation, calculating this wave beam forward signal and with frequency multiplexing wave
The second order cross ambiguity function of beam forward signal；
(30) peak value searching: search second order cross ambiguity function obtains peak value；
(40) small signal detection: by peak value compared with detection threshold, if peak value is greater than detection threshold, judgement detects multiple with frequency
With small signal, otherwise it is judged to being not detected with being multiplexed small signal frequently；
(20) cross ambiguity function calculates step
(21) signal subsection: set earth station transmitting signal as s (t), r1(t) and r2It (t) is what grounded receiving station received respectively
The forward signal of wave beam is multiplexed from this wave beam and with frequency, by when a length of T sampling point be equally divided into K sections, then every section when a length of T1=
T/K, the signal of kth section are as follows:
r1k(t)=r1(t+kT1),t∈[0,T1),
r2k(t)=r2(t+kT1),t∈[0,T1)；
(22) cross ambiguity function is sought in segmentation: calculating cross ambiguity function, the cross ambiguity function of kth section on day part respectively are as follows:
Wherein, D is signal arrival time difference, and Δ f is that signal arrival rate is poor, φk=-2 π Δ fkT1To be carried out to each segmentation CAF
The phase correction terms of phase compensation；
(23) related cumulative: subsection fuzzy functional dependence is added up, total cross ambiguity function is obtained, is shown below,
(30) the peak value searching step includes:
(31) it searches for maximum value: searching for the maximum value of cross ambiguity function in detection bandwidth；
(32): there is the characteristics of spectral peak at signal arrival time difference, difference on the frequency according to cross ambiguity function in setting search thresholding, if
Surely thresholding is searched for；
(33) determine peak value: calculating the ratio of maximum value and mean value, if the ratio great-than search thresholding, judgement is to search
Peak value, otherwise judgement is not search peak value；
Small signal detection (40) step specifically:
Determine whether to detect according to the following formula and be multiplexed small signal frequently together,
2. small signal detecting method according to claim 1, which is characterized in that described (22) segmentation asks cross ambiguity function to walk
Suddenly specifically:
The cross ambiguity function of kth section is expressed as discrete form, is shown below,
Wherein, r1k(nTs) and r2k(nTs) be sampling after signal, N be kth segment data sampling point number, TsFor the sampling period, when
Prolong D=mTs, Fs=1/TsFor sample frequency, Fs/ Q is frequency displacement resolution cell, frequency displacement Δ f=p (Fs/ Q), above formula is carried out such as
Lower aprons,
Wherein,
I.e. by N point instantaneous correlation functionIt is divided into N2Section, to N in every section1Point calculates mean value, then only needs to calculate
N2The cross ambiguity function of point.
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| CN103905129A (en) * | 2014-01-22 | 2014-07-02 | 中国人民解放军理工大学 | Signal detection and signal information interpretation method based on spectral pattern analysis |
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| US20040077379A1 (en) * | 2002-06-27 | 2004-04-22 | Martin Smith | Wireless transmitter, transceiver and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103076599A (en) * | 2013-01-04 | 2013-05-01 | 清华大学 | Time-frequency domain aliasing multi-signal detecting method |
| CN103746757A (en) * | 2014-01-08 | 2014-04-23 | 中国人民解放军理工大学 | Single-satellite interference source positioning method based on satellite-borne multi-wave-beam antenna |
| CN103905129A (en) * | 2014-01-22 | 2014-07-02 | 中国人民解放军理工大学 | Signal detection and signal information interpretation method based on spectral pattern analysis |
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| Wei Zhang.An Efficient Algorithm for TDOA/FDOA Estimation Based on Approximate Coherent Accumulative of Short-Time CAF.《Wireless Communications and Signal Processing（WCSP）》.2011,第1-4页. |
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