Background technology
With expanding economy, oil and natural gas has become the most important energy of the national economic development.Long distance pipeline
As most preferable, the economic means of transportation of oil and natural gas, it has been widely used.Oil-gas pipeline is energy transport
Once leaking combustion explosion easily occurs for main artery, pipeline, not only influences the safety in production of pipeline, will also give the country and people group
Many life bring about great losses with property.
The detecting and warning system of application oil-gas pipeline mainly has following several at present:Electronic impulse type fence, microwave wall
Alarm, active infrared alarm, leakage cable type perimeter detection warning system, electret vibration wireline warning system and optical fiber
Sensor perimeter alarm system.Compared with electric transducer warning system, fibre optical sensor has very in sensing network application
Obvious technical advantage:It can be provided up to 100 kilometers in the case where not needing any outdoor active device (being not required to power supply)
The safety monitoring of distance, is not limited by terrain environments such as the height of landform, complications, turning, bendings, has broken infrared ray, microwave
Wall etc. is only applicable to the limitation that sighting distance and flat site are used.Therefore ground using optical fiber measurement vibration as pipeline pre-warning system
The main method studied carefully.But how rationally effective analysis is carried out to fiber laser arrays signal, set up which type of event model
More effectively, as the big focus and difficult point in research.
Also there is substantially deficiency in current fiber-optic vibration signal transacting, its mentality of designing is usually the method directly detected, will
The signal detected is directly sent to display, and the changes in amplitude of clutter and noise is shown simultaneously, the inspection to echo signal
Survey ability is determined by operator to the monitoring of display.But, monitoring result error obtained by this processing method is big, report
Police is inaccurate, the detection of long range complex vibration is faced a severe challenge, and is badly in need of carrying out long-distance optical fiber vibration inspection on this basis
Survey technique study.
The subject matter that existing research is present is not set up suitable model, particularly do not set up suitable signal
Detection model, so that the long range early warning system that production has been put into is less efficient or even lies idle, optical fiber early warning
Signal transacting link in system turns into the main bottleneck of system and industry development.It is, therefore, desirable to provide a kind of suitable
Model realizes the detection of vibration event, to improve the stability of detection probability and false-alarm probability.
The content of the invention
The present invention is based on the optical fiber early warning system vibration source detection algorithm of self-adaption constant false alarm rate (GO/SO-CFAR) to solve
The problem of to fiber-optic vibration signal detection.
Optical fiber early warning system vibration source detection method based on self-adaption constant false alarm rate (GO/SO-CFAR), it includes:To light
Fine vibration signal is acquired;Set up self-adaption constant false alarm rate (GO/SO-CFAR) detector model;Signal without friction is carried out
GO/SO-CFAR is detected, compares the relation of actual false alarm rate and setting false alarm rate, it is ensured that detector normal work;To homogeneous background
Signal is detected, obtains the detection performance under homogeneous background;Multiple target background signal is detected, obtained in multiple target
Detection performance under background;Adjust signal to noise ratio in both environments respectively, then carry out GO/SO-CFAR detections, draw detection performance
Curve.
Wherein, detection threshold value meets following relation:
S=TZ
Wherein, S is threshold value;Z is power level, and its value is divided into two kinds of situation considerations, if it is determined that result k values are more than with reference to single
The half of member, i.e. k>During R/2,OtherwiseT is the normalized factor, and its value is according to false-alarm probability Pfa
Try to achieve,
Self-adaption constant false alarm rate (GO/SO-CFAR) detector set up by such scheme, ensure that the false-alarm of detection
Rate is constant, and has stronger detectability under homogeneous background and multiple target background.
According to an aspect of the invention, there is provided a kind of signal detecting method based on self-adaption constant false alarm rate, it is special
Levy and be to include:
Set up adaptive false alarm rate detector;
Experimental data without friction is detected by self-adaption constant false alarm rate detector, it is ensured that actual false alarm rate and the void of setting
Alert rate is extremely approached, i.e., absolute error ensures in the 1e-4 orders of magnitude;
The signal under homogeneous background and under multiple target background is detected respectively with self-adaption constant false alarm rate, respectively
Its detection probability is tried to achieve, and changes the signal to noise ratio of data, multi-group data is detected, the detection under different signal to noise ratio is obtained
Probability, shows it and detects performance.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described.Obviously, described embodiment is only a part of embodiment of the invention, rather than whole embodiments.Based on this
Embodiment in invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with root
Other embodiment is obtained according to these accompanying drawings, the scope of protection of the invention is belonged to.
Shown in Figure 1, Fig. 1 is the optical fiber early warning system based on self-adaption constant false alarm rate (GO/SO-CFAR) of the present invention
The flow chart of system vibration source detection algorithm.As shown in figure 1, disclosed in the present embodiment based on self-adaption constant false alarm rate (GO/SO-
CFAR optical fiber early warning system vibration source detection algorithm) includes:
S101:Fiber-optic vibration signal is acquired;
S102:Set up self-adaption constant false alarm rate (GO/SO-CFAR) detector model;
S103:Carry out self-adaption constant false alarm rate (GO/SO-CFAR) detection to signal without friction, relatively actual false alarm rate with
Set the relation of false alarm rate, it is ensured that detector normal work;
S104:Homogeneous background signal is detected, the detection performance under homogeneous background is obtained;
S105:Multiple target background signal is detected, the detection performance under multiple target Beijing is obtained;
S106:Adjust signal to noise ratio in both environments respectively, then carry out self-adaption constant false alarm rate (GO/SO-CFAR) and detect,
Draw detection performance curve.
The signal of fiber-optic vibration system is acquired in S101, N number of pulse echo data is continuously received and obtains one
Frame echo data, and each pulse echo data are handled and sampled.Wherein, M are included in each pulse echo data
According to echo time tactic range cell from left to right, different columns represent echo position.Specifically, it will receive
Each pulse echo data handled and sampled, form the signal that is arranged in matrix.
In S102, self-adaption constant false alarm rate (GO/SO-CFAR) detector model, self-adaption constant false alarm rate (GO/ are set up
SO-CFAR) detector model to the data for having formed matrix as shown in Fig. 2 carry out part deletion, then obtain threshold value, finally
Detection unit is compared with threshold value, testing result is drawn.Intermediate portions therein are deletion processes, as shown in figure 3, it is taken off
The method shown includes:
S301:To reference unit sampling sequence x(1)≤x(2)≤…≤x(R);
S302:Then the orderly sampling relatively low to k is summed
Wherein, x is the value of reference unit;ZkIt is preceding k reference unit clutter power;
S303:The normalized factor T of threshold value is obtained according to given wrong probability of erasurek, the mistake for deleting process kth step deletes
Except probability PFCIt is defined as
PFC=Pr { Dk>0|HN} (1)
Wherein, PFCFor wrong probability of erasure, HNSampled for weak clutter, DkFor test statistics,
Dk=x(k+1)-TkZk (2)
Wherein, x(k+1)For (k+1) item sampled value, TkFor the kth normalized factor of threshold value;
Mistake probability of erasure PFCIt can be write as integrated form,
Wherein,For in HNAssuming that lower DkMoment generating function, definition is
(2) formula is substituted into (4) formula, obtained
Ordered Statistic D(1),D(2)... D(k+1)Joint moment generating function be defined as
Compare (5), (6) two formulas, it can be deduced that
w1=w2=...=wk=-Tkw
And
wk+1=w
Therefore
Wherein, R is reference unit number, and wushu (7) substitutes into formula (3), obtained
According to formula (8) the normalized factor of threshold value can be obtained in the case of given wrong probability of erasure;
S304:Try to achieve adaptive threshold TkZk,+1 reference unit value of kth is compared with adaptive threshold;
S305:If x(k+1)Less than TkZk, then above-mentioned steps are repeated from increasing 1 to k, otherwise directly stop circulation, i.e.,
Illustrate x(k+1),…,x(R)Belong to strong clutter area sampling;
S306:Then k values are compared with R/2 values;
S307:If k>R/2, then judge that detection unit is in weak clutter area, by x(1),…,x(k)Clutter power Z is formed, i.e.,Its test statistics D moment generating function definition is
The definition of false-alarm probability is
Pfa=Φ (T) (10)
Wherein, PfaIt is false-alarm probability, then simultaneous formula (9), formula (10), are obtained
S308:If k<R/2, then judge that detection unit is in strong clutter area, by x(k+1),…,x(R)Forming clutter power Z isIts test statistics D moment generating function definition is
Equally by formula (12) and false-alarm definition (10) simultaneous
In summary, normalized factor T is according to false-alarm probability PfaTry to achieve, such as following formula
Finally calculate threshold value
S=TZ
Wherein, S is threshold value.
In S103, the data without friction arrived to fiber-optic vibration system acquisition carry out GO/SO-CFAR detections, parameter setting
And the false-alarm probability after detection is as shown in table 1.
Table 1
It can be seen that the error between actual false-alarm probability and setting false-alarm probability is in 1e-4 grades, illustrate that self-adaption constant is empty
Alert rate (GO/SO-CFAR) detector normal work.
In S104, the data under same group of homogeneous background are carried out with the repetition of self-adaption constant false alarm rate (GO/SO-CFAR)
10000 detections, parameter setting is as shown in table 2,
Table 2
16 width testing result figures are taken respectively, as shown in figure 4, as shown in table 3, being said by the record of testing result data again
The detection performance of bright self-adaption constant false alarm rate (GO/SO-CFAR) detector under homogeneous background.
Table 3
In S105, self-adaption constant false alarm rate (GO/SO-CFAR) is carried out respectively to the data under one group of multiple target background
10000 detections are repeated, parameter setting is as shown in table 4
Table 4
16 width testing result figures are taken respectively, as shown in figure 5, again by the record of testing result data, as shown in table 5, more
The detection performance of self-adaption constant false alarm rate (GO/SO-CFAR) detector under multiple target background can be illustrated.
Table 5
Detection mode |
Average detected probability |
Self-adaption constant false alarm rate (GO/SO-CFAR) |
0.9950 |
In S106, the data to different signal to noise ratio are detected respectively, you can obtained in the case where signal to noise ratio is different,
The detection probability value of self-adaption constant false alarm rate (GO/SO-CFAR) detector, that is, detect performance curve, under homogeneous background and many
Detect performance respectively as shown in Figure 6,7 under target background.As can be seen that the detection energy of self-adaption constant false alarm rate (GO/SO-CFAR)
Power is stronger.
It is of the invention that there is advantages below compared with existing detection method
(1), this method can be reached to fiber-optic vibration signal detection;
(2), constant false alarm rate detection method can guarantee that false-alarm probability is constant, and performance is stable;
(3), self-adaption constant false alarm rate (GO/SO-CFAR) all shown under homogeneous background and under multiple target background compared with
High detection probability, i.e. self-adaption constant false alarm rate (GO/SO-CFAR) method can guarantee that the detectability under different background.