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INVENTION
Patent of the Russian Federation RU2079888
FIBER OPTIC SYSTEM OF SECURITY SIGNALING
Applicant's name: Vasiliev Konstantin Vasilievich; Metelnikov Mikhail Alexandrovich; Mezin Vladimir Viktorovich; Pryanishnikov Vladimir Nikolaevich; Dinkevich Alexander Kimovich; Rusanov Yuri Alexandrovich
The name of the inventor: Vasiliev Konstantin Vasilievich; Metelnikov Mikhail Alexandrovich; Mezin Vladimir Viktorovich; Pryanishnikov Vladimir Nikolaevich; Dinkevich Alexander Kimovich; Rusanov Yuri Alexandrovich
The name of the patentee: Vasiliev Konstantin Vasilievich; Metelnikov Mikhail Alexandrovich; Mezin Vladimir Viktorovich; Pryanishnikov Vladimir Nikolaevich; Dinkevich Alexander Kimovich; Rusanov Yuri Alexandrovich
Address for correspondence:
Date of commencement of the patent: 1994.08.04
The invention relates to signaling devices based on fiber optics and can be used in systems of perimeter protection of territories and premises against unauthorized access. The technical result achieved by the invention consists in reducing the sensitivity to environmental noise and providing control over the state of the optical elements of the system. This result is achieved in that in a fiber optic security alarm system comprising a coherent light source 1 whose output through a section of the multimode optical fiber 2 and the light flux driver 3 is articulated to the input of the photodetector 4 whose output is connected to the input of the alarm driver 5 made In the form of a separation capacitor 6, a comparator 7, a pulse width generator 9 and an indicator element 13, the alarm generator 5 is provided with an integrator 10, a signal length selector 8, an OR gate 12 and a second comparator 11, and in that the light flux driver 3 is made In the form of a tube of a certain length from an optically opaque material.
DESCRIPTION OF THE INVENTION
The present invention relates to signaling devices based on fiber optics and can be used in systems for protecting the perimeter of territories and premises from unauthorized access.
A fencing safety system is known [1] comprising a number of tension wires, a coherent light source, an optical fiber as a sensing element, and a terminal device with a photodetector and alarm driver. When mechanical action on the fence, the optical fiber is deformed by means of special devices, while the intensity of the coherent light passing through the fiber is weakened, which is registered by the terminal device as an alarm signal.
The disadvantages of the described system are the complexity of practical implementation and the limited scope of application, due to the fact that the implementation of the system in the form of a device of tension wires, creating a physical barrier, does not allow to use it in conditions where the protected areas are surrounded by traditional fencing elements (barbed wire, mesh and t .P. ).
These shortcomings are partially eliminated in the fiber optic signaling system with an optical fiber buried in the ground as a sensitive element [2] This technical solution is the closest to the claimed.
Said fiber optic signaling system comprises a coherent light source, a section of a multimode optical fiber, a light-plate former in the form of a plate with an aperture, a photodetector and an alarm driver configured as a separation capacitor, a comparator, a pulse width generator, and an indicator element.
The disadvantages of this system are the limited scope and insufficient reliability of work due to the following reasons. One of the important parameters of the alarm system is its immunity to environmental influences. In the scheme of the alarm generator of the known solution there is no selection of the duration of the input signal, which, given the high sensitivity of the sensors on the effect of intermode interference, can lead to the activation of the alarm system with an occasional short-term single exposure. This disadvantage does not allow to install the system on the elements of the fence of the territory and open structural blocks of buildings and structures subject to environmental impact. Insufficient reliability of the system is due to the fact that there is no control circuit for the presence of constant optical power in the alarm driver circuit. Thus, under real conditions, a smooth drop in optical power in the event of degradation of a coherent light source or optical fiber results in the failure of the alarm system without the giving of an alert signal.
Another disadvantage of the known system is the complexity of its practical implementation, caused by the use of a light-flow former in the form of a plate with aperture aperture, difficult to manufacture and install.
The aim of the invention is to expand the scope of the system, increase the reliability of its operation and simplify the practical implementation.
THE TASK IS DECIDED AS THE FOLLOWING
A fiber optic security alarm system is provided comprising a coherent light source whose output through a section of the multimode optical fiber and the light flux driver is articulated to the input of the photodetector, the output of the photodetector is connected to the input of an alarm driver configured as a separation capacitor, a comparator, a pulse width generator and The first cover of the separation capacitor is in this case the input of the alarm driver itself, and the second plate is connected to the first input of the comparator, the second input of which is set to the reference level.
New in the proposed system is that the alarm generator is provided with an integrator, a signal duration selector, an OR gate and a second comparator whose first input is connected via an integrator to the first capacitor plate, a reference level is set at the second input of the second comparator, and the output is connected to The first input of the OR gate, the second input of the OR gate is connected via a pulse width generator to the output of a signal length selector whose input is connected to the comparator output, the output of the OR gate is connected to the input of the indicator element. A new device in the proposed device is that the light flux former is made in the form of a tube of a certain length from an optically opaque material that is located between a segment of a multimode optical fiber and a photodetector with the possibility of providing the necessary contrast of the specular pattern of the light flux from the end of the optical fiber to the photosensitive surface of the photodetector.
FIG. 1 shows the functional diagram of the proposed system
FIG. 2 shows the diagrams of the input and output signals in blocks
In accordance with the claimed invention, the fiber optic security alarm system (Figure 1) comprises a coherent light source 1 whose output through a section of the multimode optical fiber 2 and the light flux driver 3 is articulated to the input of the photodetector 4. The output of the photodetector 4 is connected to the input of an alarm driver 5. The alarm driver 5 is provided with a separation capacitor 6, a first comparator 7, a signal duration selector 8, a pulse width generator 9, an integrator 10, a second comparator 11, an OR gate 12 and an indicator element 13. The first input of the second comparator 11 via an integrator 10 is connected With the first cover of the separation capacitor 6. On the second input of the second comparator 11, a reference level U op2 is set and the output is connected to the first input of the OR gate 12. The second input of the OR gate 12 is connected via the pulse width generator 9 to the output of the signal length selector 8, Which is connected to the output of the first comparator 7, the first input of which is connected to the second plate of the separation capacitor 6, and to the second input the reference voltage of this comparator is applied. The output of the OR gate 12 is connected to the input of the indicator element 13.
THE PROPOSED SYSTEM WORKS AS FOLLOWS:
The radiation of the coherent light source 1 (FIG. 1) is introduced into the segment of the multimode optical fiber 2 and is fed to the input of the photodetector 4 through the light flux driver 3. As a result of intermode interference in the optical fiber, a discrete picture of bright and dark spots is formed on the photosensitive surface 4 Speckle), which is static in the absence of mechanical influences and is changed by impact, vibration or deformation of the optical fiber. The luminous flux generator 3 provides the necessary contrast of the speckle pattern to increase the sensitivity of the system.
The signal from the output of the photodetector 4 (position a in Figure 2) is fed to the input of the alarm driver 5. Depending on the intensity and duration of the mechanical action, a photocurrent is modulated on the optical fiber, whose level corresponds to the optical power at the input of the photodetector 4. Further in the signal generator Alarm 5, a two-circuit conversion of the input signal with respect to the variable and the constant component occurs. The variable component is allocated by the separating capacitor 6 and goes to the first input of the first comparator 7, on the second input of which the reference level U op1 is set . The pulses from the output of the first comparator 7 (position 6 in Figure 2) are fed to the input of the signal duration selector 8, which has a selection time 
C. In the case when C < 2, the selector starts the pulse width generator 9, Φ is set depending on the required duration of the alarm (position in Figure 2). In the case when C > 1 , the selector locks the circuit.
The constant component passes through the integrator 10 to the first input of the second comparator 11, on the second input of which the reference level U op2 is set . Depending on the optical power level at the input of the photodetector 4, the second comparator 11 generates a corresponding signal (position r in Fig. 2). This signal is fed to the first input of the OR gate 12, the second input of which is fed from the output of the first comparator 7. When a signal appears at the first or second input of the OR 12 element from the output of the OR 12 element, the alarm (position q in Figure 2) After a two-loop conversion, enters the indicator element 13.
Thus, the claimed invention allows to increase the stability of the system to random external influences, which, in turn, allows it to be installed on open fencing elements of the territory, structural blocks of buildings and structures. The input circuit for processing the input signal entered into the alarm generator 5 increases the reliability of the system operation and allows to diagnose its potential failure.
A tube made of any optical opaque material as a light flux driver is simpler in implementation, installation and configuration, which simplifies the practical implementation of the system.
CLAIM
A fiber optic security alarm system comprising a coherent light source, whose output through a section of the multimode optical fiber and the light flux driver is articulated to the input of the photodetector, the output of the photodetector is connected to the input of an alarm driver configured as a separation capacitor, a first comparator, a pulse width generator and The first tab of the separation capacitor is the input of the alarm driver, and the second electrode is connected to the first input of the first comparator, the second input of which is set to the reference level of the first comparator, characterized in that the alarm generator is provided with an integrator, a signal duration selector, And a second comparator whose first input is connected to the first capacitor plate by the integrator, a reference level of the second comparator is installed on the second input, and the output is connected to the first input of the OR gate, the second input of the OR gate is connected via the pulse length generator to the output of the signal duration selector , Whose input is connected to the output of the first comparator, the output of the OR gate is connected to the input of the indicator element.
The system according to claim 1, characterized in that the light-flow generator is made in the form of a tube of optically opaque material, the length of which is determined by the length and type of the segment of the multimode optical fiber.
print version
Date of publication 12.11.2006гг
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