INTRUSION SENSING APPARATUS FOR SECURITY FENCE

Abstract

The present invention provides an intrusion sensing apparatus for a security fence, the apparatus detecting the distribution characteristic of a frequency component of an output signal in a charge amplifier connected to a shielding multi-core cable united with a security fence, and thereby determining whether the output signal is a signal caused by the overall vibration of and a partial impact on the security fence.

Claims

1. An intrusion sensing apparatus for a security fence, comprising: a charge amplifier 110 which amplifies an amount of charges generated by friction electrification within a shielded multicore cable and outputs the amplified signal in a form of a voltage through an active filter; a signal conversion unit 120 which receives the signal output by the charge amplifier 110, converts an amplitude of the received signal so that the amplitude is enlarged or reduced in a specific size, samples the converted signal, and detects a frequency component; a feature frequency extraction unit 130 which detects a frequency signal having a feature different from a feature of a frequency signal of a predetermined charged signal by analyzing the frequency component detected by the signal conversion unit 120; and an intrusion determination unit 140 which determines whether the feature frequency signal detected by the feature frequency extraction unit 130 is vibration or an intrusion by comparing the feature frequency signal with a predetermined frequency signal for a vibration determination and a predetermined frequency signal for an intrusion determination.

2. The intrusion sensing apparatus of claim 1, wherein the signal conversion unit 120 comprises: an ADC 121 which receives the signal output by the charge amplifier 110 into a digital signal and outputs the digital signal; a scaler 122 which converts an amplitude of the digital signal converted by the ADC 121 based on predetermined environment information by enlarging or reducing the amplitude of the digital signal based on predetermined environment information so that a frequency component of the digital signal is not changed and outputs the enlarged or reduced signal; a Fourier transform unit 123 which detects a frequency component in the converted signal enlarged or reduced by the scaler 122; and a transform management unit 124 which outputs a conversion signal for guaranteeing accuracy of a frequency analysis to the ADC 121 in a specific cycle, analyzes the amplitude of the signal output by the scaler 122, and controls the Fourier transform unit 123 so that the Fourier transform unit 123 operates if the analyzed amplitude exceeds a predetermined threshold value.

3. The intrusion sensing apparatus of claim 2, wherein when a signal belonging to signals output by the ADC 121 and continuing to be generated for a specific time is received, the scaler 122 calculates an average amplitude value of the input signals, reduces an amplitude value of the input signal by the calculated average amplitude value, and outputs the reduced signal.

4. The intrusion sensing apparatus of claim 2, wherein the transform management unit 124 sets a range of the threshold value by taking into consideration size information f an electrostatic force according to a natural environment.

5. The intrusion sensing apparatus of claim 1, wherein the frequency signal for a vibration determination and the frequency signal for an intrusion determination of the intrusion determination unit 140 is a frequency signal modeled depending on a type of a predetermined security fence.

Description

DESCRIPTION OF DRAWINGS

[0021] FIG. 1 is a block diagram showing the cable connection state of an intrusion sensing apparatus using a common shielded multicore cable.

[0022] FIG. 2 is an exemplary diagram showing the state in which the intrusion sensing apparatus using a shielded multicore cable according to a conventional technology is used in a security fence.

[0023] FIG. 3 is a block diagram showing the configuration of an intrusion sensing apparatus for a security fence according to the present invention.

[0024] FIG. 4 is a block diagram showing the configuration of the signal conversion unit of the intrusion sensing apparatus for a security fence according to FIG. 3.

[0025] FIGS. 5A and 5B are graphs showing an output signal when an intrusion is generated in the intrusion sensing apparatus for a security fence according to FIG. 3.

[0026] FIGS. 6A and 6B are graphs showing an output signal when vibration is generated in the intrusion sensing apparatus for a security fence according to FIG. 3.

MODE FOR INVENTION

[0027] A preferred embodiment of an intrusion sensing apparatus for a security fence according to the present invention is described below in detail with reference to the accompanying drawings. FIG. 3 is a block diagram showing the configuration of an intrusion sensing apparatus for a security fence according to the present invention. FIG. 4 is a block diagram showing the configuration of the signal conversion unit of the intrusion sensing apparatus for a security fence according to FIG. 3.

[0028] As shown in FIGS. 3 and 4, the intrusion sensing apparatus 100 for a security fence according to the present invention is configured to include a charge amplifier 110, a signal conversion unit 120, a feature frequency extraction unit 130 and an intrusion determination unit 140 in order to determine whether a corresponding signal is a signal attributable to overall vibration and a partial impact of a security fence by detecting a distribution characteristic of the frequency components of an output signal of the charge amplifier connected to a shielded multicore cable.

[0029] The charge amplifier 110 is connected to an analog sensor unit for detecting a signal generated due to friction electrification within a shielded multicore cable having a varying electromotive force when an external force or impact is applied, amplifies the amount of charges of a signal detected by the analog sensor unit, and outputs the amplified signal in the form of a voltage through an active filter.

[0030] The signal conversion unit 120 is an element for receiving a signal output by the charge amplifier 110, converting the amplitude of the received signal by enlarging or reducing the amplitude of the received signal in a specific size, sampling the converted signal, and detecting a frequency component. The signal conversion unit 120 is configured to include an analog to digital converter (ADC) 121, a scaler 122, a Fourier transform unit 123 and a transform management unit 124.

[0031] The ADC 121 receives a signal from the charge amplifier 110, converts the received signal into a digital signal, and outputs the digital signal.

[0032] The scaler 122 is an element for converting the amplitude of the digital signal converted by the ADC 121 based on predetermined environment information by enlarging or reducing the amplitude of the digital signal so that the frequency component of the digital signal is not changed. When a signal that belongs to signals output by the ADC 121 and that continues to be generated for a specific time is received, the scaler 122 calculates an average amplitude value of the input signals, reduces the amplitude value of the input signal by a difference of the calculated average amplitude value, and outputs the reduced signal.

[0033] That is, a shielded multicore cable installed on a security fence generates vibration due to a natural environment condition, such as a natural wind and/or a rainfall. When the security fence is vibrated due to the environment condition, the output signal of the charge amplifier 110 attributable to the vibration is influenced by the direction and speed of a wind at a location where the security fence has been installed. Accordingly, in order to remove a noise signal attributable to a natural phenomenon from the output signal of the charge amplifier 110 without the distortion of a frequency component, the amplitude value of the signal converted by the ADC L21 is proportionally enlarged or reduced, converted, and output.

[0034] The Fourier transform unit 123 is an element for sampling the converted signal enlarged or reduced by the scaler 122, transforming the sampled signal into a frequency component, and outputting the frequency component. The Fourier transform unit 123 digitizes a spectrum and amplitude having resolution of 0.25 Hz. That is, when the Fourier transform unit 123 performs 2.sup.n pieces of sampling on an input signal, for example, sample data from a sampling start time to a sampling end time is calculated.

[0035] The Fourier transform unit 123 calculates the value of each frequency by performing high-speed Fourier transform on the calculated sampling data in real time. A frequency value [f(max)] having a maximum size between the start time and end time of each unit time and a corresponding voltage value are stored.

[0036] The transform management unit 124 outputs a conversion signal for guaranteeing the accuracy of a frequency analysis to the ADC 121 at a specific interval. If the range of a predetermined threshold value is exceeded as a result of the analysis of the amplitude of a signal output by the scaler 122, the transform management unit 124 controls the Fourier transform unit 123 so that it operates.

[0037] That is, the transform management unit 124 outputs a conversion signal for the start of conversion (SoC) of the ADC 121 for a predetermined specific time in order to sample the signal in each specific cycle in order to guarantee the analysis accuracy of a frequency component.

[0038] Furthermore, the transform management unit 124 sets the range of a threshold value by taking into consideration information about the size of an electrostatic force (the amplitude of a signal) according to natural environment information (e.g., wind, temperature and/or rainfall information) set by a user.

[0039] That is, in order to prevent an unnecessary signal from being detected when a security fence is vibrated under the influence of a wind, the range of a maximum threshold value and a minimum threshold value of amplitude is changed. Furthermore, the intrusion sensing apparatus may be configured to be automatically controlled when pieces of condition information are received in order to prevent a malfunction signal from being detected because a security fence is vibrated depending on the type of security fence and characteristics, such as a wind, a temperature, a rainfall in an installation area.

[0040] The feature frequency extraction unit 130 is an element for detecting a frequency signal having a feature different from that of the frequency signal of a predetermined charged signal by analyzing a frequency component detected by the signal conversion unit 120. If a security fence is widely vibrated due to a natural phenomenon, the feature frequency extraction unit 130 extracts a feature frequency signal whose vibration and an impact can be distinguished from a charge signal charged within a shielded multicore cable due to an impact of a narrow rage because the charge signal has a different frequency feature.

[0041] The feature frequency includes a frequency value [f(max)] having a maximum size, a frequency value [f(max1)] having a second size, a frequency value [f(max2)] having a third size, and a frequency value [f(max3)] having a fourth size.

[0042] FIGS. 5A and 5B show the output signal of the charge amplifier upon impact (intrusion) and show that the output signal of the charge amplifier attributable to an impact has a dense distribution of f(max1), f(max2) and f(max3) frequencies near a frequency f(max) having a maximum value.

[0043] Furthermore, FIGS. 6A and 6B show the output signal of the charge amplifier upon vibration and show that the output signal of the charge amplifier has a dense distribution of frequency values f(max1), f(max2) and f(max3) frequencies when vibration attributable to a wind is generated.

[0044] The intrusion determination unit 140 determines whether a feature frequency signal detected by the feature frequency extraction unit 130 is vibration or an intrusion by comparing the feature frequency signal with a predetermined frequency signal for a vibration determination and a predetermined frequency signal for an intrusion determination.

[0045] That is, the frequency signal for a vibration determination and the frequency signal for an intrusion determination are values stored by analyzing a distribution characteristic of frequencies based on modeling depending on the type of security fence. The intrusion determination unit 140 arranges the frequency values based on the output signal of the charge amplifier, compares the frequency values with the modeled value, and determines whether the signal output by the charge amplifier is a signal generated due to an intrusion or vibration generated by a wind, etc based on a result of the comparison.

[0046] Furthermore, the frequency signal for a vibration determination and the frequency signal for an intrusion determination are frequency signals modeled depending on the type of predetermined security fence.

[0047] Accordingly, when a security fence is vibrated, a distribution characteristic of feature frequencies different depending on the installation state of the security fence are extracted, a comparison is performed on the feature frequencies in a real time, and whether the vibration corresponds to an impact attributable to an intrusion or vibration attributable to a natural environment. Accordingly, a malfunction and erroneous alarm of a fence intrusion sensing system can be prevented.

[0048] As described above, although a preferred embodiment of the present invention has been described, those skilled in the art may understand that the present invention may be modified and changed in various ways without departing from the spirit and scope of the present invention written in the following claims.

[0049] Furthermore, the thickness of the lines, the size of the elements, etc. shown in the process of describing the embodiment of the present invention may have been exaggerated for the clarity of a description and for convenience' sake. The aforementioned terms are terms defined by taking functions in the present invention into consideration, and may be different depending on an operator's intention or usage.

[0050] Accordingly, such terms should be analyzed based on the overall contents of the specification.

DESCRIPTION OF REFERENCE NUMERALS

[0051] 100 Intrusion sensing apparatus

[0052] 110 Charge amplifier

[0053] 120 Signal conversion unit

[0054] 121 ADC

[0055] 122 Scaler

[0056] 123 Fourier transform unit

[0057] 124 Transform management unit

[0058] 130 Feature frequency extraction unit

[0059] 140 Intrusion determination unit