Detector for detecting wiretapping device transmitting illegally collected information and detection method therefor

Abstract

Disclosed are a detector for detecting a wiretapping device transmitting illegally collected information and a detection method therefor. The wiretapping detector of the present invention measures its own location within a surveillance area using ultrasonic waves and searches for wiretapping signals at a plurality of locations, thereby being capable of detecting the position of a wiretapping device by means of triangulation.

Description

Detector for detecting an eavesdropping device transmitting illegally collected information and the detection method thereof

[0001] The present invention relates to a detector capable of tracking not only an eavesdropping signal transmitting illegally collected information but also the location of the eavesdropping device, and a detection method thereof.

[0002] Eavesdropping and hidden cameras involve secretly listening to and watching, and with the advancement of technology, they are becoming increasingly miniaturized and high-performance, with various methods available. Advanced eavesdropping methods include techniques that use infrared lasers to measure changes in sound waves, as well as methods that detect electromagnetic waves emitted by computers to remotely reproduce the screen images of the target computer. The most common and widely used eavesdropping devices or hidden cameras conceal the device in a specific space to record conversations or secretly film videos, then transmit them to an external device via wireless signals.

[0003] Conventional eavesdropping detectors are devices that detect wireless signals, collecting signals used for eavesdropping using an antenna. For example, an eavesdropping detector detects wireless signals with a signal strength exceeding a preset threshold in specific frequency bands primarily used by eavesdropping devices. When a signal appearing to be an eavesdropping signal is collected, a relevant expert analyzes the spectrum of the collected wireless signal to determine whether it is an eavesdropping signal containing voice or video, or a signal from a hidden camera, thereby making a final determination of whether eavesdropping has occurred.

[0004] When an eavesdropping signal is detected, the eavesdropping device must be located. Eavesdropping devices are typically concealed and hidden within the building's interior walls or furniture structures such as desks and chairs. Therefore, traditionally, managers would walk around the surveillance area carrying a portable wireless signal detector (more precisely, an antenna connected to the detector) to search for wireless signals suspected of being eavesdropping, looking for the location with the strongest signal strength. Finally, they would visually search the area around where the wireless signal exceeds a certain strength to locate the device. Because this method is time-consuming, if the device stops transmitting a wireless signal during the search, one must wait until it resumes transmission. Moreover, an additional portable device is required for wireless signal detection, and searching a considerably large area takes a significant amount of time.

[0005] The objective of the present invention is to provide a detector and a detection method capable of detecting not only an eavesdropping signal transmitting illegally collected information but also the location of the eavesdropping device.

[0006] Another objective of the present invention is to provide a method for detecting eavesdropping devices by using a single eavesdropping detector and detecting the location of the eavesdropping device using triangulation, without the need to scan the entire surveillance area while carrying a portable detection device or to search using multiple detection devices.

[0007] The eavesdropping detection system of the present invention provides a method for effectively detecting an eavesdropping device by detecting eavesdropping signals at multiple detection locations, measuring the detection locations using ultrasound, and measuring the distance to the eavesdropping device using the signal strength, thereby proposing a method for detecting the location of the eavesdropping device using triangulation.

[0008] The eavesdropping detection system of the present invention can detect the location of an eavesdropping device. The eavesdropping detection system of the present invention includes a reflector column, an eavesdropping detector, and a control server.

[0009] Reflector columns are columns with a horizontal cross-section that is convex polygonal and are placed at designated locations within the surveillance area.

[0010] A listening detector is positioned at the nth detection position facing the nth surface of the reflector column to measure the signal strength of the listening signal and outputs ultrasound toward the nth surface to measure the Time of Flight (TOF) of receiving the reflected wave, wherein the signal strength of the listening signal and the ultrasonic time of flight are measured at multiple detection positions while varying n. Here, n is a positive integer.

[0011] The control server calculates the location of the eavesdropping device on the virtual plan of the surveillance area by calculating the plurality of detection locations and the distance from the plurality of detection locations to the eavesdropping device. To this end, the control server calculates the detection location using the distance calculated using the flight time and the angle of the nth surface based on the position of the reflector column on the virtual plan, and calculates the distance from the detection location to the eavesdropping device using the signal strength.

[0012] According to an embodiment, when the control server obtains a first circle with a radius R1, the distance from a first point within the monitoring area to the eavesdropping device, and obtains a second circle with a radius R2, the distance from a second point to the eavesdropping device, if one of the two intersection points of the first circle and the second circle is located outside the monitoring area and the other is located inside the monitoring area, the intersection point located inside the monitoring area can be determined as the location of the eavesdropping device.

[0013] According to another embodiment, the reflector column may be a column having a horizontal cross-section of an equilateral triangle, and a material for reflecting the ultrasound may be attached or coated on its outer surface.

[0014] According to another embodiment, the eavesdropping detector may measure the flight time when the intensity of the reflected wave received after emitting ultrasound toward the nth surface is greater than or equal to a preset threshold.

[0015] According to another embodiment, the eavesdropping detector may further include a display unit that displays a virtual floor plan of the surveillance area on a screen. The eavesdropping detector may receive a floor plan showing the location of the eavesdropping device from the control server and display it on the display unit.

[0016] Eavesdropping detection system's method for detecting eavesdropping devices

[0017] The eavesdropping detection system of the present invention can detect the location of an eavesdropping device. The method for measuring the location of an eavesdropping device of the present invention includes a placement step and a measurement step performed by an eavesdropping detector, and a calculation step and a step of calculating the location of the eavesdropping device performed by a control server.

[0018] In the eavesdropping detector deployment phase, the eavesdropping detector is placed at a detection position facing the nth face of a reflector column installed at a designated location within the surveillance area. Here, the horizontal cross-section of the reflector column is a convex polygon, and n is a positive integer. During the measurement phase, the eavesdropping detector placed at the detection position detects an eavesdropping signal and measures the signal strength, and outputs ultrasound toward the nth face to measure the Time of Flight (TOF) for receiving the reflected wave. During the calculation phase, the control server calculates the detection position using the distance calculated using the Time of Flight and the angle of the nth face relative to the position of the reflector column on the virtual plan of the surveillance area, and calculates the distance from the detection position to the eavesdropping device using the signal strength.

[0019] The eavesdropping detector of the present invention can detect the location of an eavesdropping device by triangulation by placing a reflector column within a surveillance area and measuring its own position within the surveillance area using ultrasound while searching for eavesdropping signals at multiple points.

[0020] The present invention allows for the simple identification of at least three detection locations using reflective pillars to detect the location of a listening device according to the triangulation method, and enables the rapid approximation of the location of the listening device in a relatively wide surveillance area even if there is some error in the calculation of the location of the listening detector or the location of the listening device. Therefore, the effort required to scan the entire surveillance area to detect a listening device by holding an antenna, as in the conventional method, can be reduced.

[0021]

[0022] FIG. 1 is a block diagram of an eavesdropping detection system according to one embodiment of the present invention,

[0023] FIG. 2 is a block diagram of the eavesdropping detector of the present invention,

[0024] FIG. 3 is a drawing illustrating an example of a virtual plan view of a surveillance area according to the present invention, and

[0025] FIG. 4 is a flowchart provided for explaining the method for detecting an eavesdropping device according to the present invention.

[0026]

[0027] The present invention will be described in more detail below with reference to the drawings.

[0028] Referring to FIG. 1, the eavesdropping detection system (100) of the present invention can detect an eavesdropping device (10) that illegally obtains information while hidden within a surveillance area. Here, the eavesdropping device (10) may use various eavesdropping methods, but it is a device that transmits eavesdropped information to an external device using a wireless communication signal. A hidden camera that transmits illegally filmed video to an external device using a wireless communication signal also corresponds to the eavesdropping device (10) of the present invention. Hereinafter, the wireless communication signal transmitted by the eavesdropping device (10) to an external device is referred to as an "eavesdropping signal."

[0029] The eavesdropping detection system (100) includes a reflector column (110), an eavesdropping detector (130), and a control server (150). Multiple eavesdropping detectors (130) may be connected to the control server (150) via wired or wireless communication.

[0030] The reflector column (110) is a column to which a material capable of totally reflecting the ultrasonic waves emitted by the eavesdropping detector (130) is attached or coated on all or part of its outer surface, and is positioned vertically at a point within the surveillance area. The reflector column (110) may be fixedly installed at a designated location within the surveillance area, but may also be positioned whenever necessary.

[0031] Based on the vertical arrangement, the reflector column (110) is a column in which the horizontally cut cross-sectional shape is a convex polygon. It is preferable that the interior angles of the horizontal cross-section of the reflector column (110) are all of the same size, but it is not necessary. For example, the reflector column (110) may be a triangular column with an equilateral cross-section as in FIG. 1, a rectangular column with a square cross-section, or a column with more faces.

[0032] The reflector column (110) is positioned in a designated position (z0 in FIG. 3) within the surveillance area and serves as a reference point for measuring the position of the eavesdropping detector (130) placed within the surveillance area using triangulation. The position of the reflector column (110) may be anywhere within the surveillance area, but it is preferable to position it in the center of the space within the surveillance area so that the eavesdropping detector (130) can be positioned facing each side of the reflector column (110). When the reflector column (110) is positioned, the position is fixed to a single position pre-set based on the horizontal cross-section, thereby fixing the oriented angle of each side of the horizontal cross-section. The position and position of the reflector column (110) are pre-specified and registered in the control server (150), each side is distinguished by an identification number, and the oriented angle of that side is registered in the control server (150). For example, the reflector column (110) of FIG. 3 is a triangular prism with a horizontal cross-section that is an equilateral triangle, and its orientation is specified so that each side is oriented at -60°, 60°, and 180° relative to the north of the drawing. For convenience of explanation, the side oriented at -60° is referred to as the first side (111), the side oriented at 60° as the second side (113), and the side oriented at 180° as the third side (15). According to the embodiment, a mark indicating the position and orientation of the reflector column (110) may be displayed or attached to the floor of the monitoring area.

[0033] In order to calculate the location of the eavesdropping device (10), the eavesdropping detector (130) measures the Received Signal Strength Indicator (RSSI) of the eavesdropping signal at at least three locations (hereinafter referred to as 'detection locations'), and the control server (150) calculates the distance from the detection locations to the eavesdropping device (10) based on the RSSI measured by the eavesdropping detector (130). When an administrator moves the eavesdropping detector (130) of the present invention around and detects the eavesdropping signal at at least three detection locations, the location of the eavesdropping device (10) can be calculated according to the triangulation method.

[0034] At this time, in order to calculate the location of the eavesdropping device (10) using the triangulation method, three detection locations must be known. The present invention uses a reflector column (110) to specify the three detection locations and presents a limitation that the eavesdropping detector (130) measures at a location facing one of the multiple outer surfaces of the reflector column (110). Here, the fact that the eavesdropping detector (130) faces one surface of the reflector column (110) means that the ultrasonic waves emitted from the ultrasonic transceiver (131) of the eavesdropping detector (130) are incident perpendicularly or nearly perpendicularly on the opposing surface of the reflector column (110), thereby allowing the ultrasonic waves reflected from the opposing surface of the reflector column (110) to be received. In a broad sense, an opposing location is sufficient if it is a location where the ultrasonic transceiver (131) can receive the ultrasonic waves reflected from the opposing surface of the reflector column (110).

[0035] As explained below, the angle directed by the surface facing the eavesdropping detector (130) becomes the angle of incidence of total reflection of the ultrasonic waves emitted by the ultrasonic transceiver (131). By using the time of flight (TOF) of the ultrasonic waves emitted and the reflected waves received, the distance from the eavesdropping detector (130) to the reflector column (110) can be calculated, thereby determining the current position of the eavesdropping detector (130), i.e., the detection position.

[0036] The eavesdropping detector (130) detects an eavesdropping signal transmitted by the eavesdropping device (10) to an external device and performs the characteristic ‘location measurement using ultrasound’ of the present invention to calculate the location of the eavesdropping device (10). A plurality of eavesdropping detectors (130) may be connected to the control server (150), and each eavesdropping detector (130) is distinguished by an identification code.

[0037] Referring to FIG. 2, the eavesdropping detector (130) includes a communication unit (201), an input unit (203), a signal collection unit (205), an ultrasonic transceiver (131), a memory (207), and a control unit (210).

[0038] The communication unit (201) is equipped with a wired or wireless communication interface and communicates with the control server (150).

[0039] The input unit (203) receives the identification number on the side of the reflector column (110) facing the current eavesdropping detector (130). The input unit (203) may be a keyboard that an administrator can operate to input the identification number. According to another embodiment, the input unit (203) may be a code reader (e.g., a camera, etc.) that scans a two-dimensional or three-dimensional code (e.g., a barcode, QR code, etc.) attached to each side of the reflector column (110) to read the identification number of the side.

[0040] The signal collection unit (205) is equipped with an antenna (ANT) to collect wireless signals and detect eavesdropping signals. Various conventional methods can be used to detect eavesdropping signals. For example, the signal collection unit (205) detects signals of a certain strength or higher among wireless signals in the frequency band of interest received through the antenna (ANT) as eavesdropping signals, and converts the detected eavesdropping signals into digital signals and stores them in memory (207).

[0041] The ultrasonic transceiver (131) transmits ultrasonic waves toward the front, receives reflected waves from an object in front, and measures the flight time. It is preferable to use ultrasonic waves that have a relatively narrow radiation range and strong directivity. The eavesdropping detector (130) must be positioned so that the ultrasonic transceiver (131) transmits ultrasonic waves toward the nth surface (where n is a positive integer) among the multiple outer surfaces of the reflector column (110) and receives reflected waves. This is because if the eavesdropping detector (130) is located in a position that does not face the nth surface of the reflector column (110), the ultrasonic transceiver (131) may not be able to receive reflected waves.

[0042] The control unit (210) controls the overall operation of the eavesdropping detector (130) of the present invention, detects an eavesdropping signal, measures the received signal strength of the eavesdropping signal, and calculates the ultrasonic flight time. To this end, the control unit (210) includes a signal processing unit (211) and an analysis unit (213).

[0043] The signal processing unit (211) receives a digital signal to be analyzed from the signal collection unit (205), and detects an eavesdropping signal by determining whether there is a signal with a signal strength greater than or equal to a threshold in the monitored frequency band.

[0044] The analysis unit (213) calculates the strength of the intercepted signal (RSSI) based on the detection result of the signal processing unit (211), and measures the ultrasonic flight time by measuring the time it takes for the ultrasonic transceiver (131) to transmit ultrasonic waves and receive reflected waves. The flight time is measured when the strength of the reflected waves received after the ultrasonic transceiver (131) transmits ultrasonic waves toward the reflector column (110) is greater than or equal to a preset threshold.

[0045] The analysis unit (213) provides 'event information', including the identification number of the opposing surface received through the input unit (203), the ultrasonic flight time, and the strength of the intercepted signal (RSSI), to the control server (150) through the communication unit (201).

[0046] As explained above, the present invention measures the RSSI of an eavesdropping signal at at least three detection locations to calculate the location of the eavesdropping device (10), and calculates the distance from each of the at least three detection locations to the eavesdropping device (10) based on the RSSI. Therefore, to calculate the location of the eavesdropping device (10), the administrator must move the eavesdropping detector (130) of the present invention to three locations to detect the eavesdropping signal.

[0047] The control server (150) receives event information provided by the eavesdropping detector (130) and calculates the location of the eavesdropping device (10) using triangulation. To this end, the control server (150) includes a location calculation unit (151) and a device detection unit (153).

[0048] The location calculation unit (151) calculates the location of the eavesdropping detector (130), i.e., the detection location, using the ‘identification number of the opposing surface’ included in the event information and the ultrasonic flight time whenever ‘event information’ is provided from the eavesdropping detector (130). The location calculation unit (151) receives at least three event informations from the eavesdropping detector (130) and calculates at least three detection locations sequentially.

[0049] By using the ultrasonic flight time, the distance from the eavesdropping detector (130) to the reflector column (110) can be calculated, and by checking the identification number of the opposing surface, the angle directed by that surface can be checked. The position calculation unit (151) holds the position (z0) of the reflector column (110), and the angle and identification number of each surface. FIG. 3 is a plan view illustrating a surveillance area according to an example of the present invention. Referring to FIG. 3, the reflector column (110) is positioned at position (z0) as indicated in the virtual plan view (P), and each side is designated to be directed at -60°, 60°, and 180° relative to the north of the drawing. For example, if the eavesdropping detector (130) is located at a first point (SP1) facing the first surface (111) and the distance (D1) measured by ultrasound from the eavesdropping detector (130) is calculated, the first point (SP1), which is the current location of the eavesdropping detector (130), can be calculated. If the eavesdropping detector (130) is located at a first point (SP1a) that does not face the first surface (111) almost vertically, it becomes difficult to receive ultrasound from the eavesdropping detector (130) and thus the distance cannot be measured; therefore, the eavesdropping detector (130) must be located at a first point (SP1) that faces the first surface (111) almost vertically. When the eavesdropping detector (130) is moved to a second point (SP2) facing the second surface (113) and the distance (D2) measured by ultrasound at the second point (SP2) is calculated, the second point (SP2), which is the current location of the eavesdropping detector (130), can be displayed on a virtual plan (P). When the eavesdropping detector (130) is moved from the second point (SP2) to a third point (SP3) facing the third surface (115) and the distance (D3) measured by ultrasound at the third point (SP3) is calculated, the third point (SP3) can be displayed on a virtual plan (P).

[0050] The device detection unit (153) can calculate the location of the eavesdropping device (10) by triangulation by drawing a first circle (C1) with radius R1 at a first point (SP1) calculated by the location calculation unit (151), drawing a second circle (C2) with radius R2 at a second point (SP2), and drawing a third circle (C3) with radius R3 at a third point (SP3). If a first circle (C1) with radius R1, the distance from the first point (SP1) to the eavesdropping device (10), is obtained, and a second circle (C2) with radius R2, the distance from the second point (SP2) to the eavesdropping device (10), is obtained, and if one of the two intersection points of the first circle (C1) and the second circle (C2) is located outside the surveillance area and the other is located inside the surveillance area, then the intersection point located inside the surveillance area can be determined as the location of the eavesdropping device without the need to obtain a third circle.

[0051] Although one eavesdropping detector (130) is shown in FIG. 1, multiple eavesdropping detectors (130) monitoring different monitoring areas can be connected to the control server (150).

[0052] Hereinafter, with reference to FIGS. 3 and 4, a method for detecting an eavesdropping device, that is, a method for detecting the location of an eavesdropping device, will be explained focusing on the operation of the signal processing unit (211) and the analysis unit (213) of the present invention.

[0053] <Deployment of Eavesdropping Detector: S401>

[0054] The eavesdropping detector (130) is positioned facing the nth surface among the plurality of outer surfaces of the reflector column (110). Here, n is 0 <n≤N을 만족하는 양의 정수이고, N은 반기둥의 면의 수이다.

[0055] For example, if the eavesdropping detector (130) is located at point 1a (SP1a), it is within the surveillance area and is a location where eavesdropping signals can be detected, but because it is not a location that is vertically opposite to one of the multiple faces of the reflector column (110), the control server (150) cannot verify the location of point 1a (SP1a). Therefore, the administrator must move and position the eavesdropping detector (130) to a location that is opposite to one of the multiple faces of the reflector column (110). Here, it is sufficient for the eavesdropping detector (130) to be opposite one of the multiple faces of the reflector column (110), and it is not necessary to be opposite sequentially starting from the first face (111) in order. For convenience of explanation, it is assumed here that the eavesdropping detector (130) is positioned to be opposite the first face (111) among the multiple faces of the reflector column (110).

[0056] At this time, the placement of the eavesdropping detector (130) is completed by obtaining the identification number of the first surface (111) through the input unit (203). For example, if the input unit (203) is a keyboard, the administrator can input the identification number of the first surface (111) by key input. If the input unit (203) is implemented as a code reader, the administrator can input the identification number of the first surface (111) by scanning a two-dimensional identification code (e.g., a barcode or QR code, etc.) attached to the first surface (111) using the input unit (203) of the eavesdropping detector (130). Here, the two-dimensional identification code is a coded version of the identification number of the first surface (111), and the analysis unit (213) can recognize the identification number of the first surface (111) from the two-dimensional identification code scanned by the code reader.

[0057] <Detecting eavesdropping signals and measuring RSSI: S403, S405>

[0058] When the placement of the eavesdropping detector (130) is completed, the signal collection unit (205) of the eavesdropping detector (130) detects an eavesdropping signal and converts it into a digital signal, and the signal processing unit (211) receives the digital signal to be analyzed from the signal collection unit (205) and determines whether there is a signal with a signal strength greater than or equal to a threshold in the monitored frequency band to detect the eavesdropping signal.

[0059] The analysis unit (213) calculates the strength of the intercepted signal (RSSI) based on the detection result of the signal processing unit (211).

[0060] Ultrasonic Flight Time Measurement: S407

[0061] When the signal processing unit (211) detects an eavesdropping signal, the analysis unit (213) controls the ultrasonic transceiver (131) to emit ultrasonic waves toward the front and measures the time taken to receive reflected waves to measure the ultrasonic flight time. The flight time is measured when the ultrasonic transceiver (131) emits ultrasonic waves toward the reflector column (110) and the intensity of the received reflected waves is greater than or equal to a preset threshold.

[0062] Meanwhile, Step S407 may be performed in parallel with Step S405 or before Step S405.

[0063] <Detection position calculation: S409, S411>

[0064] The analysis unit (213) generates event information including the identification number of the surface received in step S401, the RSSI of the eavesdropping signal measured in step S405, and the ultrasonic flight time, and provides it to the management server (150).

[0065] The location calculation unit (151) of the control server (150) calculates the location of the eavesdropping detector (130), i.e., the detection location, whenever 'event information' is provided from the eavesdropping detector (130) in step S409, using the identification number of the surface facing the reflector column (110) included in the event information and the ultrasonic flight time.

[0066] In the example of FIG. 3, when the surface facing the eavesdropping detector (130) becomes the first surface (111), the position of the eavesdropping detector (130) is in the -60° direction relative to the position (z0) of the reflector column (110). By using the ultrasonic flight time measured by the eavesdropping detector (130) to determine the distance D1 from the reflector column (110), a first point (SP1) located D1 away in the -60° direction relative to the position (z0) of the reflector column (110) can be calculated.

[0067] When the face facing the eavesdropping detector (130) changes to the second face (113), the position of the eavesdropping detector (130) becomes 60° relative to the position (z0) of the reflector column (110). By using the ultrasonic flight time measured by the eavesdropping detector (130) to determine the distance D2 from the reflector column (110), a second point (SP2) located D2 away in the 60° direction relative to the position (z0) of the reflector column (110) can be calculated.

[0068] The location calculation unit (151) repeats this process whenever 'event information' is provided from the eavesdropping detector (130) in step S407.

[0069] <Measure RSSI at 3 or more detection locations and calculate detection locations: S413>

[0070] When step S407 is completed, the administrator returns to step S401 to move the eavesdropping detector (130) to change its position and orientation so that it faces another side of the reflector column (110) and enters a new side identification number. For example, since steps S403 to S407 were performed in a position facing the first side (111), the administrator moves to a position facing the second side (113) and a position facing the third side (115) while entering a new identification number, and repeats steps S403 to S409, the management server (150) repeats step S411 each time.

[0071] The eavesdropping detection system (100) calculates the detection location by repeating this process at three or more detection locations.

[0072] <Calculation of listening device location: S415>

[0073] When the position calculation unit (151) calculates three detection positions, the device detection unit (153) can calculate the location (SP4) of the eavesdropping device by triangulation by drawing a first circle (C1) with radius R1 at the first point (SP1) calculated by the position calculation unit (151), drawing a second circle (C2) with radius R2 at the second point (SP2), and drawing a third circle (C3) with radius R3 at the third point (SP3), and display it on the plan view (P).

[0074] The method for detecting an eavesdropping device of the eavesdropping detection system (100) of the present invention is performed in the manner described above.

[0075] Example of implementation

[0076] Referring to FIG. 5, an eavesdropping detector (500) according to another embodiment of the present invention has the same configuration and operates in the same way as the eavesdropping detector (130) of FIG. 2, but may further include a display unit (501) that displays a plan view (P) of a surveillance area. The display unit (501) can display the plan view (P) of FIG. 3 on a screen using various conventional display means.

[0077] According to an embodiment, when the device detection unit (153) of the control server (150) calculates the location (SP4) of the eavesdropping device using the triangulation method in step S415, the location information is provided to the eavesdropping detector (500), and the eavesdropping detector (500) can display the location of the eavesdropping device on the plan view after having a virtual plan view of the monitoring area in advance.

[0078] Alternatively, the device detection unit (153) of the control server (150) can calculate the location (SP4) of the eavesdropping device using triangulation in step S415, generate a plan view image showing the location, and provide it to the eavesdropping detector (500). The device detection unit (153) can calculate the location (SP4) of the eavesdropping device using triangulation and display it on the plan view (P) by drawing a first circle (C1) with radius R1 at a first point (SP1), drawing a second circle (C2) with radius R2 at a second point (SP2), and drawing a third circle (C3) with radius R3 at a third point (SP3), according to the scale of the plan view.

[0079] The device detection unit (153) provides a floor plan image showing the location (SP4) of the eavesdropping device to the eavesdropping detector (500), and the analysis unit (213) of the eavesdropping detector (500) displays the image provided by the control server (150) on the display unit (501). Through this, the manager can visually confirm the location of the eavesdropping device (10) and easily discover the eavesdropping device (10) at the site of the surveillance area.

[0080] The method for detecting an eavesdropping device according to the present invention is characterized by using a reflector column (110) to identify at least three detection locations in order to detect the location of the eavesdropping device according to the triangulation method. However, even if there is a slight error between the ultrasonic flight time confirmed by the reflector column (110) and the distance to the eavesdropping device confirmed by the RSSI of the eavesdropping signal from the detection location, the location of the eavesdropping device (10) can be found approximately quickly in a relatively wide surveillance area.

[0081] According to another embodiment, by implementing the operation of the location calculation unit (151) and device detection unit (153) of the control server (150) so that the control unit (210) of the eavesdropping detector (500) performs the operation, the eavesdropping detector (500) may operate in a stand-alone manner without the control server (150) to calculate the location of the eavesdropping device (10) and display it on the display unit (501).

[0082] Although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above. It is understood that various modifications can be made by those skilled in the art without departing from the essence of the invention as claimed in the claims, and such modifications should not be understood individually from the technical spirit or perspective of the present invention.

Claims

1. In a wiretapping detection system for detecting the location of a wiretapping device, A reflective column positioned at a designated location within a surveillance area and having a horizontal cross-section that is a convex polygon; An eavesdropping detector positioned at the nth detection position facing the nth surface of the above-mentioned reflector column to measure the signal strength of an eavesdropping signal and to measure the Time of Flight (TOF) of receiving a reflected wave by outputting ultrasound toward the nth surface, wherein the signal strength of the eavesdropping signal and the ultrasonic Time of Flight are measured at multiple detection positions while varying n. n is a positive integer; and It includes a control server that calculates the location of the eavesdropping device on the virtual floor plan of the surveillance area by calculating the plurality of detection locations and calculating the distance from the plurality of detection locations to the eavesdropping device. The above-described control server calculates the detection position using the distance calculated using the flight time based on the position of the reflector column on the above-described virtual plan and the angle of the above-described nth surface, and calculates the distance from the detection position to the above-described eavesdropping device using the above-described signal strength.

2. In Paragraph 1, The above control server is, A wiretapping detection system characterized by determining the location of the wiretapping device by determining the intersection point within the monitoring area as the location of the wiretapping device when, at a first circle with a radius R1, the distance from a first point within the monitoring area to the wiretapping device, and at a second circle with a radius R2, the distance from a second point to the wiretapping device, one of the two intersection points of the first circle and the second circle is located outside the monitoring area and the other is located inside the monitoring area.

3. In Paragraph 1, An eavesdropping detection system characterized in that the above-mentioned reflector column is a column having a horizontal cross-section of an equilateral triangle, and a material for reflecting the above-mentioned ultrasound is attached or coated on its outer surface.

4. In Paragraph 1, The above-mentioned eavesdropping detector is, An eavesdropping detection system characterized by measuring the flight time when the intensity of the reflected wave received after emitting ultrasound toward the nth surface is greater than or equal to a preset threshold.

5. In Paragraph 1, The above-mentioned eavesdropping detector is, It further includes an input unit for receiving the identification number of the nth surface among the plurality of surfaces of the above-mentioned reflector column, and An eavesdropping detection system characterized by the above-mentioned control server verifying the angle information of the nth side stored in memory using the above-mentioned identification number.

6. In Paragraph 1, The above-mentioned eavesdropping detector is It further includes a display unit that displays a virtual floor plan of the above-mentioned surveillance area on a screen, and An eavesdropping detection system characterized by receiving a floor plan showing the location of the eavesdropping device from the control server and displaying it on the display unit.

7. In a method for detecting eavesdropping devices, A step of placing an eavesdropping detector at a detection position facing the nth face of a reflector column installed at a designated location within a surveillance area, wherein the horizontal cross-section of the reflector column is a convex polygon and n is a positive integer; A measurement step in which the eavesdropping detector detects an eavesdropping signal at the above detection location and measures the signal strength, and outputs ultrasound toward the nth surface to measure the Time of Flight (TOF) of receiving the reflected wave; A calculation step in which a control server calculates the detection position using the distance calculated using the flight time and the angle of the nth surface based on the position of the reflector column on the virtual plan of the surveillance area, and calculates the distance from the detection position to the eavesdropping device using the signal strength; and A detection method characterized by including a step of calculating the distance from a plurality of detection locations to the eavesdropping device by repeating the measurement and calculation steps while changing the above n, and the control server calculating the location of the eavesdropping device in the virtual plan using triangulation.

8. In Paragraph 7, In the step of calculating the location of the above-mentioned eavesdropping device, A detection method characterized by determining the location of the eavesdropping device by determining the intersection point within the surveillance area as the location of the eavesdropping device when, at a first point within the surveillance area, a first circle with a radius R1, the distance from the first point to the eavesdropping device, and at a second point with a radius R2, the distance from the second point to the eavesdropping device, one of the two intersection points of the first circle and the second circle is located outside the surveillance area and the other is located inside the surveillance area.

9. In Paragraph 7, A detection method characterized in that the above-mentioned reflector column is a column having a horizontal cross-section of an equilateral triangle, and a material for reflecting the above-mentioned ultrasound is attached or coated on its outer surface.

10. In Paragraph 7, In the above measurement step, A detection method characterized by the above-described eavesdropping detector measuring the flight time when the intensity of the received reflected wave is greater than or equal to a preset threshold after emitting ultrasonic waves toward the nth surface.

11. In Paragraph 7, The angle of the nth surface above The above-mentioned eavesdropping detector receives the identification number of the nth side through the input unit and provides it to the control server, and A detection method characterized by the above-mentioned control server verifying the angle information of the nth surface stored in memory using the above-mentioned identification number.

12. In Paragraph 7, A detection method characterized by further including the step of the control server providing the eavesdropping detector with a plan showing the location of the eavesdropping device calculated by triangulation, and the eavesdropping detector displaying the plan showing the location of the eavesdropping device on a display unit.

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