JP5007284B2 - Wireless monitoring system - Google Patents

Description

  The present invention relates to a wireless monitoring system using a camera device and a monitor device capable of wireless communication with each other.

  Conventionally, in a monitoring system that monitors intruders and suspicious persons in a house such as a detached house or an apartment house, or in a non-house such as a business office, a camera device and a monitor are provided for the convenience of installation of the camera device. Wireless monitoring systems that transmit and receive image data and the like by wireless communication between devices are used. For example, in Patent Document 1, a wireless sensor is arranged around a camera device and wirelessly communicates with each other, thereby eliminating communication between the monitor device and the wireless sensor as a base unit, thereby reducing the load on the monitor device. A wireless monitoring system is shown.

In communication between a camera device and a monitor device, in order to enable long-distance communication, a complicated modulation / demodulation method such as spread spectrum or OFDM (orthogonal wave frequency division multiplexing) is usually used, or an error correction code, etc. Or added.
JP 2004-128659 A

  However, modulation / demodulation methods such as spread spectrum and OFDM have the problem that the system configuration becomes complicated and costs increase, and error correction codes have an upper limit on the transmission speed in wireless transmission where the usable frequency band is limited. There was a problem that it could not be raised.

  The present invention has been made to solve the above-described problems, and is a wireless monitor capable of performing high-sensitivity and high-speed communication between a camera device and a monitor device while having a simple and inexpensive configuration. The purpose is to provide a system.

  In order to achieve the above object, the invention of claim 1 has an image pickup means for picking up an image and a transmission means for wirelessly transmitting data of the image picked up by the image pickup means, and is installed in a specific place. A phased array antenna having a plurality of camera devices, a plurality of antennas for receiving radio signals transmitted from the transmission means of the camera devices, and a phase changing means for changing the directivity of the antennas, and the phased array A signal demodulating means for demodulating a radio signal received by the antenna, a filter means for filtering the signal demodulated by the signal demodulating means, a display means for displaying an image based on the signal passed through the filter means, And a monitor device having control means for controlling the phase changing means, signal demodulating means, filter means and display means. In the line monitoring system, the control unit measures noise reception intensity for each predetermined direction while changing the directivity of the phased array antenna, and stores the noise reception intensity as one of the camera apparatuses. A signal including a camera ID is transmitted, and the received intensity of the signal received in each of the predetermined directions is measured while changing the directivity of the phased array antenna, and the received intensity of the signal in each of the predetermined directions An S / N ratio of noise reception intensity is calculated, and when performing communication with the camera device based on the calculated S / N ratio, a directivity direction of the phased array antenna that maximizes the calculated S / N ratio is determined, stored, and When communicating with the camera device, the directivity of the phased array antenna is matched with the stored direction.

  According to a second aspect of the present invention, in the wireless monitoring system according to the first aspect, the monitor device wirelessly communicates with the plurality of camera devices using the same frequency channel. .

  A third aspect of the present invention is the wireless monitoring system according to the second aspect, comprising a plurality of the camera devices and a plurality of the monitor devices, and using the frequency channels assigned to the respective monitor devices. The camera device and the plurality of monitor devices communicate wirelessly with each other, and the control means transmits the signal from all camera devices on a first frequency channel assigned to any monitor device other than itself, While changing the directivity of the phased array antenna, the reception intensity in the second frequency channel assigned to itself in each predetermined direction is measured, and this is stored as the noise reception intensity. In the second frequency channel, A signal including a camera ID is transmitted from any camera device, and the directivity of the phased array antenna is changed The reception intensity of the constant signal received for each direction of measured, and calculates the SN ratio of the received strength of the received intensity and the noise of the signal for each of the predetermined direction.

  According to a fourth aspect of the present invention, in the wireless monitoring system according to the third aspect, the camera includes a plurality of the camera devices and three or more monitor devices, and uses the frequency channel assigned to each monitor device. The apparatus and the monitor device communicate with each other wirelessly, and the control means transmits from all camera devices on a channel adjacent to the frequency channel assigned to itself among the frequency channels assigned to each monitor device. Then, while changing the directivity of the phased array antenna, the reception intensity of the signal received for each predetermined direction is measured, and this is stored as the noise reception intensity.

  According to a fifth aspect of the present invention, in the wireless monitoring system according to the second aspect, the control unit is a frequency used for communication in the other system from a camera device adjacent to the camera device of the other system. The reception intensity of the signal received for each predetermined direction is measured while being transmitted through a channel and the directivity of the phased array antenna is changed, and this is stored as the reception intensity of noise.

  According to a sixth aspect of the present invention, in the wireless monitoring system according to the first aspect, the control means changes the directivity of the phased array antenna at each specific time, and receives the noise reception intensity for each predetermined direction. Is measured and stored as the noise reception intensity at each specific time, and the SN ratio is calculated from the signal reception intensity and the noise reception intensity at each specific time for each of the predetermined directions. In performing communication with the camera device at specific times based on the S / N ratio, the directional direction of the phased array antenna that maximizes the calculated S / N ratio is recognized and stored.

  A seventh aspect of the present invention is the wireless monitoring system according to any one of the first to sixth aspects, wherein the control means sets the phased array antenna in an omnidirectional state in a normal communication standby mode. Controlling the phase change means to identify the camera device that has transmitted the communication permission request signal from the camera ID included in the communication permission request signal when the communication permission request signal transmitted from any camera device is received. The phase changing means is controlled so as to obtain the directivity of the phased array antenna in which the calculated SN ratio is maximized when communicating with the stored camera device.

  According to an eighth aspect of the present invention, in the wireless monitoring system according to the seventh aspect, the filter means transmits a first band filter that passes a first band signal, and a second band signal wider than the first band. A second band pass filter that allows one of the filters to be selected, and the control means selects the first band pass filter in a normal communication standby mode. Controlling the filtering means to select the second band filter when receiving a communication permission request signal transmitted from one of the camera devices, and receiving image data in a high-speed communication mode. It is characterized by.

  According to the first aspect of the present invention, the control means measures the noise reception intensity for each predetermined direction, stores this as the noise reception intensity, and receives the signal reception intensity and the noise reception intensity for each predetermined direction. The S / N ratio is calculated, and the directivity direction of the phased array antenna that maximizes the S / N ratio when communicating with the camera device is recognized and stored. As a result, it is possible to set the optimum directivity of the phased array antenna for communication, taking into account the effects of stationary noise generated in the surrounding environment, and to create a modulation / demodulation method that requires a complicated system configuration. High-sensitivity communication can be performed between the camera device and the monitor device with a simple and inexpensive configuration without use.

  According to the invention of claim 2, since the monitor device wirelessly communicates with a plurality of camera devices using the same frequency channel, all the systems constituting the system using one frequency band are used. Can communicate with other camera devices. This facilitates coexistence with other wireless communication systems.

  According to invention of Claim 3, the image image | photographed with the some camera apparatus with the some monitor apparatus in one wireless monitoring system can be confirmed simultaneously and separately. At this time, for the monitor device, a signal transmitted to another monitor device becomes noise, which may affect communication. Therefore, the control means measures the reception intensity by transmitting from all camera apparatuses on the first frequency channel assigned to any monitor apparatus other than itself, and stores this in advance as the noise reception intensity. The S / N ratio is calculated. As a result, when communication is simultaneously performed using another frequency channel (first frequency channel) in the system, the influence of noise due to radio waves of the first frequency channel leaking into the frequency band assigned to the system is taken into account. Thus, the optimal directivity of the phased array antenna can be set for communication, and communication with higher sensitivity can be performed between the camera device and the monitor device.

  According to the invention of claim 4, in the wireless monitoring system including a plurality of camera devices and three or more monitor devices, the control means is a channel adjacent to the frequency channel assigned to the control device from all the camera devices. Transmit and measure the received intensity of the received signal, and store this as the received intensity of noise. As a result, the signal-to-noise ratio is calculated by considering only the signal of the frequency channel that may affect the communication as noise, so that the calculation process can be performed easily and quickly.

  According to the invention of claim 5, the control means causes the camera device adjacent to the camera device of another system to transmit on a frequency channel used for communication in another system, and regards the received signal as noise and determines the SN ratio. Is calculated. Therefore, even when camera devices of other systems are arranged at adjacent positions, the directivity of the phased array antenna can be adjusted to the optimum direction for communication.

  According to the invention of claim 6, since the SN ratio is calculated by measuring the received intensity of noise at every specific time, the influence of noise generated from the surrounding environment that regularly varies according to the time zone is taken into account. Thus, the optimal directivity of the phased array antenna can be set for communication, and communication with higher sensitivity can be performed between the camera device and the monitor device.

  According to the seventh aspect of the present invention, the control means controls the phase changing means so that the phased array antenna is in an omnidirectional state in the normal communication standby mode. Thereby, it is possible to wait for communication from the camera device in all directions within the communication area. On the other hand, when the communication permission request signal transmitted from any one of the camera devices is received, the control means controls the phase changing means so that the directivity of the phased array antenna matches the direction of the camera device. The reception intensity of the radio signal transmitted from the apparatus and received by the phased array antenna can be increased. Thereby, the stability of communication with a camera apparatus can be improved.

  According to the invention of claim 8, since the control means controls the filter means so as to select the first band filter in the normal communication standby mode, it is mixed in the signal demodulated by the signal demodulation means. Noise can be effectively removed. Therefore, without using a modulation / demodulation method that requires a complicated system configuration, it is possible to increase the sensitivity of reception and increase the communication distance with the camera device. On the other hand, when the communication permission request signal transmitted from one of the camera devices is received, the control means controls the filter means so as to select the second band filter. Can be used for high-speed communication. As a result, for example, high resolution (high resolution and high frame rate) moving images captured by a camera device can be transmitted and received at a high bit rate, and it is possible to more accurately grasp the details of images that were previously ambiguous. It becomes.

(Embodiment 1)
A wireless monitoring system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a wireless monitoring system provided as a facility such as a residence. The wireless monitoring system 1 includes a plurality of camera devices 2 and a monitor device 3 that displays images captured by the camera devices 2. Each camera device 2 and the monitor device 3 can communicate with each other wirelessly using the same frequency channel.

  The camera device 2 captures an image and outputs it as electronic data, and an image sensor (imaging means) 21 such as a CCD (Charge Coupled Device) and a transmission / reception unit that wirelessly transmits / receives electronic data of the image captured by the image sensor 21. (Transmission means) 22 and the like. The camera device 2 is installed in a key place such as a residence.

  The monitor device 3 includes a phased array antenna (phase array antenna) 30, a transmission / reception selector switch 33, a reception unit 34, a filter unit 35, a transmission unit 36, a baseband processing unit 37, a display unit 38, a control unit (control means) 39, and the like. It is constituted by. The phased array antenna 30 includes, for example, a plurality of antennas 31a, 31b, 31c, 31d. . . And the corresponding phase converters 32a, 32b, 32c, 32d. . . Etc., and each antenna 31a, 31b, 31c, 31d. . . The directivity is changed by converting (phase-shifting) the phase of the radio wave emitted from the camera device 2, and wireless signals are transmitted to and received from the transmission / reception unit 22 of each camera device 2. Each antenna 31a, 31b, 31c, 31d. . . The phase of the radio wave radiated by is converted by the phase conversion unit 32. The transmission / reception selector switch 33 switches the transmission / reception operation of the monitor device 3 according to the control signal output from the control unit 39. The reception unit 34 includes a tuner 34a that receives radio waves via the phased array antenna 30, a reception demodulation unit (signal demodulation means) 34b that demodulates a signal received by the tuner 34a, and the like. The antennas 31a, 31b, 31c, 31d. . . And phase converters 32a, 32b, 32c, 32d. . . Can be increased or decreased as appropriate. As a basic principle, antennas 31a, 31b, 31c, 31d. . . Since the directivity of the phased array antenna 30 tends to increase by increasing the number of antennas 31a, 31b, 31c, 31d. . . Increase the number of.

  The filter unit 35 filters unnecessary components of the reception baseband signal demodulated by the reception demodulating unit 34b to increase reception sensitivity. The filter unit 35 includes a narrow band filter (first band filter) 35a that passes a relatively narrow first band received baseband signal, and a wideband filter that passes a second band received baseband signal wider than the first band. (Second band filter) 35b, and any one of the filters can be alternatively selected in accordance with the control signal output from the control unit 39. That is, the narrow band filter 35 a and the wide band filter 35 b are selected by a filter changeover switch (not shown) provided in the filter unit 35. The transmission unit 36 transmits a signal to the camera device 2 via the transmission / reception selector switch 33, the phase conversion unit 32, and the phased array antenna 30. The baseband processing unit 37 processes baseband signals to be transmitted / received. The display unit 38 displays an image based on the signal processed by the baseband processing unit 37. More specifically, an image captured by any one of the camera devices 2 is displayed on the display unit 38. The control unit 39 controls the above-described units of the monitor device 3. The control unit 39 stores the direction in which each camera device 2 is installed, and controls the directivity of the phased array antenna 30 in accordance with the direction.

  2 shows the arrangement of the antennas 31a, 31b, 31c and 31d constituting the phased array antenna 30, and FIG. 3 shows the directivity of the phased array antenna 30. In the present embodiment, four half-wave dipole antennas are applied as the antennas 31a, 31b, 31c, and 31d. The antennas 31a, 31b, 31c, and 31d have a wavelength of a radio wave used for communication λ, and as shown in FIG. 2B, are perpendicular to the square plane at the apex of a square having a side of λ / 4 in a plan view. Has been placed. As described above, the antennas 31a, 31b, 31c, and 31d are arranged, and the phase converters 32a, 32b, 32c, 32d. . . By performing the phase shift by the antenna directivity, the antenna directivity on the XY plane can be controlled.

  In FIG. 2 (b), the directivity pattern of the phased array antenna 30 when the directivity of the phased array antenna 30 is matched with the A direction is shown in FIG. 3 (a), and the directivity of the phased array antenna 30 is matched with the D direction. The directivity patterns of the phased array antenna 30 are shown in FIG. The gain in the direction in which the directivity of the phased array antenna 30 is combined is the highest, and the gain in the peripheral region is also increased.

  FIG. 4 shows the communication state between each camera device 2 and the monitor device 3 and the directivity of the phased array antenna 30. The monitor device 3 operates in a normal communication standby mode and a high-speed communication mode. The normal communication standby mode is a mode in which communication start from any camera device 2 is awaited. The high-speed communication mode is a mode in which image data and the like are communicated at high speed with the camera device 2 that has started communication.

  In the normal communication standby mode, as shown in FIG. 4A, the control unit 39 controls the phased array antenna 30 to be in a non-directional state so as to be able to communicate with any camera device 2. . At this time, the control unit 39 controls to select the narrowband filter 35a, and sets the reception baseband filter to a narrow band (normal standby state). This is because the communication permission request signal from the camera device 2 is low speed, the noise is removed and the SN ratio is increased as the band of the baseband filter of the monitor device 3 is narrowed, the sensitivity is increased, and the communication area is expanded. Because you can. For example, when the transmission speed in the high-speed communication mode is 16 Mbps, but the transmission speed of the communication permission request signal from the camera device 2 is about 1.6 Mbps, communication can be performed using the narrowband filter 35a. In this case, an improvement in sensitivity of 10 log10 = 10 dB can be expected. As described above, when the antenna is omnidirectional and the narrowband filter 35a is used, the amount of noise (noise) is smaller than when the wideband filter 35b is used, and the signal-to-noise ratio of the signal is improved in all directions. The distance can be increased.

  On the other hand, in the high-speed communication mode, it is necessary to widen the reception baseband filter, which causes a problem that the reception sensitivity is deteriorated. Therefore, as shown in FIG. 4B, in the present embodiment, when the monitor device 3 receives a communication permission request signal transmitted from, for example, the camera device 2A, the control unit 39 selects the wideband filter 35b. In addition to widening the reception baseband filter, the directivity of the phased array antenna 30 is matched to the direction of the camera device 2A that starts communication, and as a result, high-speed communication can be realized without degrading sensitivity ( High-speed communication state). The “direction of the camera device 2 </ b> A” here refers to, for example, a direction in which the reception intensity (the electric field intensity of the received signal) or the SN ratio is maximized when the directivity of the phased array antenna 30 is directed in that direction. The phase direction of the phased array antenna 30 that is optimal for communication with the camera device 2A (which is not always the same as the direction in which the camera device 2A exists due to the surrounding radio wave propagation environment).

  FIG. 5 shows a procedure for starting communication by switching the operation mode of the monitor device 3 from the normal communication standby mode to the high-speed communication mode in the wireless monitoring system 1. The monitor device 3 is in a state where it can communicate with the camera device 2 installed where it is waiting for communication from the camera device 2 in the normal communication standby mode (# 1). When any trigger input is made to any camera device 2 and a communication permission request signal is transmitted from the camera device 2 accordingly (YES in # 2), the monitor device 3 receives the communication permission request signal ( # 3). The control unit 39 of the monitor device 3 specifies the direction of the camera device 2 to start communication from the camera ID included in the received signal (# 4), switches the operation mode of the monitor device 3 to the high-speed communication mode, A communication permission signal is transmitted to the camera device 2 (# 5). At this time, the directivity of the phased array antenna 30 is matched with the direction of the camera device 2 that starts communication, and the wideband filter 35b is selected to widen the reception baseband filter. When the camera device 2 receives the communication permission signal (YES in # 6), the camera device 2 starts high-speed transmission of image data from the camera device 2 to the monitor device 3 (# 7). Thereby, one-to-one communication is performed between any one of the camera devices 2 and the monitor device 3.

  In the present embodiment, the control unit 39 of the monitor device 3 stores the camera ID assigned to each camera device 2 and the direction of each camera device 2 in the table shown in FIG. 6, and starts communication. The directivity of the phased array antenna 30 is adjusted to the direction 2.

  6A shows the direction of each camera device 2 viewed from the monitor device 3, and FIG. 6B shows the camera ID assigned to each camera device 2 by the control unit 39 of the monitor device 3 and each camera device. Tables for storing two directions are shown respectively. Camera IDs 001 to 100 are assigned to the camera apparatuses 2A to 2D, respectively, and 000 to 111 are assigned as direction codes to the A direction to the H direction, as shown in FIG. 6A. The control unit 39 stores the camera ID and the direction code in association with each camera device, reads the direction code, identifies the direction in which each of the camera devices 2A to 2D is installed, and starts communication. The directivity of the phased array antenna 30 is matched with the direction of the device 2.

  FIG. 7 shows a procedure for creating the table shown in FIG. 6B and starting communication with the camera device 2 based on the table. The table is created when, for example, one of the camera devices 2 is installed and the power of the monitor device 3 and the camera device 2 is turned on. When the power of the monitor device 3 and the camera device 2 is turned on (# 11), a signal including its own camera ID is transmitted from the camera device 2, and the control unit 39 of the monitor device 3 that receives the signal transmits the signal. Is registered (# 12). For example, in FIG. 6B, the camera IDs 001 to 100 of the four camera devices 2 are registered, but the camera IDs 000 to 111 of the eight camera devices 2 can be registered. When registration of the camera IDs of all the camera devices 2 is completed (YES in # 13), the control unit 39 of the monitor device 3 starts setting the camera direction of the camera device 2 (# 14). First, the control unit 39 of the monitor device 3 recognizes the direction of the camera device 2 (# 15) and creates a table by storing the direction code (# 16). In the present embodiment, the directivity of the phased array antenna 30 can be set to eight directions A to H, the camera device 2 recognizes which of the eight directions A to H corresponds, and the camera device Set the direction of 2. The direction of the camera device 2 may be set by a system administrator manually completing the table, but may be automatically set by the control unit 39. The processes of # 15 and # 16 are repeated until the setting of the direction of all the camera devices 2 is completed (NO in # 17). When completed (YES in # 17), the process ends.

  The table shown in FIG. 6B is created by the above procedure, and the control unit 39 refers to this table to identify the direction of the camera device 2 that starts communication at # 4 in FIG. Can do. For example, when the camera ID included in the communication permission request signal received by the monitor device 3 at # 3 in FIG. 5 is 001, the control unit 39 sets the camera device 2 in the B direction from the corresponding direction code 001. And phase converters 32a, 32b, 32c, 32d. . . To control the directivity of the phased array antenna 30 in the B direction. By using the table shown in FIG. 6B, the directivity of the phased array antenna 30 can be controlled by one microcomputer as the control unit 39, so that the equivalent function is realized by hardware. As a result, the system can be easily managed and the cost can be reduced. Here, the number of connectable cameras and the installation directions are 8 and 8 directions, respectively, but can be appropriately increased or decreased according to the target system.

  Hereinafter, in step # 15 illustrated in FIG. 7, a procedure in which the control unit 39 of the monitor device 3 recognizes the direction of the camera device 2 will be described. As described above, the antennas 31a, 31b, 31c and 31d are arranged as shown in FIG. 2, and the phase converters 32a, 32b, 32c, 32d. . . The antenna directivity on the XY plane can be controlled by performing the phase shift by.

  FIG. 8 shows the relationship between the antenna directivity and the amount of phase shift. Here, the corresponding amount of phase shift is shown for a total of nine cases of obtaining omnidirectionality and obtaining directivity in 8 directions in 45 ° increments around the Z axis. Therefore, the directivity can be controlled more finely. The wireless monitoring system 1 is roughly divided into two operation modes: a learning mode and a communication mode. The learning mode is a mode for the monitor device 3 to assign the optimum antenna directivity to each camera device 2 and is mainly implemented after the installation of the wireless monitoring system 1 and before entering the communication mode. The communication mode is a mode for performing communication between the monitor device 3 and each camera device 2, and includes the high-speed communication mode and the communication standby mode.

  In the learning mode, the monitor device 3 sets all the phase shift amounts of the phase converters 32a (phase shifter PS1), 32b (phase shifter PS2), 32c (phase shifter PS3), and 32d (phase shifter PS4) to 0. Set the antenna directivity to omnidirectional. Here, the test signal including the ID information of the camera device 2A is continuously transmitted from the camera device 2A. When the monitor device 3 receives the test signal from the camera device 2A, it first sets the phase shift amounts of the phase shifters PS1 to PS4 to 90 °, 90 °, 0 °, and 0 °, respectively. When the phase shift amount is set in this way, the directivity of the antenna is set in the A direction as shown in FIG. 8, and the received signal strength at this time is stored in the storage unit in the baseband processing unit 37. Next, the phase shift amounts of the phase shifters PS1 to PS4 are set to 64 °, 0 °, −64 °, and 0 °, respectively. When the phase shift amount is set in this manner, the directivity of the antenna is set in the B direction, and the received signal strength at this time is stored in the storage unit in the baseband processing unit 37. Similarly, the received signal strength in each case is obtained for the eight antenna directivities. As a result, it is determined that the camera apparatus 2A exists in the direction of the directivity of the antenna having the strongest received signal strength, and is stored in the table in FIG. Similarly, for the camera devices 2B to 2D, the direction is recognized and stored in the table. By appropriately setting the phase shift amount of the phase shifters PS1 to PS4, the antenna directivity may be changed by 1 ° and the direction of the camera device 2A may be recognized based on the received intensity.

  FIG. 9 shows a procedure in which the control unit 39 of the monitor device 3 recognizes the direction of the camera device 2. This flowchart shows an example in which the antenna directivity is changed by 45 ° sequentially from the A direction to the H direction in the clockwise direction, and the received intensity is measured (the same applies to FIGS. 11, 13, and 15 below). ). First, the control unit 39 of the monitor device 3 adjusts the directivity of the phased array antenna 30 to the A direction (# 31), and measures the reception intensity in a state where transmission from all the camera devices 2 is stopped. The value is stored as the received intensity of noise in the A direction (# 32). Then, control unit 39 changes the directivity of phased array antenna 30 by 45 degrees clockwise (NO in # 33, # 34), and returns to # 32. When the processes of # 32, # 33, and # 34 are repeated in this manner to store the received intensity of noise in all directions (YES in # 33), the control unit 39 sets the directivity of the phased array antenna 30 to be non-directional. (# 35).

  Then, the control unit 39 continuously transmits a signal including the camera ID from the camera device 2 that sets the direction (# 36). When the monitor device 3 receives the signal (# 37), the control unit 39 directs the phased array antenna 30 to point. Match the direction to the A direction (# 38). When the monitor device 3 receives the signal (# 39), the control unit 39 calculates the SN ratio in the A direction from the received signal strength at # 39 and the received noise strength stored at # 32 and stores it (# 40). . Then, control unit 39 changes the directivity of phased array antenna 30 by 45 degrees clockwise (NO in # 41, # 42), and returns to # 39. When the processes of # 39, # 40, # 41, and # 42 are repeated in this way and the SN ratios in all directions are stored (YES in # 41), the control unit 39 determines the direction with the maximum SN ratio as the direction of the camera device. (# 43), and the process ends.

  According to the wireless monitoring system 1 of the first embodiment, the control unit 39 measures the noise reception intensity for each predetermined direction, stores this as the noise reception intensity, and receives the signal reception intensity and noise for each direction. The S / N ratio of the received intensity is calculated, and the directivity direction of the phased array antenna having the maximum S / N ratio is recognized and stored when communicating with the camera device 2. Accordingly, the optimum directivity of the phased array antenna 30 can be set for communication with the camera device 2 in consideration of the influence of stationary noise generated in the surrounding environment, and a complicated system configuration is required. Highly sensitive communication can be performed between the camera device 2 and the monitor device 3 with an inexpensive configuration without using the modulation / demodulation method. Further, since the monitor device 3 communicates with a plurality of camera devices 2 by radio using the same frequency channel, the monitor device 3 communicates with all the camera devices 2 constituting the system using one frequency band. be able to. This facilitates coexistence with other wireless communication systems.

  Further, the control unit 39 controls the phase converters 32a, 32b, 32c, 32d... So that the phased array antenna 30 is in a non-directional state in the normal communication standby mode. . . To control. Thereby, it is possible to wait for communication from the camera device 2 in all directions in the communication area. On the other hand, when receiving a communication permission request signal transmitted from any one of the camera devices 2, the control unit 39 causes the phase converters 32 a and 32 b to direct the directivity of the phased array antenna 30 toward the camera device 2. 32c, 32d. . . Therefore, the reception intensity of the radio signal transmitted from the camera device 2 and received by the phased array antenna 30 can be increased. Thereby, without using a modulation / demodulation system that requires a complicated system configuration, it is possible to increase the sensitivity of reception and to increase the communication distance with the camera device 2.

  In addition, since the control unit 39 controls the filter unit 35 so as to select the narrowband filter 35a in the normal communication standby mode, the noise mixed in the signal demodulated by the reception demodulation unit 34b is effective. Can be removed. Therefore, it is possible to increase the reception sensitivity and improve the stability of communication with the camera device 2 without using a modulation / demodulation method that requires a complicated system configuration. On the other hand, when the communication permission request signal transmitted from any one of the camera devices 2 is received, the control unit 39 controls the filter unit 35 so as to select the wideband filter 35b. High-speed communication can be performed using the radio waves. Thereby, for example, a high-resolution (high resolution and high frame rate) moving image captured by the camera device 2 can be transmitted and received at a high bit rate, and the details of an image that has been vague in the past can be grasped more accurately. It becomes possible.

(Embodiment 2)
A wireless monitoring system according to another embodiment of the present invention will be described with reference to FIGS. As illustrated in FIG. 10, the wireless monitoring system 1 according to the second embodiment includes a plurality of camera devices 2A to 2D and two monitor devices 3A and 3B. The monitor device 3A wirelessly communicates with the camera devices 2A to 2D using the frequency channel CH1 assigned to itself, and the monitor device 3B wirelessly communicates with the camera devices 2A to 2D using the frequency channel CH2 assigned to itself. If the monitor device 3A and the camera device 2A communicate with each other using the frequency channel CH1, and the monitor device 3B and the camera device 2B communicate with each other using the frequency channel CH2 at the same time, they are transmitted from the camera device 2A. This signal may become a noise component for the monitor device 3B. Therefore, in the present embodiment, the direction of the camera device 2B with respect to the monitor device 3B is set in consideration of the presence of the camera device 2A that is a noise generation source for the monitor device 3B, and the monitor device 3B is connected to the camera device 2B. To achieve stable communication.

  FIG. 11 shows a procedure in which the control unit 39 of the monitor device 3B recognizes the direction of each camera device 2 in the wireless monitoring system 1 of the second embodiment. First, the control unit 39 of the monitor device 3B matches the directivity of the phased array antenna 30 with the direction A (# 51), and transmits the signal from all the camera devices 2 through the frequency channel CH1 (first frequency channel). Then, the reception intensity in the frequency channel CH2 is measured, and the value is stored as the reception intensity of the noise in the A direction (# 52). Then, control unit 39 changes the directivity of phased array antenna 30 by 45 degrees clockwise (NO in # 53, # 54), and returns to # 52. When the processes of # 52, # 53, and # 54 are repeated in this way to store the received intensity of noise in all directions (YES in # 53), the control unit 39 sets the directivity of the phased array antenna 30 to be non-directional. Then, transmission from all camera apparatuses 2 is stopped (# 56).

  Then, the control unit 39 continuously transmits a signal including the camera ID from the camera device 2 that sets the direction on the frequency channel CH2 (second frequency channel) (# 57), and the monitor device 3B receives the signal. (# 58), the directivity of the phased array antenna 30 is adjusted to the A direction (# 59). When the monitor device 3 receives the signal (# 60), the control unit 39 calculates the SN ratio in the A direction from the received intensity of the signal received at # 60 and the received intensity of the noise stored at # 52 (# 61). . Then, control unit 39 changes the directivity of phased array antenna 30 by 45 degrees clockwise (NO in # 62, # 63), and returns to # 60. When the processes of # 60, # 61, # 62, and # 63 are repeated in this manner and the SN ratios in all directions are stored (YES in # 62), the control unit 39 determines the direction with the maximum SN ratio of the camera device 2. The direction is stored (# 64), and the process is terminated. The direction of the camera device 2 set in this way may be different from the direction in which the camera device 2 is actually installed, but as shown in FIG. 10, it is transmitted simultaneously on different frequency channels in the system. If it is, the antenna direction most suitable for communication can be set while considering it as a noise component.

  According to the wireless monitoring system 1 of the second embodiment, images captured by a plurality of camera devices 2 by a plurality of monitor devices 3 in one wireless monitoring system 1 can be confirmed simultaneously and separately. At this time, the control unit 39 causes the first frequency channel assigned to any one of the monitor devices 3 other than itself to transmit from all the camera devices 2 and measures the reception intensity at the frequency assigned to itself. The signal-to-noise ratio is calculated by storing this in advance as noise reception intensity. As a result, when communication is simultaneously performed using another frequency channel (first frequency channel) in the system, the influence of noise due to radio waves of the first frequency channel leaking into the frequency band assigned to the system is taken into account. Thus, the direction of the camera device 2 can be accurately recognized, and communication with higher sensitivity can be performed between the camera device 2 and the monitor device 3.

(Embodiment 3)
A wireless monitoring system according to still another embodiment of the present invention will be described with reference to FIGS. As illustrated in FIG. 12, the wireless monitoring system 1 according to the third embodiment includes a plurality of camera devices 2A to 2D and three or more monitor devices 3A, 3B, and 3C. The monitor device 3A uses the frequency channel CH1 allocated to itself, and the camera devices 2A to 2D. The monitor device 3B uses the frequency channel CH2 allocated to itself, and the monitor devices 3A to 2D and the monitor device 3C Wireless communication is performed with the camera devices 2A to 2D using the allocated frequency channel CH3. Here, it is assumed that each frequency channel has a higher frequency band in the order of channels CH1, CH2, and CH3.

  In the wireless monitoring system 1 according to the third embodiment, the monitoring devices 3A, 3B, and 3C set the direction of the phased array antenna 30 by using a signal transmitted on a channel adjacent to the frequency channel assigned to the monitoring device 3A, 3B, and 3C as noise. More specifically, the monitor device 3A treats a signal transmitted using the channel CH2 adjacent to the frequency channel CH1 allocated to itself as noise, and transmits the signal using the channel CH3 of a frequency band farther than that. The signal is not treated as noise because it has little effect on its own communication. Similarly, the monitor device 3C treats the signal transmitted using the channel CH2 adjacent to the frequency channel CH3 allocated to itself as noise, and the signal transmitted using the channel CH1 of the frequency band farther than that is Do not treat as noise. In the monitor device 3A and the monitor device 3C, the control unit 39 may perform substantially the same processing as that of the wireless monitoring system 1 of the second embodiment, and a description thereof will be omitted. On the other hand, the monitor device 3B treats a signal transmitted using the channels CH1 and CH3 adjacent to the frequency channel CH2 allocated to itself as noise.

  In FIG. 13, as shown in FIG. 12, the monitor device 3A and the camera device 2A use the frequency channel CH1, the monitor device 3B and the camera device 2B use the frequency channel CH2, and the monitor device 3C and the camera device 2C. Shows a procedure in which the control unit 39 of the monitor device 3B recognizes the direction of each camera device 2 in the case where each communicates using the frequency channel CH3. First, the control unit 39 of the monitor device 3B matches the directivity of the phased array antenna 30 with the A direction (# 71), and transmits it from all the camera devices 2 on the frequency channel CH1 (first frequency channel). Then, the reception intensity is measured and the value is stored as the reception intensity of the noise in the A direction (# 72). Then, control unit 39 changes the directivity of phased array antenna 30 by 45 degrees clockwise (NO in # 73, # 74), and returns to # 72. Thus, by repeating the processes of # 72, # 73 and # 74 and storing the received intensity of noise in all directions (YES in # 73), the frequency channel CH3 (third frequency channel) is transmitted from all the camera devices 2. The received intensity is measured in the transmitted state, and the value is stored as the received intensity of the noise in the A direction (# 75). Then, control unit 39 changes the directivity of phased array antenna 30 by 45 ° clockwise (NO in # 76, # 77), and returns to # 75. If the processes of # 75, # 76, and # 77 are repeated in this way to store the received intensity of noise in all directions (YES in # 76), the control unit 39 sets the directivity of the phased array antenna 30 to non-directional. The transmission from all the camera devices 2 is stopped (# 79). Subsequent processing (# 80 to # 87) is substantially equivalent to # 57 to # 64 in FIG. In # 85, the SN ratio may be calculated separately from the received noise intensity stored in # 72 and the received noise intensity stored in # 72, or the S / N ratio is calculated by combining the two. May be. The direction of the camera device 2 set in this way may be different from the direction in which the camera device 2 is actually installed, but as shown in FIG. 12, it is transmitted simultaneously on different frequency channels in the system. If it is, the antenna direction most suitable for communication can be set while considering it as a noise component.

  According to the wireless monitoring system 1 of the third embodiment, the control unit 39 transmits from all the camera apparatuses 2 on the channel adjacent to the frequency channel assigned to itself, and measures the received intensity of the received signal. Is stored as the noise reception intensity. As a result, the signal-to-noise ratio is calculated by considering only the signal of the frequency channel that may affect the communication as noise, so that the calculation process can be performed easily and quickly.

(Embodiment 4)
A wireless monitoring system according to still another embodiment of the present invention will be described with reference to FIGS. As illustrated in FIG. 14, the wireless monitoring system 1 according to the fourth embodiment corresponds to a case where another wireless monitoring system 100 is installed adjacently. For example, this applies to a case where another wireless monitoring system 100 is installed adjacent to a residence where the wireless monitoring system 1 is installed. The wireless monitoring system 100 includes a plurality of camera devices 2E, 2F, 2G and a monitoring device 3D, and performs communication using a frequency channel CH4 different from the wireless monitoring system 1 (using the frequency channel CH2). To do. When the frequency bands of the frequency channel CH2 and the frequency channel CH4 are close, a signal transmitted from the camera device 2E using the frequency channel CH4 may become a noise component for the monitor device 3B. Therefore, in the present embodiment, the direction of the camera device 2 with respect to the monitor device 3B is set in consideration of the presence of the camera device 2E that is a noise generation source for the monitor device 3B, and between the monitor device 3B and the camera device 2 is set. To achieve stable communication. More specifically, since the monitor device 3B cannot control the operation of the camera device 2E of another system, the frequency channel used in the other wireless monitoring system 100 from the camera device 2B closest to the camera device 2E in its own system. The S / N ratio is calculated by using CH4 as a noise component. Note that the system administrator selects the camera device 2B closest to the camera device 2E and sets the frequency channel CH4, for example.

  FIG. 15 shows a procedure in which the control unit 39 of the monitor device 3B recognizes the direction of each camera device 2 when another wireless monitoring system 100 is installed adjacently as shown in FIG. Yes. The control unit 39 of the monitor device 3B first adjusts the directivity of the phased array antenna 30 to the A direction (# 91), and measures the reception intensity in a state of being transmitted from the camera device 2B on the frequency channel CH4. The value is stored as the received intensity of noise in the A direction (# 92). Here, the camera device 2B is a camera device adjacent to the camera device 2E of another wireless monitoring system 100, and the frequency channel CH4 is a frequency channel used in another wireless monitoring system 100. Then, control unit 39 changes the directivity of phased array antenna 30 by 45 ° clockwise (NO in # 93, # 94), and returns to # 92. When the processes of # 92, # 93 and # 94 are repeated in this way to store the received intensity of noise in all directions (YES in # 93), the control unit 39 sets the directivity of the phased array antenna 30 to be non-directional. The transmission from all the camera devices 2 is stopped (# 96). Subsequent processing (# 97 to # 104) is substantially equivalent to # 57 to # 64 in FIG. The direction of the camera device 2 set in this way may be different from the direction in which the camera device 2 is actually installed, but as shown in FIG. 14, the camera device 2E is installed adjacently. When another wireless monitoring system 100 is communicating at the same time, the directivity of the phased array antenna 30 most suitable for communication can be set while considering the signal as a noise component.

  According to the wireless monitoring system 1 of the fourth embodiment, the control unit 39 causes the camera device 2B adjacent to the camera device 2E of another system 100 to transmit and receive the frequency channel CH4 used for communication in another system. The signal-to-noise ratio is calculated by regarding the signal as noise. Therefore, even when the camera device 2E of another system 100 is disposed at an adjacent position, the directivity of the phased array antenna 30 can be adjusted to the optimum direction for communication.

  The present invention is not limited to the configuration of the above-described embodiment, and may be configured to perform communication by matching the directivity of the phased array antenna 30 in the direction of the camera device 2 set based on at least the SN ratio in advance. That's fine.

  The present invention can be variously modified. For example, cooking is often performed at a specific time zone or watching a television in the home, and accordingly, specific noise may be generated from an electromagnetic cooker or the like at a specific time zone. Therefore, while changing the directivity of the phased array antenna 30 at each specific time, the reception intensity of the ambient noise of the monitor device 3 is measured for each predetermined direction, and this is used as the noise reception intensity at each specific time. You may memorize | store and use for calculation of SN ratio. In this case, the direction of the camera device 2 can be accurately recognized in consideration of the influence of noise generated from the surrounding environment that regularly varies according to the time zone, and the camera device 2 and the monitor device 3 can be recognized. Communication with each other can be performed with higher sensitivity.

  Further, the number of antennas constituting the phased array antenna 30 is not limited to four and may be any number. Further, the number and arrangement of the camera devices 2 are not limited to the example illustrated in FIG. 4 and can be set as appropriate according to the monitoring area. Moreover, you may comprise a radio | wireless communications system combining the camera apparatus 2 and the monitor apparatus 3 in each said embodiment suitably.

1 is a block diagram showing a configuration of a wireless monitoring system according to Embodiment 1 of the present invention. (A) is a perspective view which shows the example of arrangement | positioning of the antenna which comprises the phased array antenna applied to the system, (b) is the top view. Diagram showing directivity of phased array antenna The figure which shows the communication state of each camera apparatus and a monitor apparatus, and the directivity of a phased array antenna. 6 is a flowchart illustrating a procedure for starting communication by switching the operation mode of the monitor device from a normal communication standby mode to a high-speed communication mode in the wireless monitoring system. (A) stores the direction of each camera device viewed from the monitor device in the wireless monitoring system of the second embodiment, and (b) stores the camera ID and direction assigned to each camera device by the control unit of the monitor device. The figure which shows the table for doing. The flowchart which shows the procedure which produces the table shown in FIG.6 (b). The figure which shows the relationship between the directivity of a phased array antenna, and the amount of phase shifts. The flowchart which shows the procedure in which the control part of a monitor apparatus recognizes the direction of a camera apparatus. FIG. 5 is a block diagram illustrating a schematic configuration of a wireless monitoring system according to a second embodiment. 9 is a flowchart illustrating a procedure in which the control unit of the monitor device recognizes the direction of the camera device in the second embodiment. FIG. 9 is a block diagram illustrating a schematic configuration of a wireless monitoring system according to a third embodiment. 10 is a flowchart illustrating a procedure in which the control unit of the monitor device recognizes the direction of the camera device in the third embodiment. FIG. 9 is a block diagram illustrating a schematic configuration of a wireless monitoring system according to a fourth embodiment. 9 is a flowchart illustrating a procedure in which the control unit of the monitor device recognizes the direction of the camera device in the fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless monitoring system 2 Camera apparatus 3 Monitor apparatus 30 Phased array antenna (phase array antenna)
33 Transmission / reception changeover switch 34b Reception demodulation unit (signal demodulation means)
35 Filter section 35a Narrow band filter (first band filter)
35b Wide band filter (second band filter)
38 display unit 39 control unit (control means)

Claims (8)

A plurality of camera devices installed at a specific location, having imaging means for capturing an image, and transmission means for wirelessly transmitting data of the image captured by the imaging means;
A phased array antenna having a plurality of antennas for receiving radio signals transmitted from the transmission means of the camera device and a phase changing means for changing the directivity of the antennas, and a radio received by the phased array antenna Signal demodulating means for demodulating the signal, filter means for filtering the signal demodulated by the signal demodulating means, display means for displaying an image based on the signal passed through the filter means, the phase changing means, the signal In a wireless monitoring system comprising a monitoring device having a demodulation means, a filter means and a control means for controlling the display means,
The control means includes
While changing the directivity of the phased array antenna, measure the noise reception intensity for each predetermined direction, store this as the noise reception intensity,
Transmitting a signal including a camera ID from any camera device, and measuring the reception intensity of the signal received for each of the predetermined directions while changing the directivity of the phased array antenna,
Calculating the signal-to-noise ratio of the signal reception strength and the noise reception strength for each of the predetermined directions;
In performing communication with the camera device based on the calculated SN ratio, the directivity direction of the phased array antenna that maximizes the calculated SN ratio is determined and stored, and stored in communication with each camera device. A wireless monitoring system characterized by matching the directivity of a phased array antenna to a direction.   The wireless monitoring system according to claim 1, wherein the monitor device wirelessly communicates with the plurality of camera devices using the same frequency channel. A plurality of the camera devices, and a plurality of the monitor devices, the plurality of camera devices and the plurality of monitor devices wirelessly communicate with each other using a frequency channel assigned to each monitor device;
The control means includes
The first frequency channel assigned to any monitor device other than the self device is transmitted from all camera devices,
While changing the directivity of the phased array antenna, measure the reception strength in the second frequency channel assigned to itself for each predetermined direction, and store this as the noise reception strength,
In the second frequency channel, a signal including a camera ID is transmitted from one of the camera devices, and the reception intensity of the signal received in each of the predetermined directions is measured while changing the directivity of the phased array antenna.
The radio monitoring system according to claim 2, wherein an S / N ratio between the reception intensity of the signal and the reception intensity of the noise is calculated for each of the predetermined directions. A plurality of the camera devices and three or more monitor devices, and the camera device and the monitor device communicate with each other wirelessly using a frequency channel assigned to each monitor device,
The control means includes
Of the frequency channels assigned to each monitor device, the channel adjacent to the frequency channel assigned to itself is transmitted from all camera devices,
The radio monitoring system according to claim 3, wherein the reception intensity of the signal received in each predetermined direction is measured while changing the directivity of the phased array antenna, and this is stored as the reception intensity of noise. . The control means includes
Transmitting from a camera device adjacent to the camera device of another system on a frequency channel used for communication in the other system;
The radio monitoring system according to claim 2, wherein the reception intensity of a signal received in each predetermined direction is measured while changing the directivity of the phased array antenna, and this is stored as a noise reception intensity. . The control means includes
While changing the directivity of the phased array antenna for each specific time, measure the noise reception intensity for each predetermined direction, store this as the noise reception intensity for each specific time,
An SN ratio is calculated from the reception strength of the signal and the reception strength of noise at each specific time for each predetermined direction,
2. The communication apparatus according to claim 1, further comprising: recognizing and storing a directivity direction of the phased array antenna in which the calculated S / N ratio is maximized when communicating with the camera device at a specific time based on the calculated S / N ratio. The wireless monitoring system according to 1. The control means includes
In the normal communication standby mode, the phase changing means is controlled so that the phased array antenna is in a non-directional state,
When a communication permission request signal transmitted from any one of the camera devices is received, the camera device that has transmitted the communication permission request signal from the camera ID included in the communication permission request signal is identified and stored. The phase change means is controlled so as to obtain the directivity of the phased array antenna that maximizes the calculated S / N ratio when performing communication. The wireless monitoring system described. The filter means includes a first band filter that passes a first band signal and a second band filter that passes a second band signal wider than the first band, and selects either filter. Are selectable,
The control means includes
In the normal communication standby mode, the filter means is controlled to select the first band filter,
When receiving a communication permission request signal transmitted from any camera device, the filter means is controlled to select the second band filter, and image data is received in a high-speed communication mode. Item 8. The wireless monitoring system according to Item 7.

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