JP3246565B2 - Monitoring system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a monitoring system,
In particular, the present invention is suitable for use as a surveillance system in which video cameras are provided at a plurality of locations and each video camera monitors the installation location.

[0002]

2. Description of the Related Art As a conventional monitoring system, a single bus line can only transmit image signals from one video camera. Therefore, there are multiple monitoring locations,
In order to transmit the image, sound and detection signal from the sensor at the same monitoring location, a dedicated transmission line is provided for each, connecting the monitoring location with the monitoring center, and the monitoring center remotely controls each video camera. At the same time, an image signal and an audio signal from the video camera and a detection signal from the sensor are reproduced on a monitor or the like, and the state of the monitoring place is monitored.

[0003]

In the conventional system, three cables are required to transmit an image signal, an audio signal, and a detection signal from a sensor from a single monitoring location, and the monitoring location is required. If the number is increased, the number of connection cables also increases as the number of monitoring places increases, and installation work and maintenance and inspection require a lot of cost. The present invention
The image signal from the imaging unit and the detection signal from the sensor unit are time-division multiplexed into an image signal, and the audio signal from the microphone is time-axis-compressed and superimposed on the same image signal and transmitted. It is an object of the present invention to provide an economical surveillance system in which a place and a master control device can be connected and monitored by a single bus line so that installation work and maintenance and inspection can be omitted.

[0004]

FIG. 1 is an electric circuit block diagram of a monitoring system showing one embodiment of the present invention.
As shown in the figure, an imaging unit (not shown) that captures an image of a predetermined monitoring target area and outputs an image signal, and a microphone (12 to 15) that collects sound in the same area, converts the sound into an audio signal, and outputs the signal. )
And a plurality of video cameras (1 to 4) each including a sensor unit (8 to 11) for detecting environmental information in the same area and outputting a detection signal, connected to the master control device 5 via a bus line, Means for transmitting the image signal and the detection signal in a time-division multiplexed manner to the video cameras (1 to 4); And transmits the image signal, the audio signal, and the detection signal of the sensor unit, and controls each of the video cameras (1 to 4) by the master controller 5;
The time-division multiplexed signal is demodulated and output as an image signal, an image is displayed based on the output, an audio signal superimposed and superimposed on the image signal in a time axis is decompressed and demodulated in the time axis, and output. The sound is reproduced based on the output.

FIG. 2 is an electric circuit block diagram of a signal processing unit provided in each of the video cameras of FIG. 1. A means for time-division multiplexing and transmitting the image signal and the detection signal is provided by the imaging unit 20. An A / D converter 21 for converting an image signal of a captured monitoring target area into a digital signal, a field memory 22 for storing the digital signal, and data read from the field memory 22 and detected by the sensor unit 23 In response to the detection signal, an address control unit 24 that performs address control, a line memory 25 that writes, reads, and outputs a predetermined position in accordance with the address given by the address control unit 24, and outputs the output from the line memory 25 An output unit 33 that converts the signal into an analog signal and sends the signal to a bus line;
And a control unit 26 for determining a command signal input from the controller and outputting a control signal. Based on the control signal, the imaging unit 20, the field memory 22, and the address control unit 2
4 and the line memory 25 are controlled.

A means for compressing and superimposing the audio signal on the time axis during the vertical blanking period of the image signal and transmitting it is a microphone 28 and an audio signal collected and converted by the microphone 28 in a monitoring target area. A / D converter 29 that converts the digital signal into a digital signal and outputs the digital signal, and a memory 30 that compresses the digital signal on the time axis. The output from the memory 30 is input to the output unit 33, 33, the image signal input from the line memory 25 and the memory 30
Is switched to the audio signal input from the controller, and the audio signal is superimposed during the vertical blanking period of the image signal, converted to an analog signal and transmitted to the bus line.
A clock signal for sampling of the / D converter 29 is supplied, a clock signal for writing and reading to and from the memory 30 is supplied, and an output switching signal of the output unit 33 is output.

FIG. 3 is a block diagram of the master control device shown in FIG.
It is an electric circuit block diagram of a signal processing part. The image signal input through the bus line is branched and one is input to the control unit 37, the other is input to the A / D converter 36,
The A / D converter 36 converts the digital signal into a digital signal and splits the digital signal. One is input to an image reproducing circuit, and the other is input to an audio reproducing circuit. The image reproducing circuit includes an address control section 38 for controlling the address of the digital signal, and a field memory 39 for writing, reading and outputting at a predetermined position according to the address given by the address control section 38.
A D / A converter 40 that converts the output into an analog signal and outputs the image signal as an image signal; and separates the time-division multiplexed detection signal from the input image signal at the sensor unit and inputs the image signal. A control unit 37 that outputs a control signal in accordance with the operation signal, a display control unit 41 that converts a detection signal separated by the control unit 37 into a display signal, and an image signal and display from the D / A converter 40. A synthesizing unit 42 for synthesizing the display signal from the control unit 41 and outputting the synthesized signal.
In addition to controlling the address control unit 38 and the field memory 39 based on the control signal from the control unit 7, a synchronizing signal and a command are generated and transmitted to the bus line.

The audio reproducing circuit includes a memory 44 for extending the audio signal in the digital signal on a time axis, and a memory 44 for expanding the audio signal.
And a D / A converter 45 that converts an input from the A / D converter into an analog signal and outputs the same, and supplies a clock signal for sampling at the A / D converter 36 and a clock signal for writing and reading to and from the memory 44. The audio signal is extended on the time axis and reproduced by the control unit 37 that performs the reproduction.
Further, a command signal is generated in accordance with the operation signal input by the control unit 37 and transmitted to the transmission side. The command signal is input to the control unit 26 on the transmission side, and the control unit 26 is controlled in response to the command signal. By switching the output unit 33 in accordance with the control signal output from the controller, the audio signal can be superimposed at a predetermined position in the vertical blanking period.

[0009]

According to the present invention, a plurality of video cameras 1 to 4 are connected to the master control unit 5 by one bus line, and the video signals (1 to 4) are transmitted to the video cameras (1 to 4). Means for transmitting in a time-division multiplexed manner, and means for transmitting the audio signal by compressing the time axis in the vertical blanking period of the image signal and superimposing the same, and transmitting the image signal, the audio signal, and the detection signal of the sensor unit. The master control unit 5 demodulates the time-division multiplexed signal and outputs it as an image signal. Based on the output, an image is displayed, and the audio signal superimposed on the image signal by time axis compression is expanded in time axis. The demodulated signal is output, and the sound is reproduced based on the output. FIGS. 4A and 4B are explanatory diagrams showing the configuration of signals used for transmitting image signals according to the present invention. Four video cameras 1 to 4 are used. A case is shown in which a captured image signal is displayed as four child screens on a main screen. FIG. 4A shows the configuration of each field. As shown in FIG. 4A, signals are transmitted using 525/2 horizontal scanning lines per field, similarly to a normal television signal. So that each video camera 1
, The image signals are written to, read out from, and output from the field memories 22 provided for the four video cameras. It can be transmitted in the field.

FIG. 4B shows a configuration of each horizontal scanning line. As shown in FIG. 4B, an image of each video camera is displayed as a 1/4 child screen on a main screen of the monitor. For example, the image of one video camera has two, one horizontal scanning line, and the number of lines to be transmitted is reduced to 1, 3, 5 or less. The scanning lines are transmitted, and the detection signal of the sensor unit and one horizontal scanning line are divided and transmitted in one part. As shown in FIG. 3, the master control device 5 separates the detection signal of the sensor unit time-division multiplexed by the control unit 37 from the transmitted signal, converts it into a display signal by the display control unit 41, and outputs the display signal. In addition, the transmitted signal is written into the field memory 39 in a predetermined order, read out and output, thereby demodulating the time-division multiplexed signal, outputting the demodulated signal as an image signal, synthesizing it with the display signal, and inputting it to a monitor or the like. Therefore, the plurality of video cameras 1 to 4 are connected to the master control device 5 with one bus line, and the image signals and the detection signals of the sensor unit are transmitted and reproduced. It becomes possible.

As shown in FIG. 2, an audio signal from a microphone is compressed on a time axis and transmitted by being superimposed on an image signal from an image pickup unit. For example, if an audio signal is converted into a digital signal by the A / D converter 29 using a sampling frequency of 30 KHz, the audio signal is 30 KB.
(Kilobyte) digital signal. If a signal of 60 fields per second is used as an image signal in the same manner as a normal television signal, 30 KB / 60 =
It is enough to transmit a 500B (byte) audio signal,
An audio signal of 500 samples is transmitted during 1H of the horizontal scanning line for each field.
Write using a 30 KHz clock signal, and add 4 fsc (burst signal, 3.58 MH) to the read clock signal.
The audio signal is read out using the frequency of about 4 times z), and the audio signal is compressed on the time axis and output from the memory 30.

FIG. 5 is an explanatory diagram of the position of the audio signal superimposed on the image signal. As shown in FIG. 2, a counter that uses a vertical synchronization signal as a reset signal and a horizontal synchronization signal as a clock signal is provided in the control unit 26, and the counter controls the scanning line according to a command signal input to the control unit 26. And outputs a control signal to the output unit 33.
And by switching the image signal input from the line memory 25 to output the audio signal from the memory 30, the audio signal is superimposed immediately after the burst signal on the horizontal scanning line. It is possible to output the image signal. Therefore, it is possible to transmit the image signal and the audio signal by one cable by compressing and superimposing the audio signal on the image signal on the time axis.

[0013]

FIG. 1 is an electric circuit block diagram of a monitoring system showing one embodiment of the present invention. 1 to 4 are video cameras, 5 is a master control device, and video camera 1
And a master controller 5 are connected by one bus line, and each of the video cameras 1 to 4 has an imaging unit (not shown) for imaging a predetermined monitoring target area and outputting an image signal;
A microphone (12 to 15) for collecting sound in the same area, converting the sound into an audio signal and outputting the signal, and a sensor unit (8 to 11) for detecting environmental information of the same area and outputting a detection signal;
Further, a means for transmitting the image signal and the detection signal in a time-division multiplexed manner and a means for transmitting the audio signal by compressing the time axis in a vertical blanking period of the image signal and superimposing the audio signal are provided. And an audio signal and a detection signal of the sensor unit. The master control device 5 controls the video cameras 1 to 4, demodulates the time-division multiplexed signal from the transmitted signal and outputs it as an image signal, and displays an image on a monitor 6 or the like based on the output, and displays the image. The audio signal superimposed on the signal by time axis compression is expanded on the time axis, demodulated and output, and the sound is reproduced by the amplifier 7 or the like based on the output.

FIG. 2 is an electric circuit block diagram of a signal processing unit provided in each of the video cameras of FIG. 1. First, transmission of an image signal will be described. Reference numeral 20 denotes an imaging unit which converts the state of the monitoring place into an image signal, outputs the image signal, inputs the image signal to an A / D converter 21, samples the image signal input by the A / D converter 21, and converts the image signal into a digital signal. The output is converted and input to the field memory 22. In the field memory 22, the input image signal is written to a predetermined position, read out, and output, so that the image signal from the imaging unit 20 is set to a predetermined size and a predetermined position as shown in FIG. Video cameras 1 to 4
Is divided into one field and transmitted.

Reference numeral 23 denotes a sensor unit, which detects environmental information of a monitoring target area, outputs a detection signal, and outputs a detection signal.
4, the address control unit 24 adds an address to the detection signal and the data read from the field memory 22 and outputs the data. The data is input to the line memory 25, and according to the address given by the line memory 25, By writing, reading and outputting at a predetermined position, FIG.
As shown in (B), the horizontal scanning lines of the image signal from the imaging unit 20 are thinned out for each line and transmitted.
3, 5 or less, compressing the horizontal time axis so that two horizontal scanning lines are transmitted during 1H, and dividing the detection signal of the sensor unit 23 and one horizontal scanning line into one part And transmit it. An output unit 33 converts an output from the line memory 25 into an analog signal and outputs the signal, and transmits a time division multiplexed signal to a bus line via an input / output terminal 34.

Reference numeral 26 denotes a control unit, which discriminates a synchronization signal and a command from a control signal input from the master control device 5 via a bus line, and outputs a control signal. The control signal is input to the imaging unit 20 to control the camera angle of the imaging unit 20 and to supply a clock signal for signal processing. The control signal is input to the field memory 22 and written. And a clock signal for read and read, so that an image signal from the imaging unit 20 can be superimposed on a predetermined position of a field at a predetermined size,
The control signal is input to the address control unit 24 and the imaging unit 2
The number of a scanning line on which both signals are superimposed on the image signal from 0 and the detection signal of the sensor unit 23 is specified.
The control signal is input to the line memory 25, clock signals for writing and reading are supplied, and a horizontal scanning line of an image signal from the imaging unit 20 is thinned out on a scanning line of a designated number, so that a horizontal time axis is obtained. Is compressed so that the image signal and the detection signal of the sensor unit 23 can be superimposed.

FIG. 3 is a block diagram of the master controller shown in FIG.
FIG. 2 is an electric circuit block diagram of a signal processing unit. First, reproduction of an image signal will be described. Reference numeral 35 denotes an input / output terminal, which is connected to the input / output terminal 34 of FIG. 2 by one bus line, branches a transmitted signal, inputs one of the signals to a control unit 37, and The detection signal of the sensor unit time-division multiplexed at 37 is separated and input to the display control unit 41, which converts the signal into a display signal and outputs the signal.
Is being entered. The other side is input to an A / D converter 36, which converts the time-division multiplexed signal input from the A / D converter 36 into a digital signal, outputs the digital signal, and inputs the digital signal to an address control unit 38. . The address control unit 38 adds an address to the input digital signal and outputs the digital signal.
Input to the field memory 39 and the field memory 3
According to the address given in step 9, write to a predetermined position, read out and output, input to the D / A converter 40,
The signal is converted into an analog signal by the D / A converter 40, output as an image signal, input to the synthesizing unit 42, and synthesized with the image signal from the display control unit 41 and output via the output terminal 43. , And the output is input to the monitor 6 shown in FIG.
An image signal captured by each of the video cameras 1 to 4 is displayed on the parent screen of the monitor 6 as four child screens, and environmental information detected by the sensor unit can be displayed on each child screen.

The control section 37 outputs a control signal in accordance with the input operation signal, and outputs the control signal to the address control section 38.
And assigns an address to the image signal from the imaging unit 20 which is superimposed on the scanning line of the designated number, and inputs the same control signal to the field memory 39 to generate the write and read clock signals. And supplies an image signal from the imaging unit 20 in accordance with the address.
9 to be read, output, and
A synchronizing signal and a command are generated in accordance with the input operation signal and transmitted to the bus line. Note that when increasing the number of video cameras installed,
In FIG. 4A, the number of horizontal scanning lines applied to the image signal of one video camera is reduced, and the image signal of each video camera is superimposed on one field. In FIG. The image signal of each video camera and the detection signal from the sensor unit may be transmitted as a time-division multiplexed signal by appropriately thinning out the horizontal scanning lines of the signal and compressing the time axis in the horizontal direction.

Next, transmission of an audio signal will be described with reference to FIG. Reference numeral 28 denotes a microphone, which collects sounds in a monitoring target area, converts the collected sounds into audio signals, and outputs the audio signals to an A / D converter 29.
Is being entered. The A / D converter 29 converts the input audio signal into a digital signal using a 30 KHz clock signal input from the control unit 26, outputs the digital signal, and inputs the digital signal to the memory 30. The memory 30 has a FIFO (first-in firs
Using a t-out) type memory, the digital signal from the A / D converter 29 is written with the clock signal input from the control unit 26, read out in order, and output, and 30 KHz is used as the write clock signal. Then, the audio signal is compressed on the time axis using a frequency of 4 fsc as a clock signal for reading and input to the output unit 33.

The image signal from the image pickup unit 20 is branched and one is input to the control unit 26. The control unit 26 detects a horizontal synchronizing signal or a burst signal in the image signal and generates a clock signal of the generated clock signal. The other of the split image signals is input to the A / D converter 21 so that the timing and the phase are matched, and the A / D converter 21 outputs the image signal using a clock signal having a frequency of 4 fsc input from the control unit 26. The signal is converted into a digital signal and output, and the signal processing described above is performed and input to the output unit 33. The output unit 33 receives a control signal from the control unit 26 and normally outputs the image signal. The output unit 33 switches the output unit 33 at a predetermined position in a vertical blanking period of the image signal.
It outputs the audio signal input from 0,
The output unit 33 outputs an image signal on which the audio signal is superimposed. The output unit 33 includes a switch circuit 31 and a D / A converter 32. The switch circuit 31 receives an audio signal from the memory 30 and an image signal from the line memory 25, and The signal input to the switch circuit 31 can be switched and output according to a control signal from the D / A converter 32. The output is converted to an analog signal by a D / A converter 32 and transmitted to a bus line via an input / output terminal 34. Is done.

Next, reproduction of an audio signal will be described with reference to FIG. An image signal on which an audio signal transmitted via the bus line is superimposed is input via an input / output terminal 35. The input is branched and one of the input signals is input to a control unit 37. To detect the horizontal synchronizing signal or the burst signal in the image signal so that the timing and the phase of the clock signal to be generated coincide with each other, and the other of the branched signals is inputted to the A / D converter 36, and the A / D
The converter 36 converts the digital signal into a digital signal based on a clock signal having a frequency of 4 fsc from the control unit 37 and outputs the digital signal. The output is branched, and one is input to an image signal processing circuit to reproduce an image signal. Are input to the memory 44. A memory of a FIFO (first-in first-out) type is used as the memory 44, and only the audio signal which is compressed on the time axis and superimposed on the digital signal from the A / D converter 36 is extracted. It is written with a clock signal having a frequency of 4 fsc input from the control unit 37, and is similarly read out and output in the order of writing with a 30 KHz clock signal input from the control unit 37. The compressed portion is decompressed by extending the time axis and input to the D / A converter 45. The restored audio signal is supplied to the D / A converter 4
5, the signal is converted into an analog signal, output via an output terminal 46, and the output is input to the amplifier 7 or the like shown in FIG. 1 to reproduce an audio signal.

Further, an analog command signal is generated in accordance with the operation signal input by the control unit 37 and transmitted to the transmitting side via the input / output terminal 35, as shown in FIG.
On the transmission side, the analog command signal transmitted via the input / output terminal 34 is input to the A / D converter 27,
The digital signal is converted into a digital signal so that it can be input to the control unit 26 by the / D converter 27, and the command signal is input to the control unit 26, and the switch circuit 31 is switched by the control signal from the control unit 26 to Is output, a predetermined position of the vertical blanking period, for example, as shown in FIG.
Microphone 1 provided in video camera 1 shown in FIG.
2 can be superimposed. Similarly, the signal processing unit provided in the video camera 2 superimposes the audio signal from the microphone 13 shown in FIG.
Similarly, audio signals from the microphones can be superimposed at predetermined positions and output. In FIG. 4B, the sensor detection signal may be superimposed on the vertical blanking period, similarly to the audio signal, instead of being superimposed on the image signal superimposition period of the horizontal scanning line. At this time, in FIG. 2, a detection signal from the sensor unit 23 is input to the switch circuit 31, and switching is performed at a position of a predetermined number of horizontal scanning lines by a switching signal from the control unit 26.
What is necessary is just to make it output the detection signal from the sensor part 23 from the switch circuit 31.

[0023]

As described above, according to the present invention,
An image signal obtained by time-division multiplexing an image signal from each image pickup unit of a video camera provided at a plurality of monitoring locations and a detection signal from each sensor unit at a predetermined position, and the image signal is an audio signal from each microphone. Is time-axis-compressed and superimposed at a predetermined position and transmitted, and the master control device reproduces the time-division multiplexed signal and reproduces the time-axis-compressed and superimposed audio signal during the vertical blanking period of the image signal. An economical surveillance system that can connect multiple monitoring locations and the master controller with a single bus line for monitoring, saving installation work and maintenance. Can be provided.

[Brief description of the drawings]

FIG. 1 is an electric circuit block diagram of a monitoring system according to an embodiment of the present invention.

FIG. 2 is an electric circuit block diagram of a signal processing unit provided in each of the video cameras of FIG. 1;

FIG. 3 is an electric circuit block diagram of a signal processing unit provided in the master control device of FIG. 1;

FIGS. 4A and 4B are explanatory diagrams showing a configuration of a signal used for transmitting an image signal according to the present invention.

FIG. 5 is an explanatory diagram of a position of an audio signal to be superimposed on an image signal.

[Explanation of symbols]

 Reference Signs List 1 video camera 2 video camera 3 video camera 4 video camera 5 master control device 6 monitor 7 amplifier 8 sensor 9 sensor 10 sensor 11 sensor 12 microphone 13 microphone 14 microphone 15 microphone 20 imaging unit 21 A / D converter 22 field memory 23 sensor Unit 24 address control unit 25 line memory 26 control unit 27 A / D converter 28 microphone 29 A / D converter 30 memory 31 switch circuit 32 D / A converter 33 output unit 34 input / output terminal 35 input / output terminal 36 A / D converter 37 control unit 38 address control unit 39 field memory 40 D / A converter 41 display control unit 42 synthesis unit 43 output terminal 44 memory 45 D / A converter 46 output terminal

Claims (6)

(57) [Claims] 1. An imaging unit for capturing an image of a predetermined monitoring target area and outputting an image signal, a microphone for collecting sound of the same area, converting the sound into an audio signal and outputting the signal, and detecting environmental information of the same area. A plurality of video cameras having a sensor unit that outputs a detection signal, a bus line connecting to a master control device, a means for transmitting the image signal and the detection signal to the video camera by time-division multiplexing, Means for transmitting an image signal, a sound signal, and a detection signal of a sensor unit in a time axis compressed and superimposed manner during a vertical blanking period of the image signal, and transmitting the video signal by a master controller. Along with controlling the camera, demodulate the time-division multiplexed signal and output it as an image signal, display an image based on the output, and time-decompress and demodulate the audio signal superimposed on the image signal by time axis compression. Output And a sound reproduction system based on the output. 2. A first-A means for converting the image signal and the detection signal by time-division multiplexing and transmitting the image signal of a monitoring target area imaged by the image pickup unit into a digital signal.
/ D converter, a first field memory for storing the digital signal, and a first address control unit for performing address control on data read from the first field memory and a detection signal detected by the sensor unit. And the first
A line memory for writing, reading and outputting at a predetermined position according to the address given by the address control unit;
An output unit that converts an output from the line memory into an analog signal and sends the analog signal to the bus line; and a first unit that determines a command signal input from the master controller via the bus line and outputs a control signal. 2. The monitoring system according to claim 1, further comprising a control unit, wherein the control unit controls the imaging unit, the first field memory, the first address control unit, and the line memory based on the control signal. system. 3. The image processing apparatus according to claim 2, wherein the master control device branches an image signal input through the bus line, and branches one of the image signals into a second image signal.
A circuit for inputting to the control unit, a circuit for inputting the other to the fourth A / D converter, converting the digital signal into a digital signal, and outputting the digital signal; a second address control unit for controlling the address of the digital signal; A second field memory for writing, reading and outputting at a predetermined position in accordance with the address given by the unit, a first D / A converter for converting the output into an analog signal and outputting it as an image signal, A second control unit that separates a time-division multiplexed detection signal from the sensor unit from an image signal and outputs a control signal in response to an input operation signal; and a detection signal separated by the second control unit. A display control unit that converts the
A synthesizing unit for synthesizing and outputting the image signal from the first D / A converter and the display signal from the display control unit, and the second address control unit based on the control signal from the second control unit. 3. The monitoring system according to claim 1, further comprising controlling the second field memory and the second field memory, generating a synchronization signal and a command, and transmitting the generated signal to the bus line. 4. 4. The microphone according to claim 1, wherein said means for compressing and superimposing the audio signal on the time axis during the vertical blanking period of the image signal and transmitting the signal is a microphone and a second A for converting the audio signal from the microphone into a digital signal and outputting the digital signal. / D converter, and a first memory for compressing the digital signal on the time axis. An output from the first memory is input to the output section, and an image signal input from the line memory at the output section. And the audio signal input from the first memory, and superimposes the audio signal during the vertical blanking period of the image signal, converts the signal into an analog signal, and sends the analog signal to the bus line. A sampling clock signal for the second A / D converter is supplied, a clock signal for writing to and reading from the first memory is supplied, and an output switching signal for the output section is output. The monitoring system according to claim 1 or 2, wherein 5. A fourth A / D converter for converting an image signal input via the bus line into a digital signal, and a second A / D converter for extending an audio signal in the digital signal on a time axis. A second D / A converter for converting an input from the second memory into an analog signal and outputting the analog signal, wherein the second control unit supplies a sampling clock signal for the fourth A / D converter And the second
The monitoring system according to claim 1, 23, or 4, wherein a clock signal for writing to and reading from the memory is supplied. 6. A command signal is generated in accordance with an operation signal input by the second control unit and transmitted to a transmission side. The command signal is input to a first control unit of the video camera, and 5. An audio signal is superimposed on a predetermined position in a vertical blanking period in the first memory by a control signal output from the first control unit in response to the signal. Or the monitoring system according to 5.