GB2215568A

GB2215568A - CCTV/surveillance system

Info

Publication number: GB2215568A
Application number: GB8804032A
Authority: GB
Inventors: Paul Fletcher; Alan Dawe
Original assignee: PHOTO SCAN Ltd
Current assignee: PHOTO SCAN Ltd
Priority date: 1988-02-22
Filing date: 1988-02-22
Publication date: 1989-09-20
Also published as: GB8804032D0

Abstract

A closed-circuit television system makes use of a cable broadcast television distribution system 20 to transmit signals from a surveillance camera 10 through a return channel 26 in the cable system to a monitor/control station 16. At this location camera control signals are generated which are appropriately modulated 30 and transmitted in the forward direction through a path 32 in the cable network. The control signals are demodulated 40 and applied to the camera to control e.g. its orientation, or zoom or focus. <IMAGE>

Description

INFORMATION TRANSMISSION This invention relates to information transmission systems and methods.

In the field of closed circuit television (CCTV) used for surveillance purposes it is known to have a TV camera which is adjustable, in terms of orientation, zoom or focus for example, and which is controlled from a location remote from the camera and where the display is monitored. To this end the camera video output is transmitted by a suitable special cable to the control monitor location, and control signals are transmitted over cable from the control monitor location to the camera.

In certain places cable television systems exist which provide video channels between various physically-remote locations. Such cable TV systems broadcast several television channels from a broadcasting station or stations to a large plurality of users.

Some such cable TV systems have a return video channel which allows video signals to be transmitted back from one of the user locations in the opposite direction to the direction of transmission of the broadcast TV signals. It is known to use part of such a system to transmit CCTV signals from a fixed surveillance camera to a monitor station. The present invention is defined in the appended claims to which reference should now be made.

In accordance with this invention we propose transmitting control signals from the monitor station to the camera to control the camera along the same cable TV transmission system as is used for the broadcast TV distribution and the returning CCTV signal.

The method can be used for various types of surveillance including monitoring traffic movements, or protecting property, plant, machinery or vehicles. Additionally or alternatively public address signals can be transmitted from the monitor station to the camera location by the method.

The invention will be described by way of example with reference to the accompanying drawing, which shows a block diagram of an information transmission system embodying the invention.

As shown in the drawing the CCTV system includes a camera 10 at a surveillance location 12 and a monitor display 14 at a monitor/control location 16. To connect the two locations use is made of a cable broadcast TV distribution system 20 which distributes broadcast TV signals in a forward direction as shown by channels 18.

At the monitor/control location 16 a display control unit 22 receives a video signal on a line 24 which is returned by a return video channel 26 in the cable system 20. The unit 22 also connects to a keyboard and control unit 28 which generates control signals which are applied to a transmitter 30. The transmitter 30 modulates the control signals onto an appropriate frequency and applies an output to a forward transmission path 32 in the cable distribution system which may be a video channel or a separate data channel.

At the surveillance location a receiver 40 receives the control signals from the transmission path 32 and demodulates them to baseband. The signals are, applied through a pulse shaper 42 to a decoder unit 44 which decodes them for application to the camera.

The unit 44 also receives the video output from the camera 10 and applies it over a line 46 to the return video channel 26.

The display control unit 22 and the decoder 44 are standard CCTV units. The transmitter 30 and receiver 40 can conveniently be specially adapted telemetry equipment such as sold by Wood and Douglas Ltd., Reading, England as their RF Telemetry Link TT400MS/TR400S. It is altered so as to work at the required frequency range which may for example be of the order of 150MHz rather than normal telemetry frequencies of 450MHz.

The control signals can control a variety of camera functions including: pan, tilt, zoom, focus, iris opened or closed, or camera selection, and can be used also for auxiliary function such as turning floodlights on for example.

The system permits users of CCTV systems to send their pictures to remote locations for monitoring or control purposes using a cable television company's circuits and to select and control cameras over the same circuits.

The user has complete flexibility in locating his cameras' control and monitoring equipment anywhere within the cable television company's system or via any national or international links that are available and suitable.

Claims

1. An information transmission system comprising a plurality of forward video transmission channels for transmission of broadcast video signals from at least one source station to a large number of user stations, at least one return video channel for transmission of video signals in the return direction, video surveillance means at a surveillance location for generating a surveillance video signal applied to the return video channel, monitor means remotely located with reference to the video surveillance means and connected to the return video channel to monitor the returning surveillance video signal, control signal generation means associated with the monitor means for generating control signals and connected to the transmission system for transmission of the control signals in the forward direction over the transmission system, and means at the surveillance location connected to the transmission system and responsive to the control signals to perform surveillance functions.

2. A system according to claim 1, in which the surveillance means comprises a video camera and the control signals control the camera operation.

3. A method of information transmission comprising transmitting over a cable distribution network a plurality of broadcast television signals from at least one source station to a large number of user stations, providing a return video channel in the cable distribution network, and transmitting surveillance video signals from a surveillance channel over the return videol channel to a monitor station, wherein control signals are transmitted from the monitor station to the surveillance station over the cable distribution network to perform surveillance functions at the surveillance station.

4. A method according to claim 3, in which the control signals are transmitted over a video channel in the network.

5. A method according to claim 3, in which the control signals are transmitted over a data channel in the network.

6. A method according to claim 3, in which the control signals are replaced by public address signals.

7. An information system substantially as herein described with reference to the drawing.

8. A method of information transmission substantially as herein described with reference to the drawing.