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CCTV and alarm devices in one installation More information about CCTV can be fund in our Internet CCTV guide Marek Dzioch Translated by Agnieszka Domagała Not so long time ago these both systems (CCTV and alarm system) were treated as two separate systems. Presently devices offered by manufacturers, alarm devices as well as CCTV elements are designed to make combined work mode between them possible by the ability of common connection and cooperation in order to ensure even better security of object against unauthorized people and other alarm situations. It should be remembered that well designed security system of object consists of a few security sub-systems i.e. construction (including architectural), mechanical, electromechanical and electronic. Division of alarm devices Alarm devices can be divided in two groups. Alarm outputs of almost all sensors are adapted to connection with typical devices equipped with contact inputs type NO or NC (logic of sensors usually relay on changing their status after security zone intrusion). It allows direct and simple connection of them with popular devices used in alarm technique or with CCTV devices, without any additional devices. Sensors. Infrared sensors PIR - alarm trigger is made by the detection of infrared radiation's differences, happening between object (intruder) and background (environment) in sensor's field of view. Device's alarm output switching goes after object's detection. The range of work is limited by angle and maximal range. In advanced PIR sensors, regulation of work threshold depending on light's intensity is possible (ability of work during the nighttime only) and also regulation of outer circuit switching on time (1s - 20 min). There are available PIR sensors integrated in one housing with camera i.e. camera B/W and color camera with motion detection sensor and audio module code M1094 or M10951 Infrared barriers - made of transmitter and receiver. Transmitter emits beam of infrared radiation, which drops into receiver. Switching of alarm output goes when optical connection with transmitter and receiver is broken (intrusion) Exemplary devices of this group: M1656, M1659 Glassbreak sensor - consists of two lines, the first of, them reacts to impacts onto window pane, and the second reacts to glass breaking. Construction of device allows it to be installed in 10m distance from secured window pane. Two system (dual) alarm sensor - sensor using two separate effects separately detected and processed, and then analyzed together by sensor's CPU. For example device may consist of passive infrared detector and glassbreak, or more often - passive infrared detector and microwaves, placed in common housing. Each of these two systems may have separate relay outputs. Opening sensors (doors, windows) - contactor sensors, electromechanical contact sensors - whom alarm signal is the change of position (open or closed), state of contacts. Impact sensor - layout that reacts to shocks that are effect of impacts. Ultrasound detectors - its rule of work depends on the fact that generator generates acoustic wave (40 kHz) that returns with unchanged frequency. In the case when moving object occurs inside secured room, the change of frequency and returning signal follows (Doppler's effect) alarm is triggered. There are also gas sensors available (hydrogen, carbon-dioxide, methane, butane) or even more popular smoke detectors. Smoke detector is sensitive to specific burring products and/or pyrolysis (aerosols). It mostly consists of infrared radiation transmitter and receiver placed in one housing and cooperating outlaying mirror or prism reflector. The rule of work depends on air optical transparency analysis in area between sensor and mirror or reflector. Distress beacons Optical-sound distress beacons are destined for use in burglary and robbery signalizing alarm systems and in fire signalizing systems. Sound distress beacons - depending on model, sound intensity is from the range from 85 dB to 125 dB, it's usually piezoelectric. Optical distress beacons - having the form of little lamp, illuminating diode or a device, which consist of discharging lamp with high efficient transformer with high energy flash visible in normal conditions up to 3000m. Executive devices: We include different types of devices having influence on realization of basic functions to this group i.e. grant (or not) access to specific zones (simple electromagnetic bars, or more advanced locks equipped with magnetic card readers with ability of control additional executive devices), devices controlling lighting or devices used fro radio notification of alarm situation. Electromagnetic locks - these locks rule of work depends on generation of adequate strong attraction force (electromagnetic force) from 250 Kg to more than 750 Kg. In electromagnetic bars, which holding elements is specially formed metal tap i.e. in pin form Good class locks are also equipped in various kind micro switchers informing about door opening state. Other group of devices having a use in access control systems, playing a role of locks blocking or stonewalling access to specific zones, are various kind gates, tollgates and also motive devices of drive in gates. Standard VCR initiated by PIR sensor. We can distinguish two types of these devices: standard VCR "home use", which recording time, depending on the length of used tape is maximally a few hours (video cassette 240 min, LP mode - record time 480min). The second group is CCTV video cassette recorders so called Time Lapse, whom recording time, depending on model type is up to 960 hours. Characteristic feature of these VCRs is fact that they can record particular half images (frames) from one or only a few cameras, hence significantly increasing maximal recording time. Caution: Realization of time lapse recording and playback is possible after the use of additional device, called multiplexer. High availability of home VCRs causes that large group f people wants to use them as camera image recorder even for the price of shorter recording time than CCTV VCRs offer. Continuous registration of single camera image (24h) without video tape change isn't possible for home VCR. However continuous recording isn't necessary in many surveillance systems, only registration of alarm situations that is situations in which security zone is violated. There is simple way to build, for a low cost, such a system, which by the use of additional elements i.e. alarm remote controller M1099 and various kind sensors (motion, smoke, door opening et al.), allows to use this "home video cassette recorder".
Dividers with alarm connector BQ 406 M4008 Divider (quad) is device allowing displaying a few camera images simultaneously on one monitor. Dividers have usually 4 or 8 inputs and two video outputs (these first market usually as "main" - ability of image displaying in full screen mode or in division and the second "quad"- image always in division). Also the most of dividers is equipped in alarm connector. It mostly consist of alarm inputs linked with adequate cameras (any sensor can be connected), and alarm outputs for outer devices control.
Systems work description. Detection of motion by sensor linked with adequate camera, causes device's turn in to alarm work mode. Depending on set configuration parameters of divider, there can follow a change from division work mode to full screen work mode of current alarm camera. The use of additional monitor connected to VCR ensures further all cameras simultaneous observation in division. In turn, VCR connected to alarm divider's alarm output records only alarm events, thereby significantly prolonging the time to next cassette change. Traditional analog VCR may be replaced by digital recorder i.e. M8501 AVC721. Time lapse VCRs - by the example of Computar CTR3024-E M4407. Time lapse VCRs have a lot of other functions, which usual "home VCRs" don't have, and which make the work of systems operator, who use them, much easier. All CCTV VCRs have special alarm connector, or the set of alarm inputs and outputs. They are used for communication with other outer devices being the part of surveillance system. Bellow you can find image showing the outlook of such a connector with description, by the example of time lapse VCR CTR3024-E M4407 of Computar company.
Systems work description. Thanks to connection of any sensor (i.e. PIR motion sensor) to alarm input (SET IN), in the moment of its activation (security zone violation) signal turning VCR to recording mode is triggered. Obviously it's one of the simplest solutions and nothing crosses a path for signal controlling VCRs work to be coming from previously described alarm outputs - sequencer with motion detection or dividers. Cooperation of multiplexers and alarm devices Multiplexer combines all features of sequencers and dividers, however advanced image processing functions ensure wide range of functions unavailable in previously described devices. The most important are: better way of signal recording on VCR: full screen record of images simultaneously from all cameras - "frame by frame". Thereby parameters of registered image are not spoiled and it is possible to playback in division and in full screen mode. The second of main multiplexer's features is built in motion detection system. Multiplexer allow to detect and notify alarm situations, registration of information about alarms on video cassette together with cameras images and later playback of this information. In the case of digital recorder use, all this information is registered in hard disk drive memory.. Motion detection is treated as alarm and signalized to outside, it can also trigger alarm outputs. Any devices can be connected to alarm outputs, which control signal is "closing or opening of contact in circuit". Right configured (programmed) multiplexer allows, not only to automatically turn on VCRs recording, but also to change (increase) the speed of video tape shift (in alarm recording mode) in order to ensure better quality of recorder image.
Digital recorders (digital VCRs - recording on HDD). By the use of it we can not only trigger recording mode, or turn device to alarm mode, what will effect on execution of previously programmed operations by it (i.e. generation of acoustic signal, closing/opening of adequate alarm connector's contacts, turning to other recording speed mode). It is also possible to execute other functions such as, control of recorder from the level of computer through RS232 connector.
Below you can find simple scheme with the use of digital recorder, camera and alarm sensor (motion, opening, smoke et al.).
Recorder starts to record only in moment when its alarm connector is triggered by the signal coming from alarm sensor. Image from camera is being recorded as long as it's defined by installator (in recorder's menu). After this period, if the sensor isn't triggering any longer, device stops recording mode. This solution allow to use capacity of data carrier optimally, because recorded are only situations in which something is going on. We can extend the system in simple and cheap way by adding a divider (quad i.e.M4010) and connecting it to recorder, then we can record images from 4 cameras in 2x2 division.
Digital recording - new abilities In digital recording, cooperation with alarm systems is based on image motion detection, which may activate alarm connectors, obviously there can also occur opposite direction of activation that is signal from connector activating recording mode. Alarm connectors of GeoVision and HICAP systems. They are special modules having right number of connectors, slots in the form of socket strip mounted inside computer's housing in free PCI slot. It's also possible to trigger alarm outputs using image detection or audio detection (videlicet image's change of camera and the change of audio level on audio module can cause trigger of one or more previously linked (in setup menu) with them alarm outputs. Additionally we can define the time of relay holdoff, what ensures i.e. generation of alarm signal during specified time period. Alarm inputs can be freely configured: we can set the level of signal high or low, define, which of alarm outputs will be activated and what will be the time of relay holdoff. Below you can find the scheme of registration, security and simple access control system realized basing on HICAP card. (The same system can be realized basing on GeoVision card). - module of alarm inputs/outputs (M8355) ( "blue" block - control of other elements (drive in gate, alarm and fire system's elements) - audio registration card Hera (M8354) ("green" block) - PTZ controller (M8358 +M8359) ("yellow" block)
Entry to parking area can cause: Using controller's features (M8358 +M8359) it's possible to do detailed observation of car. Card with connected signals from videophone allows to record people visiting company, as well as voice received by this device. Connection of alarm signals of fire and alarm installation to card's inputs allow to carry out previously programmed sequence i.e. transmission of image from the place of sensor's activation. |
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