Author: Philip Ridgeon and Mike Constant
ISBN No: 0 947665 25 0
Review date: 09/06/2026
No of pages: 348
Publisher: Miller Freeman UK, 630 Chiswick High Road, London W4 5BG
Year of publication: 11/09/2012
Brief:
The Principles and Practice of CCTV is a technical book but with aspects for the end user.
By Philip Ridgeon and Mike Constant. Second edition 2000. <br><br>
The Principles and Practice of CCTV is a technical book but with aspects for the end user – namely the chapters on ‘surveying for CCTV’, ‘specifying CCTV systems’ and ‘testing and commissioning systems’. There are useful checklists for a system brief and camera locations. What is striking is that pitfalls as the authors put it are ‘created by a poorly structured or ill-thought out specification’ – the same as with any product or service. A layman’s little knowledge can be dangerous indeed Interestingly, the first question directed at the end user is: do you really need CCTV? A site must have finite reasons for considering CCTV, whether it’s for industrial espionage or to replace or supplement manned guarding. Setting down what you the end user expect the system to achieve can be a simple statement, but can help with the design of the layout. There’s a couple of pages of examples of provisions for the customer to give to the CCTV installer – such as sub-contracting (not without the customer’s permission) and health and safety (yes, do comply with all of it). The authors admit that Murphy’s Law does happen, but ‘there is no excuse for sheets of graph paper covered with correting fluid and nearly unreadable. There are many project planning software programs around’. Any of them are better than the plan for a seven-camera town centre scheme that has 15 boxes that with three ticks to show procurement ticked in week one, five cameras in week tow and two in week three. Finally, the book goes through testing and commissioning, from testing components to training operators. ‘The usual methods of testing CCTV systems are very subjective and can vary from site to site’ – hence legal problems. The book recommends the ROTAKIN device.
Both authors have an engineering background: today Mike Constant is a consultant while Philip Ridgeon was made UK Sales Manager for manufacturer Gyyr in 1997. The main point to their second edition is the coverage of digital technology, that has advanced far since the first editiion of 1994. The authors argue that the primary successes of digital recorders have been in event recording, ‘where fast recording and search makes digital recorders most attractive’. Digital recorders that include multiplexers helps to make them cost effective, the authors add. Earlier, they point out that while digital is the obvious way forward, and advances are fast, analogue recorders score on price: ‘… a videotape costing a few pounds can store over 432,000 high quality colour images, using a recorder costing a few hundred pounds. To store the same number of pictures digitally is very costly, both in storage media and hardware required to write to it.’ The rest of the chapter tells you all you need to know about digital storage media and types of digital video recorder. An example of the fast developments in digital is in the page on use of digital video recordings in evidence; it is no fault of the authors, who point out that there is ‘continuing debate over the admissibility of digital video recordings for evidential purposes’. Most digital processing includes some form of encryption, and methods of maintaining the integrity of digital storage will certainly be developed.
The chapter on fibre optics is equally thorough, including a highly useful glossary (there’s another, longer glossary at the end of the book). The chapter concludes: ‘Efficiency in transmission may not be the only reason for considering fibre optic cables. There can be significant savings where there are long cable runs or multiple cables needed.’ It’s a technical book, but it does apply the technology to the reasons in the field. For instance, in the chapter on video motion detection, the authors make it clear: ‘The primary function of a VMD system is to relieve CCTV operators from the stress of monitoring one or many screens of information that may not change for long periods. The VMD system will be monitoring all the cameras in the system, and only reacting when there is suspicious activity in one of the scenes.’ And if an intruder generates an alarm and is out of view of the camera before it is displayed, so that the operator sees a blank screen, at the time of detection ‘many VMD systems will capture an alarm image sequence containing one or more freeze frames’.
A chapter on interfacing with other systems will be of interest to security managers, because as the authors say, CCTV is seldom on its own. They discuss interfaces with access control systems and a PC, and links to alarm receiving centres.
Earlier, chapter four on lenses opens with an interesting comparison between humans and CCTV as surveillance devices: ‘The human eye is an incredibly adaptable device that can focus on distant objects and immediately refocus on something close by. It can look into the distance or at a wide angle nearby. It can see in bright light or at dusk, adjusting automatically as it does so. It also has a long ‘depth of field’, therefore, scenes over a long distance can be in focus simultaneously. It sees colour when there is sufficient light, but switches to monochrome vision when there is not. It is also connected to a brain that has a faster updating and retentive memory than any computer …. The brain accepts all the data and makes an immediate decision to move to a particular image of interest … By contrast, the basic lens of a CCTV camera is an exceptionally crude device.’ It sounds a persuasive case for using guards for surveillance. However, though it is not the sort of book for the authors to say so, cameras do not get cold and do not nip back to the car or the office for a sandwich or to clean fishing tackle or do the crossword. The authors do make the point about the correct selection of the lens: ‘The problem is that the customer may have a totally different perspective of what a lens can see compared to the reality. This is because most people perceive what they want to view as they see it through their own eyes. Topics such as identification of miscreants or numberplates must be subjects debated frequently between installing companies and customers.’ As in many things, it’s a question of compromise; as the authors explain: ‘It is just not possible to view the whole of a large loading bay and read all the vehicle number plates with one camera.’ The rest of the lenses chapter includes many tables, formulae and much data on what lens is right for what application.<br><br>
Monitors are another overlooked part of the CCTV system, the authors say, and they have an important diagram on ergonomics and the control room operator. There’s all you need to know besides about (to list the chapter headings) the fundamentals of video, cameras, monitors, video switching, analogue video recording, housings, remote positioning devices, control systems, multiple screen displays, light and illumination, and transmission. Right from the start there are plenty of clear black and white diagrams and tables that break with the text of what could have been a most forbidding book. It isn’t, to the authors’ credit. They make the point that security applications are the widest use of CCTV, but other applications are almost unlimited, from photography from hot air balloons to time-lapse recordings of Wallace and Grommit style animated figures. Maybe that’s something for the security manager to bear in mind when he is drawing up the budget.
