Training in the Principles of CCTV
From CCTV Information
Are we getting it right at last?
There is certainly training available for CCTV engineers but as yet no formal qualifications, either City and Guilds or NVQs. SITO is currently working on a formal qualification but it is not yet available and could be some time before it is. In the meantime we have to do with videos, lecturing, etc. but no really structured courses.
Many years ago in about nineteen canteen I remember discussing with Mike Tennant, who was with Tavcom and then Gyyr, the amount of hype and misinformation that abounded in the CCTV industry. ( Still my hobbyhorse today). In particular the total lack of training available apart from some manufacturers. The problem with manufacturers training is that it obviously is centred around their products and still includes a considerable content of sales pitching. Many things have changed over the years, especially the technical support provided by manufacturers. However even they get frustrated at the number of times they are called out to apparent problems with their products, only to find it is often some totally unrelated problem, like incorrect terminations.
So, when Mike Tennant said that he was going to set up a training company, Tavcom Training, I wondered whether he was going to put his money where his mouth used to be! The company has now been set up for several months now and I thought it would be an idea to see what progress had been made in this void in the industry.
Mikes intention was to set up training in an innovative and practical manner. There is great emphasis placed on practical hands-on sessions in between the theory. The training room is pleasantly informal and limited to ten delegates. With more than ten people Mike found that the practical sessions could not be effectively managed. Adjacent to the training room is a workshop kitted out with the usual range of test equipment including an oscilloscope, light meter, power supplies, etc. At the other end is a room fitted out with a wide rang of CCTV components. There are several examples of multiplexers, monitors, VCRs, matrix switchers, quad units, transmission systems, etc. This is where delegates can actually program multiplexers, set up time lapse VCRs, program matrices and interconnect all different configurations. The equipment in this room represents a huge investment plus items kindly provided by many manufacturers.
It is interesting to note that Tavcom Training are the only company certified by IPSA to issue certificates of competence in CCTV to delegates passing an approved written examination. There are currently two, two day courses available, a basic introduction to CCTV for engineers new to the industry with little or no knowledge of CCTV. The other is an advanced CCTV course for more experienced engineers and for those who have passed the basic course. Tavcoms’ policy is not to issue certificates of attendance because they are pretty meaningless in terms of what a delegate has learned. Those who achieve a pass mark of 50% at the end of the course receive a certificate from IPSA, those who don’t, get nothing except 10% discount off a repeat course! The basic course must be passed to qualify for acceptance on the advanced course.
The most impressive aspect of the training set up is the balance between theory and practice. During the workshop sessions, delegates actually get to carry out such activities as ;
- Setting up monitors.
- Looping through and setting terminations. Seeing the result of incorrect termination.
- Using an oscilloscope to measure video signals.
- Fit lenses to cameras and connect auto iris lenses.
- Back focus cameras with zoom lenses.
- Fit and test BNC connections.
- Set up Time lapse VCRs and program 24 hour mode and set to switch to 3 hour on alarm input.
- Select and connect power supply units.
- Calculate lens fields of view.
- Understand Operational Requirements and the use of the Rotakin.
- Set up and program several types of multiplexer.
For the evening of the first day, delegates, are given a simple system to design and specify using a distributors’ catalogue to select the most appropriate components.
Another interesting mini project is that a subject is set at about 50 Metres away, and they have to calculate the lens to provide a given percentage of the subject on the screen. A camera is then set up with the selected lens and displayed on a monitor to see the actual result of the selection. Sometimes with surprising results!
There is an optional extra day offered devoted to fault finding in the workshop and demonstration room. During this day the delegates are required to connect up various items of equipment which may or may not be faulty. Mike has acquired quite a few nasties for this day, such as auto iris lenses with incorrect wiring, cameras with the back focus not working, providing a C-mount lens with a CS-mount camera and many others to test the resources of trainees to determine and correct the fault.
A typical assessment paper for the basic course:
Can you score 50%?
Ql Each frame of video information is made up of 2 fields, how many fields are there per second? (Monitors - 2 marks)
Q2 How many lines of information are contained in a CCIR video picture, is it 50, 312 or 625? (CC TV - 2 marks)
Q3 If you intend to install Qty 2 - 500 Waft floodlights off the same fused spur, what rating of fuse should you use? (Health & Safety - 2 marks)
Q4 In CCTV terminology, what do the letters CCD stand for? (Cameras - 2 marks)
Q5 Modern cameras may use either "C" or "CS" mount lenses. Which of the following statements is true to ensure correct focusing?
A) A 'CS' mount lens can be fitted to a 'C' mount camera provided a 5mm Collar is fitted.
B) A 'C' mount lens when fitted with a 5mm collar can be used with a 'CS' mount camera.
C) A’CS’ mount lens can be fitted to a’ CS’ mount camera provided that a 5mm collar is used. Lenses - 2 marks
Q6 Coaxial cable is a most common method of video transmission. Using RG59 cable, what losses, in percentage, are typical over a 200 metre run of this cable. (Cables - 2 marks)
Q7 When focusing a camera fitted with a zoom lens, what is the recommended procedure for setting accurate tracking focus from narrow angle to wide angle view? (Lenses -5 marks)
Q8 Modern cameras v,/ill operate on one of three input voltages, what are they? (Power supplies - 3 marks)
Q9 The electronic signal generated by a camera is known as the composite signal and has an industry standard of 1 volt peak to peak. What are the voltage levels for: Sync............White..........Black............ (Cameras - 6 marks)
Q10 What unit of measurement is used to measure the amount of light available at the scene to be viewed? (Lighting - 2 marks)
Ql1 In CCTV terminology what do the letters PSU denote? (Terminology - 2 marks)
Q12 When using an oscilloscope, what time setting should the oscilloscope be set to in order to display the composite video signal waveform so as to view two fields simultaneously? (Test equipment 4 marks)
Q13 What is the standard termination impedance (Ohms) for CCTV equipment? (Monitors & cables - 2 Marks)
Q14 When using a time-lapse video recorder in a 24hour mode, what is the recommended number of times a VHS cassette tape should be used before replacing it? (Tape management 2 marks)
Q15 What is the recommended ratio, base width in relation to height, when using a scaffold tower? (Health & safety2 marks)
Q16 The measurement of light is expressed in nano Metres. When choosing an lnfrared light for covert use. ( Not able to see the red glow) what filter type should be used. Is it 715nM, 85OnM, or 5OnM? (Lighting - 2 Marks)
Q17 What does the expression "OR" denote when compiling a site survey? (Site surveying- 2 Marks)
Q18 Y-C is an expression used when using S/VHS video recorders. What do the letters Y-C denote? Y............C..............(Video recorders 2 marks)
Q19 A camera housing used in an external position should be selected with an IP rating. What is the minimum IP rating required? (Housings2 marks)
Q20 When connecting a video picture from one monitor and looping through to another monitor, which position is the Hi-Z / 75 Ohm switch set to on the first monitor? (Monitors & cabling 2 marks)
How did you get on?
Typical advanced questions
Ql Sketch the waveform, indicating the elements of a video composite signal and the voltage levels. (cameras & CCTV introduction - 10 marks)
Q2 Describe how to use a lens calculator. (Lenses 5 marks)
Q3 Explain vertical interval switching. (switchers 10 points)
Q4 RG 59 Coaxial cable is a common cable used in CCTV installations. What approximate losses are incurred over 250 Metres. Your answer may be expressed in dB or percentage terms. (Cables 5 marks)
Q5 When using an oscilloscope, what time setting should the oscilloscope be set to in order to display the composite video signal waveform so as to view two fields simultaneously? (Test equipment 5 marks)
Q6 What is the standard termination impedance for CCTV equipment? (Monitors & cables - 2Marks)
Q7 Explain conditional refreshment techniques. ((Video transmission 10 marks)
Q8 Explain the principles of video time share multiplexing.(video multiplexer IO marks)
Q9 In video motion detection applications, list 5 common problems associated with unwanted alarms. (Video motion detection 10 marks)
Q10 Sketch a six camera system and the interconnections required to operate as a matrix switcher - configuration 6 camera inputs and two monitor outputs. (matrix switching 10 marks)
Ql1 Give three methods of transmitting camera control telemetry. (telemetry 6 marks)
Q12 Explain on which telephone network system1 1. A modem is used. 2.A terminal adapter is used(Video transmissions 4 marks)
Q13 Describe a ground loop and what steps must be taken to correct the problems encountered. (Cables IO marks)
Q14 Give four current technology principles for providing video transmission by telephone networks. (Video transmission 8 marks)
How did you get on with that one? Note that some of the questions may have been duplicated in these examples, in practice the questions set to all delegates are recorded to prevent such repetition. Also there is a large bank of questions from which a selection is made for each course
I now think, not only has Mike put his money where his mouth was but has achieved a significant breakthrough in expanding education in this desert if CCTV knowledge. I also believe that this is setting the standard for future training in the industry. Having said that, there is still a great deal of development in the training of CCTV system designers needed.
With the facilities and wide range of equipment installed it seemed a natural idea to fill yet another gap in the industry knowledge base. This is, objective, comparative testing of similar products. The first project is already under way, which is comparative tests on seven different multiplexers. The signals from four cameras were fed simultaneously to all the multiplexers and each multiplexer recorded onto identical individual time lapse VCRs. Both live pictures and replays of recordings could be viewed on individual monitors. The full range of tests will include, subjective evaluation of picture quality, actual field update time, measurement using specialised test equipment, the benefits of Y/C outputs where available, ease of programming, ease of making connections and looping through, readibility of installation and user manuals, etc. It is hoped that the results may be published in the next issue of CCTV today. Plans are in hand to continue testing phoneline transmission systems, cameras, digital recording, domes and anything that is generally confused by manufacturers‘ specmanship’.
See Also: Tavcom Training Courses
This chapter is supplied by Mike Constant and was originally published in CCTV Today. Mike is the author of 'The Principles & Practice of CCTV' which is generally accepted as the benchmark for CCTV installation in the UK.