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CCTV VIDEO TRAINING MANUAL
Someone once said, "Knowledge is the key to success". This rule also applies to the installation and maintenance of CCTV camera equipment. Have you ever installed a CCTV camera system and then had to go back to solve a problem that was overlooked. A basic understanding of CCTV video signals, can save you hundreds of man hours, improve customer relations and increase job profitability all at the same time. This manual will discuss problems and solutions for CCTV camera installations.
To discuss video let's start with the unit of measure, the I.R.E. unit. I.R.E. stands for Institute of Radio Engineers, this regulating body set the standards of measure for the video industry. This standard has been adopted by all industries in the United States and other parts of the world. 140 I.R.E. units is equal to 1 Volt Peak to Peak. I.R.E. units are easier to use because they divide into a video signal evenly.
For example proper Sync on a camera is 40 I.R.E. units, the Voltage equivalent would be 0.2857143 Volts. Unfortunately this voltage cannot be measured on the Volt Ohm Milliamp Meter that you use for checking contacts. An oscilloscope has been used by some people for this purpose, but it is bulky and does not read in I.R.E. Most people would rather use the simple 40 I.R.E. units of measure. Fortunately some equipment manufacturers sell hand-held battery operated meters to measure the video signal in I.R.E. units. This equipment is compact, extremely accurate and simple to use. Some units like the "CAMERA MASTER" can even help to set the focus of a camera more accurately.
HOW SYNC PULSE AMPLITUDE EFFECTS CCTV INSTALLATIONS.
A CCTV video camera creates synchronization pulses to lock the viewing monitor on the picture. These pulses occur at a rate of 15,750 times a second. There is one synchronization pulse or (sync pulse) for each line in the picture frame. The sync pulse tells the video monitor to start drawing a video line across the picture screen. When it gets to the end of the screen another sync pulse begins the next line, and so forth until the screen has been filled with lines. It takes 262 and a half lines to form a frame, and two frames to form the video picture we see on the monitor.
The proper level for sync is 40 I.R.E. units. If the sync signal from the camera is too small in amplitude the picture will break up or roll. If the sync pulse is too big, any black portion of the picture will be more gray and the dynamic range of the picture will be degraded. Peak white level will also be compressed causing a blooming effect (loss of picture definition).
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