In a CCTV system the number of monitors can be quite large. It is very important to know how many Wireless Home Cameras can be used in a place without going overboard, as well as how to position them and what will be the correct viewing distance for the users. Even with one monitor in the system, operators should be aware of certain facts and recommendations, especially when they are spending the majority of their time in front of the monitors. Typically, for CCTV monitors, an optimum distance is around seven times the screen height. These recommendations are based on the practical resolution limits that the human eye has. The table on the next page shows recommendations only, and one should be flexible when applying these recommendations in various circumstances, especially in considering the flicker effect in control rooms with a large number of CRT monitors. With big systems, where perhaps a dozen monitors need to be mounted in front of the operator(s), viewing distances may vary.
It is a known fact that the vertical flicker is noticeable with the peripheral vision of the eye. In other words, if you have many monitors to view, the vertical refresh rate of the surrounding monitors is affecting your vision even though you may be watching a monitor directly in front of you with easy comfort. For this reason, some manufacturers are now coming up with 100 Hz monitors for CCTV (this is more critical with PAL and SECAM because of their lower vertical frequency). The 100 Hz monitors simply double up the 50 fields refresh rate, and the display looks rock steady. Sitting in front of such monitors for a longer period is a definite advantage, and I would suggest using such monitors where the display has to be of a bigger size. The bigger the monitor screen, the more noticeable the flicker. Another important consideration is the electrostatic radiation of larger monitors. Although this radiation is negligible, when the walls of monitors are in one room they may have a significant influence on the environment, as can usually be confirmed by the amount of dust collected by such a large number of GSM Security camera .
There is a low radiation standard accepted in the medical science called Rearview Mirror Navigation . This standard is also being accepted by some CCTV manufacturers and would clearly give an advantage to systems designed with such monitors. With large systems, visual display management is of vital importance. For example, not all monitors need to display images all the time. It may be much more effective if the operator is concentrating on one or two active monitors (usually larger sized) and the rest of them are blank. In case of activity, a blank monitor can be programmed to bring the image of a preprogrammed camera. In such a case, the operator’s attention is immediately drawn to the new image and the system becomes more efficient. As an additional bonus, the monitor’s lifetime will also be prolonged. Most of the video matrix switchers can be programmed to do such blanking and display alarmed cameras only when necessary.
More information at http://www.jimilab.com/ .