3. The system has two primary functions depending on how it is designed, protect the life within the building, giving the occupants sufficient warning of an outbreak of fire, so they can evacuate safely and protect the building & its contents by summoning the fire brigade at the earliest opportunity.
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23. The term camera comes from the Latin camera obscura, which means “dark room.”
24. Tube cameras work on the principles of photosensitivity, based on the photo-effect.
25. Advantages of CCD Cameras:- • Very low minimum illumination performance (down to 0.1 lx at the object); • No geometrical distortions due to a precise two-dimensional construction; • Low power consumption; • No need for high voltage for beam acceleration; • Small size; • No influence of external EMFs; and, most importantly, • Unlimited lifetime of electrons generated by photo-effect.
26. Colors may be separated using:- • RGB stripe filter • Complementary colors mosaic filter
33. In CCTV, as in broadcast TV, the majority of monitor display units are CRTs, which means they use cathode ray tube technology, designed to convert the electrical information contained in the video signal into visual information
35. The liquid crystal display consists of a liquid suspension between two glass or plastic panels. Crystals in this suspension are naturally aligned parallel with one another, allowing light to pass through the panel. When electric current is applied, the crystals change orientation and block light instead of allowing it to pass through, turning the crystal region dark.
