Cascadia Digital video recorder Manual do Utilizador descarregar pdf (Página 26)

CCTV Glossary

Cascadia Video Products LLC

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O/P - Output.

Objective - The very first optical element at the front of a lens.

Ocular. The very last optical element at the back of a lens (the one closer to the CCD chip).

Ohm - The unit of resistance. The electrical resistance between two points of a conductor where

a constant difference of potential of 1 V applied between these points produces in the conductor a

current of 1 A, the conductor not being the source of any electromotive force.

Oscilloscope (also CRO, from cathode ray oscilloscope) - An electronic device that can measure

the signal changes versus time. A must for any CCTV technician.

Overscan - A video monitor condition in which the raster extends slightly beyond the physical

edges of the CRT screen, cutting off the outer edges of the picture.

Output impedance - The impedance a device presents to its load. The impedance measured at

the output terminals of a transducer with the load disconnected and all impressed driving forces

taken as zero.

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