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Glossary - I
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- I/O
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Input/Output
- I/P
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Input. A signal which is applied to a piece of electric apparatus or the terminals on the apparatus to which a signal or power is applied.
- IEC
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International Electrotechnical Commission (also CEI).
- Imaging Device
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A vacuum tube or solid state device in which the vacuum tube light sensitive face plate or solid state light sensitive array provides an electronic signal from which an image can be created.
- Impedance
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A property of all metallic and electrical conductors which describes the total opposition to current flow in an electrical circuit. Resistance, inductance, capacitance and conductance have various influences on the impedance, depending upon frequency, dielectric material around conductors, physical relationship between conductors and external factors. Impedance is often referred to with the letter Z. It is measured in Ohms, whose symbol is the Greek leter Omega.
- Inserter
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A device for providing additional information, normally superimposed on the picture being displayed; this can range from one or two characters to full screen alphanumeric text. Usually, such generators use the incoming video signal sync pulses as a reference point for the text insertion position, which means if the video signal is of poor quality the text stability with also be of poor quality.
- Interference
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Disturbances of an electrical or electromagnetic nature that introduce undesirable responses in other electronic equipment.
- Interlace scanning
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A technique of combining two television fields in order to produce a full frame. The two fields are composed of only odd and only even lines, which are displayed one after the other but with the physical position of all the lines interleaving each other, hence interlace. This type of television picture creation was proposed in the early days of television with the intention to have a minimum amount of information yet achieve flickerless motion.
- Interline transfer
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This refers to the one of the three principles of charge transferring in CCD chips. The other two are Frame transfer and Frame interline transfer.
- IP index
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IP stands for Index of Protection, which is defined by a numbering system that describes the quality of protection of an enclosure from outside influences, such as moisture, dust and impact.
- IR light
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Infra red light, invisible to the human eye. It usually refers to wavelengths longer than 700nm. Monochrome (B/W) cameras have extremely high sensitivity in the infra red region of the light spectrum.
- Iris
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A means of controlling the size of a lens aperture and therefore the amount of light passing through the lens.
- ISDN
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Intergrated Services Digital Network. This is the newer generation telephone network which uses 64 kb/s speed of transmission (being a digital network, the signal bandwidth is not expressed in kHz, but rather a transmission speed). This is much faster than a normal PSTN telephone line, which at best can go up to 14.4 kb/s without data compression. To use the ISDN network you have to talk to your communications provider, but in general a special set of interface units (like modems) are required.
- ISO
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International Standards Organisation
- ITU
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International Telecommunications Union (also UIT)
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