- Jack
- Electronics: A socket or connector into which a plug may be inserted. Click here for illustrations of various audio video jacks and plugs.
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- Jaggies
- Digital Video: A term used to describe the stair-stepped appearance of a curved or angled line in digital imaging. The smaller the pixels, and the greater their number the less apparent the "jaggies". Also known as Pixelization.
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- Japanese Future Public Land Mobile Telecommunications Services: see J-FPLMTS.
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- Japanese Digital Cellular: see JDC.
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- Japan Total Access Communication System: see J-TACS.
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- JDC
- Acronym: Japanese Digital Cellular
- Telephony: The Japanese cellular system (renamed to PDC). It uses the upper 900 MHz and 1.5 GHz bands.
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- J-FET
- Acronym: Junction Field-Effect Transistor
- Electronics: A voltage-controlled transistor in which the source-to-drain conduction is controlled by the gate-to-source voltage and that has a channel consisting of either an N-type (N-channel) or P-type (P-channel) semiconductor material with the gate consisting of the opposite semiconductor type. See FET and MOSFET.
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- J-FET, N-type
- Electronics: A J-FET that has a channel consisting of an N-type semiconductor material, with electrons as the primary charge carrier.
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- J-FET, P-type
- Electronics: A J-FET that has a channel consisting of a P-type semiconductor material, with electron deficiencies as the primary charge carrier.
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- JFIF
- Acronym: JPEG File Interchange Format
- Digital Video: A specific type of the JPG file format. Also known as EXIF.
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- J-FPLMTS
- Acronym: Japanese Future Public Land Mobile Telecommunications Services
- Telephony: The Japanese equivalent of the IMT-2000 third-generation technology standard.
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- Jitter
- Audio: A distortion that occurs during digital audio extraction (ripping) or conversion to analog. Jitter correction helps restore the audio to its original condition.
- Video: A distortion caused by intermittent variations in the characteristics (such as frequency, amplitude, etc.) of a signal.
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- Joint Photographic Experts Group: see JPEG.
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- Joule
- Electronics: A measure of the amount of energy delivered by one watt of power
in one second or 1 million watts of power in one microsecond. The Joule
rating of a surge protection device is the amount of energy that it can
absorb before it becomes damaged. Named for James Prescott Joule.
1 Joule = 0.5 x (Capacitance in Farads) x (Voltage^2)
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- JPEG, JPG:
- Acronym: Joint Photographic Experts Group
- Digital Video: A lossy compression format, this is the most common type of image file format used in digital cameras.
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- J-TACS
- Acronym: Japan Total Access Communication System
- Telephony: The narrowband analog cellular FM system used in Japan. The channels are 12.5 KHz wide and use subaudio signaling.
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- Jughead
- Internet: A search engine for Gopher sites. Similar to Veronica, but with fewer options and a smaller index of sites.
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- Jukebox
- Audio: A type of software that catalogues and plays recorded MP3 and other digital files according to the user's settings.
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- Junction
- DIY, Electronics: The region separating two layers in a semiconductor material.
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- Junction, p-n
- Electronics: The region separating the p layer and the n layer in a semiconductor.
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- Junction Field-Effect Transistor: see J-FET.
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