Guardian Technologies DFT 150/175 manual 15Glossary, DVST Installation Guide, Page

DVST Installation Guide Glossary

15Glossary

DVST	Digital Video Storage and Transmission
ISDN	Integrated Services Digital Network - A digital telephone system capable of
	transmitting data, speech, images and text.
PSTN	Public Subscriber Trunk Network - The standard telephone system used for
	speech and fax communication.
Speed of Update	The time taken to refresh a single picture.
Software	Video data compression achieved by computer program processing.
Compression
Hardware	Video data compression taking place in specialised purpose built microchips.
Compression
k bytes	Measurement expressing the size of digital computer memory
k bits per	Measurement expressing the speed at which data can be transmitted.
second
Compression	Taking standard video signals and reducing these into compact digital data.
Decompression	Taking digitally compressed DVST information and restoring this to normal
	video images.
Complete	Each time the picture is transmitted, or stored to memory, the entire picture is
compression	compressed.
Conditional	Update only the parts of the picture that have changed. The first time the
Updating	picture is transmitted the entire picture is compressed. Thereafter only the
	parts of the picture that change are transmitted.
DAT	Digital Audio Tape, the new technology for recording digital information on a
	special tape cassette. Massive storage can be achieved in a very small
	package.
MODEM	MOdulator/DEModulator used to connect the DVST unit to a standard
	telephone line.
Terminal	Used to connect the DVST to an ISDN digital telephone line.
Adapter

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