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8083XDS-AD Analog and SD-SDI XDS Encoder
Page 1-10
JULIAN DATE: The Julian day number is a count of days elapsed since
Greenwich mean noon on January 1, 4713B.C. January 1st, 1993 was JD
2448989; January 1st, 2000 was JD 2451545.
MODIFIED JULIAN DATE (MJD): The Modified Julian Date is a
continuous count of the number of days elapsed since 17 November 1858.
It is often more useful than conventional calendar dates for record keeping
over long periods of time, since the MJD's of two events can easily be
subtracted to determine the time difference in days. Usually, the MJD is
specified as a number with 5 significant digits. As an example, the MJD for
1 January 1995 is 49718, meaning that this many days have elapsed
between 17 November 1858 and 1 January 1995. The Modified Julian
date is calculated by subtracting 2400000.5 days from the Julian Date.
Thus the Modified Julian Day 1 begins at Greenwich midnight.
LED: Light Emitting Diode.
LINEAR TIME CODE (LTC): A digital code used for timing and control
purposes on videotape and associated audiotape machines. It is recorded
on a longitudinal track with audio characteristics and is referred to as LTC
(Sometimes this code is also referred to as longitudinal code or SMPTE).
Each 80 bit code word is associated with one television frame, and consists
of 26 time bits, 6 flag bits, 32 user bits and 16 sync bits. Date information
may optionally be encoded into the user bits. This code is often used for
distribution time of day information to station clock displays and automation
systems. The SMPTE 12M standard defines LTC.
PAC: Stands for Preamble Address Code. These codes are embedded
into the line 21 caption data. They define the caption text position on the
screen, and set special features such as colour, italics and underline.
PIXEL: The smallest distinguishable and resolvable area in a video image.
A single point on the screen.
picture. Derived from the words picture element.
PSIP: Program and System Information Protocol, defined in ATSC A/65.
RESOLUTION:
The number of bits (eight, ten, etc.) determines the
resolution of the signal. Eight bits is the minimum resolution for broadcast
television signals.
SERIAL DIGITAL (SDI):
form. Often used informally to refer to serial digital television signals.
STANDARD TIME: The civil time adopted for a country or region. (See
also Daylight Saving Time)
TIME ZONE OFFSET: The difference in time between the local time and
UTC
Revision 1.0.2
In digital video, a single sample of the
Digital information that is transmitted in serial
OVERVIEW
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