Tektronix SPG8000A, Руководство пользователя

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6 SPG8000A User Manual
These paragraphs describe portions of the Time flow block diagram.
Internal Time Set* : To set Time Setup to internal mode, enter the current date
and time and then set the Time Setup to Internal to transfer that time to the
Master Time. The time zone offset information is used to convert local time to
a master time. Set the local time zone offset before setting the internal time.
VITC Reader : When the instrument is genlocked to NTSC or PAL, the
Vertical Interval Time Code on the genlock reference input can be decoded and
used as the time source. This time can be viewed on the status bar and is used
as the time source for all the time code outputs. Since the phase of the video
signals are set by the genlock, the epoch system does not operate from the
VITC input. If SMPTE309 date data is available, the time and date information
on the VITC input will be used if enabled in the TIME OF DAY submenu. (See
Time of Day submenu .)
LTC Reader : When the reference source is set to INTERNAL, NTSC, PAL or
HD SYNC, the LTC signal applied to the LTC 1 input can be used at the time
source. This time can be viewed on the status bar and is used as a time source
for all the time code outputs. If SMPTE309 date data is available, the time and
date information on the LTC input will be used if enabled in the TIME OF
DAY submenu. (See
Time of Day submenu
.)
NTP Client:
An external NTP server can be the time reference when the
frequency reference is set to black burst (NTSC or PAL) or continuous wave
(CW) input, or if it is set to internal mode. This mode is useful in situations
where the GPS signal is unavailable or when VITC or LTC inputs are not
available for the time reference.
Time Setup Selection : The possible Time code sources depend on the selected
Reference source. If Genlock is the selected reference source, then VITC, LTC,
NTP, or internal time is available. If Internal is the selected reference source,
then LTC, NTP, or internal time is the time code source.
If VITC or LTC is the time code source, then the time synchronization Mode
must be se t. There are three choices. Synchronize now sets the time when the
user selects the ENTER button (if the incoming time is valid and stable).
Synchronize once sets the time once when a valid and stable time code is
detected. Follow sets the time every time a new stable and valid time is
detected.
Genlock : When NTSC or PAL is selected as the reference and the time source
is LTC or VITC with ST309 date, then the timing of the reference sync may be
used to improve the accuracy of the master time.
Master Time : The Master Time is the basis for all time code outputs and for
the phase reference of all video outputs.
Offset to TAI : TAI is the International Atomic Time, represented as the
number of seconds since the epoch of 0:00:00 January 1, 1958. Proposed
standard SMPTE 404M defines the SMPTE Epoch at that same moment. There
are exactly 8040 days and 19 leap seconds between the SMPTE Epoch (TAI)
and the GPS Epoch.
Epoch Calculations* : The number of seconds since the SMPTE Epoch is used
to precisely align video frames with the Master Time clock. For