Tektronix TG700, Руководство пользователя

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GPS7 GPS Synchronization and Timecode Module
the GPS7 module can determine "where" the GPS pulse-per-second signal is
located with respect to video framing.
Frame Engine.
The frame engine supplies frame pulse signals based on the
SMPTE Epoch to each video output. This ensures that they are properly aligned
with respect to the calculated phase for the selected video format of each output.
Output Timing.
Each video output has an independent offset that can be speci fi ed
to shift that output in order to align the video and LTC signals in the studio. This
time adjustment does not affect the timecode that is applied to that output; the
signal and timecode stay together as the timing is changed. The timing offset range
and resolution depend on the signal. See the speci
fi c output menu for details.
Leap Second Information.
The GPS signal indicates the number of leap seconds
between GPS time and UTC. As of December 31, 2008, a total of 34 leap seconds
are required for the adjustment between TAI and UTC. This information only
stays current when a GPS signal is connected. On instrument boot up, stored leap
second information is used, and an asterisk appears next to the time in the status
screen until the leap second information from the GPS signal is received.
Time Zone Offset *.
The GPS7 has a selectable offset between UTC and the local
time, usually representing the local time zone. This offset can be speci fi ed in
hours+seconds, allowing speci fi cation of time zones that do not align
with the usual hours-only offset, or for other applications not related to time zones.
You can also use this setting to set the internal time to calculate “backwards” to
the Master Time.
When the input time source is set to VITC, the instrument works similar to how it
works in internal mode, pre-correcting the master time of day by the time zone
offset. This pre-correction assumes that the incoming time code has the correct
local time, and causes the outgoing time codes to nominally match the incoming
ones, regardless of time-zone offset. This means that when switching from GPS to
VITS mode, the time-zone offset usually does not need to change. However, if
the time code synchronization mode is set to "Synchronize now" or "Synchronize
once", and the time-zone offset is changed after the time-code sync has occurred,
then the time-zone change offsets the incoming and outgoing time codes until the
user reasserts the time synchronization.
Leap Second Apply *.
Leap seconds, when required, are added on June 30, and/or
December 31, at 23:59:60 UTC. That is, the minute preceding midnight has
61 seconds instead of 60, numbered 0..60 instead of 0..59. This might be an
inconvenient time to make a local clock adjustment. For example, this is during
prime time for the North American Eastern Time Zone. Therefore, the GPS7
gives the option of deferring the leap second adjustment (if any) on these dates
for up to 24 hours.
DST Change *. Daylight Saving Time (DST) changes twice a year in many time
zones, but some locations do not observe daylight savings time. The GPS7 has
a user programmable DST adjustment to the time zone offset that is made by
TG700 TV Signal Generator Platform User Manual 3–107