Tektronix VITS 200 Instruction Manual page 19

Getting Started
Insert/Delete Functions
Automatic VIRS Detection
Automatic Closed
Captioning Detection
1–2
H Vertical Interval Reference Signal (VIRS)
H Red Field
H 0 IRE Flat Field (0% Black)
H 7.5% Black
For instruments with S/N B020249 and above:
H FCC Composite 20 IRE (Std, Opt 1C only)
H CBC Composite 15 –360 (Opt 1C only)
H BTA Ghost Cancellation Reference (Opt 1J)
H Phillips Ghost Cancellation Reference (Std and Opt 1C)
When called as a full field test signal, only the GCR Positive will be used.
H Korean Ghost Cancellation Reference (Opt 1K)
The VITS 200 may be programmed to insert any internally-generated signal,
external input, or the source identification. These may be inserted on lines 10
through 23 or on lines 17 through 30. VITS can be programmed on even and
odd fields or in a four-field sequence. The VITS 200 may be genlocked to either
the Program signal or the EXTERNAL 1 input. If you like, you can program the
same signal or external input to be inserted on more than one line. This may be
useful in insertion of external data signals, such as Teletext.
Four external inputs are provided for inserting externally-generated test and data
signals. These inputs may be either AC-coupled and clamped, or DC-coupled.
See the Operating Basics section for details of how to change the external input
coupling. The VITS 200 confirms that the inputs are synchronous with the
program signal before allowing it to be inserted in the vertical interval.
When the AUTO VIRS function is selected, the VITS 200 will check the
specified line(s) and field(s) for a VIRS signal on the incoming Program Video.
If VIRS is detected as being present in the proper location, the signal is passed
with no processing. However, if VIRS is not detected on the specified line(s)
and field(s), then the internally-generated VIRS signal will be inserted on them.
The AUTO CAPT function sets the VITS 200 to examine specified line(s) and
field(s) for close-captioned text. This consists of checking the specified line(s)
and field(s) of the incoming program video for any activity greater than 285 mV.
If there is activity above this level, it is passed with no processing. If there is no
activity at this level, then the selected External Input is inserted onto the line.
For example, Auto Capt 1 would insert the signal applied to the EXT 1 input
onto the specified line(s) and field(s) as close-captioned text.
VITS 200