Burst Electronics VDS-3 - Manual (Page 3)

For the DIP switch, this is the most strict setting. This setting will
only pass video with near RS-170A quality. If you would like to
accept less than perfect video, such as a VCR in the Pause mode or
non-interlaced Blue Screen mode, then set the switch to Down,
Down, Down, Down.
The composite sync tip trigger threshold may be adjusted from
the factory preset of -20 IRE. To adjust this trigger point, a wave-
form monitor, a source of stable video and an attenuator are re-
quired. Input the desired sync level and adjust the pot. DIP switch
position 1 must be up.
When any of the first three switches are up, the microcontroller
will test the associated input pins for valid signals. When a switch
is down, the test for that signal will be skipped. All enabled tests
must pass consecutively before input A is considered good.
Detection time will increase in relation with how many signal tests
are enabled. Detect times will substantially increase if Sw 4 is up,
loss of video detect will take approximately 4 seconds.
If the frame test is enabled, progressive scan video signals (blue
screen) and VCR search and pause modes will be detected as bad
video.
DIP Switch Function
Sw1 Up Test the sync tip level
Sw2 Up Test the vertical sync (good for end of tape)
Sw3 Up Test the frame signal (Blue screen test)
Sw4 Up Sample each enables input 10 times
2 Video Detector