HP 54710A User's Reference Manual page 298

User Defined TV
The user defined TV trigger mode allows for triggering on TV signals that are
used in other parts of the world, and for triggering on nonstandard TV signals
(like high definition TV).
Arm on Softkey The Arm on softkey allows you to set the oscilloscope
to trigger on a low or high state. A high is a voltage above the trigger
level, and a low is a voltage below the trigger level. You can also qualify
that state further by defining the state be present less than a selected
time (30 ns to 160 ms) and greater than a selected time (20 ns to 150
ms).
Trigger on Softkey The Trigger on softkey allows you to set the
oscilloscope to trigger on a positive or negative slope. Negative polarity
means that the scope arms on a high state and triggers on a negative
slope. Positive polarity means that the scope arms on a low state and
triggers on a positive slope.
Edge Number Softkey The Edge number softkey allows you to select
an edge number from 1 to 16 million to trigger the oscilloscope.
User defined TV To trigger on field 2, negative sync, using the 525 line standard. In the user
example
defined TV menu press the Arm on... softkey. Set State to high, Present <
to 28 µs, and Present > to 26 µs. Set the Trigger on softkey to negative
slope. Edge 1 is the first line in field 2. To compute the correct edge
number, include half lines in you calculation.
Trigger Menu
Mode
18–19