Theory of Operation
1-4 WFM700 Series Waveform Monitors Service Manual
The External Reference module provides synchronization for the WFM700
instrument, allowing you to sync the display to an analog video input. The
Reference Module accepts PAL and NTSC signals with bi-level sync (SD) or
tri-level sync (HD) input, so that timing of the SDI input signals can be
compared to the analog sync reference. The External Reference module
automatically detects the input standard. The Reference Board timing signals are
available to both the Input Module and Real-Time-Display Module.
The sync signal from the External Reference module is embedded in a data
stream of 27 MHz (for SD video), and 74.25 MHz or 74.1758 MHz (for HD
video). This data stream is called the TRS signal, and contains H, V, and F
information. The External Reference module acts as a data hub or router for TRS
(timing reference signal) signals to and from the input modules (slots 0 or 1) and
the Real-Time Display module.
HREF IN LOOP-THROUGH. Compensated for 75 8impedance; requires
proper termination at one end of the loop-through connector or at the
receiver in a monitored system. Provides for connection of an external
synchronization signal such as black burst or composite video.
HAUX IN. Future capability.
HVGA PIX MON. A copy of the PIX G/Y, B/Pb, R/Pr pix mon outputs. This
allows using an inexpensive VGA monitor for non-critical HD applications.
Most computer monitors will not lock to 50 Hz vertical rates or to Standard
Definition line rates, so this may not work in all applications.
HPIX G/Y, B/Pb, R/Pr. Provides three 75 8component signal outputs to drive
a component picture monitor. You can set the output format to YPbPr or
HAUX OUT 1 / AUX OUT 2. Future capability.