Tektronix WFM700 Series, Service Manual

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WFM700 Series Waveform Monitors Service Manual
1- 1
Theory of Operation
This chapter contains a module-level description of the WFM700 instrument.
Two block diagrams are provided to aid the descriptions. Figure 1--1 on
page 1--8 shows the signal flow of the instrument and Figure 1--2 on page 1--9
shows the control flow.
Operating Conditions
The electrical specifications of the instrument are listed in the WFM700 Series
Technical Reference document and apply over an ambient temperature range of
+0
_
C to +40
_
C. The rated accuracies are valid when the instrument is
calibrated in an ambient temperature range of +20
_
C to +30
_
C.
Overview
The WFM700 accepts either SD (Standard Definition) or HD (High Definition)
serial video data at the input connectors of an installed Input Module (in either
slots 1 or 2 of the WFM700 mainframe). The applied video signal is sent to SD
and HD equalizers (to compensate for signal degradation due to cable loss) and
to the eye sampler. The compensated serial video signal is converted to parallel
video and a clock signal is recovered. The parallel signal is further processed to
extract the embedded audio signal, detect the video format, and generate an RGB
Analog video signal. The embedded audio is encoded into AES signals that are
sent to the optional Audio module by way of the audio bus.
The parallel video signal is sent to the Real-time Display module on a digital
bus, 10 bits for SD video and 20 bits for HD video. The RGB video is sent to the
Reference module on the analog bus for component video output at the PIX G/Y,
PIX B/Pb, and PIX R/Pr connectors and the VGA PIX MON connector.
The Real-Time Display module accepts the parallel video signal from the
selected Input Module. The video signal is processed to display the information
in various forms on the raster display. The output from the Real-Time Display
module is sent to the Main Interface board via LVDS pairs. There the video
signal is added with text and graticule information from the VGA controller. The
combined video signal is sent to the LCD and the EXT VGA output connector.
Timing is accomplished by using the clock and TRS (timing reference signal)
from the video input signal. A clock and and TRS (from an analog video signal)
can be input via the External Reference module using the AUX IN connector.