Tektronix WFM700 Series, Руководство по обслуживанию

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Performance Verification
2- 16
WFM700 Series Waveform Monitors Service Manual
This test checks the serial video output signal into a 75
8
load.
Performance Requirement. This test verifies performance characteristics and is
listed in the test record.
1. Connect the SD video generator to INPUT B using a 75
8
cable.
2. Set the SD video generator for a 525-format 100% color bars signal.
3. Connect the SERIAL OUT to the 75
8
input of the test oscilloscope using a
75
8
cable. Use a 75
8
-to-50
8
adapter on the input of the test oscilloscope
if necessary.
4. Press the INPUT button and select Input B .
NOTE
. If testing a WFM7HD, a display message will report
I
unsupported
standard
I
. This will not affect the test.
5. Measure the signal amplitude on the test oscilloscope and note this measure-
ment. The following substeps will help obtain a measurable display on the
test oscilloscope.
a. Ensure that the termination is correct on the test oscilloscope.
b. Set the vertical scale to 200 mV/div, horizontal scale to 5 ns/div, and the
trigger position to 90%.
c. Set the display style to dots.
d. Set the trigger level to zero, and to neglect glitches of either polarity for
widths to 30 ns.
e. The oscilloscope display should show a few random transitions followed
by 30 ns with no transitions. This is followed by the triggering transi-
tion. See Figure 2--3.
f. When measuring, disregard signal noise. Measure the waveform
amplitude from the centers of the high and low levels in the region from
5 ns to 10 ns before the triggering transition.
g.
Note the signal amplitude.
6. Calculate the percent amplitude error with the formula below using the
measured value from step 5.
Amplitude Error
Æ
Measured mV 800 mV
É
8
7. CHECK that the calculated error is between 5%.
Serial Video Output