Filter
Top Products
Chapter 3: Testing Performance
To test time measurement accuracy
3–19
Figure 3-12
Measurement Settings for Time Interval Measurement
15 Verify the period is 25 ns ± 44 ps, minimum 24.956 ns and maximum 25.044 ns. Record
the minimum and maximum readings in the Performance Test Record.
16 Change the signal generator frequency to 100 MHz (10 ns period).
17 Select horizontal from the setup menu. Set the position to –11 ns.
18 Clear measurement statistics.
Do this by clicking Clear Meas (Clear All) on the measurement toolbar, then selecting Delta time
from the Time submenu of the measure menu.
19
The delta time reading should be 10 ns ± 43 ps, minimum 9.957 ns and
maximum 10.043 ns. Record the minimum and maximum readings in the
Performance Test Record.
20 Change the signal generator frequency to 20 MHz (50 ns period).
21 Select horizontal from the setup menu. Set the scale to 100 ns/div, position to –11 ns.
22 Clear measurement statistics as in step 18 and restart the measurement.
23 The delta time reading should be 50 ns ± 283 ps; minimum 49.72 ns and maximum
50.28 ns. Record the minimum and maximum readings in the Performance Test Record.
24 Change the signal generator frequency to 1 MHz (1 µs period).
25 Select horizontal from the setup menu. Set the scale to 1 µs/div, position to –11 ns.
For valid statistical data
In equivalent time mode, measurement specifications are valid with sixteen or more acquisitions averaged.
Statistics accumulated before the required number of averaged acquisitions may show the instrument to
fail the specification. This is particularly true for minimum and maximum in this case since they are set by
measurements taken with the fewest averages.
If the procedure above is followed exactly, the required number of acquisitions are averaged before
statistics are turned on. Therefore, if you clear and restart measurements, averaging and statistics are
restarted simultaneously and the result is erroneous data collected from the early averages.
If in doubt about the statistical data, after #Avg is complete select Clear Measurements or Clear All from
the Measure menu tool bar, then repeat the custom measurement again. This restarts the statistics without
restarting averaging and the result is valid statistical data.