Viavi T-BERD 5800, Руководство пользователя

Страница: 60 / 100

Chapter 4 1PPS Wander Analysis
Analyzing 1PPS wander
T-BERD/MTS 5800 Timing Expansion Module User Manual
Page 44 22112315, Rev. 004 July 2017
TIE is measured, and MTIE/TDEV is calculated. To view the supporting results, display
the 1 PPS Analysis category.
Analyzing 1PPS wander
After you accumulate TIE data, you can analyze the data for wanter using the On-board
Wander Analysis tool.
To analyze 1PPS wander
1 Measure TIE and calculate the MTIE/TDEV (see “Measuring TIE and calculating
MTIE/TDEV” on page 42 ).
2 Select the Wander Analysis soft key.
The graphical wander analysis screen appears with the TIE tab selected.
3 Select the Update TIE Data soft key.
This refreshes the data in the Wander Analysis screen. All of the TIE samples
accumulated so far (including those gathered since the tool itself was launched)
are redrawn, and then MTIE and TDEV are recalculated.
The TIE graph appears. The Wander Analyzer automatically displays the last
block of continuous valid data.
4 To observe another block of data, select the Current Block field, type the block
number, and then select
OK .
The data block you specified appears.
A block of TIE data is a contiguous subset of all TIE samples that is not inter-
rupted by any alarms. For Wander measurements, TIE values are sampled at a
constant rate. If an alarm occurs (e.g. LOS), the receiver is not able to produce
meaningful TIE values and stops producing TIE entries until it is able to recover.
These alarms separate the whole measurement into sections, or “blocks”.
NOTE:
• You can run on-board Wander Analysis while the test is in progress;
however, if you restart the test, the data collected previously will be
cleared. If you want to preserve the data for the previous measurement,
save the data before restarting the test.
• Saved data cannot be loaded into the on-board Wander Analysis tool; it
calculates MTIE and TDEV on all the data accumulated during the course
of the current test.
• Wander analysis is restricted to the first 8.64 million samples. If your
measurement contains more samples, you must export the wander data
for offline analysis.
For detailed information about saving and exporting wander data, see “Saving
and exporting TIE measurement data” on page 46 .