Teledyne LeCroy USBTracer_Trainer - Users Manual - Manual (Page 113)

USB Protocol Suite User Manual Chapter 5: Reading a Trace
LeCroy Corporation
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5.5 Time Stamp
The Time Stamp field displays the time in “Seconds.Nanoseconds” (decimal).
The Time Stamp is at the beginning of the packet or bus condition. However, the
Time Stamp is at the end of Sync for Low and Full Speed packets.
In the General tab of the Display Options, you can set the Time Stamp Position to be
At the end, At the beginning, or Merge with Packet/Transaction/Transfer. See
“General Display Options” on page 144.
To change the time stamp, right-click the Time Stamp field to display the Time Stamp
menu:
You can:
• Place the Zero Time Stamp at this packet
• Show the recorded Time Stamp
• Place the Zero Time Stamp at the first packet
• Place the Zero Time Stamp at the trigger packet.
Note: You cannot place the Zero Time Stamp at a packet when in Calendar.
You can also go to the Time After in seconds, or the Time Before in seconds.
Note: Time stamps are corrected to match our more accurate 2.5 ppm clock. After the
error due to calculating via 2 ns nominal timing of symbols reaches 8 nsec, the system
will correct the next time stamp by using the value obtained from the 2.5 ppm time stamp
clock. This can result in “jumps” either forward or backward by this amount of time in
captures, and may result in “blank” locations in the Link Tracker view. These should not
be construed as mistakes in the traffic, but as a modification necessary for us to provide
the most accurate time stamps over the range of a trace.