Agilent Technologies 3458A User Manual page 362

362 Appendix E High Resolution Digitizing With the 3458A
The trigger error is orders of magnitude greater than timebase error and jitter. Two
effects cause this. The 3458A has no delay line, so there is a trigger latency, a
time delay between the trigger and the commencement of the measurement, that
is fixed by the firmware, the clock, and the timing circuits. It is specified to be
less than 175 ns for an external trigger. The accuracy of the trigger can also be
affected by noise on the trigger signal and time interpolator variation between
measurements. This is of the order of 50 ps as well except in very noisy cases,
where it is advisable to use the 3458A's trigger filter which reduces the bandwidth
of the trigger circuit to a nominal value of 70 kHz.
Figure 64. The effects of
timebase jitter is shown
here. For the 3458A
Multimeter, the jitter is
50ps RMS. This jitter is
repeatable so it can be
characterized and
corrected.