Gentec-EO MACH 6 - Manual (Page 41)

Mach 6 User’s Manual Revision 2.1 41
tracking had been turned on, the trigger level would have followed the pulse as it drifted
and no data would have been lost.
Now suppose in the previous example trigger tracking had been on. The trigger level
would have followed the pulse down as it drifted 12%. If the Mach 6 is then disarmed,
but the laser is left running at the same repletion rate, the pulse will stay at the same level,
but the trigger will return to its non-corrected state. When Mach 6 is disarmed, no
measurements are being taken and therefore no information about the pulse drift is
available to use for trigger tracking. When Mach 6 is rearmed, no triggers will occur as
the trigger level is still too high relative to the drifted pulse.
The solution to this is to readjust the trigger until the trigger LED illuminates, to use the
Zero Baseline button, or to press the Autoset button.
Zero Baseline
The DC level of a pulse for a Pyro Electric sensor is dependant on the average energy. If
the DC level drifts out of the ADC range and the Out of Range LED illuminates, pressing
this button will cause the instrument to readjust the DC level in the instrument to
compensate for this drift.
Autoset
This button calls the Autoset VI. This VI attempts to find the best range and trigger level
for the signal being measured. The flow is:
1. Set the trigger source to internal.
2. Set the trigger delay to 0ns.
3. Set trigger level to 7%
4. Set the Range to Top Range.
5. Test for triggering.
If no triggers are present, the VI reduces the range to the next lowest and tests for
triggering. It repeats this process until the lowest range is reached. If no triggers are
present, it then reduces the trigger level 1% at a time until either triggering occurs or the
minimum trigger level is reached.
When a trigger is found, the VI returns the discovered setup to the Instrument Controls
Display.
Measuring Data
Once range and trigger setting have been made, and the trigger LED is illuminated, then
data can be acquired. Press the ARM button. The ARM LED will illuminate indicating
that pulses are being measured. The Mach 6 can store 4,194,303 pulses in internal
memory. At 100,000 PPS, this is over 40 seconds of data. At 1,000 PPS, this is almost 70