Gentec-EO MACH 6 - Manual (Page 38)

Mach 6 User’s Manual Revision 2.1 38
Getting Ready to Measure Data
The Mach 6 instrument and applications software provide a versatile high speed
measurement system. It must be properly set up to work well. The following sections
discuss the controls that set up the instrument for measuring data.
Range Setting
The available ranges are dictated by the probe in use. Use the range control to set the
range to a value appropriate for the expected energy. Note that energy values above the
range value can be measured, but accuracy may be reduced. In general, the smallest range
that will contain the expected energy should be used, i.e., if the maximum energy to be
measure is 189μJ, the use the 200μJ range. Note that this energy can be measured in the
2mJ range with a trigger level below 9%, or an external trigger, but more accurate results
will be obtained in the 200μJ range.
Trigger Level Setting
If internal trigger is used, then the trigger level is set to a value that is less that the lowest
expected energy. For example, energies from 1.8mJ to 15mJ are expected. Select the
20mJ range, and set the trigger level to less than 1.8 / 20 x 100 = 9 %. You may have to
experiment with the trigger level until the trigger LED illuminates.
Trigger Source Setting
The trigger source can be set to internal or external. Internal trigger generates a trigger
event whenever the pulse exceeds the trigger level. External triggering generates a trigger
even whenever a TTL pulse is received on the External trigger input. A measurement is
taken when a trigger even is generated, so with external triggering missing or runt pulses
can be discovered.
Trigger Polarity (Slope) Setting
In external trigger mode, the rising or falling edge of the TTL pulse may be selected as
the trigger event.
Trigger Delay Setting
The Mach 6 instrument samples the pulse being measured to determine the pulse energy.
In order to accurately measure the energy, the trigger event must be temporally aligned
with the pulse. This alignment is accomplished by setting the trigger delay. For internal
triggering, the delay is set to the default value of 0ns and the user need not do anything.
When set to internal triggering the instrument compares the amplitude of each pulse from
the sensor to the set trigger level. If the pulse amplitude exceeds the set trigger level, then