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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

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Gentec-eo MACH 6 Manuel d'utilisateur Page 38