Gentec-EO MACH 6 - Manual (Page 32)

Mach 6 User’s Manual Revision 2.1 32
the mode of X is 4 because that is the value that most often occurs in X.
Pulses Below Threshold
When the Search Data for Missing Pulses button is pressed, the current data set is
examined. Any pulses with energy less than the threshold are flagged as missing, and
their time stamps are recorded and displayed. This can be used with internal and external
triggering, but it is most effective when used with external triggering.
Pulses Below Trigger
With internal triggering, if the pulse is below the trigger level, no trigger will occur, but
the period timer will still be running. This means that the period will be longer between
the pulses adjacent to the missing pulses. The applications software examines the pulse
data for this condition and records the time stamps where the period is discontinuous.
From the continuous period data, the true period can be found and used to count how
many pulses were missing in the discontinuities.
Average Frequency
The measured average frequency of the data set.
Pulse Jitter
The difference between the maximum and minimum pulse periods in the data set.
The FFT Display
Figure 7 shows the FFT Display of the Applications Software.
This is useful for finding
periodic disturbances in the data. The plot shown was taken with an 11 kHz AM
modulation applied to the 50 kHz pulse signal. The 11 kHz modulation is clearly seen.