User`s guide

5-43
Making Measurements
Making time measurements automatically
Fall Time
The fall time of a signal is the time difference between the crossing of the upper
threshold and the crossing of the lower threshold for a negative-going edge. The
X cursor shows the edge being measured. For maximum measurement
accuracy, set the sweep speed as fast as possible while leaving the complete
falling edge of the waveform on the display. The Y cursors show the lower and
upper threshold points.
Rise Time
The rise time of a signal is the time difference between the crossing of the lower
threshold and the crossing of the upper threshold for a positive-going edge. The
X cursor shows the edge being measured. For maximum measurement
accuracy, set the sweep speed as fast as possible while leaving the complete
rising edge of the waveform on the display. The Y cursors show the lower and
upper threshold points.
+ Width
+ Width is the time from the middle threshold of the rising edge to the middle
th re sh ol d o f th e n ex t f al ling ed ge . T he X c ur so rs sh ow the pu ls e b eing me as ur ed .
The Y cursor shows the middle threshold point.
– Width
– Width is the time from the middle threshold of the falling edge to the middle
thr eshold of the next rising edge . The X curs or s show the pulse being mea sured.
The Y cursor shows the middle threshold point.
X at Max
X at Max is the X axis value (usually time) at the first displayed occurrence of
the waveform Maximum, starting from the left-side of the display. For periodic
signals, the position of the maximum may vary throughout the waveform. The
X cursor shows where the current X at Max value is being measured.
To measure the peak of an FFT:
aSelect FFT as the math function in the Math menu.
b Choose Math as the source in the Quick Meas menu.
c Choose Maximum and X at Max measurements.
Maximum units are in dB and X at Max units are in Hertz for FFT.