8-17
IM 701510-01E
Analyzing W
aveforms
8
Points to note relating to waveform computation
• Computation cannot be carried out on snapshot waveforms or recalled waveforms.
• Computation between channels is carried out using the original acquisition data which are
then displayed using P-P compression. In case the input coupling is AC and an offset
voltage is applied, the offset part will not be included in computation.
• Addition and subtraction computation is carried out regardless of the V/DIV setting of the
channels. Therefore, in case of cursor measurement or automated measurement of trace 3
(or MATH), the displayed unit will become “div”.
• The voltage axis sensitivity of channel 1 and 2 being V1 and V2 respectively, the voltage
axis sensitivity of the computation result becomes (4/SENS) x V1 x V2/div. Therefore, in
case of cursor measurement or automated measurement of trace 3 (or MATH), the
displayed unit will become “V
2
”.
• The computed waveform displayed on trace 3 (or MATH) is P-P compressed data. When
this data is stored or saved on the internal memory/floppy disk/SCSI device, information
indicating that this is a computed waveform and the voltage axis information after the
computation are not stored or saved. Therefore, if this data is recalled or loaded and then
a measurement is made using the cursors or automated measurement of waveform
parameters, correct values will not be displayed. To display the correct values, save the
waveform data on CH1 and CH2 from the acquisition memory to the floppy disk/SCSI
device as binary data. Then, load the data and redo the waveform computation.
Waveform data in the acquisition memory cannot be stored in the internal memory.
• If the computed result due to adding or subtracting is larger than 10.24 div or the result
due to multiplying is larger than 13 div, a chopped waveform will be displayed as in the
following diagram. This is due to the fact that the computed result exceeds the display
range.
• Even if "OFF" is selected at the waveform math setting menu, the phase shift function is
still effective. To disable the phase shift function, set the phase shift to 0 div.
8.5 Performing Waveform Math (Addition, Subtraction and Multiplication)
