User manual

3152B User Manual Publication No. 980935 Rev. M
3-16 Operation Astronics Test Systems
waveform shapes:
func:shap sin Selects the sine waveform
func:shap tri Selects the triangle waveform
func:shap squ Selects the square waveform
func:shap puls Selects the pulse waveform
func:shap ramp Selects the ramp waveform
func:shap sinc Selects the sinc waveform
func:shap gaus Selects the Gaussian waveform
func:shap exp Selects the exponential waveform
func:shap nois Selects the noise waveform
func:shap dc Selects the DC waveform
After you select a waveform shape, you may specify
the waveform
parameters. Chapter 5 explains the commands
available for
specifying parameters of standard waveforms.
Note
The number of points used for defining a standard
waveform depends upon the programmed frequency.
Therefore, some parameter changes may not have any
effect on the waveform because the number of points do
not provide enough resolution to show the difference.
The number of waveform points varies, depending up
on the output
frequency. The reason for this variation is that even standard
waveforms are in a manner similar to that of arbitrary waveforms,
except that the 3152B stores standard waveforms in a
permanent
internal
library for immediate use. At low frequencies, the number of
points for each standard waveform is 1,000. Therefore,
waveform
modifications are possible in increments of 1/1,000
of the total
waveform. For example, if you want to modify the duty cycle
of a
square waveform, the resolution for the duty cycle is 0.1%.
At higher frequencies,
the number of points used for generating
waveforms decreases according to the following relationship:
Output Frequency = Sample Clock Frequency / Waveform Points
Since the maximum sample clock frequency is 250
MS/s, the only
way to increase frequency is by reducing the number of waveform
points
(when the standard waveform frequency is > 250 kHz). The
reduced number of points available at higher frequencies decreases
timing resolution for the standard waveforms. For example,
for a
25 MHz square wave, only ten points per period are available
.
Therefore, duty cycle resolution is decreased to 10% increments.