Tabor Electronics 5064, User Manual

Page: 128 / 369

3
Using the Instrument
Pulse Design Limitations
3-57
that clocks memory points. The rate of the sample clock defines the
incremental resolution. Consider that you want to generate 100 ms
pulse rates with 1 ms high time pulse and the rest of the period low.
In this case, the generator can select the 1 kS/s to 10 kS/s clock
rate because this is enough for generating a high signal of 1 ms
using just 100 to 1000 memory points. However, when you want to
define much smaller pulse widths at larger rep rates, the number of
points that are used for the generation increases as a function of
the period. The limitation is set by the number of memory points;
with the basic model 2074, the incremental resolution is 1 in 1
million. This increases to 1 in 2 million if you purchased the Model
2074 with option 1 (2 M memory expansion) installed.
2. Sum of pulse parameters cannot exceed the period
While designing a pulse shape, bear in mind that the generator will
detect automatically if you are trying to mess with the mathematics.
Therefore, remember, the sum of all parameters cannot exceed the
period. Always start your pulse design by assigning the correct
pulse period and only then work your way down the parameters list.
3. Only single and double pulse can be designed
Just as a stand-alone pulse generator, the capability that is built into
the digital pulse generator allows generation of these two
waveforms. This allows generation of single or double pulse
patterns having a fixed high and low amplitude values. In case you
need to design complex trains of pulse waveforms, you can always
do it using the Pulse Composer in ArbConnection. The pulse
composer allows creation of complex pulse trains without limiting
amplitude, shape and number of pulses in one pulse train.
4. Inter-channel parameter dependency
As explained in 1 above, the pulse is created digitally using a
sample clock generator that clocks memory points. The 2074 has
only one sample clock generator and therefore, most of the pulse
parameters that are associated with time interval are shared across
the channels. When designing a pulse on one channel, bear in mind
that some parameters will be exactly the same on the other
channel. These are: Period, rise, high and fall times, double state
and double state delay. The rest of the parameters are not inter-
channel dependent and can be designed within the limitation of the
pulse generator, as specified in Appendix A.