Aim-TTI TGA1240 Series, Инструкция по эксплуатации

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For periods above 1·25ms the maximum number of points in the waveform (50,000) becomes the
factor determining pulse width and delay resolution. For example, with the period set to 100ms,
the smallest pulse width and delay increment is 2µs (100ms
÷
50,000). This may appear to cause
significant “errors” at extreme settings (e.g. setting 100ns in the above example will still give an
actual width of 2µs) but in practical terms a 1 in 50,000 resolution (0·002%) is quite acceptable.
Pulse period can be adjusted irrespective of the pulse width and delay setting (e.g. can be set
smaller than the programmed pulse width) because, unlike a conventional pulse generator, pulse
width and delay are adjusted
proportionally as the period is changed. For example, if, from the
default pulse settings of 100µs period/50µs width, the period is changed to 60µs the pulse width
actual
changes to 30µs even though the
program
width is still 50µs; to get a 50µs width
with the period at 60µs the width must be re
−
entered as 50µs after the period has been changed.
Period can also be changed from the
PULSE PERIOD
screen called by pressing the FREQ
key with Pulse mode selected.
PULSE PERIOD
100·0 us
◊
freq period
♦
The new setting can be entered either as a period in the way already described or as a frequency
by first pressing the
freq
soft
−
key. However, changing the period/frequency from this screen
is slightly different from changing period on the
pulse setup
screen. When changing from
this screen the number of points in the waveform is never changed (just as with a true arb) which
means that the shortest period/highest frequency that can be set is number of waveform points
x25.00ns. To achieve faster frequencies (up to the specification limit) the period must be changed
from the pulse set
−
up screen; changing the frequency from this screen causes the number of
points to be reduced as the period is reduced (for periods <1·25ms).
Pulse-train Setup
Pulse
−
trains are turned on with the
pulse-train
softkey on the
STANDARD WAVEFORMS
screen; pressing the
setup…
soft
−
key beside
pulse-train
calls the first of the setup
screens:
Enter no of pulses
in train (1-10):
2
◊
done next
◊
The number of screens used for the setup depends on the number of pulses in the pulse
−
train.
The first three screens define the parameters that apply to the whole pattern (number of pulses,
overall pulse
−
train period and baseline voltage); subsequent screens define the pulse level, width
and delay for each pulse in turn (3 screens for pulse 1, then 3 screens for pulse 2, etc.). Pressing
next
on any screen calls the next setup screen, finally returning the display to the
STANDARD
WAVEFORMS
screen from which pulse
−
train can be turned on and off; pressing
done
returns
the display directly to the
STANDARD WAVEFORMS
screen from any setup screen. The
pulse
−
train is built only after
next
is pressed after the last parameter setup or whenever
done
is pressed, assuming a change has been made. The first screen, shown above, sets the
number of pulses (1
−
10) in the pattern; enter the number of pulses directly from the keyboard or
by using the rotary control.