Fluke 291 User Manual page 81

291, 292, 294
Users Manual
The pulse level can be set on this screen between -5·0 V and +5·0 V by direct keyboard
entries or by using the rotary control. As with the baseline level described above the set
pulse levels are only output if the amplitude setting is set to maximum (10 V p-p into
50Ω) on the AMPLITUDE screen and terminated in 50 Ω. Adjusting the amplitude
scales both the peak pulse levels and baseline together, thus keeping the pulse shape in
proportion as the amplitude is changed, exactly as for arb waveforms. Output levels are
doubled when the output is not terminated.
Note that by pressing the Pulse soft key on this (and subsequent screens) the pulse to
be edited can be directly set from the keyboard or by using the rotary control; this is
useful in directly accessing a particular pulse in a long pulse train instead of having to
step through the whole sequence.
Pressing next calls the pulse width screen for the first pulse:
The width can be entered directly from the keyboard or by using the rotary control. Any
value in the range 10·000000 ns to 99·999999 s can be programmed but the actual value
may differ; for this reason the actual pulse width is shown below the program
width. The variation between program and actual will only really be noticeable
for very short pulse-train periods (only a few points in the pulse-train) and very long
periods (each of the 50,000 points has a long dwell time) for exactly the same reasons as
described in the Pulse Set-up section above, where there is a detailed explanation.
Pressing next calls the pulse delay screen for the first pulse:
The pulse delay is entered in the same way as pulse width and, again, the actual
delay is shown below the program delay for the same reasons. The delay value that
can be entered must be in the range ±(pulse-train period -1 point); positive values delay
the pulse with respect to waveform sync from SYNC OUT; negative values cause the
pulse to be output before the waveform sync.
Pressing next on this screen calls the first of the 3 screens for setting the parameters of
pulse 2, and so on through all the pulses in the pulse-train. In this way all parameters of
all pulses are set. The pulse-train is built when next is pressed on the last screen of
the last pulse or when done is pressed on any screen.
Care must be taken that the set widths and delays of the individual pulses are compatible
with each other and the overall pulse-train period, i.e. delays must not be such that pulses
overlap each other and delays + widths must not exceed the pulse-train period;
unpredictable results will occur if these rules are not followed.
Once the pulse-train has been defined the period can be adjusted irrespective of the pulse
width and delay settings for the individual pulses because, unlike a conventional pulse
10-6
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Pulse 1 width
• program 25·000000us
actual 25·000000us
done next
Pulse 1 delay
• program+0·0000000ns
actual +0·0000000ns
done next
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