User Manual LW120
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50
TTL
POWER
I
0
OUTPUT
LeCroy
MODEL
100 MS/s ARBITRARY WAVEFORM
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CHAN
1
SYNC
CHAN
2
RESET
CURSOR
MAN
TRIG
TRIGGER
AMPLITUDE
FREQUENCY
UTILITY
WAVEFORM
Figure 3-21. Programming the Sample Clock for the Modulating
Arbitrary Waveform
FM Sclk 1.000000MS/s
8. You’ll now need to use ArbExplorer to generate your modulating
waveform. Invoke ArbExplorer, select the modulated waveforms
option and press the FM Composer button on the Modulation
panel.
9. Refer to the Figure 3-22 and modify the Wavelength field to
have 10,000 points. After you modify the field, press the
Wavelength button. The number of points is derived from the
following relationship:
Number of Points = FM Sclk / 100Hz = 1M / 100 = 10,000
10. Now you have to program the deviation range. At the beginning
of this example we computed and showed that the LW120 is
using 32 points to generate this waveform. Note that the
deviation range is given on sample per second and use the
following relationship to compute the number for the deviation
range:
Deviation Range = 100 KHz x 32 = 3.2 MS
After you complete updating the above field, the FM Composer
will have the following coordinates:
The Y axis shows the frequency deviation range. The center
line shows 64 MS and the high and low limits are +65.6 MS and
–62.4 MS, respectively.
The X axis shows the length of the arbitrary modulating
waveform. The length is in points. In our example, the first point
is 0 and the last is 9999 (total of 10,000 points).
11. Now that you have the Y and X parameters set, you can
generate the shape of the modulating waveform. ArbExplorer
has a library of standard waveform that include: Sine, Triangle,
Square, Exponential, Pulse and Random Noise waveforms. You
can use one of these waveforms, or import coordinates from an
Using The Instrument 3-26