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162 Agilent E1441A Function Generator Tutorial
Appendix C
even numbers only (rounded down)
Equations:
Compute the modulation pre-scaler divider:
(truncated to integer value ≥ 1)
Compute the number of points for the modulation waveform length:
(rounded down to even number)
Waveshapes are automatically expanded or compressed to match length “P”
computed above and downloaded into modulation RAM.
Example: Assume that you need to phase-continuously frequency hop between
the following nine frequencies every 200
µs.
15.0 MHz, 1.001 MHz, 9.780 MHz, 12.375 MHz, 0.5695 MHz,
3.579 MHz, 0.8802 MHz, 0.6441 MHz, and 10.230 MHz.
Solution: Create a modulation arbitrary waveform that is precisely sampled in
FM
modulation.
Fs = 1 / (9 x 200
µs) = 555.555 kHz (effective point clock)
Points (P) = (C/S) / Fs = 2250
S=1. If P greater than 4096, divide C by the smallest S to bring
P within range. Round down to an even P value.
Modulation Frequency (F) = (C/S) / 2 x 2250 = 555.55555 Hz
Round down in sixth digit to get modulation frequency to set.
Set the modulation frequency to 555.555 Hz.
Set the carrier frequency to (Max F + Min F) / 2 = 7.784750 MHz.
Set deviation (pk) frequency to (Max F – Min F) / 2 = 7.215250 MHz
Create and download a nine-segment arbitrary waveform with the values shown
below. Each segment is 250 points long (2250/9) for a total of 2,250 points. Use the
DATA VOLATILE command download to achieve 12-bit frequency resolution for
each point.
y = mX + b
To Check: Enable
FM by sending the following commands:
"FM:STATE ON"
"FM:INT:FREQ 555.555"
"DIAG:PEEK? 0,0,0"
enter results < Prescale# (S) >,< Points (P) >
S
k
F
---
=
P
2 C
×
1 S+()
F
×
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=