Model 8642A/B Operation
MODULATION OSCILLATOR
Description The Signal Generator's internal modulation oscillator is the modulation source for
internal AM, FM, $M, and pulse modulation. The modulation oscillator signal is also the
source for the MOD OUTPUT connector when the modulation output level is set.
Internal modulation (such as AM, FM, <t>M, and pulse modulation) is described in those
specific operating instructions. However, the modulation frequency and the modulation
output level are discussed here.
Table 3-24. Modulation Oscillator Operating Characteristics
Electrical
Characteristics
Frequency Range
Frequency Resolution
Frequency Accuracy
Output Distortion (>0.5 Vpk)
Output Level Range
Output Level Resolution
Output Level Accuracy
Output Impedance
Performance
Limits
20 Hz to 100 kHz
1%
of setting
2%
of setting
<0.02%
<0.15%
0 to 3.3 Vpk
4 mV
±(4%
+ 15 mV)
600 ohms ±10%
Conditions
0.02 to 15.8 kHz
>15.8 kHz
Within 1s
Procedures Note: Put the instrument in its initialized state by selecting I INSTR PRESET I.
MOD FREQ
How to Set Modulation Frequency
rrvlOD FREQ I and the value of the desired output frequency (in kHz or Hz).
The modulation frequency cannot be turned off with the [ OFF ON~l key, but the
modulation oscillator can be considered off if the modulation output (MOD OUT) is off
and no internal modulation source is in use.
MOD OUT
How to Set Modulation Output Level
The Signal Generator can be set to produce a sinewave signal at the MOD OUTPUT
connector by selecting:
MOD OUT ( rsHm I MOD FREQ I ) and the desired peak-voltage output level (in V or
mV).
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