Model 8642A/B
Operation
MODULATION, PULSE
Description The Signal Generator can pulse modulate its RF output either with the variable
internal modulation oscillator or with a dc-coupled external source applied to the
AM/PULSE INPUT.
When the internal pulse modulation source is selected, the pulse repetition rate can be
changed by varying the modulation oscillator frequency. The duty cycle will always
be 50% for internal pulse modulation.
Table 3-23. Pulse Modulation Operating Characteristics
Electrical Characteristics
Pulse Modulation
Pulse On/Off Ratio
Rise/Fall Time
Minimum Pulse Width
Maximum Repetition Frequency
Nominal Peak
Input Level Required
Performance Limits
>30 dB
>45 dB
<3.5 /us
6 /its
50 kHz
1.5V
Conditions
Output Levels <+15 dBm
1
RF Frequency <1057.5 MHz
RF Frequency >1057.5 MHz
2
10%
to 90%
1
0utput level accuracy is typically ±3 dB.
2
8642B,
Band 10.
Procedures Note: Put the instrument in its initialized state by selecting [ INSTR PRESET I.
INT
How to Set Pulse Modulation with the Internal Source (Using the Modulation Oscillator)
Source
PULSE
(i SHIFT i rmr\) rwn
Rate
I MOD FREQ I and the desired value of modulation frequency (in kHz or Hz).
Pulse Modulation
PULSE ([ SHIFT I rATvn ) and ( OFF ON I
3-127
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