Amplitude Modulation (AM) and Frequency Modulation (FM)
Modulating Source
The instrument accepts an internal or external modulation source. On a two-channel instrument you can modulate
one channel with the other.
l Modulating source: Internal (default), Other Channel, or External.
l With the External source, an external waveform modulates the carrier waveform. The modulation depth (AM) or
frequency deviation (FM) is controlled by the ±5 V signal level on the rear-panel Modulation In connector. The
external modulation input has -3 dB bandwidth of 100 kHz.
l AM example: with modulation depth 100%, when the modulating signal is at +5 V, the output will be at the max-
imum amplitude. When the modulating signal at -5 V, the output will be at minimum amplitude.
l FM example: with deviation of 10 kHz, then a +5 V signal level corresponds to a 10 kHz increase in frequency.
Lower external signal levels produce less deviation and negative signal levels reduce the frequency below the car-
rier frequency.
l Front-Panel
After enabling AM or FM, select the modulating source as shown:
l SCPI:
AM:SOURce {INTernal|EXTernal|CH1|CH2}
FM:SOURce {INTernal|EXTernal|CH1|CH2}
76 Agilent 33500 Series Operating and Service Guide
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