Quick guide to the output controls and sockets:
version G85793 2014
Modulation:
Amplitude modulation (am) varies the loudness of the generator output.
A signal of +/-160mV gives 100% modulation, i.e. the loudness will vary from 100% to 0% in response to the input
signal.
This is best observed by connecting an oscilloscope to the high impedance output.
Setting the signal generator to around 10kHz, and applying a modulation signal of between 50 and 500Hz will
show the effect well. The internal speaker will make the combined sound audible.
Applying a modulation frequency closer to the main or “carrier” frequency will produce some strange and
interesting effects which might find use in electronic music.
Frequency modulation varies the frequency of the generator output.
When “fm” is selected, the frequency output is locked at approximately 6 in whichever decade is
selected. A modulation signal of +/-5V will then swing the frequency through the full decade from 1 to 11.
Smaller signals will give smaller swings.
Connecting an oscilloscope will show the frequency variation best, if the modulating signal is at a similar
frequency to the main or “carrier”.
Both types of modulation provide examples of how a signal can be superimposed on a carrier frequency, which
is the basis of am and fm radio transmissions.
version G85793 2017
