UNI-T UTG1000 Series User Manual page 26

2) External Source
When modulation source is external, parameter list will hide the modulation wave option and modulation
frequency option, and carrier waveform will be modulated by an external waveform. AM modulation depth is
controlled by ±5V signal level of external modulation input terminal. For example, if modulation depth value is set
to 100%, AM output amplitude is the maximum when external modulation signal is +5V, AM output amplitude is the
minimum when external modulation signal is -5V.
Modulation Shape Frequency Setting
When modulation source is internal, frequency of modulation shape can be modulated. After enabling AM function,
range of modulation wave frequency is 2mHz~50kHz (default is 100Hz). Press Parameter→Modulation Frequency
to change. When modulation source is external, parameter list will hide the modulation shape option and
modulation frequency option, and carrier waveform will be modulated by an external waveform. The range of
modulation signal input from external is 0Hz~ 20Hz.
Modulation Depth Setting
Modulation depth indicates the extent of amplitude variation and is expressed as percentage. Suitable setting range
of AM modulation depth is 0% to 120%, and the default is 100%. When modulation depth is set to 0%, the constant
amplitude (a half of the carrier wave amplitude that has been set) is output. Output amplitude changes as
modulation waveform changes when modulation depth is set to 100%. The instrument output a peak-peak voltage
less than ±5V (is connected with 50Ω terminal) when modulation depth is more than 100%. If need to change, press
Parameter→Modulation Depth in amplitude function interface. When modulation source is external, output
amplitude of the instrument is controlled by ±5V signal level of external modulation input terminal (Input/CNT
probe) in rear panel. For example, if modulation depth value in parameter list has been set to 100%, AM output
amplitude is the maximum when external modulation signal is +5V, AM output amplitude is the minimum when
external modulation signal is -5V.
Comprehensive Example
Firstly, make the instrument work in amplitude modulation (AM) mode, then set a sine wave with 200Hz from the
internal of the instrument as a modulation signal and a square wave with frequency of 10kHz, amplitude of
200mVpp and duty cycle of 45% as a carrier wave signal. Finally, set modulation depth to 80%. Specific steps are
seen as following:
1) Enable Amplitude Modulation (AM) Function
Press Menu→Modulation→Type→Amplitude Modulation in turn.
24 UTG1000A Series