User Manual

2)External source

In case of external modulation source, modulation wave and frequency will be hidden in

parameter list, when an external waveform will be used to modulate carrier waveform.

Duty ratio deviation of PWM is controlled by ±5V signal level on external analog modulation

input terminal (Modulation In connector) of back panel. For example, if duty ratio deviation

in parameter list is set to be 15%, duty ratio of carrier signal (pulse wave) increases by

15% when external modulation signal is +5V. Lower external signal level generates less

deviation.

Set modulation frequency

When modulation source is internal, frequency of modulation wave can be modulated.

After enabling PWM function, default of modulation wave frequency is 100Hz.

Press Param → ModFreq to change. Modulation frequency range: 2mHz~1MHz. 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(impulse wave). The range of modulation signal input from external is 0Hz~ 20Hz.

Set duty ratio deviation

Duty ratio deviation is deviation of modulated waveform from the current carrier duty ratio.

The range of PWM duty ratio is 0%~49.99%, 20% by default. You can change it with

multi-functional knob and direction key on interface for using PWM function or by pressing

Param → DutyDev

Duty ratio deviation is change in duty ratio of modulated waveform relative to original

pulse waveform (%).

Duty ratio deviation should not be more than current duty ratio of pulse wave.

The sum of duty ratio deviation and current duty ratio of pulse wave must be ≤99.99%.

Duty ratio deviation is restricted by minimum duty ratio of pulse wave and the current

edge time.

Comprehensive example

First make the instrument run in PWM mode, and then set an internal sine wave of 1kHz

as modulation signal and a pulse wave with frequency of 10kHz, amplitude of 2Vpp, duty

ratio of 50% and rising/falling time of 100ns as carrier signal. Finally set duty ratio deviation

to be 40%. The specific steps are as follows:

1)Use PWM function

Press Menu → Mod → Type → PMW successively (if Type is not highlighted, it may be

necessary to press soft key Type twice to display the next screen of sub-tags) to use

PWM function.

Figure 4-23　Select PWM function