2 Select PWM. Press Mod key, select type as PWM. 3 Set the width deviation. Press the Deviation softkey and set the value to 20% using the numeric keypad or the knob and cursor keys. 4 Set the modulating frequency. Press the PWM Freq softkey and then set the value to 5 Hz using the numeric keypad or the knob and cursor keys. 5 Select the modulating waveform shape. Press the Shape softkey to select the shape of the modulating waveform. For this example, select a sine wave.
At this point, the function generator outputs a PWM waveform with the specified modulation parameters (if the output is enabled).
6 View the waveform. Of course, to really view the PWM waveform, you would need to output it to an oscilloscope. If you do this, you will see how the duty cycle deviation varies, in this case, from 0% to 50%. At a modulation frequency of 5 Hz, the deviation is quite visible.
Amplitude Modulation (AM) A modulated waveform consists of a carrier waveform and a modulating waveform. In AM, the amplitude of the carrier is varied by the instantaneous voltage of the modulating waveform. The function generator will accept an internal or external modulation source. To Select AM Modulation ? The function generator will allow only one modulation mode to be enabled at a time. For example, you cannot enable AM and FM at the same time. When you enable AM, the previous modulation mode is turned off. ? The function generator will not allow AM to be enabled at the same time that sweep or burst is enabled. When you enable AM, the sweep or burst mode is turned off.
? Front-Panel Operation: You must enable AM before setting up any of the other modulation parameters. Press Mod key and then select “AM” using the Type softkey. The AM waveform is output using the present settings for the carrier frequency, modulating frequency, output amplitude, and offset voltage.
Carrier Waveform Shape ? AM carrier shape: Sine, Square, Ramp, Pulse, Arbitrary or Harmonic waveform. The default is Sine. You cannot use noise, or dc as the carrier waveform.
? Front-Panel Operation: Press any of the front-panel function keys except Noise. For arbitrary waveforms, press Arb and then choose the Select Type softkey to select the active waveform.
Carrier Frequency The maximum carrier frequency depends on the function selected as shown below. The default is 1 kHz for all functions.
FunctionMinimum FrequencyMaximum Frequency
SineSquareRampPulseArbs1μHz1μHz1μHz1μHz1μHz200MHz60MHz5MHz50MHz50MHz
? Front-Panel Operation: To set the carrier frequency, press the Freq softkey for the selected function. Then use the knob or numeric keypad to enter the desired frequency.
Modulating Waveform Shape The function generator will accept an internal or external modulation source for AM. ? Modulating waveform shape (internal source): Sine, Square, Ramp, Noise, or Arb waveforms (Sinc, Exp Fall, Haver Sine, Lorentz, Gause, Dual Tone, ECG). The default is Sine. ? Sine
When modulating waveform shape is Sine, display on the generator.
When modulating waveform shape is Sine, display on the oscilloscope.
Edited by WisdomAugust at 2019-12-5 09:54
? NoiseWhen modulating waveform shape is Noise, display on the generator.