How to Use the Modulated Waveform Function of HDG6000B?

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How to Use the Modulated Waveform Function of HDG6000B?

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To Output a Modulated Waveform


A modulated waveform consists of a carrier and a modulating waveform. In AM (amplitude modulation),
the amplitude of the carrier is varied by the amplitude of the modulating waveform. For this example, you
will output an AM waveform with 80% modulation depth. The carrier will be a 5 kHz sine wave and the
modulating waveform will be a 200 Hz sine wave.



AM waveform display on oscilloscope

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1 Select the function, frequency, and amplitude of the carrier.

Press Sine key and then press the Freq, Ampl, and Offset softkeys to configure the carrier waveform.

For this example, select a 5 kHz sine wave with an amplitude of 5 Vpp.

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2 Select AM.

Press Mod key and then select “AM” using the Type softkey.

3 Set the modulation depth.

Press the AM Depth softkey and then set the value to 80% using the numeric keypad or the knob and

cursor keys.

4 Set the modulating frequency.

Press the AM Freq softkey and then set the value to 200 Hz using the numeric keypad or the knob and

cursor keys.

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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 an AM waveform with the specified modulation parameters

(if the output is enabled).

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To Output an FSK Waveform

You can configure the function generator to “shift” its output frequency between two preset values using

FSK modulation. The rate at which the output shifts between the two frequencies (called the “carrier

frequency” and the “hop frequency”) is determined by the internal rate generator or the signal level on

the front-panel Trig connector. For this example, you will set the “carrier” frequency to 3 kHz and the

“hop” frequency to 500 Hz, with an FSK rate of 100 Hz.

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1. Select the function, frequency, and amplitude of the carrier.

Press Sine key and then press the Freq, Ampl, and Offset softkeys to configure the carrier waveform.

For this example, select a 3 kHz sine wave with an amplitude of 5 Vpp.

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2 Select FSK.

Press Mod key and then select “FSK” using the Type softkey.

3 Set the “hop” frequency.

Press the Hop Freq softkey and then set the value to 500 Hz using the numeric keypad or the knob and cursor keys.

4 Set the FSK “shift” rate.

Press the FSK Rate softkey and then set the value to 100 Hz using the numeric keypad or the knob and cursor keys.

At this point, the function generator outputs an FSK waveform (if the output is enabled).

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To Output a PWM Waveform

You can configure the function generator to output a pulse width modulated (PWM) waveform. HDG6162B

provides PWM for square carrier waveforms, and PWM is the only type of modulation supported for Square

waveforms. In PWM, The pulse width of the carrier waveform varies with the voltage level of the modulating

waveform.

You can specify either a duty or a deviation to be controlled by the modulating waveform.

For this example, you will specify a deviation for a 1 kHz square waveform with a 100 Hz sine wave modulating

waveform.

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1 Select the carrier waveform parameters.

Press Square key and then press the Freq, Ampl, Offset, Width, and Edge Time softkeys to configure

the carrier waveform. For this example, select a 1 kHz square waveform with an amplitude of 1 Vpp, a

zero offset, a phase of 0 degree, and a duty of 50%.