MT Modulate AM (DSB)

Performs double sideband (DSB) amplitude modulation. This node performs signal processing on data and operates independently of hardware settings. Use this node in both simulated and hardware-equipped applications.

1378

Inputs/Outputs

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message signal

Message signal used to modulate the carrier wave.

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modulation index

Desired modulation index of the AM modulated waveform parameter. A value of 0.7, for example, corresponds to a modulation index of 70%. A value greater than unity may cause overmodulation and distortion. The node ignores this parameter if you set the suppress carrier? parameter to TRUE.

Default value: 1.0

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peak message amplitude

Peak message amplitude of the message signal parameter. The node uses this value to scale or normalize the input message signal prior to modulation. This value must be positive.

Default value: 1.0

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Default value: No error

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suppress carrier?

A Boolean that determines whether to suppress the carrier of the modulated signal.

TRUE The DC component corresponding to the carrier tone in the amplitude-modulated baseband signal is suppressed.
FALSE The output amplitude-modulated baseband signal consists of a DC component corresponding to the carrier tone.

Default value: FALSE

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AM modulated waveform

The modulated complex baseband time-domain data for demodulation.

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t0

The trigger (start) time of the Y array.

Default value: 0.0

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dt

Time interval between data points in the Y array.

Default value: 1.0

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Y

The complex-valued signal-only baseband modulated waveform. The real and imaginary parts of this complex data array correspond to the in-phase (I) and quadrature-phase (Q) data, respectively.

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Adjusting the Carrier Phase

initial phase MT Upconvert Baseband initial phase

Avoiding Distortion

message signal

Prescaling Behavior

This node prescales the message signal parameter by the scalar peak amplitude prior to modulation. The default value of 1.0 for peak message amplitude indicates that no prescaling occurs.

Double Sideband (DSB) Amplitude Modulation Formula

The output amplitude-modulated signal is represented by the following equations, depending on the setting of the suppress carrier? parameter:

sDSB(t)=1+k×m(t)max⁡|m(t)|sDSB(t)=1+k×m(t)max⁡|m(t)|
sDSBSC(t)=m(t)max⁡|m(t)|sDSBSC(t)=m(t)max⁡|m(t)|

where

m(t) represents the message signal data

S DSB (t) and SDSBSC(t) represent the AM modulated signal

k represents the modulation index