Demodulates a double sideband (DSB) amplitude-modulated signal.
The modulated complex baseband time-domain data for demodulation.
The trigger (start) time of the Y array.
Time interval between data points in the Y array.
The complex-valued time-domain data array. The real and imaginary parts of this complex data array correspond to the in-phase (I) and quadrature-phase (Q) data, respectively.
The expected modulation index of the AM demodulated waveform parameter. This value is used to scale the AM demodulated waveform parameter.
Error conditions that occur before this node runs. The node responds to this input according to standard error behavior.
Default: no error
A Boolean that determines whether the carrier has been suppressed in the incoming AM-DSB-modulated waveform.
Demodulation proceeds according to one of the following methods, depending on whether suppressed carrier? is set to TRUE or FALSE.
The incoming baseband AM-DSBSC modulated signal can be expressed as the following equations:
where is an AM-DSBSC modulated waveform, and is any time-varying phase ambiguity.
The node squares the signal when computing the phase estimate of . This squaring operation removes the 180 degrees phase ambiguity relative to the sign of . The computed phase estimate is used to generate a complex tone that is added back to the input signal to generate the equivalent DSB signal with carrier and unity modulation index. Thereon, envelope detection is performed for computing the AM demodulated waveform output .
The recovered message signal can be obtained from the following relationships:
The incoming baseband AM-DSB modulated signal can be expressed by the following equations:
where is a DSB modulated waveform and is any time-varying phase ambiguity. AM-DSB demodulation involves performing envelope detection. The AM demodulated waveform (t) is given by the following equation:
where represents the modulation index.
The recovered message signal.
Wire the AM demodulated waveform parameter to any LabVIEW waveform measurement node for further analysis. If the information signal is a single tone (normalized) and modulation index is set to 1.0 with suppressed carrier? set to FALSE, the peak amplitude value of the AM-demodulated waveform represents the true modulation index of the incoming AM-modulated waveform.
The mean zero-to-peak amplitude, in volts, of the IF carrier wave.
Error information. The node produces this output according to standard error behavior.
Demodulation using this node depends on whether suppressed carrier? is set to TRUE or FALSE.
Where This Node Can Run:
Desktop OS: Windows
FPGA: Not supported