MT Downconvert Passband VI

LabView Analog Modulation

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MT Downconvert Passband VI

Downconverts real passband signal data of a user-specified bandwidth. The complex instance of this VI downconverts a complex baseband signal, centered around a nonzero center frequency, to a center frequency of zero. The baseband I/Q signal (complex envelope) is returned in the downconverted waveform parameter.

Note Using a downconversion filter with this VI may lead to the apparent loss of samples in the output waveform. Refer to Filter Delay for more information about this effect.

Use the pull-down menu to select an instance of this VI.

Details

MT Downconvert Passband (Complex)

Downconverts a complex baseband signal, centered around a nonzero center frequency, to a center frequency of zero.

MT Downconvert Passband (Complex)

complex waveform specifies the signal for downconversion in passband form.

	t0 specifies the trigger (start) time of the acquired signal.
	dt specifies the time interval between data points in the acquired signal.
	Y specifies the complex array representing the signal for downconversion.

carrier frequency specifies the center frequency of the passband, in hertz. This frequency is downconverted to 0 Hz. Enter the expected carrier frequency of the incoming signal for downconversion.

passband bandwidth specifies the bandwidth of the passband signal data. This parameter is ignored if reset? is FALSE.

enable filter specifies whether to perform software filtration on the downconverted data.

TRUE	When enable filter is TRUE, the downconverted waveform is filtered using a software FIR filter. This is the default value.
FALSE	Set enable filter to FALSE to disable the downconversion filter and generate unfiltered data in the downconverted waveform.

initial phase specifies the initial phase, in degrees, of the software local oscillator used in the downconversion process. This parameter is ignored if the reset? parameter is FALSE. Use initial phase to match the phase of the incoming modulated carrier and the local oscillator(s) of the downconversion process.

reset? specifies whether to use values input to the initial phase parameter, the passband bandwidth parameter, and the enable filter parameter.

TRUE	When reset? is TRUE, this VI uses these parameter values at each function call.
FALSE	Set reset? to FALSE to disregard these parameters and continue using values supplied in the previous call. Reusing previous input values is useful when sequential data blocks represent contiguous signal data. This is the default value.

error in (no error) accepts error information wired from previously called VIs. Use this information to decide if any functionality should be bypassed in the event of errors from other VIs. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.

	status is either TRUE (X) for an error, or FALSE (checkmark) for no error or a warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.
	code identifies the error or warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.
	source describes the origin of the error or warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.

downconverted waveform (complex) returns the downconverted signal in complex envelope format.

	t0 returns the trigger (start) time of the acquired signal.
	dt returns time interval between data points in the acquired signal.
	Y returns 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.

ripple returns the deviation of the passband gain from the nominal gain of 0 dB.

filter length returns the number of taps in the filter.

error out passes error or warning information out of a VI to be used by other VIs. Right-click the front panel error out indicator and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.

	status is either TRUE (X) for an error, or FALSE (checkmark) for no error or a warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.
	code identifies the error or warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.
	source describes the origin of the error or warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.

MT Downconvert Passband (Real)

Downconverts real passband signal data of a user-specified bandwidth.

MT Downconvert Passband (Real)

complex waveform specifies the signal for downconversion in passband form.

	t0 specifies the trigger (start) time of the acquired signal.
	dt specifies the time interval between data points in the acquired signal.
	Y specifies the complex array representing the signal for downconversion.

passband bandwidth specifies the bandwidth of the passband signal data. This parameter is ignored if reset? is FALSE.

enable filter specifies whether to perform software filtration on the downconverted data.

TRUE	When enable filter is TRUE, the downconverted waveform is filtered using a software FIR filter. This is the default value.
FALSE	Set enable filter to FALSE to disable the downconversion filter and generate unfiltered data in the downconverted waveform.

reset? specifies whether to use values input to the initial phase parameter, the passband bandwidth parameter, and the enable filter parameter.

TRUE	When reset? is TRUE, this VI uses these parameter values at each function call.
FALSE	Set reset? to FALSE to disregard these parameters and continue using values supplied in the previous call. Reusing previous input values is useful when sequential data blocks represent contiguous signal data. This is the default value.

	status is either TRUE (X) for an error, or FALSE (checkmark) for no error or a warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.
	code identifies the error or warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.
	source describes the origin of the error or warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.

downconverted waveform (complex) returns the downconverted signal in complex envelope format.

	t0 returns the trigger (start) time of the acquired signal.
	dt returns time interval between data points in the acquired signal.
	Y returns 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.

ripple returns the deviation of the passband gain from the nominal gain of 0 dB.

filter length returns the number of taps in the filter.

	status is either TRUE (X) for an error, or FALSE (checkmark) for no error or a warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.
	code identifies the error or warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.
	source describes the origin of the error or warning. Right-click the front panel error in control and select Explain Error or Explain Warning from the shortcut menu for more information about the error displayed.

Details

When the enable filter parameter is TRUE, the downconverted I/Q signal is filtered by a software lowpass FIR filter whose design parameters are dictated by the following considerations:

If carrier frequency is greater than passband bandwidth, the filter stopband begins at carrier frequency.
If carrier frequency is less than passband bandwidth, the filter stopband begins between carrier frequency and 2×carrier frequency–passband bandwidth/2.

Note This VI performs signal processing on data and operates independently of your hardware setttings. This VI can be used in simulated as well as hardware-equipped applications. This VI is unaffected by the hardware settings configured using the MT Configure Downconversion Settings VI.

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