Downconverts a complex baseband signal, which is centered around a non-zero center frequency, to a center frequency of zero. This node can be used in simulated as well as hardware-equipped applications.

complex waveform

Signal for downconversion in passband form.

t0

The trigger (start) time of the acquired signal.

Default: 0.0

dt

Time interval between data points in the acquired signal.

Default: 1.0

Y

The complex array representing the signal for downconversion.

carrier frequency

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

passband bandwidth

The bandwidth, in Hz, of the passband signal data. The node ignores this parameter if you set the reset? parameter to FALSE.

Filter parameters.

passband ripple

The ripple in the passband, in dB. The ripple is the ratio of the maximum deviation from the average passband amplitude to the average passband amplitude. The value must be greater than zero.

Default: 0.01

stopband start

The start of the stopband, Hz.

Default: 0

compute filter stopband ?

A Boolean that determines whether to compute the stopband start or use the value that you specify in the stopband start parameter.

 TRUE Computes the stopband start based on the carrier frequency and passband bandwidth parameters. FALSE Uses the value that you specify in the stopband start parameter.

Default: TRUE

stopband gain

The stopband gain, in dB. The gain is the negative of the minimum attenuation of the stopband with respect to the average amplitude of the passband.

Default: -96

error in

Error conditions that occur before this node runs. The node responds to this input according to standard error behavior.

Default: no error

enable filter

A Boolean that determines whether to perform software filtration on the downconverted data.

 TRUE The node filters the downconverted waveform parameter using a software FIR filter. FALSE Disables the downconversion filter and generates unfiltered data in the downconverted waveform parameter.

Default: TRUE

reset?

A Boolean that determines whether to use values specified by the initial phase, passband bandwidth, enable filter, passband ripple, and stopband start parameters.

 TRUE The node uses these parameter values at each call. FALSE The node ignores these parameters and continues using values supplied in the previous call. Reusing previous input values is useful when sequential data blocks represent contiguous signal data.

Default: FALSE

initial phase

The initial phase, in degrees, of the software local oscillator used in the downconversion process. The node ignores this parameter if you set the reset? parameter to FALSE. Use the initial phase parameter to match the phase of the incoming modulated carrier and the local oscillator(s) of the downconversion process.

downconverted waveform

The downconverted signal in complex envelope format.

t0

The trigger (start) time of the acquired signal.

dt

Time interval between data points in the acquired signal.

Y

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

The deviation of the passband gain from the nominal gain of 0 dB.

filter length

Number of taps in the filter.

error out

Error information. The node produces this output according to standard error behavior.