# MT Measure Rho (G Dataflow)

Version:
Last Modified: February 7, 2018

Calculates rho given an acquired and ideal waveform.

Rho is a measure of correlation between the measured complex waveform and the ideal complex waveform. To generate the ideal waveform, use the digital modulation nodes with the same system parameters given to the digital demodulation nodes, and then modulate the output bit stream returned by the demodulation node.  ## received complex waveform

The actual output waveform from the digital demodulation node. Wire the recovered complex waveform parameter from the digital demodulation node to this parameter. ### t0

Trigger (start) time of the Y array.

Default: 0.0 ### dt

Time interval between data points in the Y array.

Default: 1.0 ### 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. ## ideal complex waveform

The reference waveform. Obtain this waveform by remodulating the output bit stream from the digital demodulation node. ### t0

Trigger (start) time of the Y array.

Default: 0.0 ### dt

Time interval between data points in the Y array.

Default: 1.0 ### 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. ## error in

Error conditions that occur before this node runs.

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

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error  If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error ## rho

The measured rho of the received complex waveform. ## error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error  If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

## Rho

Rho (ρ) is a measurement that evaluates modulation quality. It is calculated by finding the correlation between the recovered waveform and an ideal waveform that has been reconstructed from the demodulated bits. The received demodulated waveform is compared to an ideal waveform obtained by remodulating the output bit stream of the digital demodulation process. The ρ measurement is related to EVM because EVM measures the vector difference between the measured and ideal signals, while ρ measures the correlation between the two signals. The value of ρ can range from 0.0 to 1.0, inclusive. The following table illustrates the ranges for ρ and degree of correlation between measured and ideal signals.
Ranges for ρ Degree of correlation between measured and ideal signals
ρ=0.0 Uncorrelated
0.0 < ρ < 1.0 Partially correlated
ρ = 1.0 Perfectly correlated

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application