Last Modified: January 9, 2017

Applies various I/Q impairments to the complex baseband modulated waveform.

A value that indicates which set of equations is used to represent impairments.

In the equations in the following table,
$I$ is the real component and
$Q$ is the imaginary component of each sample in the **input complex waveform**.
${I}^{\prime}$ and
${Q}^{\prime}$ are the real and imaginary components of the corresponding sample in the **output complex waveform**.
${I}_{\circ}$ is **I DC Offset (%)** / 100, and
${Q}_{\circ}$ is **Q DC Offset (%)** / 100.

Name | Description |
---|---|

Vertical Shear | The definition uses the following equations for I/Q impairments: ${I}^{\prime}=a*\text{\hspace{0.17em}}I+\text{\hspace{0.17em}}{I}_{\circ}$ ${Q}^{\prime}=a*\mathrm{sin}\left(\phi \right)\text{\hspace{0.17em}}*\text{\hspace{0.17em}}I+\text{\hspace{0.17em}}b*\text{\hspace{0.17em}}\mathrm{cos}\left(\phi \right)\text{\hspace{0.17em}}*\text{\hspace{0.17em}}Q+\text{\hspace{0.17em}}{Q}_{\circ}$ where φ is the specified quadrature skew, in radians
$\gamma $ = 10 $a=\gamma *\text{\hspace{0.17em}}b$ $b=\sqrt{\frac{2}{1+{\gamma}^{2}}}$ In matrix form, these equations are represented by $\left[\begin{array}{c}{I}^{\prime}\\ {Q}^{\prime}\end{array}\right]=S\left[\begin{array}{c}I\\ Q\end{array}\right]+\left[\begin{array}{c}{I}_{\circ}\\ {Q}_{\circ}\end{array}\right]$ where $S=\left[\begin{array}{cc}a& 0\\ a*\mathrm{sin}\phi & b*\mathrm{cos}\phi \end{array}\right]$ |

Axis Shear | With this option selected, this node uses an impairment definition that simplifies the conversion between measured impairments and their inverse impairments. For example, you may want to measure the I/Q impairments of a system and compensate for those impairments by applying the inverse impairments to the generated or received waveform. Using the Axis Shear definition, given a measured skew and imbalance (in dB), the inverse impairments are -1.0 * ${I}^{\prime}=I*\text{\hspace{0.17em}}\sqrt{\gamma}-Q*\left(\frac{\phi}{2}\right)+{I}_{\circ}$ ${Q}^{\prime}=-I*\left(\frac{\phi}{2}\right)+Q*\left(\frac{1}{\sqrt{\gamma}}\right)+{Q}_{\circ}$ where
$\gamma $ = 10 φ is the specified quadrature skew, in radians In matrix form, these equations are represented by $\left[\begin{array}{c}{I}^{\prime}\\ {Q}^{\prime}\end{array}\right]=S\left[\begin{array}{c}I\\ Q\end{array}\right]+\left[\begin{array}{c}{I}_{\circ}\\ {Q}_{\circ}\end{array}\right]$ where $S=\left[\begin{array}{cc}\sqrt{\gamma}& -\phi /2\\ -\phi /2& \frac{1}{\sqrt{\gamma}}\end{array}\right]$ |

**Default: **Vertical Shear

The desired DC offset of the I waveform as a percentage of full scale of the **input complex waveform**. Valid values are between -100 and +100.

**Default: **0.0

The modulated complex baseband waveform data.

Trigger (start) time of the **Y** array.

**Default: **0.0

Time interval between data points in the **Y** array.

**Default: **1.0

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.

The desired DC offset of the Q waveform as a percentage of the **input complex waveform**. Valid values are -100 to +100, inclusive.

**Default: **0

The desired ratio of I gain to Q gain, in dB. Valid values are between -6.0 and +6.0.

**Default: **0

The desired quadrature skew of the complex waveform in degrees. Valid values are between -30.0 and +30.0 degrees.

**Default: **0

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

**Default: **no error

The desired frequency offset, in Hertz (Hz), to apply to the **output complex waveform**.

**Default: **0

The impaired complex baseband modulated waveform data returned by this node.

Trigger (start) time of the **Y** array.

**Default: **0

Time interval between data values in the **Y** array.

**Default: **1.0

**Where This Node Can Run: **

Desktop OS: Windows

FPGA: Not supported