Table Of Contents

MT Apply IQ Impairments (G Dataflow)

Last Modified: January 9, 2017

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

connector_pane_image
datatype_icon

impairment definition

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 and Q are the real and imaginary components of the corresponding sample in the output complex waveform. I is I DC Offset (%) / 100, and Q is Q DC Offset (%) / 100.

Name Description
Vertical Shear

The definition uses the following equations for I/Q impairments:

I = a * I + I

Q = a * sin ( φ ) * I + b * cos ( φ ) * Q + Q

where

φ is the specified quadrature skew, in radians

γ = 10(IQ gain imbalance/20)

a = γ * b

b = 2 1 + γ 2

In matrix form, these equations are represented by

[ I Q ] = S [ I Q ] + [ I Q ]

where

S = [ a 0 a * sin φ b * cos φ ]

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 * skew and -1.0 * imbalance. This definition uses the following equations for IQ impairments:

I = I * γ Q * ( φ 2 ) + I

Q = I * ( φ 2 ) + Q * ( 1 γ ) + Q

where

γ = 10(IQ gain imbalance/20)

φ is the specified quadrature skew, in radians

In matrix form, these equations are represented by

[ I Q ] = S [ I Q ] + [ I Q ]

where

S = [ γ φ / 2 φ / 2 1 γ ]

Default: Vertical Shear

datatype_icon

i dc offset

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

datatype_icon

input complex waveform

The modulated complex baseband waveform data.

datatype_icon

t0

Trigger (start) time of the Y array.

Default: 0.0

datatype_icon

dt

Time interval between data points in the Y array.

Default: 1.0

datatype_icon

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.

datatype_icon

q dc offset

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

datatype_icon

iq gain imbalance

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

Default: 0

datatype_icon

quadrature skew

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

Default: 0

datatype_icon

error in

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

Default: no error

datatype_icon

frequency offset

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

Default: 0

datatype_icon

reset?

A Boolean that determines whether this node continues applying the impairments using the previous iteration states.

TRUE Restarts the impairment generation process.
FALSE Continues applying the impairments using the previous iteration states.

Default: TRUE

datatype_icon

output complex waveform

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

datatype_icon

t0

Trigger (start) time of the Y array.

Default: 0

datatype_icon

dt

Time interval between data values in the Y array.

Default: 1.0

datatype_icon

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.

datatype_icon

error out

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

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported


Recently Viewed Topics