Quadrature Tracking

In the AD936x, quadrature tracking is on always on for the transmitter and on by default for the receiver. The tracking algorithm expects a complex quadrature signal at the input.

Tx Quadrature Tracking Calibration

Quadrature tracking for the AD936x RF chipset takes place on the RF transmitter and is on always on for the transmitter. For more information, see Tx Quadrature Calibration in [2].

Rx Quadrature Tracking Calibration

Real-only signals may cause the received signal to oscillate, so Communications Toolbox™ Support Package for Analog Devices® ADALM-Pluto Radio features require complex input signals regardless of the setting for quadrature tracking.

Direct conversion receivers often impose an I/Q imbalance on the in-phase and quadrature components of the signal. I/Q imbalance, can degrade the BER performance for QAM and PSK systems. By enabling quadrature tracking, you can reduce I/Q imbalance in the I/Q channels of a received complex signal. The reduced I/Q imbalance enables more robust receiver processing. In addition, this reduction allows you to focus on designing the baseband algorithm without worrying about I/Q imbalance that is introduced by the analog front end. Quadrature tracking for the AD936x RF chipset takes place on the RF receiver and can be implemented at baseband or RF.

For more information, see IQ Correction section in [1] and Rx Quadrature Tracking Calibration in [2].

Quadrature Tracking in Receiver Block

With the receiver block, quadrature tracking at RF and baseband is on by default. To disable quadrature tracking, on the Advanced tab of the receiver block, clear the Enable quadrature correction parameter.

Quadrature Tracking in Receiver System Object

With the receiver System object™, quadrature tracking at RF and baseband is on by default. To disable quadrature tracking, show the advanced properties by setting the ShowAdvancedProperties property to true. Then set the EnableQuadratureCorrection property to false.

rx = sdrrx('Pluto');
rx.ShowAdvancedProperties = true;
rx.EnableQuadratureCorrection = false;

See Also

Functions

Blocks

Objects

References

[1] Analog Devices Wiki 'AD9361, AD9364 and AD9363 > IQ Correction', https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms2-ebz/ad9361#iq_correction

[2] Analog Devices AD9364 Reference Manual - UG-673.