IQ

The IQ service utilizes the phase-coherency of the Acconeer pulsed radar to produce stable In-phase and Quadrature (IQ) components, capable of detecting fine movement occurring in a target scene. Such micro-motions can be used in, for instance, presence detection in front of the sensor, detection of breathing rate and obstacle detection.

The In-phase and Quadrature components are represented as complex values, generating a complex set of \(N_D\) samples represented as \(x[d]\), where \(d\) is the delay sample index. Each complex value has an amplitude and a phase as in \(x[d] = A_de^{i\phi_d}\). A \(2\pi\) phase rotation of an IQ data point corresponds to a movement at the specific distance of \(\lambda/2 \approx 2.5\) mm, providing high relative spatial resolution.

Similarly to the Envelope service the amplitudes obtained through the IQ service provide a method for examining the reflectivity at different distances from the radar sensor. These two services are however differently optimized. The Envelope service is optimized for providing an accurate envelope estimate, while the IQ service is optimized for producing a phase-stable estimate. Thus, one should only use the IQ service if phase information is of importance.

iq.py contains example code on how the IQ service can be used. Detection of micro-motions using the IQ service in a target scene has many use cases, some of which are presented in breathing.py, sleep_breathing.py, obstacle_detection.py, and phase_tracking.py.

For further reading on the IQ service we refer to the IQ documentation on the Acconeer developer page.