When considering quadrature modulation, the x axis is called the I (in-phase) axis, and the y axis is called the Q (quadrature) axis. Polar modulation makes use of polar coordinates, r (amplitude) and Θ (phase).
When considering quadrature modulation, the x axis is referred to as the I (in-phase) axis, and the y axis is referred to as the Q (quadrature) axis. Polar modulation utilizes polar coordinates, r (amplitude), and Θ (phase).