IQdemodulering

IQdemodulation is a fundamental process in digital signal processing, particularly in wireless communication systems. It refers to the act of extracting the original information-bearing signal from a modulated carrier wave. The term "IQ" stands for In-phase and Quadrature, which are two orthogonal components of a modulated signal. These components are typically derived from the complex baseband representation of a signal.

In essence, IQdemodulation reverses the process of IQ modulation. During modulation, the information is encoded onto an amplitude and/or phase shift of a carrier signal. This modulated signal can be mathematically represented as a combination of its in-phase (I) and quadrature (Q) components. For example, in Quadrature Amplitude Modulation (QAM), the amplitude of the carrier is varied according to the data, and this variation is split between the I and Q paths.

The demodulation process involves multiplying the received, possibly noisy, signal by a local oscillator signal that is synchronized in frequency and phase with the original carrier. This multiplication produces two outputs, one proportional to the in-phase component and the other to the quadrature component. These two components, the I and Q signals, together contain the original information. Further processing, such as filtering and sampling, is then performed on the I and Q signals to recover the original digital data stream. Accurate synchronization of the local oscillator with the incoming signal is crucial for successful IQdemodulation.