Quadratuurimodulaation

Quadratuurimodulaation, often abbreviated as QAM, is a digital modulation scheme used in telecommunications to encode digital data onto an analog carrier signal. It achieves this by altering both the amplitude and the phase of the carrier wave. QAM is a bandwidth-efficient technique because it can transmit more bits per symbol compared to simpler modulation schemes like Amplitude Shift Keying (ASK) or Phase Shift Keying (PSK) alone.

In QAM, the carrier signal is typically represented as a sine wave. The modulation process involves two orthogonal components of the carrier signal, often referred to as the in-phase (I) and quadrature (Q) components. The digital data is split into pairs or groups of bits, and each group is mapped to a specific combination of amplitude and phase for the I and Q components. This mapping creates a constellation diagram, where each point represents a unique symbol corresponding to a specific bit pattern. The number of points in the constellation, known as the order of QAM (e.g., 16-QAM, 64-QAM, 256-QAM), determines how many bits can be transmitted per symbol. Higher order QAM allows for greater data rates but also requires a cleaner signal and more robust receivers to combat noise and interference. QAM is widely employed in various communication systems, including Wi-Fi, cellular networks, and digital television broadcasting.