overmodulaatio

Overmodulaatio, also known as overmodulation, is a phenomenon in amplitude modulation (AM) where the modulating signal exceeds the maximum allowable modulation index. This occurs when the modulation depth surpasses 100%, causing distortion in the transmitted signal. In standard AM transmission, the modulation index should be kept below or equal to 100% to ensure a clear and undistorted signal.

When overmodulation happens, the amplitude of the carrier wave is clipped, resulting in the generation of unwanted spectral components, notably sidebands and increased harmonic distortion. This distortion can lead to interference with adjacent channels and reduce the quality of the received audio or data signals.

Overmodulation often occurs due to inaccuracies in the modulation process, such as excessive input audio levels or malfunctioning equipment. To prevent overmodulation, transmitters are typically equipped with limiting circuits or automatic gain control systems that maintain the modulation index within permissible limits.

In broadcasting and communication systems, maintaining proper modulation levels is crucial for optimal signal quality and spectral efficiency. Overmodulation is generally undesirable, as it undermines signal integrity and can violate regulatory standards for spectrum usage. Correcting overmodulation involves adjusting the modulation input or employing control mechanisms to ensure the modulation index remains within the safe operational range.

In summary, overmodulation is a state where the modulation exceeds 100%, leading to signal distortion and potential interference. Proper regulation and control are essential to prevent overmodulation and ensure effective communication.