Subbandsystemen

Subbandsystemen, often translated as subband systems, are a fundamental concept in signal processing, particularly in areas like audio compression and digital communications. They involve dividing a wide frequency band of a signal into several narrower frequency ranges, known as subbands. This decomposition allows for the analysis and processing of the signal at different frequency resolutions.

The primary advantage of using subband systems lies in their ability to exploit the psychoacoustic properties of human perception, especially for audio signals. For example, in audio compression codecs like MP3 or AAC, the signal is split into subbands. Perceptual models then determine which subbands are more or less important to human hearing. Less important subbands can be quantized more coarsely or even discarded entirely, leading to significant data reduction without a perceptible loss in audio quality.

In digital communications, subband systems can be used to adaptively allocate resources to different frequency channels based on their quality or capacity. This allows for more efficient use of the available bandwidth. The process typically involves analyzing the signal in each subband, applying appropriate processing (e.g., quantization, filtering, modulation), and then reconstructing the signal. Common techniques for implementing subband decomposition include the use of filter banks, such as quadrature mirror filters (QMF) or conjugate quadrature filters (CQF). These filter banks are designed to decompose and reconstruct the signal with minimal aliasing.