ABSTRACT
The most familiar telecommunications system is the public telephone network. The basic building block of this system is the voice channel. A voice channel is usually considered to have a 4-kHz bandwidth (see Figure 5.1). In reality, the effective channel ranges from 300 Hz to 3400 Hz, with the remainder of the bandwidth used for guard or protection bands, or to accommodate special signals. Bandwidth of a typical telephone channel. https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9781351077101/dc2e9018-094e-4ae7-a1ce-d60f60ae2b1a/content/fig5_1.tif"/>
