Analog Data Transmission

Abstract

In many cases the characteristics of the communications channel, for example bandwidth restrictions, make it difficult or impossible to transmit digital data at baseband, however it is encoded. The most commonly quoted example is that of a public switched telephone channel, which is severely band limited to between 300 Hz and 3.3 kHz, restricting the transmission of baseband signals. Other examples are optical fibre channels, which can only pass frequencies in the hundreds of GHz range or radio wave and microwave channels which could similarly not support direct digital transmission.