One approach to microprocessor implementation of 4800 b/s data modem for telephone channels

The microprocessor-based implementation of data modems has been attracting a great deal of scientific interest in the past decade. It is a kind of an interdisciplinary field where both information theory and microprocessor engineering strongly interact. A number of different microprocessor-based modems are avavilable on the market. For most of the modems with speeds above 2400 b/s it is common that implementation is based on the bit-slice processor. In case of speeds above 2400 b/s, it is considered that slow and cheap MOS microprocessors (e.g., Intel 8085) can be used only at the cost of simplifications in the algorithms for signal demodulation and detection, i.e., at the cost of decreased performance. This paper, however, describes the MOS microprocessor-based implementation of the 4800 b/s modem which was achieved without deterioration of modem performance.