JPL's Wireless Communication Reference Website

Chapter: Analog and Digital Transmission

Advantages of Digital Transmission

Many analog systems are now being replaced by digital systems. we see this trend in cellular telephony, cordless telephones, broadcasting and many other services.

Examples of Digital Systems

Audio Quality


Figure: Sound Quality (in MOS) versus signal-to-interference ratio. Indigo: digital; orange: analog

Digital transmission can guarantee that the audio quality is acceptable or good for signals above a certain threshold. Above the threshold, the quality mainly depends on the speech coding algorithm. The GSM speech coding works at 9.6 kbit/s.

With analogue transmission, increasing the C/I improves performance. This is why some users, particularly those that mostly make their calls when stationary close to a base station, prefer the analog sound quality over a tightly designed digital system with heavy speech compression.

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JPL's Wireless Communication Reference Website 1993, 1995.