9.2 - What are digital systems?

Data networks are already digital and telephones are fast becoming so. That means that the signals carried are not waves (like sine waves) which are subject to deterioration as they are fed through cables, but consist of a series of pulses. If a distorted wave is received, it is usually impossible to reshape it to the form it had when transmitted because we have no information to tell us what that shape was originally. If a digital pulse becomes distorted, it can be reshaped, because we know that it was rectangular. Information sent digitally is encoded using the binary system, which has only two numbers, 1 and 0. The rectangular pulse represents 1 and the absence of a pulse at the expected time is a 0. Some of the low value binary equivalents of decimal numbers are shown in Table 9.1

A lot more numbers are required in the binary system than in the decimal, and vast numbers of binary digits will be required to represent a complex wave-shape, such as that generated by the microphone in a telephone. Modern electronics is quite able to handle these large numbers of digits, so most means of communication are becoming digital.

The increasing introduction of cabling systems with higher bandwidths are allowing digital systems to become faster and their use is becoming commonplace. Wireless systems, using radio waves in place of cables are being developed; but such systems, of course, require little or no data cabling.