We presently live in an analogue world and the common theme among all these analogue signals is their infinite possibilities. There is an infinite number of tones we can hear, and an infinite number of what we can smell. Likewise, there is an infinite amount of colors to paint an object (the difference is usually indiscernible to our eyes).
Whereas, digital signals and objects are in the finite realm although, there is a limited set of values they can be. This means there are two highest possible values; 255, 4,294,967,296, or anything lower than ∞ (infinity).
In telecommunication, there are a number of differences between analogue and digital transmission. Ample knowledge of these differences and understanding of the conversions between analogue and digital transmission is of great importance.
Below are some of the major differences between analogue and digital transmission.
1. Waveform (Signal)
An analogue waveform is continuously variable in both frequency and amplitude while a digital waveform occurs as a discrete signal that is represented either by changes in light levels or changes in voltage.
2. Traffic measurement
An analogue system measures traffic in Hertz (Hz). For example, a telephone channel is 4KHz. But in a digital system, traffic measurement is done in bits per second (bps). For example, an E-1 line transports 2.048Mbps and a T-1 line carries 1.544Mbps.
The analogue system has a low bandwidth (4KHz). Because of the limited channel bandwidth, data transmission rates are low (up to 33.6Kbps). The reverse is the case however in a digital system transmission. Digital systems can support high-speed data and applications that involve video and multimedia because they have a high bandwidth.
4. Network capacity
The network capacity on an analogue system is low. Only one conversation can occur per telephone channel. On the flip side, the network capacity on a digital system is high. Due to the availability of multiplexers, multiple conversations to share a communications channel can be enabled. Hence, a greater transmission efficiency can be achieved with a digital telecommunication system.
5. Power requirements
Analogue systems require high power. This is because there is a wide range of frequencies and amplitudes for their signals. However, a digital system requires low power because only two discrete signals (the one and the zero) need to be transmitted.
6. Network manageability.
It is very difficult to manage an analogue system. This is because a lot of labor is needed to maintain and control the network. This is because analogue devices do not provide management information streams that allow the device to be remotely managed. Digital devices are smart and have alerts, alarms, traffic statistics, etc. This has made it easier for technicians to remotely monitor and manage the various network elements.
Intruders can easily tap into an analogue circuit. When they do so, they hear the voice stream in its original form. It is usually difficult to detect an intrusion. A digital system, however, is well secured. Encryption can be used making it difficult for intruders to interpret.
8. Error rates
There is a very high probability of error when using an analogue transmission. About 1 in 100,000 bits is guaranteed to have an error. Digital transmission is, however, more precise. With a twisted pair, only about 1 in 10 million bits per second will have an error and with fiber, only about 1 in 10 trillion bits will have an error.