Any continuous signal is an analog signal

Analog and digital (transmission technology)

In transmission technology, a distinction is made between information and the signal. The information describes what is being transmitted. The signal defines how it is transmitted. Both information and the signal can be analog or digital.

An analog signal is a physical quantity that can assume continuous values ​​in the course of the size (amplitude) as well as in the course of time.
A digital signal (digitus: finger, Latin) is a physical quantity that can only take on certain discrete values. The values ​​correspond to the number of agreed states. If two states are agreed, then the signals are binary (digital).

Analog signals consist of a continuous signal or data stream. There is no such thing with digital signals. When digital data is generated, it usually arises in an explosive manner. The volume of data then often exceeds a level that can no longer be processed. The data must then be cached so that it is not lost.

 Signal / transmission / network
AnalogousDigital
informationAnalogousDirectlyCodec
Digitalmodeminterface

A distinction is made between analog and digital signals or between analog and digital information. There are a total of 4 different signal and information combinations.

Analog information - analog signal (direct)

If analog information is to be transmitted in analog, this is relatively easy. No special interface is necessary. There are certain interfaces and processing elements here too, but their function is relatively simple. In principle it is like connecting a loudspeaker to an audio amplifier. The signal is routed from the amplifier to the loudspeaker via a cable. And the loudspeaker outputs the signal as sound.

Digital information - analog signal (modem)

It becomes more difficult when digital information is to be transmitted in analog form. A typical case is the use of a modem that converts the digital data from a computer system into analog signals for transmission over the telephone network.
Modem is an artificial word. It consists of the terms modulator and demodulator.

Digital information - digital signal (interface)

It would be easy to assume that digital information could be transmitted digitally without any problems. But far from it. Digital signals have the disadvantage that they are very susceptible to interference. Before transmission, digital signals have to be prepared in a complex manner for transmission.

Transferring analog information digitally (codec)

When analog information has to be converted into digital signals, a codec is responsible for this. It is a made-up word consisting of a coder and a decoder. The analog signal is encoded into a digital signal and decoded in reverse. During coding, an analog value is given a digital value, which is then transmitted. At the receiver, the digital value is decoded into the analog value.

Advantages of digital transmission

If an item of information requires more bandwidth than is available, the information is not simply cut off, but buffered and transmitted one after the other. This is not possible with analog signals.

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