Digital signal binary number and computer use
The very first computers used binary numbers, and they are still used today. Every computer is made up of many electronic components. That is why a basic knowledge of electronics is needed to understand how and why binary numbers are used in computers. A computer is built with many connections and components, which are used to transfer and store data, as well as communicate with other components.
Most of that storing, transferring, and communicating happens with digital electronics. In electronics, a voltage level or current flow is a way to represent a value. For example, 5V volts or 0. The makers of electronic devices could, of course, assign any meaning that they want to different voltage values. You would end up with 0. This means that when building an electronic device, it is most often desired to have the energy consumption as low as possible and to have a low voltage.
Furthermore, electronic signals are not always very steady and can vary because of surrounding influences, like nearby internal circuits for other electronic devices. This might then lead to voltage levels where it gets difficult to distinguish which value it represents. As a result, we cannot divide the 5V into 10 steps.
The values could be misinterpreted. A computer might suddenly make wrong calculations because of random interference. The shape of the waveform depends the transmission scheme, which may be either:.
In communications, sources of interference are usually present, and noise is frequently a significant problem. The effects of interference are typically minimized by filtering off interfering signals as much as possible and by using data redundancy.
The main advantages of digital signals for communications are often considered to be the immunity to noise that it may be possible to provide, and the ability, in many cases such as with audio and video data, to use data compression to greatly decrease the bandwidth that is required on the communication media.
In computer architecture and other digital systems, a waveform that switches between two voltage levels or less commonly, other waveforms representing the two states of a Boolean value 0 and 1, or Low and High, or false and true is referred to as a digital signal or logic signal or binary signal when it is interpreted in terms of only two possible digits.
The clock signal is a special digital signal that is used to synchronize many digital circuits. The image shown can be considered the waveform of a clock signal. Logic changes are triggered either by the rising edge or the falling edge. The given diagram is an example of the practical pulse and therefore we have introduced two new terms that are:. Although in a highly simplified and idealized model of a digital circuit we may wish for these transitions to occur instantaneously, no real world circuit is purely resistive and therefore no circuit can instantly change voltage levels.
This means that during a short, finite transition time the output may not properly reflect the input, and will not correspond to either a logically high or low voltage.
The two states of a wire are usually represented by some measurement of an electrical property: Voltage is the most common, but current is used in some logic families. A threshold is designed for each logic family. When below that threshold, the signal is low , when above high. To create a digital signal, an analog signal must be modulated with a control signal to produce it.
As we have already seen, the simplest modulation, a type of unipolar line coding is simply to switch on and off a DC signal, so that high voltages are a '1' and low voltages are '0'. In digital radio schemes one or more carrier waves are amplitude or frequency or phase modulated with a signal to produce a digital signal suitable for transmission. In Asymmetric Digital Subscriber Line over telephone wires , ADSL does not primarily use binary logic; the digital signals for individual carriers are modulated with different valued logics, depending on the Shannon capacity of the individual channel.
Often digital signals are "sampled" by a clock signal at regular intervals by passing the signal through an "edge sensitive" flip-flop. When this is done the input is measured at those points in time, and the signal from that time is passed through to the output and the output is then held steady till the next clock. This process is the basis of synchronous logic , and the system is also used in digital signal processing. However, asynchronous logic also exists, which uses no single clock, and generally operates more quickly, and may use less power, but is significantly harder to design.
From Wikipedia, the free encyclopedia. This article is about digital signals in electronics. For digital data and systems, see Digital data. For digital signals that specifically represent analog waveforms, see Digital signal signal processing. For other uses, see Digital signal disambiguation. For a broader coverage related to this topic, see Signal electrical engineering.
Digital signal signal processing. A logic signal waveform: The Art Of Electronics, 2nd Ed.