Signal (electrical engineering)
In electrical engineering, a signal is a physical quantity that transmits information, functioning as a time-varying voltage that can convey diverse forms of data, including audio and video. Signals can travel through physical mediums like wires or wirelessly through the air, and they are processed by electronic devices known as transmitters and receivers. Signals are categorized into two primary types: analog and digital. Analog signals are continuous and can take an infinite number of values, while digital signals consist of discrete values represented in binary format, typically as patterns of 1s and 0s.
Digital signals have several advantages over analog signals, such as increased resistance to noise, the ability to transmit more information per second, and the capacity for infinite copying without quality loss. In contrast, analog signals can degrade over time and are more susceptible to interference, leading to noise that can distort the original message. Devices like HDMI cables utilize digital signals to connect multimedia sources and displays, illustrating the practical applications of these concepts in everyday technology. Understanding how signals work is essential for grasping the principles of modern communication and electronics.
Signal (electrical engineering)
In electrical engineering, a signal is a physical quantity or impulse that transmits information. A signal is a time-varying quantity, which means it is a voltage, or electrical potential expressed in volts, that can change over time.
Signals convey information between devices by sending and receiving information. This information can be in the form of audio, video, or encoded data. Signals can pass through wires or the air. They are encoded in a transmitter, which is an electronic device that conveys signals. The receiver of the signals decodes the information. As an example, a computer's audio card can transmit sound signals to its speakers.
Analog Signals vs. Digital Signals
Signals exist in two forms: analog and digital. An analog signal is continuous, carrying on for infinity with constant fluctuations. This means that an analog signal contains an infinite number of values. A pure audio signal is an example of an analog signal.
A digital signal has a pattern of bits of information and discrete, or discontinuous, values. This means that digital signals are finite and have a limited set of values. The number of values in a digital signal can range from two to infinity. The information in a digital signal is translated into binary format. Binary format is a format in which the digital signal is represented by a pattern of bits that are either 1 (on) or 0 (off). This means digital signals can either be on or off. The signals are pulses that represent the 1s and 0s, or the on and off states. For example, sound can be converted into 1s and 0s (the digital code), producing waves. The receiver obtains the waves, decodes the pulses, and creates a copy of the original sound. Signals transmitted by HDMI (High-Definition Multimedia Interface) cables are examples of digital signals. HDMI cables allow the user to connect a digital audio and video source to a digital audio and video display device. For example, HDMI cables connect a DVD player to a high-definition television.
Objects such as clocks, multimeters, and joysticks can display data in either analog or digital form. Timing graphs can be used to identify whether a signal is analog or digital. A timing graph has a horizontal x-axis, where time is plotted, and a vertical y-axis, where voltage is plotted. A timing graph of an analog signal has a smooth, continuous wave. A timing graph of a digital signal has a square wave.
Circuits, or circular paths along which electricity travels, can use analog signals, digital signals, or a combination of both. Analog circuits are typically more complex than digital circuits are. Circuits that use both forms of signals have analog and digital components. For example, a microcontroller may have digital components along with analog circuitry.
Digital signals have some advantages over analog signals. For example, digital signals are more technologically compatible than analog signals are. The precise signal level is not as crucial in digital signals as it is in analog signals. This means that electronic equipment can understand digital signals that are altered in transmission. Compared to analog signals, digital signals are able to transmit more information per second. Digital signals also can be copied and reproduced indefinitely, whereas analog signals eventually wear down over time. An example is an MP3 audio file versus a vinyl record album. An MP3 file can be copied and played indefinitely, whereas a vinyl record album can warp, become scratched, or be damaged. This can negatively affect the sound quality of the record album. Copies of analog signals do not have the same degree of quality as digital signals.
Noise
As signals travel, they become weaker and pick up noise. Noise creates an unwanted disturbance that interferes with the original signal. For example, a radio station may have noise in the form of crackles or hisses. With noise, extra information is added to the original signal. This extra information makes the signal weaker and different from the original signal. Noise on a radio station may be so severe that music cannot be heard clearly.
A signal that is amplified has noise that is also amplified. Analog signals and analog circuits are more vulnerable to noise than digital signals and digital circuits. With the on state of a digital signal, noise is typically high in amplitude. However, devices such as digital televisions produce high quality digital transmissions that are basically free from noise because the devices contain electronics in the amplifiers that are able to ignore noise. This means the noise in these transmissions typically is not sent along with the original signal. Furthermore, digital signals that are disturbed by noise can be recovered easier than analog signals with noise.
Bibliography
"Analog vs. Digital." SparkFun. SparkFun Electronics. Web. 29 Dec. 2014. https://learn.sparkfun.com/tutorials/analog-vs-digital
"Carrying Analogue and Digital Information." Bitesize. BBC. Web. 29 Dec. 2014. http://www.bbc.co.uk/schools/gcsebitesize/science/21c/radiation‗life/waves‗communicationrev2.shtml
“Coding and Storing Information.” Bitesize. BBC. Web. 29 Dec. 2014. http://www.bbc.co.uk/schools/gcsebitesize/science/21c/radiation‗life/waves‗communicationrev3.shtml
"Definition of Analog Signal." Chegg. Chegg Inc. Web. 29 Dec. 2014. http://www.chegg.com/homework-help/definitions/analog-signal-4
"Definition of Digital Signal." Chegg. Chegg Inc. Web. 29 Dec. 2014. http://www.chegg.com/homework-help/definitions/digital-signal-4
"Digital Signals." University of St. Andrews. University of St. Andrews. Web. 29 Dec. 2014. http://www.st-andrews.ac.uk/~www‗pa/Scots‗Guide/info/signals/digital/digital.htm
“LED TV: What Is HDMI?” Samsung. Samsung Telecommunications America, LLC. Web. 29 Dec. 2014. http://www.samsung.com/us/support/faq/FAQ00000540/55185/UN58H5005AFXZA
Strickland, Jonathan. "Does Digital Sound Better than Analog?: Analog and Digital Signals" HowStuffWorks. InfoSpace LLC. Web. 29 Dec. 2014. http://electronics.howstuffworks.com/digital-versus-analog1.htm