What Is A Signal?
Expressions, sounds, actions and gestures all convey information to us and these are the means by which people communicate with one another. Similar to signal, the transmission of information from one system to another constitutes communication. Or to put it another way, a signal is a function that represents data or information.
An electromagnetic wave known as a signal transfers information through a physical medium. Here, the information is transformed into an electromagnetic signal, either analog or digital and transmitted from sender to receiver.
Voltage and current are two examples of time-varying quantities that are used to represent data. Data can be transmitted by varying these quantities with respect to time. Similar to signal which is represented as a function of the frequency domain rather than the time domain.
A message signal is passed through an encoder and a modulator to be transmitted through a medium and it is passed through a decoder and a demodulator to be received at the other end.
Signals are divided into two categories based on their nature.
- Analog Signals: Signals which are continuous and time-varying in nature are analog signals
- Digital Signals: Signals which are discrete are called digital signals.
Analog Signals
An analog signal is signals and wavelengths transmitted over communications lines such as the sound of a voice over the phone line. A dial-up modem for computers is an example of a device that transforms digital data into an analogue signal for transmission over phone lines.
Electrical, optical and speech signals are a few examples of analogue signals. Analog signals include radio signals as well. Every signal needs a medium to travel through. For example,
Cables are necessary for the propagation of electrical signals.
Free space is necessary for the propagation of speech signals or voice. We can also say that the air serves as a propagation medium for speech signals. However, analogue signals exhibit more noise and distortion during transmission than digital ones.
Example: The distance of a car travelling with constant time with a specific time can be considered as an example of an analog signal.
The average marks of the 30 students in a classroom in five subjects can be considered as an example of a digital signal.
Characteristics Of Analog Signal
- These sorts of electronic signals are time-varying.
- It is often either periodic or non-periodic.
- The lowest and highest values are either positive or negative.
- Analog signal output form is like Curve, Line or Graph, so it’s going to not be meaningful to all or any.
- The accuracy of the analog signal isn’t high in comparison to the digital signal.
- Analog Signal works on continuous data.
- It helps you to live natural or physical values.
Types Of Analog Signals
An electrical signal is an example of a type of energy that transmits information. From one source to another, information is transmitted using electrical energy. Periodic and non-periodic signals are the two types of analogue signals.
Periodic Signals
An analog signal that repeats over a period of time is known as the periodic signal, such as a sine wave and a cosine wave. Equations can easily be used to represent periodic signals.
Aperiodic Signals
An analog signal that does not repeat over a period of time is known as an Aperiodic signal, such as a noise signal. Although it is a continuous signal, its pattern is not repeated. Using mathematical equations to represent an aperiodic signal is challenging.
Advantages Of Analog Signals
- It is easier to process.
- It has a coffee cost and is portable.
- Analog Signals are best fitted to audio and video transmission.
- It Uses less bandwidth than digital sounds.
- Not necessary in Analog Signals to shop for a replacement graphics board.
- It has Less bandwidth.
- It possesses higher density.
- It is a natural sort of sound.
- It provides a more accurate representation of a sound.
- Binary digits 0 and 1 represent the optical pulse for storing, processing and transmitting the information.
Disadvantages Of Analog Signals
- Analog tends to possess a lower quality signal than digital.
- Analog wire is expensive and not easily portable.
- In this, it has Low availability of models with digital interfaces.
- The cables are sensitive to external influences.
- Recording analog sound on tape is sort of expensive if the tape is broken.
- Quality is definitely lost.
- Tape is becoming hard to seek out.
- It is quite difficult to synchronize analog sound.
- Digital sounds can cut an analog acoustic wave which suggests that you simply can’t get an ideal reproduction of a sound.
- It offers limitations in editing.
- Most of the sound-capturing devices such as phones etc may become confusing to store a digital signal.
- It offers poor multi-user interfaces.
- Data can become corrupted in analog signals.
Important Terms
The following are some essential terms that are widely used in signals.
Bit Interval
The time needed to send one bit is known as the bit interval.
Bit Rate
The amount of bits transmitted or sent in a second is known as the bit rate. Bits per second are used to express it.
Bit rate = 1 / Bit interval
Bandwidth
It is defined as the frequency range over which an information signal is transmitted. The difference between the signal’s upper and lower frequency bounds is known as the bandwidth.
BW = f2-f1
Period
The reciprocal of frequency is called the period. It is the length of one cycle in one unit of time or one second. T stands for the period.
T = 1 / f
Data Rate Limits
The speed at which we can send data, measured in bits per second, is a crucial component of data communication. Data rate depends upon three factors.
- The level of signal we use.
- Bandwidth is available.
- The quality of the channel.
Nyquist Bit Rate
The Nyquist bit rate formula is used to determine the theoretical maximum bit rate for a noiseless channel.
Bit rate = 2 * bandwidth * Log 2L
In this formula, L stands for the number of levels used to represent data; bit rate refers to the bit rate in bits per second and bandwidth is the channel bandwidth.
Increasing the levels of the signal may reduce the reliability of the system.