Signal: Advantages, Disadvantages, Application, Conversion Process.

Signal:

A signal is an electromagnetic or electrical current that carries data from one system or network to another.

In electronics, a signal is often a time-varying voltage that is also an electromagnetic wave carrying information, though it can take on other forms, such as current.

The major difference between analog and digital signal is that the analog signals have continuous electrical signal where as digital signals are non- continuous signal.

However, let’s study about them in more details in the following sections. Here, we will discuss advantages, disadvantages, applications of analog and digital signal in detail.

There are two main types of signals used in electronics: analog and digital signals.

Analog Signal:

An analog signal is a time-varying and generally bound to a range (e.g. +12V to -12V), but there is an infinite number of values within that continuous range. An analog signal uses a given property of the medium to convey the signal’s information, such as electricity moving through a wire. In an electrical signal, the voltage, current, or frequency of the signal may be varied to represent the information. Analog signals are often calculated responses to changes in light, sound, temperature, position, pressure, or other physical phenomena.

A digital signal is a signal that represents data as a sequence of discrete values. A digital signal can only take on one value from a finite set of possible values at a given time. With digital signals, the physical quantity representing the information can be many things:

· Variable electric current or voltage

· Phase or polarization of an electromagnetic field

· Acoustic pressure

· The magnetization of a magnetic storage media

Digital: Advantages and Disadvantages:

Digital signals are used in all digital electronics, including computing equipment and data transmission devices. In digital system, information is transmitted in digital form i.e., 0 or 1. To convert the analog signal into digital signal, analog to digital converter and further digital to analog converter is used to again convert it into analog signal.

Advantages of using digital signals are follows:

· Digital signals can convey information with less noise, distortion, and interference.

· Digital circuits can be reproduced easily in mass quantities at comparatively low costs.

· Digital signal processing is more flexible because DSP operations can be altered using digitally programmable systems.

· Digital signal processing is more secure because digital information can be easily encrypted and compressed.

· Digital systems are more accurate, and the probability of error occurrence can be reduced by employing error detection and correction codes.

· Digital signals can be easily stored on any magnetic media or optical media using semiconductor chips.

· Digital signals can be transmitted over long distances.

Disadvantages of using digital signals are follows:

· A higher bandwidth is required for digital communication when compared to analog transmission of the same information.

· DSP processes the signal at high speeds, and comprises more top internal hardware resources. This results in higher power dissipation compared to analog signal processing, which includes passive components that consume less energy.

· Digital systems and processing are typically more complex.

Analog: Advantages and Disadvantages:

Analog signal are the continuous signal which can be directly given to the electronics equipment. There are many advantages and disadvantages compare to digital signal.

Advantages of using Analog are as follows:

· Analog signals are easier to process.

· Analog signals best suited for audio and video transmission.

· Analog signals are much higher density, and can present more refined information.

· Analog signals use less bandwidth than digital signals.

· Analog signals provide a more accurate representation of changes in physical phenomena, such as sound, light, temperature, position, or pressure.

· Analog communication systems are less sensitive in terms of electrical tolerance.

Disadvantages of using Analog are as follows:

· Data transmission at long distances may result in undesirable signal disturbances.

· Analog signals are prone to generation loss.

· Analog signals are subject to noise and distortion, as opposed to digital signals which have much higher immunity.

· Analog signals are generally lower quality signals than digital signals.

Applications of Analog and Digital Signal:

Traditional communication use analog signal for audio and communication systems. However, with advances in silicon process technologies, digital signal processing capabilities, encoding algorithms, and encryption requirements — in addition to increases in bandwidth efficiencies — many of these systems have become digital. They are still some applications where analog signals have legacy use or benefits. Most systems that interface to real-world signals (such as sound, light, temperature, and pressure) use an analog interface to capture or transmit the information. A few analog signal applications are listed below:

· Audio recording and reproduction

· Temperature sensors

· Image sensors

· Radio signals

· Telephones

· Control systems

Conversion of Analog Signal to Digital Signal:

Most of the image sensors are in the analog signal, and digital processing cannot be applied on it, as it requires infinite memory to store because signals have an infinite value that is why we cannot store it.

To create a digital image, we can convert data into digital form.

For the conversion there are two steps:

1. Sampling

2. Quantization

Sampling:

It is a process of reduction of continuous signal into discrete signal such a way that original signal can be recover back. The sampling is done at Nyquist rate also known as Nyquist Sampling Theorem so that signal can be recover without any losses. However, during the process of conversion, there is always a loss which should be recovered using an anti-aliasing effect. The sampled signal is followed by filters such as low pass filter, bandpass filter, high pass filter.

Fig. 1: Type of Sampling theorem

Quantization:

Quantization is a process of mapping input signal values from a large set to constrained output values in smaller sets within the finite number of elements. Truncation and rounding are the example of quantization process.