Definition: A modulation technique where the width of the pulses of the pulsed carrier wave is changed according to the modulating signal is known as Pulse Width Modulation (PWM). It is also known as Pulse duration modulation (PDM). Basics of Pulse Width Modulation It is a type of Pulse Time Modulation (PTM) technique where the timing of the carrier pulse is varied according to the modulating signal. In pulse duration modulation (PDM), the amplitude of the pulse is kept constant and only … [Read more...] about Pulse Width Modulation (PWM)
Pulse Amplitude Modulation (PAM)
Definition: A modulation technique in which the amplitude of the pulsed carrier signal is changed according to the amplitude of the message signal is known as Pulse Amplitude Modulation (PAM). Simply put, the transmission of data takes place by the variation of the amplitude of pulse according to the modulating signal. Basics of PAM The technique does not show much variation in comparison to continuous wave modulation. The only difference is that the carrier in the pulse modulation … [Read more...] about Pulse Amplitude Modulation (PAM)
Pulse Code Modulation (PCM)
Definition: A technique by which analog signal gets converted into digital form in order to have signal transmission through a digital network is known as Pulse Code Modulation. It is abbreviated as PCM. PCM systems are basically signal coders also known as waveform coders. PCM allows the representation of the continuous time message signal as a sequence of binary coded pulses. The binary form permits only 2 probable states i.e., 0 and 1. The major steps involved in PCM is sampling, … [Read more...] about Pulse Code Modulation (PCM)
Time Division Multiplexing (TDM)
Definition: A multiplexing technique by which multiple data signals can be transmitted over a common communication channel in different time slots is known as Time Division Multiplexing (TDM). It allows the division of the overall time domain into various fixed length time slots. A single frame is said to be transmitted when it’s all signal components gets transmitted over the channel. Theory of TDM As we know, multiplexing allows the transmission of several signals over a common … [Read more...] about Time Division Multiplexing (TDM)
Phase Shift Keying – PSK
Definition: A digital modulation technique that transmits data by varying the phase of the carrier wave in accordance with the digital modulating signal, is called Phase Shift Keying (PSK). The easiest form of PSK is BPSK i.e., binary phase shift keying. However, PSK can be extended to 4 level and 8 level PSK that totally depends on the need of the system. Principle of BPSK BPSK technique is the simplest among all the PSK techniques. In this, each signalling element is represented by a … [Read more...] about Phase Shift Keying – PSK
Frequency Shift Keying – FSK
Definition: A digital modulation technique that allows data transmission by changing the frequency of the carrier wave according to the digital modulating signal is known as frequency shift keying (FSK). It is the most straightforward and efficient digital signal transmission scheme. Theory of Frequency Shift Keying The simplest form of FSK is Binary frequency shift keying (BFSK). Here, the frequency of the carrier wave changed between discrete binary values of the modulating signal. Thus, … [Read more...] about Frequency Shift Keying – FSK
Amplitude Shift Keying – ASK
Definition: A digital modulation technique in which the amplitude of the carrier wave is altered according to the modulating signal (bitstream) is known as Amplitude Shift Keying (ASK). It is the easiest and straightforward digital modulation scheme. ASK is sometimes known as On-Off keying because the carrier wave swings between 0 and 1 according to the low and high level of input signal respectively. Theory of Amplitude Shift Keying In ASK, frequency and phase of the carrier wave is kept … [Read more...] about Amplitude Shift Keying – ASK
Digital Instruments
Definition: The instruments that are used to express the measuring quantity in numeric format is known as Digital Instruments. A digitized information is somewhat easy to be handled and transmitted thus widely preferred nowadays. Quantization is the basis of working of a digital instrument. It is an act of transforming an analog signal into its digital form. Digital instruments are composed of logic circuits that carry out measurement of the quantities. Due to several advantages of … [Read more...] about Digital Instruments
Optical Amplifier
Definition: Optical amplifier is a device used in an optical communication system to directly amplify (boost) optical data signal without changing it into its electrical form. By making use of Optical amplifiers in optical fiber communication, the optical integrity of the whole system is retained. Need of Optical amplifier During signal transmission, it is necessary to employ amplifiers within the network in order to have a distortionless data signal. When we talk about an optical … [Read more...] about Optical Amplifier
Difference Between LED and OLED
The crucial difference between LED and OLED is that LED does not work on the principle of self-illumination as it needs a backlight for its operation. As against OLED is a self-illuminating type device as it does not require a backlight in order to initiate its operation. Another major difference between LED and OLED is that a wider viewing angle is noticed in the case of OLED. At the same time, black level is more dominant in OLED as compared to LED. We will discuss some more important … [Read more...] about Difference Between LED and OLED