Definition: An astable multivibrator is a type of multivibrator that does not require a triggering pulse thus, sometimes known as a free-running multivibrator. It necessarily provides square wave as its output. Astable multivibrator is called so because both the states present here are unstable i.e., quasi-stable. This means output swings between 0 and 1 and neither 0 nor 1 is the stable state. Here, the successive transition is made from one quasi-state to other after some pre-decided … [Read more...] about Astable Multivibrator
Multivibrator
Definition: An electronic device that produces a non-sinusoidal waveform as its output is known as a Multivibrator. The generated non-sinusoidal waveforms are basically a square wave, rectangular wave, a triangular wave, sawtooth wave, or ramp wave etc. It is a 2 stage RC coupled amplifier that operates in two modes. The modes are basically termed as states of the multivibrator. Basics of Multivibrator The multivibrator is a switching circuit and its basic configuration is shown … [Read more...] about Multivibrator
Pulse Position Modulation (PPM)
Definition: A modulation technique that allows variation in the position of the pulses according to the amplitude of the sampled modulating signal is known as Pulse Position Modulation (PPM). It is another type of PTM, where the amplitude and width of the pulses are kept constant and only the position of the pulses is varied. Simply put, the pulse displacement is directly proportional to the sampled value of the message signal. To understand the generation of the PPM signal, it is … [Read more...] about Pulse Position Modulation (PPM)
Delta Modulation (DM)
Definition: A modulation technique that converts or encodes message signal into a binary bit stream is known as Delta Modulation. Here only 1 bit is used to encode 1 voltage level thus, the technique allows transmission of only 1 bit per sample. As PCM has the property of converting message signal directly into a sequence of a binary coded pulse, this resultantly increases the bandwidth requirement of the system. So, in order to remove the drawbacks of PCM, delta modulation is … [Read more...] about Delta Modulation (DM)
Pulse Width Modulation (PWM)
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