ASK FSK PSK Modulation / Digital Modulation Techniques / Amplitude, Frequency and Phase Shift Keying

This Video discusses Digital Modulation Techniques (ASK, FSK and PSK). The Waveforms, Definition and Basic Concepts of each digital modulation Techniques are discussed here. This Video also explains the basic difference between digital modulation and analog modulation. The digital modulation techniques are amplitude shift keying (ASK), frequency shift keying (FSK) and Phase shift keying (PSK). Digital Modulation Techniques Lectures [HD] /playlist/PLDp9Jik5WjRs5ismlsqP_Q3JNlWOe-2an First of all let's understand, what is modulation? Modulation is a process, where some characteristic of the carrier wave (amplitude, frequency or phase) is varied in accordance with the instantaneous value of the modulating (message or baseband) signal. So if amplitude of the carrier wave is varied, then it is called as amplitude modulation, but if frequency or phase of the carrier wave is varied, according to the instantaneous value of the modulating signal, then it is known as frequency modulation or phase modulation respectively. So now let's Understand the basic difference between continuous wave modulation and digital modulation- Difference between Continuous Wave Modulation and Digital Modulation- Amplitude Modulation (AM), Frequency Modulation (FM) and Phase Modulation (PM) are the examples of Continuous Wave (CW) modulation, while Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK) and Phase Shift Keying (PSK) are examples of Digital Modulation Techniques. The basic difference between continuous wave Modulation and digital modulation techniques is based on the nature of message signal (modulating signal). In continuous wave modulation, the message signal is of analog nature but in digital modulation, the message signal is of digital nature (Binary or M-ary encoded version). In both of these modulation techniques, the carrier wave is of analog form. Here it is interesting to note that, the three forms of digital modulation techniques that is ASK, FSK and PSK are analogous to AM, FM and PM of continuous wave modulation respectively. Amplitude shift keying (ASK) In ASK, the amplitude of the carrier wave is changed (switched) according to the digital input signal (modulating signal). Therefore amplitude shift keying is analogous to Amplitude Modulation (analog modulation). ASK is analogous to AM, because in Amplitude Modulation (AM), amplitude of the carrier wave is changed according to the instantaneous value of the modulating (message) signal, in the same way in ASK also, the amplitude of the carrier wave is switched (varied) according to the instantaneous value of the modulating signal (digital input signal). The difference is only of the nature of the modulating signal. In amplitude modulation, the modulating signal is of analog kind but in digital modulation, it is a stream of digital bits. the amplitude of the sinusoidal carrier wave is switched, as per the digital input signal. The carrier wave is either not transmitted or transmitted for digital input signal '0' or '1' respectively. That is why amplitude shift keying (ASK) is also called as "ON - OFF Keying (OOK)". Frequency Shift Keying (FSK) If the frequency of sinusoidal carrier wave is varied (switched) as per the digital input signal, then it is known as the frequency shift keying (FSK). It is analogous to frequency modulation (analog modulation). The reason behind why FSK is analogous to FM, is.... In Frequency Modulation (FM), the frequency of the carrier wave is varied according to the instantaneous value of the modulating signal, in the same way in frequency shift keying also, the frequency of the sinusoidal carrier wave is varied (switched) as per the digital input signal. The difference is only of the nature of the modulating signal. In FM the modulating signal is of analogue nature while in FSK modulating signal is digital. So here the basic purpose of Frequency Shift Keying (FSK), is to modulate (change/switch) the frequency of the carrier wave, according to the digital input signal. So in Frequency Shift Keying (FSK), we have two types of frequencies of the carrier wave, low frequency for the transmission of '0' and high frequency for the transmission of '1'. In this way, in Frequency Shift Keying (FSK), the information of the digital input signal is present in the frequency variations of the carrier wave. That is why it is known as frequency shift keying. Now let's discuss the Phase Shift Keying (PSK) Phase Shift Keying (PSK) In phase shift keying, phase of the carrier wave (analog) is varied as per the digital input signal. Phase shift keying is analogous to Phase Modulation (analogue phase modulation). The phase shift keying is very much similar to Phase Modulation (PM). Electronics and Communication (ECE) Lecture Videos (GATE and IES) /playlist/PLDp9Jik5WjRtkw7q3aaVvMtLJiiw62V-H #Modulation #modulationTechniques

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