Frequency Shift Keying (FSK) modulation is the process of modulating a digital signal onto a carrier that is composed of one of two frequencies, one frequency for high - and the other frequency for low.
FSK demodulation is the process of recovering the original signal by detecting the frequencies involved in the original modulation. Typically, this is done with a bandpass amplifier tuned to one of the two frequencies, followed by a amplitude demodulator. The output is the original signal. It is possible, though often unecessary, to use two bandpass ampliers, one for each frequency, but this is redundant. It is also possible to use a digital signal processing technique to perform a fourier transform on the input signal, but that can be complex and costly.
This is the method used in very early modems, up to around 1200 baud.
It is also possible, using FSK, to send multiple signals across one line. Simply pick suitable frequencies for each modulation state, and mix the outputs into one consolidated analog signal. On the other end, you have multiple bandpass filters running at the same time and, as long as the chosen frequencies are appropriately spaced apart, they will not interfere.
It is also possible to send analog signals with FSK. One particular system I used took six analog signals, converted them to variable duty cycle pulse trains at 10 Hz, FSK modulated them, mixed them all together, sent them over a leased line, reversed the process, and retrieved the six analog signals.
fsk and psk
demodulator
modem (modulator + demodulator)
Modulator-Demodulator stands for modem
fsk is nothing but frequency shift keying which is used in low speed modems.....
Block digram of fsk is the representation of fsk modulation
FSK stands for Frequency Shift Keying. It allows for voice and data to be digitized and transferred over analog lines. There is a maximum transfer rate of FSK data at 1.6 Mbps.
a demodulator sole function is to restore the original modulating signal. it works by removing the Carrier
Modulator/Demodulator
required larger bandwidth
advantages of fsk arelow noise,since amplitude is constantpower requirement is constantoperates in virtually any wires availablehigh data rateused in long distance communicationeasy to decodegood sensitivity
PSK (Phase Shift Keying) is advantageous over FSK (Frequency Shift Keying) and ASK (Amplitude Shift Keying) because it provides higher data rates and better spectral efficiency. PSK is less susceptible to noise and interference since phase changes are more discernible than frequency or amplitude changes. PSK also allows for easier implementation in digital communication systems.