digital modulation (fsk)
Post on 08-Sep-2015
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DESCRIPTION
TRANSCRIPT
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Frequency-Shi- Keying
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FSK
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Logic 1 input, vm(t) = + 1
Logic 0 input, vm(t) = - 1
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FSK in the frequency domain
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Frequency devia?on, f (hertz)
Where: |fm- fs| = absolute dierence
between the mark and space frequencies (hertz)
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FSK in the ?me domain
fc + f fc - f
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Truth table for BFSK modula?on
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FSK Bit Rate, Baud and Bandwidth
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FSK Bit Rate, Baud and Bandwidth
The baud for binary FSK can also be determined by subs?tu?ng N = 1
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Minimum bandwidth for FSK
Where: B = minimum Nyquist Bandwidth (hertz) f = frequency devia?on (|fm- fs|) (hertz) fb = input bit rate (bps)
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Example:
Determine: (a)peak frequency devia?on (b)minimum bandwidth (c)Baud for binary FSK signal with a mark frequency of 49 kHz, a space frequency of 51 kHz and an input bit rate of 2 kbps
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Example:
Using a Bessel Table, determine the minimum bandwidth for the same FSK signal described in the previous example, with a mark frequency of 49 kHz, a space frequency of 51 kHz, and an input bit rate of 2 kbps.
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FSK Modulator
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Noncoherent FSK demodulator
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Coherent FSK demodulator
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PLL-FSK demodulator
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Noncon?nuous FSK waveform
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Con?nuous MSK waveform
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