Instructions for Frequency Shift Keying Modulation (FSK)
- Step 1: Click on 'Generate Message' button to generate input message signal
- Step 2: Then click on 'Generate Carrier' button to generate carrier signal
- Step 3: You can change the carrier signal frequencies from the input fields
- Step 4: Click on 'Simulate FSK' button to generate Frequency Shift Keying Signal
Frequency Shift Keying (FSK) Demodulation (Coherent)
Mathematical Model of FSK
1. Modulation (FSK)
The transmitted signal $s(t)$ is defined piecewise:
Bit 1: s(t) = A sin(2Ï€ f₁ t)
Bit 0: s(t) = A sin(2Ï€ f₂ t)
Bit 0: s(t) = A sin(2Ï€ f₂ t)
2. Coherent Demodulation
The receiver correlates the signal with perfectly synchronized local carriers:
1. Correlation (Integration):
C₁ = Σ [s(t) · sin(2Ï€ f₁ t)]
C₂ = Σ [s(t) · sin(2Ï€ f₂ t)]
2. Decision Logic:
If C₁ > C₂, Output = 1; Else 0
C₁ = Σ [s(t) · sin(2Ï€ f₁ t)]
C₂ = Σ [s(t) · sin(2Ï€ f₂ t)]
2. Decision Logic:
If C₁ > C₂, Output = 1; Else 0
Why Coherent?
In Coherent detection, the receiver is phase-locked with the transmitter. We only need to correlate with the Sine component. This provides better noise performance than non-coherent methods but requires precise synchronization.