Theoretical Ber vs SNR for Amplitude Shift Keying (ASK)
The theoretical bit error rate (BER) for binary Amplitude Shift Keying (ASK) as a function of the signal-to-noise ratio (SNR) can be derived using the following expression:
If we map the binary signals to 1 and -1 in ASK, the probability of bit error will be:
Calculate the Probability of Error using Q-function for ASK:
For ASK with amplitudes 0 and 1:
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When bit '0' is transmitted, the received signal is noise only.
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When bit '1' is transmitted, the received signal is 1 + noise.
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The receiver makes a decision at the threshold 0.5.
If bit 0 is transmitted, noise must exceed +0.5.
In either case, the noise is Gaussian with mean = 0 and variance = N0/2. The probability of noise exceeding ±0.5 can be calculated with the Q-function:
Pb = Q(0.5/σ)
Where:
σ = √(0.5/2)
So:
Pb = Q(0.5/√(N0/2)) = Q(√(2(0.5)2/N0))
Since:
SNR = (0.5)2 / N0
We get:
Pb = Q(√(SNR/2))
Theoretical BER vs SNR for Frequency Shift Keying (FSK)
So, theoretical BER for binary FSK will be
Fig: Theoretical BER vs SNR for Binary ASK Modulation
Fig: Theoretical BER vs SNR for Binary FSK Modulation