Dulranga's Notes
Semester 3Data Communication and Networking

Shannon-Hartley Theorem

this theorem defines the "Absolute Theoretical Limit" we can achieve on data transmission speeds error free, over a noisy communication medium.

Formulated by Claude Shannon in 1948, it is considered the foundational cornerstone of modern information theory and telecommunications.

The Formula

The theorem expresses the maximum channel capacity (CC) as a function of bandwidth (BB) and signal-to-noise ratio (SNR\text{SNR}):

C=B⋅log⁡2(1+SNR)C = B \cdot \log_2\left(1 + \text{SNR}\right)

Variable Breakdown:

  • CC (Channel Capacity): The maximum achievable data rate in bits per second (bps).
  • BB (Bandwidth): The frequency range of the channel measured in Hertz (Hz).
  • SNR\text{SNR}: The ratio of signal power to noise power (Psignal/PnoiseP_{\text{signal}} / P_{\text{noise}}), expressed as a linear ratio (not in dB). Properties of Periodic Signals#Signal to Noise Ratio (SNR)
Important

Channel Capacity formula is calculated using log2log_2 whereas Signal-To-Noise ratio is measured using dBdB which is log10log_{10}

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