Advanced Optical Shannon Tool

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Shannon Capacity Calculator

Calculation Mode

Calculate Capacity

Calculate Symbol Rate

Calculate Required SNR

Core Shannon Parameters

Capacity / Channel

Tb/s

Symbol Rate

GBaud

SNR

OSNR Conversion

Input OSNR

Reference BW

GHz

Equivalent SNR

Equivalent OSNR

System Parameters

WDM Channels

Modulation Format

FEC Overhead

Target SNR/OSNR Margin

Results

Calc. SNR

Req. SNR

SNR Margin

Calc. OSNR

Req. OSNR

OSNR Margin

Status

Spectral Eff.

bits/s/Hz

Bits/Symbol

bits

Gross Cap/Ch

Tb/s

Net Cap/Ch

Tb/s

Total Gross

Tb/s

Total Net

Tb/s

Capacity vs SNR

Key Formulas

C = B × log₂(1 + SNR_linear)
SNR_dB = OSNR_dB + 10 log₁₀(B_ref / B)
Net Capacity = Gross Capacity × (1 - FEC_OH/100)

C = Gross Capacity/Ch (bps)
B = Symbol Rate (Hz)
SNR_linear = Linear SNR
OSNR_dB = Optical SNR (dB)
B_ref = Reference BW (Hz)
FEC_OH = FEC Overhead (%)

Overview

This tool provides an advanced interface to the Shannon-Hartley theorem (C = B log₂(1+SNR)) for optical communication systems.

It allows calculating any one core variable (Capacity, Symbol Rate, or SNR) given the other two. It also includes OSNR conversion, modulation format context, FEC overhead, and margin analysis relevant to optical network engineers.

Disclaimer: This tool calculates the theoretical Shannon limit for an AWGN channel. Real-world impairments (nonlinearities, dispersion, etc.) are not modeled. Use as a theoretical benchmark.

Calculation Modes

Select the parameter you wish to calculate using the radio buttons:

Calculate Capacity: Input Symbol Rate (B) and SNR. The tool calculates the maximum theoretical Gross Capacity (C) per channel.
Calculate Symbol Rate: Input desired Gross Capacity (C) per channel and the available SNR. The tool calculates the required Symbol Rate (B).
Calculate Required SNR: Input desired Gross Capacity (C) per channel and the available Symbol Rate (B). The tool calculates the minimum required SNR to achieve that capacity.

The input field for the variable being calculated will be disabled. Calculations update automatically as you change enabled inputs.

Parameters Explained

Core Shannon Parameters

Capacity / Channel (Tb/s): Theoretical maximum Gross data rate per wavelength channel (C). Input or Calculated.
Symbol Rate (GBaud): Rate of symbol transmission (B), related to channel bandwidth. Input or Calculated.
SNR (dB): Signal-to-Noise Ratio (electrical/baseband). A measure of signal quality. Input or Calculated.

OSNR Conversion

Input OSNR (dB): Enter an Optical SNR value measured in a specific bandwidth.
Reference BW (GHz): The bandwidth used for the Input OSNR measurement (typically 12.5 GHz for 0.1nm).
Equivalent SNR (dB): The calculated electrical SNR corresponding to the Input OSNR, Ref BW, and current Symbol Rate.
Equivalent OSNR (dB): The calculated Optical SNR (in the Ref BW) corresponding to the primary SNR field and current Symbol Rate.

System Parameters

WDM Channels (#): Number of parallel wavelengths. Scales the total system capacity.
Modulation Format: Select the intended format (e.g., QPSK, 16QAM). This displays estimated 'Req. SNR' and 'Req. OSNR' for comparison.
FEC Overhead (%): Percentage of bandwidth used by Forward Error Correction.
Target SNR/OSNR Margin (dB): Additional margin added to the Required SNR/OSNR for design robustness.

Results Explained

Calc. SNR (dB): The resulting SNR from input or calculation.
Req. SNR (dB): Estimated minimum SNR typically needed for the selected Modulation Format.
SNR Margin (dB): Calc. SNR - Req. SNR - Target Margin. Positive values are generally needed.
Calc. OSNR (dB): Equivalent OSNR in the Reference BW for the Calc. SNR and Symbol Rate.
Req. OSNR (dB): Estimated minimum OSNR typically needed for the selected Modulation Format.
OSNR Margin (dB): Calc. OSNR - Req. OSNR - Target Margin.
Status: 'PASS' if SNR Margin ≥ 0, 'FAIL' otherwise.
Spectral Eff. (bits/s/Hz): Efficiency of bandwidth usage (log₂(1+SNR)).
Bits / Symbol (bits): Gross Capacity (bps) / Symbol Rate (baud).
Gross Cap/Ch (Tb/s): Theoretical Shannon capacity (C) per channel.
Net Cap/Ch (Tb/s): Usable capacity per channel after FEC overhead.
Total Gross Cap (Tb/s): Gross Capacity/Ch × WDM Channels.
Total Net Cap (Tb/s): Net Capacity/Ch × WDM Channels.

How to Use

Select the desired 'Calculation Mode'.
Enter known values into the enabled 'Core Parameter' input fields.
Optionally, enter an 'Input OSNR' and 'Reference BW' to see the 'Equivalent SNR' for context.
Set 'WDM Channels' for your system.
Select 'Modulation Format' to see estimated requirements.
Set 'FEC Overhead' and 'Target Margin'.
Observe the 'Results' section update automatically.
Check calculated values, margins, and status.
Analyze the 'Capacity vs SNR' chart.

Keyboard Shortcuts:

Ctrl+G - Open user guide
ESC - Close modal

Shannon Capacity Calculator

Results

Key Formulas

User Guide

Overview

Calculation Modes

Parameters Explained

Core Shannon Parameters

OSNR Conversion

System Parameters

Results Explained

How to Use