Optical Rx Margin
Enter Tx power and loss (or Rx power directly) and the receiver sensitivity/overload, and I compute the margin over sensitivity, headroom to overload and dynamic range, with a verdict.
Receiver operating window
—
Sensitivity / overload of common optics
| Optic | Sensitivity | Overload | Dyn. range |
|---|
Typical datasheet values; always confirm with your module's vendor.
How it is computed · optical margin
1. Optical power is in dBm
(logarithmic scale). Received power is
Prx = Ptx − loss, or you measure it directly with a power meter.
2. The receiver has a window:
sensitivity (minimum) and overload (maximum).
The dynamic range = overload − sensitivity.
3. The margin = Prx − sensitivity
tells how much is left above the threshold; the
headroom = overload − Prx how much is left before saturating.
4. Verdict: if Prx < sensitivity
there is no link; if Prx > overload
it is overloaded (add an attenuator of
Prx − overload dB); in between, OK.
Leave ≥ 3 dB of margin.
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