Noise-equivalent radiance ($\mathrm{NER}$)

Noise-equivalent radiance is the incident radiance change producing signal-to-noise ratio one for a specified spectral and electrical bandwidth. A linear radiometer with voltage response $G=dV/dB$ and RMS voltage noise ${\sigma }_V$ has $\mathrm{NER}={\sigma }_V/|G|$. Its convention must distinguish per-sample noise from a noise amplitude per square-root bandwidth.