Photon Noise

For each signal in the radiometric table is possible to compute the photon noise. The photon noise is computed by ComputePhotonNoise

Given the incoming signal \(S\) the resulting photon noise variance is \(Var[S]=S\).

If photon gain factor \(gain_{phot}\) has been computed with multiaccum equation (see Multiaccum), then \(Var[S]= gain_{phot} \cdot Var[S]\).

The user can also add a margin to the photon noise as

<channel> channel_name
    <radiometric>
        <photon_margin> 0.4 </photon_margin>
    </radiometric>
</channel>

If photon noise margin, \(\chi\), is found in the description, then \(Var[S]= (1+\chi) \cdot Var[S]\). The noise returned is \(\sigma = \sqrt{Var[S]}\)

For each channel can be run in a script as

import exosim.tasks.radiometric as radiometric

computePhotonNoise = radiometric.ComputePhotonNoise()
phot_noise = computePhotonNoise(signal=table['signal_name'],
                                description=description,
                                multiaccum_gain=table['multiaccum_shot_gain'])