Use EOIR constraints to set a signal-to-noise ratio (SNR) on an EOIR sensor. SNR is a factor that describes the sensor response to instantaneous fields of view (IFOVs) that contain targets as compared to the mean of the local surrounding IFOVs.
For point source targets, the SNR is computed as:
where,
rTGT is the total sensor response for a target-containing-IFOV.
rBKG is the total sensor response for the mean background-only IFOV.
kσ is the RMS deviations in sensor response [electrons] for the local IFOVs surrounding the target-containing IFOV (i.e., the sensor noise floor).
For extended area targets, those with projected solid angles that are greater than the sensor's effective instantaneous field of view, the SNR is computed as:
where,
Lsignal is the "signal" radiance.
NERtot is the total noise equivalent radiance.
For more details on SNR computations, see EOIR Model Description and Validation (PDF).
Probability of target detection is generally a function of the SNR, with the larger SNR corresponding to higher detection probability. To enable the SNR constraint, select at least one of the limits (Min or Max). You can also opt to exclude exclude time intervals that satisfy the SNR constraint.