A device and method for estimating the operational effectiveness, status, and protection range of an electronic countermeasures system in real time or near real time are provided. The device and method calculate a predicted ECM power at a given location using a propagation and scenario model. Then a measured ECM power at the given location is used to determine a correction value equal to the difference between the calculated and measured ECM powers. The correction value and the propagation model are then used with a heuristic method to refine estimates of propagation and scenario parameters. The refined parameter set is used to produce a refined prediction of ECM power, which is used to create a refined correction factor. The refined correction factor is used to determine predicted ECM powers at a plurality of locations in an area around the device to determine a boundary of protection.