1. A method for measuring energy potential in a receiver receiving signals from a plurality of navigation satellites, comprising the steps of: digitizing said received signals; removing information symbols from said digitized received signals; calculating a correlation signal I; averaging said correlation signal I over a time interval T M to obtain an estimate I n of an expected value MI; calculating a variance estimate D n of said correlation signal I over a time interval T D ; and calculating an estimate SNR e of energy potential according to the algorithm 
 SNR e =20 log 10 ( I n )− K c −η dB-Hz; wherein: K c is a characteristic constant based at least in part on said variance estimate D n , and η is an energy loss based on digital processing.