A method of computing a correlation between a pseudorandom reference code and a satellite signal is provided. The method comprises receiving a satellite signal having a repeating code modulated thereon, wherein the satellite signal comprises a pseudorange; correlating the satellite signal with less than an entire length of the pseudorandom reference code with a portion of the satellite signal to produce a correlation over a period less than a period of the repeating code; and processing the correlation to form values representative of magnitude or power of the correlation to produce an energy signal.