Abstract: In locating a transmitter, a central processor calculates a matched filter detector output for each of one or more candidate transmitter locations by applying a linear filter to low frequency magnetic field measurements obtained at a plurality of receiver locations. The central processor then determines the location of the transmitter based on the one or more calculated matched filter detector outputs. The linear filter is derived for the one or more candidate transmitter locations.

Abstract: In locating a transmitter, a central processor calculates a matched filter detector output for each of one or more candidate transmitter locations by applying a linear filter to low frequency magnetic field measurements obtained at a plurality of receiver locations. The central processor then determines the location of the transmitter based on the one or more calculated matched filter detector outputs.

Abstract: The present invention is directed to a global positioning system (GPS) having improved signal-to-noise ratio for reducing the required signal level for which GPS may be implemented in electronic devices or cell phones. The acquisition function of the GPS receiver is improved by inserting new signal processing for broadband noise reduction that allows subsequent improved estimation of critical time shift and frequency shift parameters needed for GPS acquisition at lower received signal levels. The decoding of the navigation bits from the satellite transmissions is improved to provide ephemeris data needed for computing navigation solutions at lower received signal levels, by examining the output of the same new signal processing for broadband noise reduction for spikes in the power of the output time series that correspond to navigation bit flips.