Abstract: A signal receiver where the presence of a signal is determined by integrating the magnitude of the signal, and determining the value of the slope of the integrator output as a function of integration time. The slope value is compared with a first threshold value corresponding to the presence of a signal of desired power at the input to the integrator. A signal may be considered present if the slope value exceeds the first voltage value. In addition, the integrated signal is compared with a second threshold value, and a second determination of the presence of a signal is made. The first determination may be used as the sole indicator of the presence of a signal, or the first and second determinations may be combined in an AND gate to be used as an indication of signal presence.

Abstract: An apparatus (200) for determining time within a global navigation satellite receiver comprises a correlator (1), a combiner (35, 37), a comparator, and a processor. The correlator (1) comprises a means for determining a common data pattern between received signals of at least two satellites, and a means for calculating a dot product (15) for each of the at least two received signals. The combiner (35, 37) combines the calculated dot products to generate a combined dot product result. The comparator (41, 43) compares the combined dot product results with the common data pattern to generate a comparing result. The processor (47) determines a time from the comparing result.