Digital methods and apparatus reverse link signal detection and recovery in a mobile data base station

A method of detecting a dotting sequence preceding packetized data, the dotting sequence being of alternate 1s and 0s, the foregoing dotting sequence and data being phase modulated on a transmitter carrier as a transmitted signal, comprising the steps of:

• (a) receiving the transmitted signal and downshifting the received signal by multiplying the received signal by the inphase and quadrature components of a receiver carrier to obtain the inphase and quadrature components of a signal vector;
• (b) sampling the inphase and quadrature components of the signal vector at a rate that is a multiple of a locally generated estimate of the transmitted bit rate and digitizing the samples to obtain a plurality of digitized inphase and quadrature samples of the signal vector;
• (c) for each successive digitized inphase and quadrature samples of the signal vector and the digitized inphase and quadrature samples of the signal vector taken one bit time earlier using the locally generated estimate of the transmitted bit rate, determining a difference vector having a phase responsive to the difference in phase between the inphase and quadrature samples of the signal vector and the digitized inphase and quadrature samples of the signal vector taken one bit time earlier;
• (d) for a set of difference vectors based on digitized inphase and quadrature samples of the signal vector taken integer bit times apart during a time the dotting sequence may be received;
• (i) inverting the quadrature component of every other difference vector;
• and
• (ii) providing a vector sum by summing the difference vectors in the set after step (d) (i) has been performed;
• (e) determining whether the dotting sequence has been received by a magnitude of the vector sum determined in step (d) (ii).