Patent ID: 7471717

Claim:
An apparatus for acquiring spread-spectrum signals comprising: a decimator means for generating a plurality of samples based on the spread-spectrum signal; a serial-to-parallel converter means connected to the decimator means for grouping a plurality of samples into a word; a first memory means with a data width for storing the word; a correlation engine means having a plurality of partial correlation modules connected to the first memory, said correlation engine means for calculating a partial correlation between the word and a PN code segment, wherein the partial correlation module comprises: a plurality of multipliers and an adder for calculating an inner product of the word and the PN code segment to produce the partial correlation; and an accumulator means for accumulating a plurality of partial correlations to produce a complete correlation; a coherent integrator means connected to the correlation engine means for accumulating a plurality of complete correlations to generate a coherent integration; an incoherent integrator means connected to the coherent integrator means for accumulating a plurality of coherent integrations to generate an incoherent integration; and a signal detector means connected to the incoherent integrator means for checking the presence of the spread-spectrum signal based on the incoherent integration, said incoherent integrator means comprises: an incoherent memory means for storing the incoherent integration; a first squaring means for squaring an in-phase component of the coherent integration; a second squaring means for squaring a quadrature component of the coherent integration; a third squaring means for squaring a previous incoherent integration; an adding means for summing outputs of the first, second and third squaring means for generating a squared value; and a square-root means for taking a square-root of the squared value to generate the incoherent integration and for halving a number of bits required for storing the output from the adding means.