Method and apparatus for segmented code correlation

A parallel correlator comprising:

• a data memory having a sample-sequential input and a sample-parallel output, said data memory organizing the sample-sequential input into blocks of n sequential samples and providing one of said blocks to said sample-parallel output;
• a Doppler memory having a sample-sequential input and a sample-parallel output, said Doppler memory organizing the sample-sequential input into blocks of n sequential samples and providing one of said blocks to said sample-parallel output;
• a code register organized for a sample-serial or a segment-serial input and a sample-parallel output, said sample parallel output having n parallel samples, the segmented code register configured to store the input samples in their order of input and to forward shift or backward shift the registered samples on each clock cycle prior to parallel output, said forward shift shifting the registered samples by one sample position and the backward shift shifting the registered samples by one segment of samples;
• and
• an inner product calculator having three sample-parallel inputs, each of said sample-parallel inputs having n parallel samples, said inner product calculator having one output representing the inner product of the three sample-parallel inputs.

A method of segmented correlation comprising:

• providing a data memory for receiving a sample-sequential input and providing a sample-parallel output, the data memory organizing the sample serial input into blocks of n sequential samples;
• providing a code register organized for a sample-serial or a segment-serial input and a sample-parallel output, the sample parallel output having n parallel samples, the segmented code register storing the input samples in an order of input and one of forward- or backward-shifting the registered samples on each clock cycle prior to parallel output, the forward-shifting shifting the registered samples by one sample position and the backward-shifting shifting the register samples by one segment of samples per clock cycle;
• and
• correlating the output from the segmented code register with the sample serial output from the data memory to provide a correlation result representing the inner product of the data memory and the segmented code register.

A method for segmented correlation, comprising:

• providing a data memory for receiving a sample-sequential input and providing a sample-parallel output, the data memory organizing the sample serial input into blocks of n sequential samples;
• providing a Doppler memory for receiving a sample-sequential input and providing a sample-parallel output, the Doppler memory organizing the sample serial input into blocks of n sequential samples;
• providing a code register organized for a sample-serial or a segment-serial input and a sample-parallel output, the sample parallel output having n parallel samples, the segmented code register storing the input samples in an order of input and one of forward- or backward-shifting the registered samples on each clock cycle prior to parallel output, the forward-shifting shifting the registered samples by one sample position and the backward-shifting shifting the register samples by one segment of samples per clock cycle;
• and
• correlating the segmented sample output from the segmented code register with the sample serial output from the data memory and the Doppler memory to provide a an inner product result.

A machine-readable medium having stored thereon a plurality of executable instructions to be executed by a processor to conduct segmented correlation, the method comprising:

• receiving a first signal and organizing sampled elements representing said first signal as n sequential first samples;
• receiving a second signal and organizing sampled elements representing said second signal as n sequential second samples;
• cross-correlating the n sequential first samples with n sequential second samples at first clock cycle;
• circularly forward-shifting the n sequential second samples by one sample and cross-correlating the shifted n sequential second samples with n sequential first samples at second clock cycle;
• repeating the step of circularly forward-shifting the n sequential second samples for P clock cycles;
• and
• circularly backward-shifting the n sequential second samples by L elements after P+1 clock cycles.