Efficient detection of ranging code correlation function of a GNSS signal

A method of detecting a ranging code correlation function of a global navigation satellite system (GNSS) signal, the method comprising:

• receiving a digitized GNSS signal;
• correlating the digitized GNSS signal with a corresponding ranging code at each of a plurality of different offsets from a current estimate of a code delay to generate a plurality of correlation data points;
• and
• interpolating the correlation data points based on the current estimate of the code delay to generate at least one estimated correlation data point that lies between two of the correlation data points, wherein the plurality of correlation data points and the at least one estimated correlation data point provide a representation of a ranging code correlation function of the digitized GNSS signal;
• wherein the current estimate of the code delay comprises a whole component specifying a whole number of samples of the digitized GNSS signal and a partial portion specifying a fraction of a sample of the digitized GNSS signal;
• and
• wherein interpolating the correlation data points based on the current estimate of the code delay to generate at least one estimated correlation data point comprises generating an estimated correlation data point that corresponds to an offset that is shifted by the fraction of a sample from one of the different offsets.