US 11,598,883 B2 · Memory optimized GNSS correlator

Abstract

A personal navigation device includes a correlator for processing GNSS signals from a constellation of satellites A signal is received from a navigation beacon containing a repeating code word, in which the code word includes a number N of samples corresponding to N phases, and in which reception of each code word occurs within a defined time period T. The sequence of N code samples is correlated with a known code word to determine a maximum value of correlation for a particular phase of the received signal. The correlation is performed using a correlator of size M, in which M is less than N, such that N/M=P complete correlations for a partial code phase are performed such that each correlation of a partial code phase is performed within a time period of approximately T/P. All P correlations of partial code phases are completed within time T.

A method comprising:

receiving, by a global navigation satellite system receiver, a signal from a navigation beacon of a global navigation satellite system (GNSS) having a code word;
processing, by the GNSS receiver, the received signal to form a sequence of N code samples;
during a first time period:
correlating, by the GNSS receiver, a first subset of the sequence of N code samples with a first set of pseudorandom number code phase;
shifting, by the GNSS receiver, the first subset of the sequence of N code samples by a single code sample;
and
correlating, by the GNSS receiver, the shifted first subset of the sequence of N code samples with the first set of pseudorandom number code phase;
generating, by the GNSS receiver, a first partial correlation for the first subset of the sequence of N code samples;
correlating, by the GNSS receiver, the first subset of the sequence of N code samples with a second set of pseudorandom number code phase;
shifting, by the GNSS receiver, the first subset of the sequence of N code samples by a single code sample;
correlating, by the GNSS receiver, the shifted first subset of the sequence of N code samples with the second set of pseudorandom number code phase;
generating, by the GNSS receiver, a second partial correlation for the first subset of the sequence of N code samples;
and
combining, by the GNSS receiver, at least the first and second partial correlations for the first subset of the sequence of N code samples to form a complete correlation for the first subset of the sequence of N code samples;
during a second time period:
correlating, by the GNSS receiver, a second subset of the sequence of N code samples with the first set of pseudorandom number code phase;
shifting, by the GNSS receiver, the second subset of the sequence of N code samples by a single code sample;
correlating, by the GNSS receiver, the shifted second subset of the sequence of N code samples with the first set of pseudorandom number code phase;
generating, by the GNSS receiver, a first partial correlation for the second subset of the sequence of N code samples;
correlating, by the GNSS receiver, the second subset of the sequence of N code samples with a second set of pseudorandom number code phase;
shifting, by the GNSS receiver, the second subset of the sequence of N code samples by a single code sample;
correlating, by the GNSS receiver, the shifted second subset of the sequence of N code samples with the second set of pseudorandom number code phase;
and
generating, by the GNSS receiver, a second partial correlation for the second subset of the sequence of N code samples;
combining, by the GNSS receiver, at least the first and second partial correlations for the second subset of the sequence of N code samples to form a complete correlation for the second subset of the sequence of N code samples;
and
determining, by the GNSS receiver, a correlation value using at least the complete correlation for the first subset of the sequence of N code samples and the complete correlation of the second subset of the sequence of N code samples.

24 more elements

Memory optimized GNSS correlator

Life of this patent

Memory optimized GNSS correlator

Life of this patent

Abstract

Claims12