US 12,474,482 B2
System and method for global navigation satellite system (GNSS) position estimation
Himamshu Gopalakrishna Khasnis, Bangalore (IN); and Navaneetha Krishnamurthy, Bangalore (IN)
Assigned to SIGNALCHIP INNOVATIONS PRIVATE LIMITED, Bangalore (IN)
Filed by Signalchip Innovations Private Limited, Bangalore (IN)
Filed on Dec. 30, 2022, as Appl. No. 18/091,864.
Claims priority of application No. 202141062289 (IN), filed on Dec. 31, 2021.
Prior Publication US 2023/0213662 A1, Jul. 6, 2023
Int. Cl. G01S 19/30 (2010.01); G01S 19/29 (2010.01); G01S 19/37 (2010.01)
CPC G01S 19/30 (2013.01) [G01S 19/29 (2013.01); G01S 19/37 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A global navigation satellite system (GNSS) receiver for improving the accuracy of a global navigation satellite system (GNSS) position estimation using a sigma-delta based fractional interpolation in a delay-locked loop, comprises:
a correlator that correlates a GNSS C/A signal received from a satellite with a locally generated GNSS C/A code by multiplying the locally generated GNSS C/A code with incoming data samples;
an integrate and dump unit that accumulates correlation peaks from the received GNSS C/A signal;
a carrier phase discriminator that determines a phase error in the correlation peaks;
a second loop filter that averages a phase error measured by the carrier phase discriminator;
a carrier numerically controlled oscillator that generates a sinusoid to correct the phase error in the correlation peaks;
a code phase discriminator that determines a code delay between the locally generated GNSS C/A code and the C/A code present in the received GNSS C/A signal after the phase error correction;
a first loop filter that averages the code delay measured by the code phase discriminator;
a code numerically controlled oscillator that generates the local GNSS C/A code based on a unique C/A code that corresponds to the satellite; and
a sigma-delta modulator that imparts a fractional delay to the locally generated GNSS C/A code based on the averaged code delay received from the first loop filter, wherein the fractional delay is imparted to increase the accuracy of code delay tracking of the GNSS C/A signal received from the satellite, wherein the accuracy is improved by increasing a number of bits in an accumulator of the sigma-delta modulator.