A Global Navigation Satellite System (GNSS) receiver demodulates code shift keying (CSK) data utilizing correlations with combinational pseudo-random noise (PRN) codes generated for different bit positions. The GNSS receiver receives a signal including a PRN code modulated by CSK to represent a symbol (i.e., CSK modulated symbol). The GNSS receiver maintains a plurality of receiver codes, each representing a different shift in chips to the PRN code. The GNSS receiver performs a chip-by-chip linear combination of a group of receiver codes for each bit position of the CSK modulated symbol. The GNSS receiver correlates the received signal with each combinational PRN code to produce a binary value that is the CSK modulated symbol.