Global navigation satellite system (GNSS) transmit signals with code-division multiple access (CDMA) sequences. A receiver should know these sequences such that the signal can be extracted and used for positioning, navigation, and timing (PNT). This paper presents a system which estimates these sequences in a way that they could be used without prior knowledge. The L1 frequency band signals from a new NAVSTAR GPS Block III satellite were recorded and the sequences for each of its components were determined. The system was able to estimate, acquire and track L1-C/A, L1-C, L1-P(Y) and L1-M-Code successfully. Such an estimation system allows the testing and validation of GNSS signals – whether the sequence is not yet published or if it is not publicly available. Therefore, facilitating the development, evaluation and testing of any GNSS signal without prior knowledge of the system.