Abstract: A correlation system for a GNSS receiver uses an FFT engine to perform correlation and post-FFT operation. The FFT engine executes FFT operation to an input data stream so as to generate a frequency-domain correlation with frequency-domain C/A code and IFFT operation to the frequency-domain correlation result to generate post correlation data for each hypothesis, and executes FFT operation to the post correlation data of a selected hypothesis to generate a post-correlation FFT result in a programmable TDM manner. In the present invention, in addition to the FFT engine, some components such as a magnitude calculation unit and memory are shared by a correlation stage and a post-correlation stage. Therefore, hardware complexity can be reduced.

Abstract: A method for obtaining GNSS time in a GNSS receiver includes: deriving a relationship between a first clock signal and the received GNSS time; latching a second clock signal and the first clock signal at a first latching point to obtain a clock value A1 of the first clock signal and a clock value B1 of the second clock signal; calculating a GNSS time C1 corresponding to the clock value A1 according to the relationship; latching the first clock signal and the second clock signal at a second latching point to obtain a clock value A2 of the first clock signal and a clock value B2 of the second clock signal; and calculating a GNSS time C2 corresponding to the clock value A2 according to the GNSS time C1, the clock value B1, and the clock value B2. For example, the aforementioned values A1, B1, C1, B2, and C2 represent values such as TTick1, RTC1, TOW1, RTC2, and TOW2, respectively.

Abstract: The present invention discloses a variable length fast Fourier transform (FFT) system and a method for performing the FFT system in a global navigation satellite system (GNSS) signal acquisition and tracking, which includes a memory and a number of processing elements. Based on the GNSS signal tracking, the variable length FFT system performs a first FFT operation together with a first data length. Based on the GNSS signal acquisition, the variable length FET system is divided into several FFT subsystems to simultaneously perform different operations with various data lengths different from the first data length. Thus, the variable length FFT system can enhance the hardware utility and increase throughputs.

Abstract: A microcode patching system, including a memory unit comprising a first memory storing at least one microcode main instruction and a second memory providing at least one microcode patch instruction, accessed according to a selected output address, an address selecting unit providing a first output address, and a trap and patch logic unit coupled between the address selecting unit and the memory unit, determining if the first output address matches any of at least one bug address, and selecting a selected patch address for accessing the second memory or the first output address as a second output address if the first output address matches one or none of the bug addresses, respectively, wherein the second output address is coupled to the memory unit.