Abstract: 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 are disclosed. 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 FFT 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 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: Disclosed is a shared correlator for processing signals with different chip rates from respective channels. The shared correlator comprises a mode controller, a plurality of sub-correlators, a PRN code generator and a plurality of accumulators. The mode controller arranges channel allocations for respective IF signals down converted from the signals. The PRN code generator generates respective PRN codes for the respective IF signals according to the respective chip rates thereof. The sub-correlators perform correlation to the respective IF signals with the respective PRN codes to obtain respective correlating results. The accumulators accumulate the respective correlation results to obtain respective overall correlation gains of the respective IF signals according to the respective chip rates. Each sub-correlator comprises a plurality of correlator cells, correlating one IF signal with one PRN code corresponding thereto according to the chip rate of the IF signal.

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: This present invention introduces a data control apparatus and method for global navigation satellite system (GNSS). The data control apparatus has a serial transport interface for transporting data blocks at a data transfer rate from a data source. A microprocessor executes a program routine for sequentially writing the data blocks into the main memory unit at a data accessing rate. While the bit sizes of the data blocks have been pre-compressed, the decompressor will decompress the data blocks to reduce the transfer time of the data blocks through the serial interface thereby eliminating a speed bottle of the data transfer rate if the data transfer rate is slower than the data accessing rate of the main memory unit.