Method of processing a digital signal derived from an analog input signal of a GNSS receiver, a GNSS receiver base band circuit for carrying out the method and a GNSS receiver
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Abstract
An acquisition unit of a GNSS receiver base band circuit comprises a correlator (40) with a correlator shift register (43) to which a correlation sequence derived from a basic sequence characteristic for a satellite is fed by a code generator (41). Each of the N=32 or more memory cells of the correlator shift register (43) is connected to two correlator cells (44a, 44b) for multiplying digital values of the correlator sequence from the memory cell with data values of a data sequence, adding up the products and storing the sum in a register as a correlation value pertaining to one of N relative phase positions of the correlation sequence relative to the data sequence during a correlation phase. During a subsequent read-out phase the registers of each row of correlator cells (44a; 44b) are connected to form a daisy chain and the correlation values are fed through the same to appear sequentially at the output of the last register in the row while the correlator shift register (43) and the rows of registers are sequentially filled with initial values for the next correlation phase.
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Citations
46 Claims
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1-23. -23. (canceled)
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24. A method of processing a digital signal derived from an analog input signal of a GNSS receiver containing at least one encoded binary sequence characteristic of at least one GNSS satellite and consisting of repetitions of a characteristic basic sequence which extends over a basic interval, the method comprising the following subsequent steps:
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deriving at least one finite length data sequence consisting of digital data values from the digital signal, sequentially feeding digital values of a correlation sequence derived from the basic sequence to a correlator shift register comprising a plurality of sequentially connected memory cells in order to sequentially fill the memory cells of the correlator shift register with subsequent values of the correlation sequence, the subsequent values forming an initial subsequence, during a correlation phase;
feeding the correlation sequence further through the correlator shift register and correlating the data sequence with a plurality of copies of the correlation sequence having different phase positions with respect to the data sequence in parallel by in each case sequentially multiplying the data values each with the value from one of the plurality of memory cells of the correlator shift register, adding up the products to form a correlation result and storing the correlation result in one of a plurality of registers,during a read-out phase which follows upon the correlation phase;
shifting the correlation results through the plurality of registers in such a way that they appear sequentially at the output of a last one of the plurality of registers. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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- 36. GNSS receiver base band circuit, with an acquisition unit for processing the digital values of the digital signal, the acquisition unit comprising a correlator with a code generator for generating a correlation sequence derived from a characteristic basic sequence, a correlator shift register having a plurality of sequentially connected memory cells and being configured to be fed by the code generator, a plurality of correlator cells, each connected to an input of the correlator and to one of the memory cells of the correlator shift register and comprising a multiplier for multiplying a data value present at an input of the correlator with a value of the correlation sequence read from the memory cell to form a product, a register for storing a value and an adder configured to add the product to the said value, and a switch configured to connect an input of the register either to the output of the adder or to the register of a previous correlator cell where applicable.
Specification