LOW COST, HIGH PERFORMANCE GPS/GNSS RECEIVER ARCHITECTURE
First Claim
1. A low-cost GPS/GNSS receiver for receiving a satellite signal at an RF frequency (fRF), the GPS/GNSS receiver comprising:
- a front end section for receiving the satellite signal and generating a digital complex signal having a first bandwidth, the received satellite signal being converted into a complex signal before digitizing;
a signal capturing section for searching for and acquiring the satellite signal, the signal capturing section including a capture memory;
a baseband processor for tracking the acquired satellite signal; and
a signal splitter coupled to the front end section, the signal splitter splitting the digital complex signal into two bandwidths,wherein the signal splitter generates a narrowband digital complex signal having a second bandwidth substantially smaller than the first bandwidth, provides the narrowband digital signal to the capture memory, and provides the wider first bandwidth digital complex signal to the baseband processor.
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Accused Products
Abstract
A low-cost GPS/GNSS receiver receives a satellite signal at an RF frequency (fRF). The GPS/GNSS receiver includes a front end section for receiving the satellite signal and generating a digital complex signal having a first bandwidth, the received satellite signal being converted into a complex signal before digitizing, a signal capturing section for searching for and acquiring the satellite signal, the signal capturing section including a capture memory, a baseband processor for tracking the acquired satellite signal, and a signal splitter coupled to the front end section. The signal splitter splits the digital complex signal into two bandwidths, by generating a narrowband digital complex signal having a second bandwidth substantially smaller than the first bandwidth. The signal splitter provides the narrowband digital signal to the capture memory and the wider first bandwidth digital complex signal to the baseband processor.
38 Citations
43 Claims
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1. A low-cost GPS/GNSS receiver for receiving a satellite signal at an RF frequency (fRF), the GPS/GNSS receiver comprising:
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a front end section for receiving the satellite signal and generating a digital complex signal having a first bandwidth, the received satellite signal being converted into a complex signal before digitizing; a signal capturing section for searching for and acquiring the satellite signal, the signal capturing section including a capture memory; a baseband processor for tracking the acquired satellite signal; and a signal splitter coupled to the front end section, the signal splitter splitting the digital complex signal into two bandwidths, wherein the signal splitter generates a narrowband digital complex signal having a second bandwidth substantially smaller than the first bandwidth, provides the narrowband digital signal to the capture memory, and provides the wider first bandwidth digital complex signal to the baseband processor. - View Dependent Claims (2, 3, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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4. A front end section in a low-cost GPS/GNSS receiver for receiving a satellite signal at an RF frequency (fRF), the front end section comprising:
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a reference oscillator for generating a global clock signal having a reference frequency (fr); a first clock circuit for generating a first local clock signal having a first frequency; a second clock circuit for generating a second local clock signal having a second frequency, the second clock signal being a complex signal having an I-component for an I channel and a Q-component for a Q-channel; a third clock circuit for generating a third local clock signal having a third frequency, the third clock signal being a complex signal having an I-component for the I channel and a Q-component for the Q-channel; a first mixer for combining a received satellite signal with the first local clock signal to generate a first IF signal; a band-pass filter for band-pass filtering the first IF signal to have a first center frequency and a first bandwidth; a second mixer for generating a complex IF signal by combining the first IF signal with the second local clock signal; a low-pass filter for low-pass filtering the complex IF signal to have a second center frequency and the first bandwidth; an analog/digital converter for sampling the complex IF signal and generating a digital complex signal; and a third mixer for reducing the center frequency of the digital complex signal to a third center frequency by combining the digital complex signal with the third clock signal. - View Dependent Claims (5)
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6. A baseband signal processor in a low-cost GPS/GNSS receiver, the baseband processor comprising:
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a Doppler compensation phase rotator for receiving a wideband complex digital satellite signal from a front end section of the GPS/GNSS receiver, and generating a complex baseband signal having a nominally zero frequency, the complex baseband signal carrying received PN code; a PN code generator for generating a reference code; a code tracking correlator for correlating the reference code and the received PN code by sampling the complex baseband signal at a timing and polarity given by the reference code so as to generate a DLL error signal; and a DLL code tracking loop for feeding back the DLL error signal to the PN code generator, the reference code being shifted in accordance with the DLL error signal such that the reference code aligns with the received PN code. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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14. A method for processing a satellite signal having an RF frequency (fRF) in a low-cost GPS/GNSS receiver, the method comprising:
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receiving the satellite signal at a front end section; generating a complex signal having a first bandwidth from the received satellite signal using a complex clock signal; sampling the complex signal to generate a digital complex signal; splitting the digital complex signal into two bandwidths, by generating a narrowband digital complex signal from one of the split digital complex signals, the narrowband complex signal having a second bandwidth substantially smaller than the first bandwidth; providing the narrowband digital complex signal to a capture memory in a signal capturing section to search for and acquire the satellite signal; and providing the other of the split digital complex signals to a baseband processor for tracking the acquired satellite signal. - View Dependent Claims (15, 16, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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17. A method for processing a received satellite signal at an RF frequency (fRF) at a front end section in a low-cost GPS/GNSS receiver, the method comprising:
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generating a global clock signal having a reference frequency (fr); generating a first local clock signal having a first frequency; generating a second local clock signal having a second frequency, the second clock signal being a complex signal having an I-component for an I channel and a Q-component for a Q-channel; generating a third local clock signal having a third frequency, the third clock signal being a complex signal having an I-component for the I channel and a Q-component for the Q-channel; combining a received satellite signal with the first local clock signal to generate a first IF signal; band-pass filtering the first IF signal to have a first center frequency and a first bandwidth; generating a complex IF signal by combining the first IF signal with the second local clock signal; low-pass filtering the complex IF signal to have a second center frequency and the first bandwidth; sampling the complex IF signal and generate a digital complex signal; and reducing the center frequency of the digital complex signal to a third center frequency by combining the digital complex signal with the third clock signal. - View Dependent Claims (18)
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19. A method for tracking PN code in a received satellite signal in a low-cost GPS/GNSS receiver, the method comprising:
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receiving a wideband complex digital satellite signal from a front end section of the GPS/GNSS receiver; generating a complex baseband signal having a nominally zero frequency, the complex baseband signal carrying received PN code; generating a reference code; correlating the reference code and the received PN code by sampling the complex baseband signal at a timing and polarity given by the reference code so as to generate a DLL error signal; and shifting the reference code in accordance with the DLL error signal such that the reference code aligns with the received PN code. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification