UNIVERSAL ACQUISITION AND TRACKING APPARATUS FOR GLOBAL NAVIGATION SATELLITE SYSTEM (GNSS)
First Claim
1. An acquisition and tracking apparatus for tracking a plurality of spread spectrum navigation signals, each modulated according to one of a set of modulation types on a higher frequency carrier converted into an intermediate frequency signal, the carrier comprising one or more subcarriers and a navigation message modulated with a spreading code, the spreading code comprising a data component for carrying the navigation message, the spreading codes having a nominal epoch which is essentially a multiple of a predetermined time period, the apparatus comprising a plurality N of channel processors, each said channel processors including:
- a carrier demodulation module including a local carrier oscillator generating a local carrier frequency for demodulating the carrier from the intermediate frequency signal into a baseband signal;
a code frequency generation module including a local code oscillator generating a code clock (CCK) at a code frequency, for clocking the code generation module;
a code generation module generating replica of the data component, and a periodic interrupt signal which is substantially synchronous with the code epochs of the selected navigation signal;
a subcarrier combining module, generating subcarrier replicas;
a correlator module correlating the baseband signal with the replica of the data component and the subcarrier replicas, and outputting correlation signals sampled with the periodic interrupt signal;
a parameter parsing module for providing operational parameters including a nominal carrier frequency control signal to the local carrier oscillator and a code frequency control signal to the local code oscillator;
a discriminator module for processing the sampled correlation signals and generating a set of data synchronization error signals; and
and an Error Evaluation Module generating a feedback value for adjusting the local carrier frequency and a Code Frequency Feedback signal for adjusting the code frequency.
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Accused Products
Abstract
An acquisition and tracking apparatus is provided for tracking digitized spread spectrum navigation signals modulated with a spreading code according to any of a set of modulation types including Binary Phase Shift Keying (BPSK) with and without Frequency Domain Multiplexing Access (FDMA), time multiplexed BPSK, Quadrature Phase Shift Keying (QPSK), sine and cosine Binary Offset Carrier (BOC), modified, complex, and time multiplexed BOC (TMBOC), the apparatus comprising a plurality of universal tracking channels, each coupled to an interrupt module. The universal tracking channel includes a carrier demodulation module, a code generation module, a correlator module, a code frequencies generation module, and a subcarrier combining module for efficiently using the correlator resources in the correlation of the data and the pilot components of the signal within a single universal tracking channel. A corresponding method of operation is also provided.
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Citations
24 Claims
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1. An acquisition and tracking apparatus for tracking a plurality of spread spectrum navigation signals, each modulated according to one of a set of modulation types on a higher frequency carrier converted into an intermediate frequency signal, the carrier comprising one or more subcarriers and a navigation message modulated with a spreading code, the spreading code comprising a data component for carrying the navigation message, the spreading codes having a nominal epoch which is essentially a multiple of a predetermined time period, the apparatus comprising a plurality N of channel processors, each said channel processors including:
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a carrier demodulation module including a local carrier oscillator generating a local carrier frequency for demodulating the carrier from the intermediate frequency signal into a baseband signal; a code frequency generation module including a local code oscillator generating a code clock (CCK) at a code frequency, for clocking the code generation module; a code generation module generating replica of the data component, and a periodic interrupt signal which is substantially synchronous with the code epochs of the selected navigation signal; a subcarrier combining module, generating subcarrier replicas; a correlator module correlating the baseband signal with the replica of the data component and the subcarrier replicas, and outputting correlation signals sampled with the periodic interrupt signal; a parameter parsing module for providing operational parameters including a nominal carrier frequency control signal to the local carrier oscillator and a code frequency control signal to the local code oscillator; a discriminator module for processing the sampled correlation signals and generating a set of data synchronization error signals; and and an Error Evaluation Module generating a feedback value for adjusting the local carrier frequency and a Code Frequency Feedback signal for adjusting the code frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A global navigation satellite signal receiver system, comprising:
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an acquisition and tracking apparatus for tracking a plurality of spread spectrum navigation signals, each modulated according to one of a set of modulation types on a high frequency carrier with a navigation message riding on a spreading code which comprises a combination of a primary data code component for carrying the navigation message;
a primary pilot code component;
secondary data and pilot code components; and
a plurality of data and pilot subcarrier components, the apparatus comprising a plurality N of channel processors, each channel processor receiving a selected one of the navigation signals, and including;a code generation module generating local code replicas of code components of the spreading code of said selected signal; a carrier demodulation module, demodulating the carrier of said selected signal into a baseband signal; a code frequency generation module clocking the code generation module and generating local subcarrier replicas of subcarrier components of the spreading code of said selected signal; a subcarrier combining module combining the local subcarrier replicas to generate combined subcarrier replicas and multiplying said combined subcarrier replicas with weighting factors; a correlator module correlating the baseband signal with the local code replicas and the weighted combined subcarrier replicas into a set of correlation results; and a Local Interrupt Module receiving the correlation results therefrom and controlling the generating of the local code replicas and local subcarrier replicas.
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24. An acquisition and tracking apparatus for tracking a plurality of spread spectrum navigation signals, each modulated according to one of a set of modulation types on a high frequency carrier with a navigation message riding on a spreading code which comprises a combination of a primary data code component for carrying the navigation message;
- a primary pilot code component;
secondary data and pilot code components; and
a plurality of data and pilot subcarrier components, the apparatus comprising a plurality N of channel processors, each channel processor receiving a selected one of the navigation signals, and including;a code generation module generating local code replicas of code components of the spreading code of said selected signal; a carrier demodulation module, demodulating the carrier of said selected signal into a baseband signal; a code frequency generation module clocking the code generation module and generating local subcarrier replicas of subcarrier components of the spreading code of said selected signal; a subcarrier combining module combining the local subcarrier replicas to generate combined subcarrier replicas and multiplying said combined subcarrier replicas with weighting factors; a correlator module correlating the baseband signal with the local code replicas and the weighted combined subcarrier replicas into a set of correlation results; and a Local Interrupt Module receiving the correlation results therefrom and controlling the generating of the local code replicas and local subcarrier replicas.
- a primary pilot code component;
Specification