Method and apparatus for observing unknown codes on satellite positioning system
First Claim
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1. An apparatus for observing unknown codes on Satellite Positioning System, said apparatus comprising:
- a RECEIVING MEANS for receiving a known C/A code modulated on L1 carrier frequency, for receiving an unknown Y code modulated on L1 carrier frequency signal, wherein a received L1 signal contains propagation noise; and
wherein said Y code comprises a known P code and an unknown W code;
a MICROPROCESSOR SYSTEM connected to said RECEIVING MEANS for controlling said apparatus using a CONTROL signal;
a W SAMPLES STORAGE connected to said MICROPROCESSOR SYSTEM for permanently storing logged W code samples; and
at least one DIGITAL CHANNEL PROCESSING MEANS for;
(1) locally generating replica of said C/A code modulated on L1 carrier frequency signal;
(2) locally generating replica of said P code modulated on L1 carrier frequency signal, wherein said locally generated replica of L1 signal does not contain propagation noise;
(3) extracting an estimate of said Y code from said L1 signal, wherein said estimate signal contains propagation noise;
(4) correlating a locally generated replica of C/A code with a received L1 code for obtaining code and carrier lock to the L1 C/A code signal;
(5) removing said P code from said locally extracted estimate of said L1Y code to obtain a locally extracted estimate of said L1 W code;
(6) logging said L1 W-code estimates in a DATA MEMORY, at a time mark controlled by said MICROPROCESSOR; and
(7) transferring data logged in said DATA MEMORY to a W SAMPLES STORAGE for further analysis.
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Abstract
The method and apparatus for observing unknown codes on the Satellite Positioning System satellites are disclosed. The technique employs the parabolic high gain antenna to determine the energy spectrum of the unknown W code. The technique does not provide sufficient accuracy to implement the effective anti-spoofing device.
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Citations
18 Claims
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1. An apparatus for observing unknown codes on Satellite Positioning System, said apparatus comprising:
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a RECEIVING MEANS for receiving a known C/A code modulated on L1 carrier frequency, for receiving an unknown Y code modulated on L1 carrier frequency signal, wherein a received L1 signal contains propagation noise; and
wherein said Y code comprises a known P code and an unknown W code;a MICROPROCESSOR SYSTEM connected to said RECEIVING MEANS for controlling said apparatus using a CONTROL signal; a W SAMPLES STORAGE connected to said MICROPROCESSOR SYSTEM for permanently storing logged W code samples; and at least one DIGITAL CHANNEL PROCESSING MEANS for; (1) locally generating replica of said C/A code modulated on L1 carrier frequency signal; (2) locally generating replica of said P code modulated on L1 carrier frequency signal, wherein said locally generated replica of L1 signal does not contain propagation noise; (3) extracting an estimate of said Y code from said L1 signal, wherein said estimate signal contains propagation noise; (4) correlating a locally generated replica of C/A code with a received L1 code for obtaining code and carrier lock to the L1 C/A code signal; (5) removing said P code from said locally extracted estimate of said L1Y code to obtain a locally extracted estimate of said L1 W code; (6) logging said L1 W-code estimates in a DATA MEMORY, at a time mark controlled by said MICROPROCESSOR; and (7) transferring data logged in said DATA MEMORY to a W SAMPLES STORAGE for further analysis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for observing unknown codes on SPS;
- said method employing a system comprising a RECEIVING MEANS, at least one DIGITAL CHANNEL PROCESSING MEANS, and a W SAMPLES STORAGE;
said method comprising the steps of;providing said RECEIVING MEANS, said W SAMPLES STORAGE, and at least one said DIGITAL CHANNEL PROCESSING MEANS; receiving a known L1 C/A code modulated on L1 carrier frequency, and an unknown Y code modulated on L1 carrier frequency signal by said RECEIVING MEANS;
wherein a received L1 signal contains propagation noise; and
wherein said Y code comprises a known P code and an unknown W code;generating a local replica of said C/A code and a local replica of said P code modulated on L1 carrier frequency signal by each said DIGITAL CHANNEL PROCESSING MEANS; extracting an estimate of said Y code from said L1 signal by each said DIGITAL CHANNEL PROCESSING MEANS; correlating a locally generated replica of C/A code with the received L1 code for obtaining code and carrier lock to the L1 C/A code signal; removing said P code from said locally extracted estimate of said L1Y code by each said DIGITAL CHANNEL PROCESSOR to obtain a locally extracted estimate of said L1 W code; logging said L1 W code estimate in a DATA MEMORY at a time mark controlled by a MICROPROCESSOR; and transferring a logged sampled W code from said DATA MEMORY to said W SAMPLES STORAGE for further processing. - View Dependent Claims (14, 15, 16, 17)
- said method employing a system comprising a RECEIVING MEANS, at least one DIGITAL CHANNEL PROCESSING MEANS, and a W SAMPLES STORAGE;
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18. A method for logging the sampled W code generated by the Satellite Positioning System (SPS) comprising the steps of:
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selecting a satellite-vehicle (SV) to be observed; observing the selected SV by steering a PARABOLIC DISH ANTENNA to azimuth and elevation of said SV; searching by a L1 C/A TRACKER an L1 C/A code signal generated by said SV; locking to said L1 C/A code by closing the code and carrier tracking loops by said L1 C/A TRACKER; synchronizing P and X1A signals generated by a CODE GENERATOR with said SV satellite L1 C/A signal; aligning an ADJUSTABLE FREQUENCY OSCILLATOR to said SV; extracting unknown W code signals from said L1 C/A signals by a W CODE EXTRACTOR; logging sampled W code signals by a DATA MEMORY block; transferring the logged sampled W code from said DATA MEMORY to a W SAMPLE STORAGE by a MICROPROCESSOR system; and stopping the logging process when said W SAMPLE STORAGE is filled.
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Specification