Coherent GPS translator with spread spectrum pilot tone
First Claim
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1. A translator for translating Global Positioning System (GPS) signals received by a platform for retransmission to a base station, comprising:
- a) apparatus adapted to receive a raw GPS signal, said raw GPS signal being a spread spectrum signal with a first center frequency;
b) translating circuitry arranged to translate said raw GPS signal into a translated GPS signal with a different center frequency, said translating circuitry including a local oscillator whose output, when mixed with said raw GPS signal, produces said translated GPS signal;
c) a pilot tone generator connected to said translating circuitry and arranged to generate a pilot tone phase-locked to said local oscillator output;
d) modulating circuitry operatively connected to said pilot tone generator and arranged to phase modulate said pilot tone in a predetermined pattern to produce a spread spectrum pilot tone; and
e) a transmitter associated with said platform and arranged to transmit said translated GPS signal and said spread spectrum pilot tone.
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Abstract
A translator for translating GPS signals received at one location to a different frequency for ground transmission to another location uses a spread spectrum pilot tone for phase-locking the local oscillator of the ground transmitter to that of the ground receiver, thereby increasing security, enabling use of otherwise unavailable frequency spectra, allowing coherence of pilot tone and GPS signal with small coherence bandwidths, and allowing interference-free transmission of the translated GPS signal and pilot tone with the same center frequency.
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Citations
10 Claims
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1. A translator for translating Global Positioning System (GPS) signals received by a platform for retransmission to a base station, comprising:
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a) apparatus adapted to receive a raw GPS signal, said raw GPS signal being a spread spectrum signal with a first center frequency; b) translating circuitry arranged to translate said raw GPS signal into a translated GPS signal with a different center frequency, said translating circuitry including a local oscillator whose output, when mixed with said raw GPS signal, produces said translated GPS signal; c) a pilot tone generator connected to said translating circuitry and arranged to generate a pilot tone phase-locked to said local oscillator output; d) modulating circuitry operatively connected to said pilot tone generator and arranged to phase modulate said pilot tone in a predetermined pattern to produce a spread spectrum pilot tone; and e) a transmitter associated with said platform and arranged to transmit said translated GPS signal and said spread spectrum pilot tone. - View Dependent Claims (2, 3, 4, 5)
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6. A Global Positioning System (GPS) signal translation apparatus, comprising:
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a) a base station in a known first location; b) at least one platform in a second location unknown to said base station; c) a translator at said platform including; i) apparatus for receiving a raw GPS signal usable for identifying said second location, said raw GPS signal being a spread spectrum signal with a first center frequency; ii) translating circuitry arranged to translate said raw GPS signal into a translated GPS signal with a different center frequency, said translating circuitry including a local oscillator whose output, when mixed with said raw GPS signal, produces said translated GPS signal; iii) a pilot tone generator connected to said translating circuitry and arranged to generate a pilot tone phase-locked to said local oscillator output; iv) modulating circuitry operatively connected to said pilot tone generator and arranged to phase shift said pilot tone in a predetermined pattern to produce a spread spectrum pilot tone; and d) a transmitter associated with said second location and arranged to transmit said translated GPS signal and said spread spectrum pilot tone. - View Dependent Claims (7)
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8. A method for translating Global Positioning System (GPS) signals received by a platform for transmission to a base station, said method comprising the steps of:
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a) receiving a raw GPS signal, said raw GPS signal being a spread spectrum signal with a first center frequency; b) translating said raw GPS signal into a translated GPS signal with a different center frequency, said translating circuitry including a local oscillator whose output, when mixed with said raw GPS signal, produces said translated GPS signal; c) generating a pilot tone phase-locked to said local oscillator output; d) changing the phase of said pilot tone in a predetermined pattern to produce a spread spectrum pilot tone; and e) transmitting said translated GPS signal and said spread spectrum pilot tone. - View Dependent Claims (9, 10)
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Specification