Position fixing system
First Claim
1. A method of producing an ultra-wideband signal comprising:
- modulating a carrier signal by a spreading waveform which is a periodic deterministic wideband signal to generate a carrier frequency;
changing the carrier frequency by a predetermined amount at a predetermined interval to generate a predetermined amount of frequency change, wherein a reciprocal of the predetermined interval is a corresponding frequency hopping rate;
wherein there is a harmonic relationship between the carrier frequency configured to be transmitted, the predetermined amount of frequency change configured to be transmitted, and a period of the spreading waveform configured to be transmitted, so that a deterministic ultra-wideband signal having the harmonic relationship is configured to be transmitted.
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Accused Products
Abstract
In a first aspect the present invention provides a method of producing an ultra wide band signal in which a carrier signal is modulated by a spreading waveform which is a periodic deterministic wideband signal and the frequency of the carrier signal is changed by a predetermined amount at predetermined intervals (the reciprocal of this interval being the hopping rate), wherein there is a harmonic relationship between the carrier frequency, the predetermined amount of frequency change, and the period of the spreading waveform. In this way, an ultra wide band signal is created using both direct sequence and frequency hopping techniques and the signal so created may be detected using a coherent detector at a receiver. This provides a wide bandwidth signal, or even an ultra wide bandwidth (UWB) signal which mitigates the problems of multi-path signals (through coherent combining across a wide bandwidth) and also interference.
50 Citations
25 Claims
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1. A method of producing an ultra-wideband signal comprising:
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modulating a carrier signal by a spreading waveform which is a periodic deterministic wideband signal to generate a carrier frequency; changing the carrier frequency by a predetermined amount at a predetermined interval to generate a predetermined amount of frequency change, wherein a reciprocal of the predetermined interval is a corresponding frequency hopping rate; wherein there is a harmonic relationship between the carrier frequency configured to be transmitted, the predetermined amount of frequency change configured to be transmitted, and a period of the spreading waveform configured to be transmitted, so that a deterministic ultra-wideband signal having the harmonic relationship is configured to be transmitted. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for producing an ultra-wideband signal comprising:
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a modulator configured to modulate a carrier signal by a spreading waveform which is a periodic deterministic wideband signal generating a carrier frequency; and a frequency changing device configured to change the carrier frequency by a predetermined amount at a predetermined interval to generate a predetermined amount of frequency change, wherein a reciprocal of the predetermined interval is a corresponding frequency hopping rate, wherein there is a harmonic relationship between the carrier frequency configured to be transmitted, the predetermined amount of frequency change configured to be transmitted, and a period of the spreading waveform configured to be transmitted, so that a deterministic ultra-wideband signal having the harmonic relationship is configured to be transmitted. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. Apparatus for receiving a signal comprising:
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a demodulator configured to demodulate a deterministic ultra-wideband signal having a harmonic relationship between a transmitted carrier signal, a predetermined amount of transmitted frequency change, and a period of a transmitted spreading waveform, wherein the transmitted carrier signal is modulated by the transmitted spreading waveform which is a periodic deterministic wideband signal; and a synchronizer configured to synchronize a local oscillator to match a frequency of the carrier which changes by a predetermined amount at a predetermined interval to generate a predetermined amount of frequency change, wherein a reciprocal of the predetermined interval is the hopping rate; and a frequency changing device configured to change a carrier frequency of the local oscillator to predetermined values. - View Dependent Claims (22, 23)
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24. An apparatus for producing deterministic ultra-wideband signal comprising:
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modulating means for modulating a carrier signal by a spreading waveform which is a periodic deterministic wideband signal generating a carrier frequency; and means for changing the carrier frequency by a predetermined amount at a predetermined interval to generate a predetermined amount of frequency change, wherein a reciprocal of the predetermined interval is a corresponding frequency hopping rate, wherein there is a harmonic relationship between the carrier frequency configured to be transmitted, the predetermined amount of frequency change configured to be transmitted, and a period of the spreading waveform configured to be transmitted, so that the deterministic ultra-wideband signal having the harmonic relationship is configured to be transmitted.
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25. Apparatus for receiving a signal comprising:
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a means for demodulating a deterministic ultra-wideband signal having a harmonic relationship between a transmitted carrier signal, a predetermined amount of transmitted frequency change, and a period of a transmitted spreading waveform, wherein the transmitted carrier signal is modulated by the transmitted spreading waveform which is a periodic deterministic wideband signal; and a means for synchronising a local oscillator to match a frequency of the carrier which changes by a predetermined amount at a predetermined interval to generate a predetermined amount of frequency change, wherein a reciprocal of the predetermined interval is the hopping rate; and means for changing a carrier frequency of the local oscillator to predetermined values.
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Specification