Positioning system
First Claim
1. A positioning system comprising a transmitter configured to transmit a transmission including positioning data, wherein the system is configured to substantially synchronise the transmission with a reference time, and wherein the transmission is formed using a repeating pseudorandom number (PRN) code comprising a plurality of chips, andthe system is configured to determine a timing bias between the transmission and the reference time, whereinthe system is configured to change the number of chips in said transmission such that the timing bias of a subsequent pseudorandom number (PRN) code is reduced.
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Accused Products
Abstract
A positioning system (1) comprising one or more transmitters configured to transmit transmissions including positioning data, wherein the system is configured to synchronize the transmission with a reference time. The transmissions are formed using a repeating pseudorandom number (PRN) code comprising a plurality of chips. The system (1) is configured to determine a timing bias (44;54) between the first transmission and the reference time. The system (1) is configured to change the number of chips in one or more of said transmissions such that the timing bias of a subsequent pseudorandom number (PRN) code is reduced.
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Citations
15 Claims
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1. A positioning system comprising a transmitter configured to transmit a transmission including positioning data, wherein the system is configured to substantially synchronise the transmission with a reference time, and wherein the transmission is formed using a repeating pseudorandom number (PRN) code comprising a plurality of chips, and
the system is configured to determine a timing bias between the transmission and the reference time, wherein the system is configured to change the number of chips in said transmission such that the timing bias of a subsequent pseudorandom number (PRN) code is reduced.
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10. A method of synchronising a transmission with a reference time in a positioning system, wherein the transmission is formed using a repeating pseudorandom number (PRN) code comprising a plurality of chips,
determining a timing bias between the transmission and the reference time, changing the number of chips in the transmission such that the timing bias of a subsequent pseudorandom number (PRN) code is reduced.
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11. A positioning system comprising a transmitter configured to transmit one or more clock terms of a first clock relative to a reference time,
wherein the clock terms include a drift term specifying rate of change of a timing bias between said first clock and said reference time; -
wherein said drift term is calculated from a recently determined drift and a previous value of the drift term; wherein the system is configured to transmit a modified drift term applicable for a time following a frequency change of the first clock, said modified drift term including an adjustment term based on the predicted frequency change. - View Dependent Claims (12)
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13. A positioning system comprising a transmitter configured to transmit a transmission comprising one or more clock terms of a first clock relative to a reference time,
wherein the clock terms include one or more timing properties defined between said first clock and said reference time; -
wherein the system is configured to change the frequency of the first clock, wherein the system is configured to calculate and transmit clock terms prior to the frequency change, said clock terms relating to a time after the frequency change. - View Dependent Claims (14)
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15. A method of providing positioning data, comprising transmitting one or more clock terms of a first clock, said first clock substantially synchronised with a reference time,
wherein the clock terms include one or more timing properties defined between said first clock and said reference time; changing the frequency of the first clock, calculating and transmitting clock terms prior to the frequency change, wherein said clock terms relate to a time after the frequency change.
Specification