Spread spectrum alignment repositioning method
First Claim
1. A method, using a processor at a receiver, for maintaining synchronization with a transmitter-chip sequence of a spread-spectrum signal transmitted from a transmitter to the receiver, comprising the steps of:
- generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization, a marker, and data, the period for initial synchronization, the marker, and the data, processed with the transmitter-chip sequence;
transmitting, from the transmitter, the spread-spectrum signal using radio waves;
generating, at the receiver, a receiver-chip sequence;
synchronizing, to within one chip time, at the receiver, during the period for initial synchronization, the receiver-chip sequence to the transmitter-chip sequence of the spread-spectrum signal;
detecting, at the receiver, the marker of the transmitted spread-spectrum signal;
initiating, at the receiver, upon detecting the marker of the transmitted spread-spectrum signal, a first reposition delay from the marker;
demodulating, at the receiver, using the receiver-chip sequence, the data from the spread-spectrum signal during the first reposition delay;
realigning, at the receiver, after the first reposition delay, the receiver-chip sequence with the transmitter-chip sequence of the spread-spectrum signal; and
demodulating, at the receiver, the data from the spread-spectrum signal after realigning the receiver-chip sequence.
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Accused Products
Abstract
A method for maintaining spread spectrum chip sequence synchronization, over arbitrary time periods, without the use of traditional closed loop strategies. The technique can be accomplished entirely in software or with the addition of a minimum of electronic components. The receiver periodically forces a chip code reposition optimization to jog the receiver-chip sequence into a high level of synchronization after some period of time in which the receiver'"'"'s chip sequence alignment has run open loop with respect to the transmitter-chip sequence embedded in the received spread-spectrum signal. The reposition technique allows the use of very low cost crystals for the chip sequence generator time base in both receiver and transmitter, and also provides time cues in which to optimize time-of-flight radio position fixes.
147 Citations
58 Claims
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1. A method, using a processor at a receiver, for maintaining synchronization with a transmitter-chip sequence of a spread-spectrum signal transmitted from a transmitter to the receiver, comprising the steps of:
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generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization, a marker, and data, the period for initial synchronization, the marker, and the data, processed with the transmitter-chip sequence; transmitting, from the transmitter, the spread-spectrum signal using radio waves; generating, at the receiver, a receiver-chip sequence; synchronizing, to within one chip time, at the receiver, during the period for initial synchronization, the receiver-chip sequence to the transmitter-chip sequence of the spread-spectrum signal; detecting, at the receiver, the marker of the transmitted spread-spectrum signal; initiating, at the receiver, upon detecting the marker of the transmitted spread-spectrum signal, a first reposition delay from the marker; demodulating, at the receiver, using the receiver-chip sequence, the data from the spread-spectrum signal during the first reposition delay; realigning, at the receiver, after the first reposition delay, the receiver-chip sequence with the transmitter-chip sequence of the spread-spectrum signal; and demodulating, at the receiver, the data from the spread-spectrum signal after realigning the receiver-chip sequence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method using a processor at a receiver, for maintaining synchronization with a transmitter-chip sequence of a spread-spectrum signal transmitted from a transmitter to the receiver, comprising the steps of:
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generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization and a marker, with the period for initial synchronization and the marker processed with the transmitter-chip sequence; transmitting, from the transmitter, the spread-spectrum signal, using radio waves; generating, at the receiver, a receiver-chip sequence; synchronizing, to within one chip time, at the receiver, during the period for initial synchronization, the receiver-chip sequence to the transmitter-chip sequence of the spread-spectrum signal; detecting, at the receiver, an arrival of the marker in the transmitted spread-spectrum signal; and realigning, at the receiver, upon detecting the marker in the transmitted spread-spectrum signal, the receiver-chip sequence with the transmitted-chip sequence of the spread-spectrum signal, within one chip time period. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method, using a processor at a receiver, for maintaining synchronization with a transmitter-chip sequence of a spread-spectrum signal transmitted from a transmitter to the receiver, comprising the steps of:
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generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization, and a marker, with the period for initial synchronization, and the marker, processed with the transmitter-chip sequence; transmitting, from the transmitter, the spread-spectrum signal using radio waves; generating, at the receiver, a receiver-chip sequence; synchronizing, to within one chip time, at the receiver, during the period for initial synchronization, the receiver-chip sequence to the transmitter-chip sequence of the spread-spectrum signal; detecting, at the receiver, an arrival of the marker in the transmitted spread-spectrum signal; and realigning, at the receiver, after a delay from the marker, the receiver-chip sequence with the transmitter-chip sequence in the spread-spectrum signal within one chip time period. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method, using a processor at a receiver, for maintaining synchronization with a transmitter-chip sequence of a spread-spectrum signal transmitted from a transmitter to the receiver, comprising the steps of:
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generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization, and at least one of a plurality of markers and a plurality of dummy bits, with the period for initial synchronization, the plurality of markers, and the plurality of dummy bits processed with the transmitter-chip sequence; determining a maximum time between each of the plurality of markers and the plurality of dummy bits based on at least one of bit error rate and minimal detectable signal; inserting to the spread-spectrum signal at least one of a marker and dummy bits, prior to the determined maximum time; transmitting, from the transmitter, the spread-spectrum signal using radio waves; generating, at the receiver, a receiver-chip sequence; synchronizing, to within one chip time, at the receiver, during the period for initial synchronization, the receiver-chip sequence to the transmitter-chip sequence of the spread-spectrum signal; detecting, at the receiver, at least one of the marker and the dummy bits of the transmitted spread-spectrum signal; and realigning, at the receiver, after detecting at least one of the marker and the dummy bits, the receiver-chip sequence with the transmitter-chip sequence of in the spread-spectrum signal, to within one chip time. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
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38. A method, using a processor at a receiver, for maintaining synchronization with a transmitter-chip sequence of a spread-spectrum signal transmitted from a transmitter to the receiver, comprising the steps of:
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generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization, and data, with the period for initial synchronization, and the data, processed with the transmitter-chip sequence; transmitting, from the transmitter, the spread-spectrum signal using radio waves; generating, at the receiver, a receiver-chip sequence; synchronizing, to within one chip time, at the receiver, during the period for initial synchronization, the receiver-chip sequence to the transmitter-chip sequence of the spread-spectrum signal; demodulating, at the receiver, using the receiver-chip sequence, the data from the spread-spectrum signal during a first predetermined time interval; realigning, at the receiver, after the first predetermined time interval, the receiver-chip sequence with the transmitter-chip sequence of the spread-spectrum signal; and demodulating, at the receiver, the data from the spread-spectrum signal after realigning the receiver-chip sequence. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A method, using a processor at a receiver, for maintaining synchronization with a transmitter-chip sequence of a spread-spectrum signal transmitted from a transmitter to the receiver, comprising the steps of:
- generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization, a marker, and data, the period for initial synchronization, the marker, and the data, processed with the transmitter-chip sequence;
transmitting, from the transmitter, the spread-spectrum signal using radio waves; generating, at the receiver, a receiver-chip sequence; synchronizing, to within one chip time, at the receiver, during the period for initial synchronization, the receiver-chip sequence to the transmitter-chip sequence of the spread-spectrum signal; detecting, at the receiver, the marker of the transmitted spread-spectrum signal; initiating, at the receiver, upon detecting the marker of the transmitted spread-spectrum signal at the receiver, a first reposition delay from the marker; demodulating, at the receiver, using the receiver-chip sequence, the data from the spread-spectrum signal during the first reposition delay; realigning, at the receiver, upon the first reposition delay reaching a predetermined value less than a determined acceptable loss in any of minimal detectable signal and bit error rate, the receiver-chip sequence with the transmitter-chip sequence of the spread-spectrum signal; and demodulating, at the receiver, the data from the spread-spectrum signal after realigning the receiver-chip sequence. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55, 56)
- generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization, a marker, and data, the period for initial synchronization, the marker, and the data, processed with the transmitter-chip sequence;
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57. A method using a processor at a receiver, for obtaining synchronization with a transmitter-chip sequence of a spread-spectrum signal transmitted from a transmitter to the receiver, comprising the steps of:
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generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization and a marker, with the period for initial synchronization and the marker processed with the transmitter-chip sequence; transmitting, from the transmitter, the spread-spectrum signal, using radio waves; generating, at the receiver, a receiver-chip sequence; synchronizing, to within one chip time, at the receiver, during the period for initial synchronization, the receiver-chip sequence to the transmitter-chip sequence of the spread-spectrum signal; detecting, at the receiver, the marker in the transmitted spread-spectrum signal; and measuring, at the receiver, in response to the receiver detecting the marker in the transmitted spread-spectrum signal, at least one of a phase and a time position of receiver-chip sequence alignment to time stamp a known position in the transmitted spread-spectrum signal for reducing effects of time base drift on a time-of-flight radio location system.
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58. A method using a processor at a receiver, for obtaining synchronization with a transmitter-chip sequence of a spread-spectrum signal transmitted from a transmitter to the receiver, comprising the steps of:
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generating, at the transmitter, the spread-spectrum signal, with the spread-spectrum signal having a period for initial synchronization and a marker, with the period for initial synchronization and the marker processed with the transmitter-chip sequence; transmitting, from the transmitter, the spread-spectrum signal, using radio waves; generating, at the receiver, a receiver-chip sequence; synchronizing, to within one chip time, at the receiver, during the period for initial synchronization, the receiver-chip sequence to the transmitter-chip sequence of the spread-spectrum signal; detecting, at the receiver, the marker in the transmitted spread-spectrum signal; realigning, at the receiver, upon detecting the marker in the transmitted spread-spectrum signal, the receiver-chip sequence, with the transmitted-chip sequence of the spread-spectrum signal, within one chip time period; and measuring, at the receiver, in response to the receiver detecting the marker in the transmitted spread-spectrum signal, at least one of a phase and a time position of receiver-chip sequence alignment to time stamp a known position in the transmitted spread-spectrum signal for reducing effects of time base drift on a time-of-flight radio location system.
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Specification