Spread spectrum communication system
First Claim
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1. A communications system for transmitting to at least one receiving location selected information at selected times from at least one of a plurality of different transmitting location remote from said receiving location, said system comprising:
- a plurality of transmitter means each located at a corresponding one of said transmitting locations and each being capable of transmitting electromagnetic radiation in any of a succession large time units (12) initiated by a corresponding initiating event;
with that electromagnetic radiation transmitted in each said large time unit in said succession thereof having frequencies of said electromagnetic radiation in a selected bandwidth about a corresponding one of a plurality of available carrier frequencies,said plurality of transmitter means each being capable of modulating a carrier signal transmitted thereby to result in said electromagnetic radiation being transmitted during those corresponding said large time units in said succession thereof (10) such that;
said succession has a plurality of preamble time durations (12A . . . 20A) provided therein separated from a succeeding one of said preambles by a corresponding information time durations (26A . . . I) in a multiplicity of said pluralities of information time durations (12B) which preamble and separating plurality of information time durations comprise one said large time unit (12);
each of said carrier signals which occur during a corresponding preamble time duration are of a different frequency value in said plurality thereof from those of said carrier signals occurring in each other said preamble time duration in said succession of time durations;
said succession of time durations; and
each said carrier signal is modulated by an acquisition signal, such carrier signal occurring during a corresponding said information time duration being modulated by a selected data signal after modulation of said corresponding preamble; and
a receiver means located at said receiving location and being capable of receiving said electromagnetic radiation substantially reaching it which has been transmitted means, said receiver means being;
capable of determining, during each of a succession of scan time durations (1, 2, 3, 4, 5;
) shorter in tim than said preamble time duration, whether any received electromagnetic radiation detectable by said receiver means is at least a portion of one of said preamble time duration signals;
capable of recovering, through demodulating that received signal with differing ones of a plurality of demodulating signals each having a frequency based on a corresponding one of said carrier frequencies until electromagnetic radiation transmitted from one of said transmitter means detects an initial acquisition preamble time duration signal;
thereafter continuing to detect electromagnetic radiation from said one of said transmitter means and demodulating said receiving signal with said demodulating signals during such time as remains in said initial acquisition preamble time duration signal and with recovered signals occurring; and
then during that plurality of information time durations immediately following, receiving each recovered information time duration signal having a carrier frequency being demodulated based on a corresponding one of said plurality of carrier frequencies to recover data from said plurality of information time duration signals.
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Abstract
A spread spectrum communication system having a plurality of transmitters at remote locations capable of transmitting information to one or more receivers during a plurality of information time durations. A message structure interposing the plurality of information time durations with a plurality of preamble time durations, during which time the receiver detects message transmission, is also provided.
68 Citations
22 Claims
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1. A communications system for transmitting to at least one receiving location selected information at selected times from at least one of a plurality of different transmitting location remote from said receiving location, said system comprising:
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a plurality of transmitter means each located at a corresponding one of said transmitting locations and each being capable of transmitting electromagnetic radiation in any of a succession large time units (12) initiated by a corresponding initiating event;
with that electromagnetic radiation transmitted in each said large time unit in said succession thereof having frequencies of said electromagnetic radiation in a selected bandwidth about a corresponding one of a plurality of available carrier frequencies,said plurality of transmitter means each being capable of modulating a carrier signal transmitted thereby to result in said electromagnetic radiation being transmitted during those corresponding said large time units in said succession thereof (10) such that; said succession has a plurality of preamble time durations (12A . . . 20A) provided therein separated from a succeeding one of said preambles by a corresponding information time durations (26A . . . I) in a multiplicity of said pluralities of information time durations (12B) which preamble and separating plurality of information time durations comprise one said large time unit (12); each of said carrier signals which occur during a corresponding preamble time duration are of a different frequency value in said plurality thereof from those of said carrier signals occurring in each other said preamble time duration in said succession of time durations; said succession of time durations; and
each said carrier signal is modulated by an acquisition signal, such carrier signal occurring during a corresponding said information time duration being modulated by a selected data signal after modulation of said corresponding preamble; anda receiver means located at said receiving location and being capable of receiving said electromagnetic radiation substantially reaching it which has been transmitted means, said receiver means being; capable of determining, during each of a succession of scan time durations (1, 2, 3, 4, 5;
) shorter in tim than said preamble time duration, whether any received electromagnetic radiation detectable by said receiver means is at least a portion of one of said preamble time duration signals;capable of recovering, through demodulating that received signal with differing ones of a plurality of demodulating signals each having a frequency based on a corresponding one of said carrier frequencies until electromagnetic radiation transmitted from one of said transmitter means detects an initial acquisition preamble time duration signal; thereafter continuing to detect electromagnetic radiation from said one of said transmitter means and demodulating said receiving signal with said demodulating signals during such time as remains in said initial acquisition preamble time duration signal and with recovered signals occurring; and then during that plurality of information time durations immediately following, receiving each recovered information time duration signal having a carrier frequency being demodulated based on a corresponding one of said plurality of carrier frequencies to recover data from said plurality of information time duration signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for transmitting to at least one receiving location selected information from at least one of a plurality of different transmitters remote from said receiving location each transmitter capable of transmitting electromagnetic radiation in any of a succession of large time durations, said transmission being initiated by a corresponding initiating event, with that electromagnetic radiation transmitted in each said large time duration in a said succession thereof having frequencies therein in a selected bandwidth about a corresponding one of a plurality of available carrier frequencies each differing from that carrier frequency in said plurality thereof from that carrier frequency used in other said large time durations in said succession thereof;
- said plurality of transmitters each being capable of modulating a carrier signal transmitted thereby to result in transmitting said electromagnetic radiation during those corresponding said large time durations in said succession thereof so that there is a plurality of preamble time durations in said large time durations each separated from its succeeding preamble by a corresponding plurality of information time durations, said carrier signal occurring during a corresponding said preamble time duration being modulated by an acquisition signal and a said carrier signal occurring during a corresponding said information time duration being modulated by a data signal, said method comprising;
scanning through those of said plurality of carrier frequencies used in said preamble time durations, in each of a succession of scan time durations shorter than said preamble time duration, using a receiver means located at said receiving location to determine whether any received electromagnetic radiation detectable as received signals by said receiver means has been transmitted by one of said plurality of transmitter means through determining whether any of said received signals is one from which at least a portion of said acquisition signal can be recovered through demodulating that said received signal with one of a plurality of demodulating signals each having a frequency based on a corresponding one of said carrier frequencies available for use during any of said preamble time durations; sensing occurrence of a said initiating event by an initial one of said plurality of transmitting means; transmitting electromagnetic radiation from said initial transmitting means in an initial large time duration after said initiating event; detecting in said receiver means electromagnetic radiation transmitted from said initial transmitter means during one of said scan time durations and demodulating a received signal obtained therefrom using a corresponding one of said plurality of demodulating signals to recover at least part of said acquisition signal during said acquisition preamble time duration; and detecting in said receiver means electromagnetic radiation transmitted from said initial transmitter means, and demodulating said received signal obtained therefrom during that plurality of information time durations in said initial large time duration immediately following that acquisition preamble time durations using recovery signals each having a frequency based on a corresponding one of said plurality of available carrier frequencies occurring in said information time durations to recover said data signal during said information time durations. - View Dependent Claims (15, 16, 17, 18)
- said plurality of transmitters each being capable of modulating a carrier signal transmitted thereby to result in transmitting said electromagnetic radiation during those corresponding said large time durations in said succession thereof so that there is a plurality of preamble time durations in said large time durations each separated from its succeeding preamble by a corresponding plurality of information time durations, said carrier signal occurring during a corresponding said preamble time duration being modulated by an acquisition signal and a said carrier signal occurring during a corresponding said information time duration being modulated by a data signal, said method comprising;
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19. A communication system for transmission from at least one transmitter to at least one receiver wherein;
each transmitter in said system broadcasts signals in a spread spectrum manner as follows; on the occurrence of an initiating event to said transmitter, broadcasting will occur over a series of large time units, in succession, for each initiating event, said broadcast occurring in a selected bandwidth about a selected carrier frequency for at least one portion of each large time unit in said succession of large time units which carrier frequency is selected substantially uniquely over a range of available carrier frequencies for each said large time unit in said succession. - View Dependent Claims (20, 21, 22)
Specification