Method of transmitting and receiving data, system and receiver therefor
First Claim
Patent Images
1. A method of transmitting and receiving data, the method comprising the steps of:
- transmitting a narrow band data signal at an unknown-frequency-within a known range of frequencies;
receiving the data signal within the known range of frequencies;
dividing at a receiver the range of frequencies into plural frequency bands each of width less than the uncertainty in the transmission frequency of the data signal;
detecting the presence of said data signal in at least one of said frequency bands; and
demodulating the detected data signal, wherein the demodulating step includes the step of centering at least one narrow band filter on the detected signal frequency bands and wherein the time of data signals in the narrow frequency bands is determined in the detection step and used in the demodulation step.
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Abstract
A method and apparatus for transmitting and receiving data, wherein a narrow band data signal is transmitted at an unknown frequency within a known range of frequencies and received, and, at the receiver, the range of frequencies is divided into plural frequency bands each of width less than the uncertainty in the transmission frequency of the data signal, with the presence of said data signal detected in at least one of said frequency bands and thereupon demodulated.
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Citations
43 Claims
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1. A method of transmitting and receiving data, the method comprising the steps of:
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transmitting a narrow band data signal at an unknown-frequency-within a known range of frequencies;
receiving the data signal within the known range of frequencies;
dividing at a receiver the range of frequencies into plural frequency bands each of width less than the uncertainty in the transmission frequency of the data signal;
detecting the presence of said data signal in at least one of said frequency bands; and
demodulating the detected data signal, wherein the demodulating step includes the step of centering at least one narrow band filter on the detected signal frequency bands and wherein the time of data signals in the narrow frequency bands is determined in the detection step and used in the demodulation step. - View Dependent Claims (2, 3, 4, 5, 19, 33)
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6. A method of transmitting and receiving data, the method comprising the steps of:
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transmitting a narrow band data signal at an unknown frequency within a known range of frequencies;
receiving the data signal within the known range of frequencies;
dividing at a receiver the range of frequencies into plural frequency bands each of width less than the uncertainty in the transmission frequency of the data signal;
detecting the presence of said data signal in at least one of said frequency bands; and
,demodulating the detected data signal, wherein the data signal is transmitted as two sub-channels, the detection and demodulation steps being carried out on each sub-channel, the respective demodulated data signals being weighted and summed according to the quality of the signals determined in the detection step. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. Apparatus for transmitting and receiving and demodulating transmissions, the apparatus comprising:
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a transmitter for transmitting a narrow band data signal at an unknown frequency within a known range of frequencies; and
,a receiver for receiving the data signal within the known range of frequencies, the receiver having means for dividing the range of frequencies into plural frequency bands each of width less than the uncertainty in the transmission frequency of the data signal;
means for detecting the presences of said data signal in at least one of said frequency bands; and
means for demodulating the detected data signal, wherein the receiver has detection and demodulation means for detecting and demodulating data signals transmitted in two sub-channels, and further comprising adding means for weighting and summing the respective demodulated data signals according to the quality of the signals determined in the detection steps.- View Dependent Claims (17, 18, 34, 35, 36)
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20. A method of receiving data transmitted as a narrow band data signal at an unknown frequency within a known range of frequencies, the method comprising the steps of:
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receiving the data signal within the known range of frequencies;
dividing at a receiver the range of frequencies into plural frequency bands each of width less that the uncertainty in the transmission frequency of the data signal;
detecting the presence of said data signal in at least one of said frequency bands; and
,demodulating the detected data signal, wherein the transmitted data signal includes a transmitted flag sequence and a “
center-of-gravity”
calculation is performed on the quality values to provide a central frequency and a central time for each flag sequence, the results of the center-of-gravity calculation being utilized during demodulation of the data signal.- View Dependent Claims (37, 38, 42, 43)
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21. A method of receiving data transmitted as a narrow band data signal at an unknown frequency within a known range of frequencies, the method comprising the steps of:
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receiving the data signal within the known range of frequencies;
dividing at a receiver the range of frequencies into plural frequency bands each of width less that the uncertainty in the transmission frequency of the data signal;
detecting the presence of said data signal in at least one of said frequency bands; and
,demodulating the detected data signal, wherein the data signal is transmitted as two sub-channels, the detection and demodulation steps being carried out on each sub-channel, the respective demodulated data signals being weighted and summed according to the quality of the signals determined in the detection step. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A receiver for receiving and demodulating a narrow band data signal transmitted at an unknown frequency within a known range of frequencies, the receiver comprising:
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means for dividing the range of frequencies into plural frequency bands each of width less than the uncertainty in the transmission frequency of the data signal;
means for detecting the presence of said data signal in at least one of said frequency bands; and
,means for demodulating the detected data signal.
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32. A receiver for receiving and demodulating a narrow band data signal transmitted at an unknown frequency within a known range of frequencies, the receiver comprising:
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means for dividing the range of frequencies into plural frequency bands each of width less than the uncertainty in the transmission frequency of the data signal;
means for detecting the presence of said data signal in at least one of said frequency bands; and
,means for demodulating the detected data signal, and comprising detection and demodulation means for detecting and demodulating data signals transmitted in two sub-channels, and further comprising adding means for weighting and summing the respective demodulated data signals according to the quality of the signals determined in the detection steps. - View Dependent Claims (39, 40, 41)
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Specification