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| Automatic telephone answering device with multiple outgoing messages and selecting means |
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| Secured automated banking facilities |
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| Interface apparatus for communication terminal equipment units |
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| Telephonic voice message transmission control method |
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| Process for analyzing traffic localization within a cellular radiocommunication network |
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| Leaving a message on a held connection |
| FIG. 1 is a system diagram illustrating the operation of applicants' invention in a number of its ... |
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Reciprocal mode saw correlator method and apparatus
| Details |
Inventors: O'Clock, George D.; Vanderpool, Jeffrey S.;
Assignee: Omnipoint Corporation (Colarado Springs, CO)
Primary Examiner: Barron, Jr.; Gilberto
Assistant Examiner:
Attorney, Agent or Firm: Lyon & Lyon
A surface-acoustic-wave correlator for decoding a spread-spectrum signal having a data signal modulated with a plurality of chip sequences and reciprocal-chip sequences. A tapped-delay-line has a plurality of taps defining a tapped-delay-line structure matched to the chip sequence. In response to a plurality of first chips and second chips embedded in the spread-spectrum signal, the tapped-delay line generates TDL-chip sequences and inverse-TDL-chip sequences. A first transducer is acoustically coupled to the tapped-delay-line. In response to the spread-spectrum signal modulated by the chip sequence, the first transducer correlates a first group of the plurality of TDL-chip sequences and inverse-TDL-chip sequences and outputs a first correlation pulse. A second transducer is acoustically coupled to the tapped-delay-line. In response to the spread-spectrum signal modulated by the reciprocal-chip sequence, the second transducer correlates a second group of the plurality of TDL-chip sequences and inverse-TDL-chip sequences and outputs a second correlation pulse. In response to the first' correlation pulse and the second correlation pulse, a decision circuit outputs the first bit and the second bit, respectively. |
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DETAILED DESCRIPTION An object of the invention is to provide a method for demodulating multiple data bits from a phase code sequence with a single tapped-delay-line surface-acoustic-wave correlator.
Another object of the invention is to provide a spread-spectrum receiver requiring no reference code synchronization.
A further object of the invention is to provide spread-spectrum demodulation through the use of single tapped-delay-line SAW correlators which may be manufactured with highly distinctive codes.
Another object of the invention is to provide a spread-spectrum demodulator which provides a lower bandwidth to processing gain ratio and more code variability than a linear FM chirp system.
The BPSK encoded sequence is more robust with respect to bandwidth narrowing and some manufacturing tolerance variations compared with the linear FM chirp waveform.
According to the present invention, as embodied and broadly described herein, a system using a surface-acoustic-wave correlator for decoding a spread-spectrum signal having a data signal modulated with a plurality of chip sequences and reciprocal-chip sequences is provided comprising communications channel, data-sequence-generating means, chip-sequence-generating means, chip-sequence-controlling means, signal means, carrier-modulating means, power means, front-end means, tapped-delay-line means and decision means.
The data-sequence-generating means, chip-sequence-generating means, chip-sequence-controlling means, signal means, carrier-modulating means, power means, front-end means, tapped-delay-line means and decision means may be embodied as a data device, a code generator, a chip-sequence controller, a signal source, a product device, a power device, a receiver-front end, a tapped-delay line and a decision/detector circuit, respectively.
The data device generates a data-bit sequence having first bits and second bits.
The code generator repetitively generates a chip sequence having a plurality of first chips and second chips.
The chip-sequence controller outputs the chip sequence in response to each first bit, and outputs the reciprocal-chip sequence in response to each second bit
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