Remote meter reading system
First Claim
Patent Images
1. A remote meter reading system, comprising:
- means for collecting data from meters;
means for providing a carrier signal;
means for frequency modulating the carrier signal with the data to produce a first signal;
a phase modulator for receiving the first signal and producing an output signal in which the carrier signal frequency is suppressed; and
a transmitter for transmitting the output signal to a receiver.
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Abstract
A remote meter reading system uses transponders adapted to transmit a spread spectrum signal which is generated by frequency modulating data with a carrier signal. The resulting output signal is then spread by phase modulating with a pseudo-random code signal before transmission with the carrier suppressed. At the receiver, the original suppressed carrier is regenerated by squaring a first IF signal and then applying the output signal to a narrow band receiver from which the data can be recovered with a conventional FM discriminator.
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Citations
6 Claims
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1. A remote meter reading system, comprising:
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means for collecting data from meters; means for providing a carrier signal; means for frequency modulating the carrier signal with the data to produce a first signal; a phase modulator for receiving the first signal and producing an output signal in which the carrier signal frequency is suppressed; and a transmitter for transmitting the output signal to a receiver. - View Dependent Claims (2, 3, 4, 5)
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6. A transponder for use in a remote meter reading system, comprising:
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means for frequency modulating a carrier signal with data to produce a first signal; means for phase modulating the first signal with a pseudo random code to produce an output signal in which the carrier frequency is suppressed; and means for transmitting the output of the phase modulating means.
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Specification