Remote meter reading system

• US 5,959,550 A
• Filed: 10/15/1996
• Issued: 09/28/1999
• Est. Priority Date: 01/08/1996
• Status: Expired due to Fees

• Current Assignee: Advanced Technology Ramar Limited
• Original Assignee: Ramar Technology Ltd. (Advanced Technology Ramar Limited)
• Inventors: Giles, Terence George
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): WONG, ALBERT KANG
• Application Number:
  US08/720,985
• Time in Patent Office: 1,078 Days
• Field of Search: 340/870.02, 340/870.25, 340/870.26, 340/870.18, 340/870.03, 332/103, 375/200, 375/201, 375/206, 455/46, 455/67.1
• US Class Current: 340/870.02
• CPC Class Codes: H02J 13/00022 using wireless data transmission
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 40/126 using wireless data transmission

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.

Claims

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.

2. The remote meter reading system according to claim 1, wherein the phase modulator is using a pseudo-random code that has zero DC component.

3. The remote meter reading system according to claim 1, including a receiver comprising:

means for receiving the transmitted spread spectrum signal and a squaring means.

4. The remote meter reading system according to claim 3, wherein the means for receiving the transmitted spread spectrum signal comprises:

a first mixer connected to an antenna;

a first oscillator providing an input signal to the first mixer; and

a first filter connected to the first mixer output and to the squaring means input.

5. The remote meter reading system of claim 4, including a narrow band receiver having:

a second mixer connected to the squaring means output, a second oscillator providing an input signal to the second mixer and an output filter.

6. A transponder for use in a remote meter reading system, comprising:

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.