Data transmission system employing a harmonic transponder including means for varying phase in response to surrounding conditions

• US 3,911,434 A
• Filed: 02/12/1973
• Issued: 10/07/1975
• Est. Priority Date: 02/12/1973
• Status: Expired due to Term

• Current Assignee: Edward J. Cook
• Original Assignee: Edward J. Cook
• Inventors: Cook, Edward J.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Montone, G. E.
• Application Number:
  US05/331,837
• Time in Patent Office: 967 Days
• Field of Search: 343/6.5R,6.5CC,6.5SS,6.8R,6.8LC 340/58 73/146.5
• US Class Current: 342/50
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: G08C 19/12 in which the signal transmitted is frequency or phase of ac

Abstract

A telemetry system is provided wherein a passive transponder, requiring no internal power source, may be located remotely from a transmitter and receiving station and return information with respect to a remote condition. A central station transmits a signal to the transponder, which includes a transducer such as a pressure or temperature responsive device adapted to electronically alter the transmitted signal at the transducer by generating a harmonic of the carrier and varying the phase of the harmonic. The original signal is thus encoded at the transducer and is reflected back to the receiver where the signals are processed to separate and display the encoded data. The system may be used on vehicles to monitor tire pressure.

Claims

1. A data transmission system, comprising a. a transmitter adapted to generate and transmit an original radio frequency carrier signal in the form of a sine wave of a first frequency, b. a non-linear passive transponder remotely located from said transmitter for receiving said carrier signal, encoding information thereon and reflecting an encoded signal at a second frequency, and, c. a receiver located remotely from said transponder for receiving said encoded signal at said second frequency said receiver including synchronous detection circuit means for decoding said information from said encoded signal, the distance between said transponder and transmitter being less that the wavelength of said signal, d. said transponder including a transducer responsive to a physical condition, e. said transponder including signal encoding circuitry operatively connected to said transducer for altering said carrier signal in accordance with changes in said condition, f. said signal encoding circuitry including passive harmonic generating means including a rectifier adapted to generate at least one harmonic of said carrier signal and phase varying means responsive to said transducer for varying the phase of the harmonic, g. said transponder including an inductance and a double pole, three-position switch for connecting said rectifier to said inductance in one of two polar positions and for disconnecting said rectifier from said inductance and said transducer includes pressure responsive means operatively connected to said switch for selectively actuating said switch in response to said change.

2. A data transmitter according to claim 1 including means for generating and transmitting a plurality of discrete frequencies.

3. A data transmission system according to claim 1 wherein said transducer is pressure responsive.

4. A data transmission system according to claim 1 wherein said tranducer is temperature responsive.

5. A data transmission system according to claim 1 wherein said transducer includes a movable member responsive to changes in pressure.

6. A data transmission system according to claim 3 wherein said transponder is mounted to a pneumatic tire and is responsive to changes in tire pressure.

7. A data transmission system according to claim 1 wherein said transmitter is mounted to a vehicle equipped with wheelmounted pneumatic tires and at least one said transponder is mounted to at least one of said wheels and is responsive to changes in tire pressure.

8. A data transmission system, comprising a. a transmitter adapted to generate and transmit an original radio frequency carrier signal at a first frequency in the form of a sine wave of a predetermined wavelength, b. a non-linear passive transponder remotely located from said transmitter for receiving said carrier signal, encoding information thereon and reflecting an encoded signal at a second freqeuncy, and c. a receiver located remotely from said transponder for receiving said encoded signal at said second frequency, said receiver including synchronous detection circuit means for decoding said information from said encoded signal, the distance between said transponder and receiver being less than said wavelength, d. said transponder including a transducer responsive to a physical condition, e. said transponder including signal encoding circuitry operatively connected to said transducer for altering said carrier signal in accordance with changes in said condition, f. said signal encoding circuitry including passive harmonic generating means including a rectifier adapted to generate at least one harmonic of said carrier signal and phase varying means responsive to said transducer for varying the phase of the harmonic, g. said transponder including rectifying means, inductance means and capacitance means connected in parallel, at least one of said inductance and capacitance means being variable and said transducer including pressure responsive means connected to the variable means for selectively changing the variable means in response to changes in pressure.

9. A data transmission system according to claim 8 wherein said transmitter is mounted to a vehicle equipped with wheel-mounted pneumatic tires and at least one said transponder is mounted to at least one of said wheels in communication with the tire mounted thereon and responsive to changes in tire pressure.

10. A data transmission system for monitoring the pressure in pneumatic tires mounted on wheels of a vehicle, comprising a. a transmitter mounted in fixed position on said vehicle and adapted to generate and transmit an original radio frequency carrier signal of a predetermined frequency in the form of a sine wave, b. a passive transponder mounted to at least one wheel of said vehicle for receiving said carrier signal, encoding tire pressure information thereon and reflecting an encoded signal at a harmonic of said frequency, and, c. a receiver mounted in fixed position on said vehicle for receiving said encoded signal at said harmonic, said receiver including decoding circuit means for decoding said tire pressure information from said encoded signal, d. said transponder including a pressure transducer communicating with the interior of said tire and responsive to changes in tire pressure, e. said transponder including signal encoding circuitry operatively connected to said transducer for altering said carrier signal in accordance with changes in said condition, f. said signal encoding circuitry including passive harmonic generating means adapted to generate at least one harmonic of said carrier signal and phase varying means including variable non-linear rectifying means responsive to said transducer for varying the phase of the harmonic.