US 6,486,776 B1 · RF transponder and method of measuring parameters associated with a monitored object

Abstract

A radio frequency (RF) transponder (200) capable of measuring parameters associated with an object and transmitting data to an external reader/interrogator (106, 400). In use with a pneumatic tire (104), the transponder measures temperature and pressure within the tire. The transponder includes circuitry (226) for controlling windows of time (WT and WP) during which real-time temperature and pressure measurements are made, and for storing (236) calibration data, transponder ID number and the like, and for transmitting this information in a data stream (FIG. 3C) to the reader/interrogator. An excessive temperature condition may also be sensed (MTMS 218) and included in the data stream. The circuitry of the transponder is preferably implemented on a single IC chip (204), using CMOS technology, with few components external to the IC chip. The transponder is preferably passive, deriving its operating power from an RF signal provided by the exernal reader/interrogator. Data (NT) indicative of temperature and data (NP) indicative of pressure are both transmitted to the reader/interrogator, along with calibration data. A calibration data stored by the transponder and transmitted in the data stream is a slope of NT/NP, or the “ratioed” response of the temperature count divided by the pressure count, which is determined during calibration of the transponder.

Claims20

Dependent claims

A passive RF transponder, including:

an antenna;
a rectifier circuit connected to the antenna to provide electrical power from a RF signal received by the antenna to the other components of the transponder;
a modulator circuit, operatively connected to the antenna to form a RF signal output for the transponder by modulation of the RF signal received by the antenna;
a first parameter sensor for sensing a first parameter;
a second parameter sensor for sensing a second parameter;
a timing generator for generating a first timing window during which the first parameter is measured and a second timing window during which the second parameter is measured;
a first register for capturing first data indicative of the first parameter;
a second register for capturing second data indicative of the second parameter;
and
the modulator circuit impressing the first data as a first portion of a data stream on a signal output by the transponder, and impressing the second data as a second portion of the data stream on the signal output by the transponder;
characterized by:
an oscillator outputting a signal having a first frequency which is indicative of the first parameter during the first timing window, and having a second frequency which is indicative of the second parameter during the second timing window;
and
a register/counter circuit which counts the oscillations of the oscillator signal during the first timing window to capture the first data in the first register, and which counts the oscillations of the oscillator signal during the second timing window to capture the second data in the second register.

11 more elements

Method of measuring at least two parameters associated with a monitored object and outputting a signal, including the steps of:

deriving electrical power from a received RF signal;
measuring a first of the at least two parameters associated with the monitored object;
measuring a second of the at least two parameters associated with the monitored object;
generating a first timing window during which the first parameter is measured and a second timing window during which the second parameter is measured;
capturing first data indicative of the first parameter during the first timing window;
capturing second data indicative of the second parameter during the second timing window;
modulating the received RF signal to form a RF output signal;
impressing the first data as a first portion of a data stream on the RF output signal;
impressing the second data as a second portion of the data stream on the RF output signal;
characterized by:
generating an oscillating signal having a first frequency which is indicative of the first parameter during the first timing window, and having a second frequency which is indicative of the second parameter during the second timing window;
and
counting the oscillations of the oscillating signal during the first timing window to capture the first data, and counting the oscillations of the oscillating signal during the second timing window to capture the second data.

10 more elements

Dependencies are inferred from the claim text.

RF transponder and method of measuring parameters associated with a monitored object

Life of this patent

RF transponder and method of measuring parameters associated with a monitored object

Life of this patent

Abstract

Claims20