Process transmitter with orthogonal-polynomial fitting

A transmitter for measuring a process variable, comprising:

• a sensor configured to couple to a process and having a sensor output related to the process variable;
• a polynomial interpolator coupled to the sensor output having an interpolated process variable output which is a polynomial function of the sensor output, wherein terms of the polynomial function are functions of more than one exponential power of the sensor output, wherein the polynomial function reduces power consumption by the polynomial interpolator;
• a transmitter output configured to provide an output on a two-wire process control loop related to the interpolated process variable;
• and
• a power module configured to couple to the two-wire process control loop and completely power the transmitter with power received from the two-wire process control loop.

A method performed by a process transmitter for measuring a process variable of a process, the method comprising:

• sensing a parameter of the process related to the process variable and providing a sensor output related to the process variable;
• approximating the process variable by interpolation using an orthogonal-polynomial applied to the sensor output to obtain an approximated process variable wherein the orthogonal polynomial reduces power consumption required by the approximating step;
• outputting the approximated process variable on a two-wire process control loop;
• and
• completely powering the transmitter with power received from the two-wire process control loop.

A method for measuring a process variable in a process transmitter, comprising:

• sensing a parameter of the process related to the process variable and providing a sensor output related to the process variable;
• approximating the process variable using a polynomial function applied to the sensor output to obtain an approximated process variable, wherein terms of the polynomial function are functions of more than one exponential power of the sensor output wherein the polynomial function reduces power required by the approximating step;
• outputting the approximated process variable on a two-wire wire process control loop;
• and
• completely powering the process transmitter with power received from the two-wire process control loop.

A transmitter for measuring a process variable, comprising:

• sensor means for providing a sensor output related to the process variable;
• a polynomial interpolator means for determining an interpolated process variable as a function of an orthogonal-polynomial used to interpolate data from the sensor output, wherein the orthogonal polynomial reduces power consumption by the polynomial interpolator means;
• an output means for communicating an output related to the interpolated process variable on a two-wire process control loop;
• and
• a power module means for completely powering the transmitter with power from the two-wire process control loop.

A device for monitoring a process, the device measuring a process variable, comprising:

• a sensor configured to couple to a process and having a sensor output related to the process variable;
• a polynomial interpolator coupled to the sensor output having an interpolated process variable output which is a function of an orthogonal-polynomial used to interpolate the sensor output;
• a device output configured to provide an output related to the interpolated process variable;
• and
• wherein the polynomial interpolator performs computations using numerical integers with the orthogonal polynomial to reduce power consumption by the polynomial interpolator.

A device in a process control system for monitoring an industrial process, the device measuring a process variable, comprising:

• a sensor configured to couple to a process and having a sensor output related to the process variable;
• a polynomial interpolator coupled to the sensor output having an interpolated process variable output which is a polynomial function of the sensor output, wherein terms of the polynomial function are functions of more than one exponential power of the sensor output;
• a device output configured to provide an output related to the interpolated process variable;
• and
• wherein the polynomial interpolator performs computations using numerical integers with the polynomial function to reduce power consumption by the polynomial interpolator.