Pivotal Systems Corporation

Sophia Leonidovna Shtilman

Sherk Chung

Paul Tran

Yi Wang

Joseph R Monkowski

Jialing Chen

James MacAllen Chalmers

Paxton Ming Kai Chow

Vera Alexandrova Snowball

Abhijit Majumdar

Chalee Asavathiratham

Barton George Lane, Iii

An in-situ gas flow measurement controller measures the temperature and rate of pressure drop upstream from a flow control device (FCD). The controller samples the pressure and temperature data and applies the equivalent of a decimating filter to the data to produce filtered data at a slower sampling rate. The controller derives timestamps by counting ticks from the sampling clock of the A/D converter that is sampling the pressure at regular intervals to ensure the timestamps associated with the pressure samples are accurate and do not contain jitter that is associated with software clocks. The controller additionally normalizes the temperature reading to account for power supply fluctuations, filters out noise from the pressure and temperature readings, and excludes data during periods of instability. It calculates the gas flow rate accounting for possible non-linearities in the pressure measurements, and provides the computed gas flow measurement via one of many possible interfaces.

Method and apparatus for enhancing in-situ gas flow measurement performance

Embodiments of the present invention relate to managing timestamps associated with received data. According to one embodiment, data is collected from a device that generates data at a specified rate, but which lacks a built-in clock. An accurate timestamp is assigned to the data by first taking an absolute timestamp from a reference clock, and then adding a calculated amount of time to each subsequent data point based on an estimate of the sampling frequency of the device. As the generated timestamp drifts from the actual reference clock time, the sampling frequency is re-estimated based on the amount of detected drift.

Data timestamp management

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Sunnyvale, CA, United States of America

Sophia Leonidovna Shtilman