Section 6: Meter operation

Reference, Installation, and Operations Manual

June 2013

3-9000-743 Rev S

 

 

Smoothing

The Daniel Mark III Ultrasonic Gas Flow Meter meter introduces a method for smoothing the output (particularly the frequency output) by averaging samples (i.e., waveforms) collected from past batch periods with new samples for the current batch period.

Smoothing can be applied in the following increments: 0 (i.e., smoothing is disabled), 20, 40, 60, or 80%.

For example, setting Smoothing to 20% means that of the samples used for the current update, 20% will be from previously collected samples and 80% will be from the newly collected samples. Thus, if 8 new samples are collected, then those 8 samples along with the last 2 previous samples would be used together for the current update period calculations.

Meters are configured by default for Smoothing of 0% (only new samples are used for the current update period).

6.1.4Acquisition mode

The Mark III meter has two modes of normal operation: Acquisition and Measurement. The Acquisition mode is used to acquire the ultrasonic signals. This mode is entered upon powering up the meter. Once the ultrasonic signals are acquired, the Measurement mode is entered and the flow velocity is measured. The meter remains in the Measurement mode as long as at least one chord is operational. If all chords fail while in the Measurement mode, then the Acquisition mode is re-entered.

The meter operation mode is indicated by the IsAcqMode data point. When TRUE, the meter is in the Acquisition mode; when FALSE, the meter is in the Measurement mode.

The Acquisition mode uses the chords' “L” dimensions (Laird as appropriate to the meter type) and the specified minimum and maximum sound velocities (SSMin and SSMax) to determine the signal search range.

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Acquisition mode