Advanced J-Filter Test Case


System Installation Notes

Customer: Potash Corporation of Saskatchewan
System Type: FlowTrax Drift System (v3.39DRFN)
Sensor face to face distance: 14.466 meters (47.46 feet)
Sensor Baseline distance: 9.629 meters (31.59 feet)
Drift Area: 32.65 m² (1153.02 ft²)
Expected flow rate: 130 m³/s

Regular Filtering Technic

Using the standard (default) filtering and detection method for high turbulent applications, the instrument is unable to detect the 50KHz ultrasonic signal pulse. This can be seen by the red line and red arrow. The instrument here in red has detected a false signal pulse and is processing a wrong time of flight. Repeated bidirectional ultrasonic signal pulse is required to accurately measure air velocity. Based on difficult turbulent application, we have developed a J-Filter technologies which provides a method of eliminating false signal pulse which causes uncertainty in processing the time of flight measurement; showing an error mode.

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J Filtering Technic – Signal Pulse Profiling

Using the advanced J filtering and detection method (available in the advanced menu), the device is able to detect the ultrasonic signal pulse much more reliably. The red line and red arrow indicates what the device is detecting as a valid ultrasonic signal. The upstream vs the downstream as shown before now provide a clear differential in time, which is required to accurately measure air velocity. The filter has identified the signal pulse and discarded the high level of ultrasonic noise in the same frequency range.

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Readings on day of J filter test:

At 2:56 pm, the unit was reading between 127-129 m³/s.
At 3:00 pm, the unit was reading between 132-134 m³/s.
From the anemometer reading the customer took they were getting 253,000 cfm, so approximately 120 m³/s, through the drift.

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