My 200P does not show readings around zero. Why is this?
For a potentiometer wind direction vane, the range of directions for which the output signal is undefined is called the dead band.
The NRG Systems 200P has a specified (maximum) dead band of 8 degrees which provides a defined electrical range of 4 degrees to 356 degrees for the vane potentiometer.
In the case where dead band compensation is not applied, the electrical range is assumed to be 0 to 359 degrees and the direction data includes associated dead band (range) scaling error. The user will see readings over the full range of 0 to 359 degrees. As readings approach the dead band from either side, scaling error increases and is worst at the edge of the dead band.
In the case where dead band compensation is applied, the electrical range matches the useful range of the vane potentiometer thereby minimizing the dead band error. The highest reported reading would be 356 and the lowest reported reading would be 4 degrees. Any samples in the vane dead band (between 356 and 4) will be logged as 0. The 10-minute average is then calculated using those samples.
In response to industry requests for dead band compensation on wind direction data, Symphonie Data Retriever (SDR) revision 5.10.01 and higher automatically provides dead band compensation on the vane channels for NRG Systems Symphonie loggers with revision 11 and lower. Beginning at Symphonie logger revision 12, the logger will provide the dead band compensation and SDR will not. The compensation cannot be turned off in either the logger or SDR. Now that the vane dead band is being compensated for, you will not see the values 357, 358, 359, 1, 2, 3 in your data (assuming a vane offset of 0). You may still see values at 0, because averages that are exactly 0 will not be shifted. This is important to remember for those data analysts who generate histograms of vane data exported from SDR. The histograms will now have some bins without data.
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