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Setting Incremental Smoothing
in GP-HR and GP-MC loggers

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The GP-HR and GP-MC loggers have a damping facility provided on Channel 1, the first analog channel. This is provided specifically for wind direction sensors. A wind direction vane will oscillate from side to side around the true wind direction. For a point reading to be meaningful this osillation needs to be damped out. The GP-HR and GP-MC loggers use a process of Incremental Smoothing to achieve this damping.

To understand incremental smoothing we have to look at how the logger takes readings. The Potentiometer in the Wind Direction sensor is read by an analog to digital converter. This analog to digital converter gives readings of 0 (for 0 deg North) and 65535 (for 360 deg North) and  32767 (for 180 deg South). The logger can smooth the data by limiting the amount the analog to digital converter value can change in a given time period. 

When we setup a logger to read wind direction on channel 1, we can specify the amount of smoothing by entering the amount the analog to digital converter value can change in a 2 second period. 1 degree of change is 65535/360 = 182. If we want to restrict the wind vane change to 1 degree every 2 seconds, we set the Incremental Smoothing value to 182. This is very heavy damping. If we want to restrict the wind vane change to 10 degrees every 2 seconds, we set the Incremental Smoothing value to 1820.

The following table showes the amount of damping provided by the Incremental Smoothing values given.

Damping Degrees
per

2 sec
Incremental
Smoothing
Value
Very Heavily Damped 1 182
  2 364
  3 548
  4 728
Heavily Damped 5 910
  10 1820
  15 2730
Moderatly Damped 20 3640
  30 5460
  40 7280
Lightly Damped 50 9100
  60 10920
  70 12740
  80 14560
Very Lightly Damped 90 16380
No Damping   0

The Incremental Smoothing Value is set on the Omnilog Start Logger Screen.
There is an area at the bottom left of this screen for setting up Smoothing, Wind Speed avarage time and the Averaging Sub Interval.
This can only be changed when the logger is being Started.
It can not be changed while the logger is running.

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