Small wording changes
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@ -113,7 +113,7 @@ A specific issue to be aware of is *switch bounce*, which typically is seen as a
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<img src="img/CurrentDt_With_Lots_Of_Bounce.jpg" width="700">
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As this example scatterplot curve shows, you can vaguely recognize the typical rowing curve in the measurements between 0.02 and 0.08 seconds. However, you also see a lot of very small spikes where the measurements are below 0.01 seconds. Actually there are so many spikes that it masks the real signal completely for Open Rowing Monitor. It contains sections where the time between pulses is 0,00009 seconds, which would mean that the flywheel would be spinning at 120.000 RPM, which physically is impossible for a simple bicycle wheel. This type of scater plot and the underlying data clearly suggests that the sensor picks up the magnet twice or more. This is a measurement quality issue that must be adressed.
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As this example scatterplot curve shows, you can vaguely recognize the typical rowing curve in the measurements between 0.02 and 0.08 seconds. However, you also see a lot of very small spikes where the measurements are below 0.01 seconds. Actually there are so many spikes that it masks the real signal completely for Open Rowing Monitor. It contains sections where the time between pulses is 0.0001 seconds, which would mean that the flywheel would be spinning at 120.000 RPM, which physically is impossible for a simple bicycle wheel used in this example. This type of scater plot and the underlying data clearly suggests that the sensor picks up the magnet twice or more. This is a measurement quality issue that must be adressed.
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The preferred solution is to fix the physical underlying cause, this is a better alignment of the magnet or replacing the sensor for a more advanced model that only picks up specific signals. Using smaller but more powerful magnets also tends to help. However, this might not be practical: some flywheels are extremely well-balanced, and moving or replacing magnets might destroy that balance. To fix that type of error, there are two options:
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@ -187,7 +187,7 @@ A good quality curve of the time between impulses (as captured in the raw datafi
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<img src="img/maximumTimeBetweenImpulses.jpg" width="700">
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Here, aside from the startup and spindown, the blue line shows that the impulses typically vary between 0,035 and 0,120 seconds. The red line depicts the *maximumTimeBetweenImpulses*, which is set to 0.120 seconds. When using the raw datafiles, realise that the goal is to distinguish good normal strokes from noise. So at startup it is quite accepted that the flywheel starts too slow to produce valid data during the biggest part of the first drive phase. Also at the end of a session the flywheel should spin down out of valid ranges again. So *maximumTimeBetweenImpulses* could be set lower, sometimes even hitting the "peaks" of the curves, without causing issues in normal use of Open Rowing Monitor (it will add warnings in the logs). Similarily, *minimumTimeBetweenImpulses* could be slightly increased to include some valleys, without causing much issues.
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Here, aside from the startup and spindown, the blue line shows that the impulses typically vary between 0.035 and 0.120 seconds. The red line depicts the *maximumTimeBetweenImpulses*, which is set to 0.120 seconds. When using the raw datafiles, realise that the goal is to distinguish good normal strokes from noise. So at startup it is quite accepted that the flywheel starts too slow to produce valid data during the biggest part of the first drive phase. Also at the end of a session the flywheel should spin down out of valid ranges again. So *maximumTimeBetweenImpulses* could be set lower, sometimes even hitting the "peaks" of the curves, without causing issues in normal use of Open Rowing Monitor (it will add warnings in the logs). Similarily, *minimumTimeBetweenImpulses* could be slightly increased to include some valleys, without causing much issues.
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An important note is that *maximumTimeBetweenImpulses* is also used to detect wether the flywheel is spinning down due to lack of user input. Open Rowing Monitor pauses/stops the row when:
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@ -199,7 +199,7 @@ So setting the value for *maximumTimeBetweenImpulses* too high might block this
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### Review smoothing
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**smoothing** is the ultimate fallback mechanism for rowers with very noisy data. For all known rowers currently maintained by Open Rowing Monitor, **NONE** needed this, so only start working with this when the raw files show you have a very noisy signal, physical measures don't work and you can't get your stroke detection to work with other means (please note that we design the mechanisms here to be robust, so they can take a hit).
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**smoothing** is the ultimate fallback mechanism for rowers with very noisy data. Please refrain from using it, unless as a last resort (typically increasing *flankLength* is more effective and leads to better results). For all known rowers currently maintained by Open Rowing Monitor, **NONE** needed this, so only start working with this when the raw files show you have a very noisy signal, physical measures don't work and you can't get your stroke detection to work with other means (please note that we design the mechanisms here to be robust, so they can take a hit).
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This is a running median filter, effectively killing any extreme values. By default, it is set to 1 (off). A value of 3 will allow it to completely ignore any single extreme values, which should do the trick for most rowers.
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