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rini:speed_log_notes [2009/04/17 04:36] ben |
rini:speed_log_notes [2009/04/17 05:09] ben |
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* Important is display type- black on white is best for sunlight conditions. Backlight also required. Maybe white on blue would work well in sunlight? | * Important is display type- black on white is best for sunlight conditions. Backlight also required. Maybe white on blue would work well in sunlight? | ||
* Important is character support- LARGE NUMBERS are necessary. | * Important is character support- LARGE NUMBERS are necessary. | ||
- | == Basic Functional description == | + | === Basic Functional description === |
* X Buttons for functions Y | * X Buttons for functions Y | ||
* Calibration mode, 1 nautical mile, 1/2 nautical mile | * Calibration mode, 1 nautical mile, 1/2 nautical mile | ||
- | = Calibration method = | ||
* For now it seems that traveling 1 mile and counting the number of transducer clicks will provide an adequate average result | * For now it seems that traveling 1 mile and counting the number of transducer clicks will provide an adequate average result | ||
- | * Once the number of clicks for 1 mile is found, math is 1 n. mile per hour = 1 knot, choose a very small unit of time to count clicks for to allow fast updates of speed calculation (2s?) | + | * Once the number of clicks for 1 n. mile is found, math is Distance in n. mile divided by time in hours = Speed in knots, choose a very small unit of time to count clicks for to allow fast updates of speed calculation (2s?) |
- | * Click count... need to think through the math | + | |
+ | Best I can get this described in ASCII: | ||
+ | <tab><blockquote> | ||
+ | D = distance in nautical miles | ||
+ | |||
+ | T = time in hours | ||
+ | |||
+ | S = speed in knots | ||
+ | |||
+ | D/T = S | ||
+ | |||
+ | X = Number of clicks counted while traveling a calibration mile | ||
+ | |||
+ | Y = Number of clicks counted in a single sample period | ||
+ | |||
+ | Z = Sample period in Seconds | ||
+ | |||
+ | D = Y/X * 1 n.m. | ||
+ | |||
+ | T = Z/3600 | ||
+ | |||
+ | So: (Y/X * 1 n.m.) / (Z/3600) = Speed in knots for the sample period Z | ||
+ | |||
+ | E.G. If we calibrate 1 n.m. at 2500 clicks (X=2500) and our sample/update period is 2 seconds (Z=2), and over that period we count 30 clicks (Y=30), then calculated speed would be (30/2500)/(2/3600) = S = 0.012 / 0.0011 = 1.0909 knots. | ||
+ | </blockquote> | ||
[[http://www.arduino.cc/playground/Code/LCD|Arduino LCD Code notes]] | [[http://www.arduino.cc/playground/Code/LCD|Arduino LCD Code notes]] |