From 210dbaa23cdacf3a6f2d6e23493e96ee2ac9bca7 Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Thu, 4 Jun 2009 10:41:34 -0700 Subject: Use autotools, move altos to src subdir Signed-off-by: Keith Packard --- make-altitude | 192 ---------------------------------------------------------- 1 file changed, 192 deletions(-) delete mode 100644 make-altitude (limited to 'make-altitude') diff --git a/make-altitude b/make-altitude deleted file mode 100644 index ddfab5fc..00000000 --- a/make-altitude +++ /dev/null @@ -1,192 +0,0 @@ -#!/usr/bin/nickle -f -/* - * Pressure Sensor Model, version 1.1 - * - * written by Holly Grimes - * - * Uses the International Standard Atmosphere as described in - * "A Quick Derivation relating altitude to air pressure" (version 1.03) - * from the Portland State Aerospace Society, except that the atmosphere - * is divided into layers with each layer having a different lapse rate. - * - * Lapse rate data for each layer was obtained from Wikipedia on Sept. 1, 2007 - * at site MAXIMUM_ALTITUDE) /* FIX ME: use sensor data to improve model */ - return 0; - - /* calculate the base temperature and pressure for the atmospheric layer - associated with the inputted altitude */ - for(layer_number = 0; layer_number < NUMBER_OF_LAYERS - 1 && altitude > base_altitude[layer_number + 1]; layer_number++) { - delta_z = base_altitude[layer_number + 1] - base_altitude[layer_number]; - if (lapse_rate[layer_number] == 0.0) { - exponent = GRAVITATIONAL_ACCELERATION * delta_z - / AIR_GAS_CONSTANT / base_temperature; - base_pressure *= exp(exponent); - } - else { - base = (lapse_rate[layer_number] * delta_z / base_temperature) + 1.0; - exponent = GRAVITATIONAL_ACCELERATION / - (AIR_GAS_CONSTANT * lapse_rate[layer_number]); - base_pressure *= pow(base, exponent); - } - base_temperature += delta_z * lapse_rate[layer_number]; - } - - /* calculate the pressure at the inputted altitude */ - delta_z = altitude - base_altitude[layer_number]; - if (lapse_rate[layer_number] == 0.0) { - exponent = GRAVITATIONAL_ACCELERATION * delta_z - / AIR_GAS_CONSTANT / base_temperature; - pressure = base_pressure * exp(exponent); - } - else { - base = (lapse_rate[layer_number] * delta_z / base_temperature) + 1.0; - exponent = GRAVITATIONAL_ACCELERATION / - (AIR_GAS_CONSTANT * lapse_rate[layer_number]); - pressure = base_pressure * pow(base, exponent); - } - - return pressure; -} - - -/* outputs the altitude associated with the given pressure. the altitude - returned is measured with respect to the mean sea level */ -real pressure_to_altitude(real pressure) { - - real next_base_temperature = LAYER0_BASE_TEMPERATURE; - real next_base_pressure = LAYER0_BASE_PRESSURE; - - real altitude; - real base_pressure; - real base_temperature; - real base; /* base for function to determine base pressure of next layer */ - real exponent; /* exponent for function to determine base pressure - of next layer */ - real coefficient; - int layer_number; /* identifies layer in the atmosphere */ - int delta_z; /* difference between two altitudes */ - - if (pressure < 0) /* illegal pressure */ - return -1; - if (pressure < MINIMUM_PRESSURE) /* FIX ME: use sensor data to improve model */ - return MAXIMUM_ALTITUDE; - - /* calculate the base temperature and pressure for the atmospheric layer - associated with the inputted pressure. */ - layer_number = -1; - do { - layer_number++; - base_pressure = next_base_pressure; - base_temperature = next_base_temperature; - delta_z = base_altitude[layer_number + 1] - base_altitude[layer_number]; - if (lapse_rate[layer_number] == 0.0) { - exponent = GRAVITATIONAL_ACCELERATION * delta_z - / AIR_GAS_CONSTANT / base_temperature; - next_base_pressure *= exp(exponent); - } - else { - base = (lapse_rate[layer_number] * delta_z / base_temperature) + 1.0; - exponent = GRAVITATIONAL_ACCELERATION / - (AIR_GAS_CONSTANT * lapse_rate[layer_number]); - next_base_pressure *= pow(base, exponent); - } - next_base_temperature += delta_z * lapse_rate[layer_number]; - } - while(layer_number < NUMBER_OF_LAYERS - 1 && pressure < next_base_pressure); - - /* calculate the altitude associated with the inputted pressure */ - if (lapse_rate[layer_number] == 0.0) { - coefficient = (AIR_GAS_CONSTANT / GRAVITATIONAL_ACCELERATION) - * base_temperature; - altitude = base_altitude[layer_number] - + coefficient * log(pressure / base_pressure); - } - else { - base = pressure / base_pressure; - exponent = AIR_GAS_CONSTANT * lapse_rate[layer_number] - / GRAVITATIONAL_ACCELERATION; - coefficient = base_temperature / lapse_rate[layer_number]; - altitude = base_altitude[layer_number] - + coefficient * (pow(base, exponent) - 1); - } - - return altitude; -} - -real feet_to_meters(real feet) -{ - return feet * (12 * 2.54 / 100); -} - -real meters_to_feet(real meters) -{ - return meters / (12 * 2.54 / 100); -} - -/* - * Values for our MP3H6115A pressure sensor - * - * From the data sheet: - * - * Pressure range: 15-115 kPa - * Voltage at 115kPa: 2.82 - * Output scale: 27mV/kPa - * - * - * 27 mV/kPa * 2047 / 3300 counts/mV = 16.75 counts/kPa - * 2.82V * 2047 / 3.3 counts/V = 1749 counts/115 kPa - */ - -real counts_per_kPa = 27 * 2047 / 3300; -real counts_at_101_3kPa = 1674; - -real count_to_kPa(real count) -{ - return (count / 2047 + 0.095) / 0.009; -} - -for (real count = 0; count <= 2047; count++) { - real kPa = count_to_kPa(count); - real meters = pressure_to_altitude(kPa * 1000); - printf (" %d, /* %6.2g kPa %d count */\n", - floor (meters + 0.5), kPa, count); -} -- cgit v1.2.3