2 * Copyright © 2010 Keith Packard <keithp@keithp.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
20 * Sensor data conversion functions
22 package org.altusmetrum.altoslib_11;
26 public class AltosConvert {
28 * Pressure Sensor Model, version 1.1
30 * written by Holly Grimes
32 * Uses the International Standard Atmosphere as described in
33 * "A Quick Derivation relating altitude to air pressure" (version 1.03)
34 * from the Portland State Aerospace Society, except that the atmosphere
35 * is divided into layers with each layer having a different lapse rate.
37 * Lapse rate data for each layer was obtained from Wikipedia on Sept. 1, 2007
38 * at site <http://en.wikipedia.org/wiki/International_Standard_Atmosphere
40 * Height measurements use the local tangent plane. The postive z-direction is up.
42 * All measurements are given in SI units (Kelvin, Pascal, meter, meters/second^2).
43 * The lapse rate is given in Kelvin/meter, the gas constant for air is given
44 * in Joules/(kilogram-Kelvin).
47 public static final double GRAVITATIONAL_ACCELERATION = -9.80665;
48 public static final double AIR_GAS_CONSTANT = 287.053;
49 public static final double NUMBER_OF_LAYERS = 7;
50 public static final double MAXIMUM_ALTITUDE = 84852.0;
51 public static final double MINIMUM_PRESSURE = 0.3734;
52 public static final double LAYER0_BASE_TEMPERATURE = 288.15;
53 public static final double LAYER0_BASE_PRESSURE = 101325;
55 /* lapse rate and base altitude for each layer in the atmosphere */
56 public static final double[] lapse_rate = {
57 -0.0065, 0.0, 0.001, 0.0028, 0.0, -0.0028, -0.002
60 public static final int[] base_altitude = {
61 0, 11000, 20000, 32000, 47000, 51000, 71000
64 /* outputs atmospheric pressure associated with the given altitude.
65 * altitudes are measured with respect to the mean sea level
68 altitude_to_pressure(double altitude)
70 double base_temperature = LAYER0_BASE_TEMPERATURE;
71 double base_pressure = LAYER0_BASE_PRESSURE;
74 double base; /* base for function to determine pressure */
75 double exponent; /* exponent for function to determine pressure */
76 int layer_number; /* identifies layer in the atmosphere */
77 double delta_z; /* difference between two altitudes */
79 if (altitude > MAXIMUM_ALTITUDE) /* FIX ME: use sensor data to improve model */
82 /* calculate the base temperature and pressure for the atmospheric layer
83 associated with the inputted altitude */
84 for(layer_number = 0; layer_number < NUMBER_OF_LAYERS - 1 && altitude > base_altitude[layer_number + 1]; layer_number++) {
85 delta_z = base_altitude[layer_number + 1] - base_altitude[layer_number];
86 if (lapse_rate[layer_number] == 0.0) {
87 exponent = GRAVITATIONAL_ACCELERATION * delta_z
88 / AIR_GAS_CONSTANT / base_temperature;
89 base_pressure *= Math.exp(exponent);
92 base = (lapse_rate[layer_number] * delta_z / base_temperature) + 1.0;
93 exponent = GRAVITATIONAL_ACCELERATION /
94 (AIR_GAS_CONSTANT * lapse_rate[layer_number]);
95 base_pressure *= Math.pow(base, exponent);
97 base_temperature += delta_z * lapse_rate[layer_number];
100 /* calculate the pressure at the inputted altitude */
101 delta_z = altitude - base_altitude[layer_number];
102 if (lapse_rate[layer_number] == 0.0) {
103 exponent = GRAVITATIONAL_ACCELERATION * delta_z
104 / AIR_GAS_CONSTANT / base_temperature;
105 pressure = base_pressure * Math.exp(exponent);
108 base = (lapse_rate[layer_number] * delta_z / base_temperature) + 1.0;
109 exponent = GRAVITATIONAL_ACCELERATION /
110 (AIR_GAS_CONSTANT * lapse_rate[layer_number]);
111 pressure = base_pressure * Math.pow(base, exponent);
118 /* outputs the altitude associated with the given pressure. the altitude
119 returned is measured with respect to the mean sea level */
121 pressure_to_altitude(double pressure)
124 double next_base_temperature = LAYER0_BASE_TEMPERATURE;
125 double next_base_pressure = LAYER0_BASE_PRESSURE;
128 double base_pressure;
129 double base_temperature;
130 double base; /* base for function to determine base pressure of next layer */
131 double exponent; /* exponent for function to determine base pressure
134 int layer_number; /* identifies layer in the atmosphere */
135 int delta_z; /* difference between two altitudes */
137 if (pressure < 0) /* illegal pressure */
139 if (pressure < MINIMUM_PRESSURE) /* FIX ME: use sensor data to improve model */
140 return MAXIMUM_ALTITUDE;
142 /* calculate the base temperature and pressure for the atmospheric layer
143 associated with the inputted pressure. */
147 base_pressure = next_base_pressure;
148 base_temperature = next_base_temperature;
149 delta_z = base_altitude[layer_number + 1] - base_altitude[layer_number];
150 if (lapse_rate[layer_number] == 0.0) {
151 exponent = GRAVITATIONAL_ACCELERATION * delta_z
152 / AIR_GAS_CONSTANT / base_temperature;
153 next_base_pressure *= Math.exp(exponent);
156 base = (lapse_rate[layer_number] * delta_z / base_temperature) + 1.0;
157 exponent = GRAVITATIONAL_ACCELERATION /
158 (AIR_GAS_CONSTANT * lapse_rate[layer_number]);
159 next_base_pressure *= Math.pow(base, exponent);
161 next_base_temperature += delta_z * lapse_rate[layer_number];
163 while(layer_number < NUMBER_OF_LAYERS - 1 && pressure < next_base_pressure);
165 /* calculate the altitude associated with the inputted pressure */
166 if (lapse_rate[layer_number] == 0.0) {
167 coefficient = (AIR_GAS_CONSTANT / GRAVITATIONAL_ACCELERATION)
169 altitude = base_altitude[layer_number]
170 + coefficient * Math.log(pressure / base_pressure);
173 base = pressure / base_pressure;
174 exponent = AIR_GAS_CONSTANT * lapse_rate[layer_number]
175 / GRAVITATIONAL_ACCELERATION;
176 coefficient = base_temperature / lapse_rate[layer_number];
177 altitude = base_altitude[layer_number]
178 + coefficient * (Math.pow(base, exponent) - 1);
185 cc_battery_to_voltage(double battery)
187 return battery / 32767.0 * 5.0;
191 cc_ignitor_to_voltage(double ignite)
193 return ignite / 32767 * 15.0;
197 barometer_to_pressure(double count)
199 return ((count / 16.0) / 2047.0 + 0.095) / 0.009 * 1000.0;
203 thermometer_to_temperature(double thermo)
205 return (thermo - 19791.268) / 32728.0 * 1.25 / 0.00247;
208 static double mega_adc(int raw) {
212 static public double mega_battery_voltage(int v_batt) {
213 if (v_batt != AltosLib.MISSING)
214 return 3.3 * mega_adc(v_batt) * (5.6 + 10.0) / 10.0;
215 return AltosLib.MISSING;
218 static double mega_pyro_voltage(int raw) {
219 if (raw != AltosLib.MISSING)
220 return 3.3 * mega_adc(raw) * (100.0 + 27.0) / 27.0;
221 return AltosLib.MISSING;
224 static double tele_mini_3_adc(int raw) {
228 static public double tele_mini_3_battery_voltage(int v_batt) {
229 if (v_batt != AltosLib.MISSING)
230 return 3.3 * tele_mini_3_adc(v_batt) * (5.6 + 10.0) / 10.0;
231 return AltosLib.MISSING;
234 static double tele_mini_3_pyro_voltage(int raw) {
235 if (raw != AltosLib.MISSING)
236 return 3.3 * tele_mini_3_adc(raw) * (100.0 + 27.0) / 27.0;
237 return AltosLib.MISSING;
240 static double tele_mini_2_voltage(int sensor) {
243 return sensor / 32767.0 * supply * 127/27;
246 static double tele_gps_voltage(int sensor) {
249 return sensor / 32767.0 * supply * (5.6 + 10.0) / 10.0;
252 static double tele_bt_3_battery(int raw) {
253 if (raw == AltosLib.MISSING)
254 return AltosLib.MISSING;
255 return 3.3 * mega_adc(raw) * (5.1 + 10.0) / 10.0;
258 static double easy_mini_voltage(int sensor, int serial) {
260 double diode_offset = 0.0;
262 /* early prototypes had a 3.0V regulator */
266 /* Purple v1.0 boards had the sensor after the
267 * blocking diode, which drops about 150mV
270 diode_offset = 0.150;
272 return sensor / 32767.0 * supply * 127/27 + diode_offset;
275 public static double radio_to_frequency(int freq, int setting, int cal, int channel) {
283 f = 434.550 * setting / cal;
284 /* Round to nearest 50KHz */
285 f = Math.floor (20.0 * f + 0.5) / 20.0;
287 return f + channel * 0.100;
290 public static int radio_frequency_to_setting(double frequency, int cal) {
291 double set = frequency / 434.550 * cal;
293 return (int) Math.floor (set + 0.5);
296 public static int radio_frequency_to_channel(double frequency) {
297 int channel = (int) Math.floor ((frequency - 434.550) / 0.100 + 0.5);
306 public static double radio_channel_to_frequency(int channel) {
307 return 434.550 + channel * 0.100;
310 public static int[] ParseHex(String line) {
311 String[] tokens = line.split("\\s+");
312 int[] array = new int[tokens.length];
314 for (int i = 0; i < tokens.length; i++)
316 array[i] = Integer.parseInt(tokens[i], 16);
317 } catch (NumberFormatException ne) {
323 public static double meters_to_feet(double meters) {
324 return meters * (100 / (2.54 * 12));
327 public static double feet_to_meters(double feet) {
328 return feet * 12 * 2.54 / 100.0;
331 public static double meters_to_miles(double meters) {
332 return meters_to_feet(meters) / 5280;
335 public static double miles_to_meters(double miles) {
336 return feet_to_meters(miles * 5280);
339 public static double meters_to_mph(double mps) {
340 return meters_to_miles(mps) * 3600;
343 public static double mph_to_meters(double mps) {
344 return miles_to_meters(mps) / 3600;
347 public static double mps_to_fps(double mps) {
348 return meters_to_miles(mps) * 5280;
351 public static double fps_to_mps(double mps) {
352 return miles_to_meters(mps) / 5280;
355 public static double meters_to_mach(double meters) {
356 return meters / 343; /* something close to mach at usual rocket sites */
359 public static double meters_to_g(double meters) {
360 return meters / 9.80665;
363 public static double c_to_f(double c) {
367 public static double f_to_c(double c) {
368 return (c - 32) * 5/9;
371 public static double psi_to_pa(double psi) {
372 return psi * 6894.76;
375 public static double pa_to_psi(double pa) {
379 public static double n_to_lb(double n) {
380 return n * 0.22480894;
383 public static double lb_to_n(double lb) {
384 return lb / 0.22480894;
387 public static boolean imperial_units = false;
389 public static AltosDistance distance = new AltosDistance();
391 public static AltosHeight height = new AltosHeight();
393 public static AltosPressure pressure = new AltosPressure();
395 public static AltosForce force = new AltosForce();
397 public static AltosSpeed speed = new AltosSpeed();
399 public static AltosAccel accel = new AltosAccel();
401 public static AltosTemperature temperature = new AltosTemperature();
403 public static AltosOrient orient = new AltosOrient();
405 public static AltosVoltage voltage = new AltosVoltage();
407 public static AltosLatitude latitude = new AltosLatitude();
409 public static AltosLongitude longitude = new AltosLongitude();
411 public static String show_gs(String format, double a) {
413 format = format.concat(" g");
414 return String.format(format, a);
417 public static String say_gs(double a) {
418 return String.format("%6.0 gees", meters_to_g(a));
421 public static int checksum(int[] data, int start, int length) {
423 for (int i = 0; i < length; i++)
424 csum += data[i + start];
428 public static int checksum(List<Byte> data, int start, int length) {
430 for (int i = 0; i < length; i++)
431 csum += data.get(i+start);
435 public static double beep_value_to_freq(int value) {
438 return 1.0/2.0 * (24.0e6/32.0) / (double) value;
441 public static int beep_freq_to_value(double freq) {
444 return (int) Math.floor (1.0/2.0 * (24.0e6/32.0) / freq + 0.5);
447 public static final int BEARING_LONG = 0;
448 public static final int BEARING_SHORT = 1;
449 public static final int BEARING_VOICE = 2;
451 public static String bearing_to_words(int length, double bearing) {
452 String [][] bearing_string = {
454 "North", "North North East", "North East", "East North East",
455 "East", "East South East", "South East", "South South East",
456 "South", "South South West", "South West", "West South West",
457 "West", "West North West", "North West", "North North West"
459 "N", "NNE", "NE", "ENE",
460 "E", "ESE", "SE", "SSE",
461 "S", "SSW", "SW", "WSW",
462 "W", "WNW", "NW", "NNW"
464 "north", "nor nor east", "north east", "east nor east",
465 "east", "east sow east", "south east", "sow sow east",
466 "south", "sow sow west", "south west", "west sow west",
467 "west", "west nor west", "north west", "nor nor west "
470 return bearing_string[length][(int)((bearing / 90 * 8 + 1) / 2)%16];