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 public static final double gravity = 9.80665;
31 * Pressure Sensor Model, version 1.1
33 * written by Holly Grimes
35 * Uses the International Standard Atmosphere as described in
36 * "A Quick Derivation relating altitude to air pressure" (version 1.03)
37 * from the Portland State Aerospace Society, except that the atmosphere
38 * is divided into layers with each layer having a different lapse rate.
40 * Lapse rate data for each layer was obtained from Wikipedia on Sept. 1, 2007
41 * at site <http://en.wikipedia.org/wiki/International_Standard_Atmosphere
43 * Height measurements use the local tangent plane. The postive z-direction is up.
45 * All measurements are given in SI units (Kelvin, Pascal, meter, meters/second^2).
46 * The lapse rate is given in Kelvin/meter, the gas constant for air is given
47 * in Joules/(kilogram-Kelvin).
50 private static final double GRAVITATIONAL_ACCELERATION = -gravity;
51 private static final double AIR_GAS_CONSTANT = 287.053;
52 private static final double NUMBER_OF_LAYERS = 7;
53 private static final double MAXIMUM_ALTITUDE = 84852.0;
54 private static final double MINIMUM_PRESSURE = 0.3734;
55 private static final double LAYER0_BASE_TEMPERATURE = 288.15;
56 private static final double LAYER0_BASE_PRESSURE = 101325;
58 /* lapse rate and base altitude for each layer in the atmosphere */
59 private static final double[] lapse_rate = {
60 -0.0065, 0.0, 0.001, 0.0028, 0.0, -0.0028, -0.002
63 private static final int[] base_altitude = {
64 0, 11000, 20000, 32000, 47000, 51000, 71000
67 /* outputs atmospheric pressure associated with the given altitude.
68 * altitudes are measured with respect to the mean sea level
71 altitude_to_pressure(double altitude)
73 double base_temperature = LAYER0_BASE_TEMPERATURE;
74 double base_pressure = LAYER0_BASE_PRESSURE;
77 double base; /* base for function to determine pressure */
78 double exponent; /* exponent for function to determine pressure */
79 int layer_number; /* identifies layer in the atmosphere */
80 double delta_z; /* difference between two altitudes */
82 if (altitude > MAXIMUM_ALTITUDE) /* FIX ME: use sensor data to improve model */
85 /* calculate the base temperature and pressure for the atmospheric layer
86 associated with the inputted altitude */
87 for(layer_number = 0; layer_number < NUMBER_OF_LAYERS - 1 && altitude > base_altitude[layer_number + 1]; layer_number++) {
88 delta_z = base_altitude[layer_number + 1] - base_altitude[layer_number];
89 if (lapse_rate[layer_number] == 0.0) {
90 exponent = GRAVITATIONAL_ACCELERATION * delta_z
91 / AIR_GAS_CONSTANT / base_temperature;
92 base_pressure *= Math.exp(exponent);
95 base = (lapse_rate[layer_number] * delta_z / base_temperature) + 1.0;
96 exponent = GRAVITATIONAL_ACCELERATION /
97 (AIR_GAS_CONSTANT * lapse_rate[layer_number]);
98 base_pressure *= Math.pow(base, exponent);
100 base_temperature += delta_z * lapse_rate[layer_number];
103 /* calculate the pressure at the inputted altitude */
104 delta_z = altitude - base_altitude[layer_number];
105 if (lapse_rate[layer_number] == 0.0) {
106 exponent = GRAVITATIONAL_ACCELERATION * delta_z
107 / AIR_GAS_CONSTANT / base_temperature;
108 pressure = base_pressure * Math.exp(exponent);
111 base = (lapse_rate[layer_number] * delta_z / base_temperature) + 1.0;
112 exponent = GRAVITATIONAL_ACCELERATION /
113 (AIR_GAS_CONSTANT * lapse_rate[layer_number]);
114 pressure = base_pressure * Math.pow(base, exponent);
121 /* outputs the altitude associated with the given pressure. the altitude
122 returned is measured with respect to the mean sea level */
124 pressure_to_altitude(double pressure)
127 double next_base_temperature = LAYER0_BASE_TEMPERATURE;
128 double next_base_pressure = LAYER0_BASE_PRESSURE;
131 double base_pressure;
132 double base_temperature;
133 double base; /* base for function to determine base pressure of next layer */
134 double exponent; /* exponent for function to determine base pressure
137 int layer_number; /* identifies layer in the atmosphere */
138 int delta_z; /* difference between two altitudes */
140 if (pressure < 0) /* illegal pressure */
142 if (pressure < MINIMUM_PRESSURE) /* FIX ME: use sensor data to improve model */
143 return MAXIMUM_ALTITUDE;
145 /* calculate the base temperature and pressure for the atmospheric layer
146 associated with the inputted pressure. */
150 base_pressure = next_base_pressure;
151 base_temperature = next_base_temperature;
152 delta_z = base_altitude[layer_number + 1] - base_altitude[layer_number];
153 if (lapse_rate[layer_number] == 0.0) {
154 exponent = GRAVITATIONAL_ACCELERATION * delta_z
155 / AIR_GAS_CONSTANT / base_temperature;
156 next_base_pressure *= Math.exp(exponent);
159 base = (lapse_rate[layer_number] * delta_z / base_temperature) + 1.0;
160 exponent = GRAVITATIONAL_ACCELERATION /
161 (AIR_GAS_CONSTANT * lapse_rate[layer_number]);
162 next_base_pressure *= Math.pow(base, exponent);
164 next_base_temperature += delta_z * lapse_rate[layer_number];
166 while(layer_number < NUMBER_OF_LAYERS - 1 && pressure < next_base_pressure);
168 /* calculate the altitude associated with the inputted pressure */
169 if (lapse_rate[layer_number] == 0.0) {
170 coefficient = (AIR_GAS_CONSTANT / GRAVITATIONAL_ACCELERATION)
172 altitude = base_altitude[layer_number]
173 + coefficient * Math.log(pressure / base_pressure);
176 base = pressure / base_pressure;
177 exponent = AIR_GAS_CONSTANT * lapse_rate[layer_number]
178 / GRAVITATIONAL_ACCELERATION;
179 coefficient = base_temperature / lapse_rate[layer_number];
180 altitude = base_altitude[layer_number]
181 + coefficient * (Math.pow(base, exponent) - 1);
188 cc_battery_to_voltage(double battery)
190 return battery / 32767.0 * 5.0;
194 cc_ignitor_to_voltage(double ignite)
196 return ignite / 32767 * 15.0;
200 barometer_to_pressure(double count)
202 return ((count / 16.0) / 2047.0 + 0.095) / 0.009 * 1000.0;
206 thermometer_to_temperature(double thermo)
208 return (thermo - 19791.268) / 32728.0 * 1.25 / 0.00247;
211 static double mega_adc(int raw) {
215 static public double mega_battery_voltage(int v_batt) {
216 if (v_batt != AltosLib.MISSING)
217 return 3.3 * mega_adc(v_batt) * (5.6 + 10.0) / 10.0;
218 return AltosLib.MISSING;
221 static double mega_pyro_voltage(int raw) {
222 if (raw != AltosLib.MISSING)
223 return 3.3 * mega_adc(raw) * (100.0 + 27.0) / 27.0;
224 return AltosLib.MISSING;
227 static double tele_mini_3_adc(int raw) {
231 static public double tele_mini_3_battery_voltage(int v_batt) {
232 if (v_batt != AltosLib.MISSING)
233 return 3.3 * tele_mini_3_adc(v_batt) * (5.6 + 10.0) / 10.0;
234 return AltosLib.MISSING;
237 static double tele_mini_3_pyro_voltage(int raw) {
238 if (raw != AltosLib.MISSING)
239 return 3.3 * tele_mini_3_adc(raw) * (100.0 + 27.0) / 27.0;
240 return AltosLib.MISSING;
243 static double tele_mini_2_voltage(int sensor) {
246 return sensor / 32767.0 * supply * 127/27;
249 static double tele_gps_voltage(int sensor) {
252 return sensor / 32767.0 * supply * (5.6 + 10.0) / 10.0;
255 static double tele_bt_3_battery(int raw) {
256 if (raw == AltosLib.MISSING)
257 return AltosLib.MISSING;
258 return 3.3 * mega_adc(raw) * (5.1 + 10.0) / 10.0;
261 static double easy_mini_voltage(int sensor, int serial) {
263 double diode_offset = 0.0;
265 /* early prototypes had a 3.0V regulator */
269 /* Purple v1.0 boards had the sensor after the
270 * blocking diode, which drops about 150mV
273 diode_offset = 0.150;
275 return sensor / 32767.0 * supply * 127/27 + diode_offset;
278 public static double radio_to_frequency(int freq, int setting, int cal, int channel) {
286 f = 434.550 * setting / cal;
287 /* Round to nearest 50KHz */
288 f = Math.floor (20.0 * f + 0.5) / 20.0;
290 return f + channel * 0.100;
293 public static int radio_frequency_to_setting(double frequency, int cal) {
294 double set = frequency / 434.550 * cal;
296 return (int) Math.floor (set + 0.5);
299 public static int radio_frequency_to_channel(double frequency) {
300 int channel = (int) Math.floor ((frequency - 434.550) / 0.100 + 0.5);
309 public static double radio_channel_to_frequency(int channel) {
310 return 434.550 + channel * 0.100;
313 public static int telem_to_rssi(int telem) {
314 return telem / 2 - 74;
317 public static int[] ParseHex(String line) {
318 String[] tokens = line.split("\\s+");
319 int[] array = new int[tokens.length];
321 for (int i = 0; i < tokens.length; i++)
323 array[i] = Integer.parseInt(tokens[i], 16);
324 } catch (NumberFormatException ne) {
330 public static double meters_to_feet(double meters) {
331 return meters * (100 / (2.54 * 12));
334 public static double feet_to_meters(double feet) {
335 return feet * 12 * 2.54 / 100.0;
338 public static double meters_to_miles(double meters) {
339 return meters_to_feet(meters) / 5280;
342 public static double miles_to_meters(double miles) {
343 return feet_to_meters(miles * 5280);
346 public static double meters_to_mph(double mps) {
347 return meters_to_miles(mps) * 3600;
350 public static double mph_to_meters(double mps) {
351 return miles_to_meters(mps) / 3600;
354 public static double mps_to_fps(double mps) {
355 return meters_to_miles(mps) * 5280;
358 public static double fps_to_mps(double mps) {
359 return miles_to_meters(mps) / 5280;
362 public static double meters_to_mach(double meters) {
363 return meters / 343; /* something close to mach at usual rocket sites */
366 public static double meters_to_g(double meters) {
367 return meters / 9.80665;
370 public static double c_to_f(double c) {
374 public static double f_to_c(double c) {
375 return (c - 32) * 5/9;
378 public static double psi_to_pa(double psi) {
379 return psi * 6894.76;
382 public static double pa_to_psi(double pa) {
386 public static double n_to_lb(double n) {
387 return n * 0.22480894;
390 public static double lb_to_n(double lb) {
391 return lb / 0.22480894;
394 public static double acceleration_from_sensor(double sensor, double plus_g, double minus_g, double ground) {
395 if (sensor == AltosLib.MISSING)
396 return AltosLib.MISSING;
398 if (plus_g == AltosLib.MISSING || minus_g == AltosLib.MISSING)
399 return AltosLib.MISSING;
401 if (ground == AltosLib.MISSING)
404 double counts_per_g = (plus_g - minus_g) / 2.0;
405 double counts_per_mss = counts_per_g / gravity;
406 return (sensor - ground) / counts_per_mss;
409 public static boolean imperial_units = false;
411 public static AltosDistance distance = new AltosDistance();
413 public static AltosHeight height = new AltosHeight();
415 public static AltosPressure pressure = new AltosPressure();
417 public static AltosForce force = new AltosForce();
419 public static AltosSpeed speed = new AltosSpeed();
421 public static AltosAccel accel = new AltosAccel();
423 public static AltosTemperature temperature = new AltosTemperature();
425 public static AltosOrient orient = new AltosOrient();
427 public static AltosVoltage voltage = new AltosVoltage();
429 public static AltosLatitude latitude = new AltosLatitude();
431 public static AltosLongitude longitude = new AltosLongitude();
433 public static AltosRotationRate rotation_rate = new AltosRotationRate();
435 public static AltosStateName state_name = new AltosStateName();
437 public static String show_gs(String format, double a) {
439 format = format.concat(" g");
440 return String.format(format, a);
443 public static String say_gs(double a) {
444 return String.format("%6.0 gees", meters_to_g(a));
447 public static int checksum(int[] data, int start, int length) {
449 for (int i = 0; i < length; i++)
450 csum += data[i + start];
454 public static int checksum(List<Byte> data, int start, int length) {
456 for (int i = 0; i < length; i++)
457 csum += data.get(i+start);
461 public static double beep_value_to_freq(int value) {
464 return 1.0/2.0 * (24.0e6/32.0) / (double) value;
467 public static int beep_freq_to_value(double freq) {
470 return (int) Math.floor (1.0/2.0 * (24.0e6/32.0) / freq + 0.5);
473 public static final int BEARING_LONG = 0;
474 public static final int BEARING_SHORT = 1;
475 public static final int BEARING_VOICE = 2;
477 public static String bearing_to_words(int length, double bearing) {
478 String [][] bearing_string = {
480 "North", "North North East", "North East", "East North East",
481 "East", "East South East", "South East", "South South East",
482 "South", "South South West", "South West", "West South West",
483 "West", "West North West", "North West", "North North West"
485 "N", "NNE", "NE", "ENE",
486 "E", "ESE", "SE", "SSE",
487 "S", "SSW", "SW", "WSW",
488 "W", "WNW", "NW", "NNW"
490 "north", "nor nor east", "north east", "east nor east",
491 "east", "east sow east", "south east", "sow sow east",
492 "south", "sow sow west", "south west", "west sow west",
493 "west", "west nor west", "north west", "nor nor west "
496 return bearing_string[length][(int)((bearing / 90 * 8 + 1) / 2)%16];