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   1 /*
   2  * Copyright © 2010 Keith Packard <keithp@keithp.com>
   3  *
   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.
   8  *
   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.
  13  *
  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.
  17  */
  18
  19 /*
  20  * Sensor data conversion functions
  21  */
  22 package org.altusmetrum.altoslib_11;
  23
  24 import java.util.*;
  25
  26 public class AltosConvert {
  27
  28         public static final double gravity = 9.80665;
  29
  30         /*
  31          * Pressure Sensor Model, version 1.1
  32          *
  33          * written by Holly Grimes
  34          *
  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.
  39          *
  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
  42          *
  43          * Height measurements use the local tangent plane.  The postive z-direction is up.
  44          *
  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).
  48          */
  49
  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;
  57
  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
  61         };
  62
  63         private static final int[] base_altitude = {
  64                 0, 11000, 20000, 32000, 47000, 51000, 71000
  65         };
  66
  67         /* outputs atmospheric pressure associated with the given altitude.
  68          * altitudes are measured with respect to the mean sea level
  69          */
  70         public static double
  71         altitude_to_pressure(double altitude)
  72         {
  73                 double base_temperature = LAYER0_BASE_TEMPERATURE;
  74                 double base_pressure = LAYER0_BASE_PRESSURE;
  75
  76                 double 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 */
  81
  82                 if (altitude > MAXIMUM_ALTITUDE) /* FIX ME: use sensor data to improve model */
  83                         return 0;
  84
  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);
  93                         }
  94                         else {
  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);
  99                         }
 100                         base_temperature += delta_z * lapse_rate[layer_number];
 101                 }
 102
 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);
 109                 }
 110                 else {
 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);
 115                 }
 116
 117                 return pressure;
 118         }
 119
 120
 121 /* outputs the altitude associated with the given pressure. the altitude
 122    returned is measured with respect to the mean sea level */
 123         public static double
 124         pressure_to_altitude(double pressure)
 125         {
 126
 127                 double next_base_temperature = LAYER0_BASE_TEMPERATURE;
 128                 double next_base_pressure = LAYER0_BASE_PRESSURE;
 129
 130                 double altitude;
 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
 135                                     of next layer */
 136                 double coefficient;
 137                 int layer_number; /* identifies layer in the atmosphere */
 138                 int delta_z; /* difference between two altitudes */
 139
 140                 if (pressure < 0)  /* illegal pressure */
 141                         return -1;
 142                 if (pressure < MINIMUM_PRESSURE) /* FIX ME: use sensor data to improve model */
 143                         return MAXIMUM_ALTITUDE;
 144
 145                 /* calculate the base temperature and pressure for the atmospheric layer
 146                    associated with the inputted pressure. */
 147                 layer_number = -1;
 148                 do {
 149                         layer_number++;
 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);
 157                         }
 158                         else {
 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);
 163                         }
 164                         next_base_temperature += delta_z * lapse_rate[layer_number];
 165                 }
 166                 while(layer_number < NUMBER_OF_LAYERS - 1 && pressure < next_base_pressure);
 167
 168                 /* calculate the altitude associated with the inputted pressure */
 169                 if (lapse_rate[layer_number] == 0.0) {
 170                         coefficient = (AIR_GAS_CONSTANT / GRAVITATIONAL_ACCELERATION)
 171                                 * base_temperature;
 172                         altitude = base_altitude[layer_number]
 173                                 + coefficient * Math.log(pressure / base_pressure);
 174                 }
 175                 else {
 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);
 182                 }
 183
 184                 return altitude;
 185         }
 186
 187         public static double degrees_to_radians(double degrees) {
 188                 if (degrees == AltosLib.MISSING)
 189                         return AltosLib.MISSING;
 190                 return degrees * (Math.PI / 180.0);
 191         }
 192
 193         public static double radians_to_degrees(double radians) {
 194                 if (radians == AltosLib.MISSING)
 195                         return AltosLib.MISSING;
 196                 return radians * (180.0 / Math.PI);
 197         }
 198
 199         public static double
 200         cc_battery_to_voltage(double battery)
 201         {
 202                 return battery / 32767.0 * 5.0;
 203         }
 204
 205         public static double
 206         cc_igniter_to_voltage(double ignite)
 207         {
 208                 return ignite / 32767 * 15.0;
 209         }
 210
 211         public static double
 212         barometer_to_pressure(double count)
 213         {
 214                 return ((count / 16.0) / 2047.0 + 0.095) / 0.009 * 1000.0;
 215         }
 216
 217         static double
 218         thermometer_to_temperature(double thermo)
 219         {
 220                 return (thermo - 19791.268) / 32728.0 * 1.25 / 0.00247;
 221         }
 222
 223         static double mega_adc(int raw) {
 224                 return raw / 4095.0;
 225         }
 226
 227         static public double mega_battery_voltage(int v_batt) {
 228                 if (v_batt != AltosLib.MISSING)
 229                         return 3.3 * mega_adc(v_batt) * (5.6 + 10.0) / 10.0;
 230                 return AltosLib.MISSING;
 231         }
 232
 233         static double mega_pyro_voltage(int raw) {
 234                 if (raw != AltosLib.MISSING)
 235                         return 3.3 * mega_adc(raw) * (100.0 + 27.0) / 27.0;
 236                 return AltosLib.MISSING;
 237         }
 238
 239         static double tele_mini_3_adc(int raw) {
 240                 return raw / 4095.0;
 241         }
 242
 243         static public double tele_mini_3_battery_voltage(int v_batt) {
 244                 if (v_batt != AltosLib.MISSING)
 245                         return 3.3 * tele_mini_3_adc(v_batt) * (5.6 + 10.0) / 10.0;
 246                 return AltosLib.MISSING;
 247         }
 248
 249         static double tele_mini_3_pyro_voltage(int raw) {
 250                 if (raw != AltosLib.MISSING)
 251                         return 3.3 * tele_mini_3_adc(raw) * (100.0 + 27.0) / 27.0;
 252                 return AltosLib.MISSING;
 253         }
 254
 255         static double tele_mini_2_voltage(int sensor) {
 256                 double  supply = 3.3;
 257
 258                 return sensor / 32767.0 * supply * 127/27;
 259         }
 260
 261         static double tele_gps_voltage(int sensor) {
 262                 double  supply = 3.3;
 263
 264                 return sensor / 32767.0 * supply * (5.6 + 10.0) / 10.0;
 265         }
 266
 267         static double tele_bt_3_battery(int raw) {
 268                 if (raw == AltosLib.MISSING)
 269                         return AltosLib.MISSING;
 270                 return 3.3 * mega_adc(raw) * (5.1 + 10.0) / 10.0;
 271         }
 272
 273         static double easy_mini_voltage(int sensor, int serial) {
 274                 double  supply = 3.3;
 275                 double  diode_offset = 0.0;
 276
 277                 /* early prototypes had a 3.0V regulator */
 278                 if (serial < 1000)
 279                         supply = 3.0;
 280
 281                 /* Purple v1.0 boards had the sensor after the
 282                  * blocking diode, which drops about 150mV
 283                  */
 284                 if (serial < 1665)
 285                         diode_offset = 0.150;
 286
 287                 return sensor / 32767.0 * supply * 127/27 + diode_offset;
 288         }
 289
 290         public static double radio_to_frequency(int freq, int setting, int cal, int channel) {
 291                 double  f;
 292
 293                 if (freq > 0)
 294                         f = freq / 1000.0;
 295                 else {
 296                         if (setting <= 0)
 297                                 setting = cal;
 298                         f = 434.550 * setting / cal;
 299                         /* Round to nearest 50KHz */
 300                         f = Math.floor (20.0 * f + 0.5) / 20.0;
 301                 }
 302                 return f + channel * 0.100;
 303         }
 304
 305         public static int radio_frequency_to_setting(double frequency, int cal) {
 306                 double  set = frequency / 434.550 * cal;
 307
 308                 return (int) Math.floor (set + 0.5);
 309         }
 310
 311         public static int radio_frequency_to_channel(double frequency) {
 312                 int     channel = (int) Math.floor ((frequency - 434.550) / 0.100 + 0.5);
 313
 314                 if (channel < 0)
 315                         channel = 0;
 316                 if (channel > 9)
 317                         channel = 9;
 318                 return channel;
 319         }
 320
 321         public static double radio_channel_to_frequency(int channel) {
 322                 return 434.550 + channel * 0.100;
 323         }
 324
 325         public static int telem_to_rssi(int telem) {
 326                 return telem / 2 - 74;
 327         }
 328
 329         public static int[] ParseHex(String line) {
 330                 String[] tokens = line.split("\\s+");
 331                 int[] array = new int[tokens.length];
 332
 333                 for (int i = 0; i < tokens.length; i++)
 334                         try {
 335                                 array[i] = Integer.parseInt(tokens[i], 16);
 336                         } catch (NumberFormatException ne) {
 337                                 return null;
 338                         }
 339                 return array;
 340         }
 341
 342         public static double meters_to_feet(double meters) {
 343                 return meters * (100 / (2.54 * 12));
 344         }
 345
 346         public static double feet_to_meters(double feet) {
 347                 return feet * 12 * 2.54 / 100.0;
 348         }
 349
 350         public static double meters_to_miles(double meters) {
 351                 return meters_to_feet(meters) / 5280;
 352         }
 353
 354         public static double miles_to_meters(double miles) {
 355                 return feet_to_meters(miles * 5280);
 356         }
 357
 358         public static double meters_to_mph(double mps) {
 359                 return meters_to_miles(mps) * 3600;
 360         }
 361
 362         public static double mph_to_meters(double mps) {
 363                 return miles_to_meters(mps) / 3600;
 364         }
 365
 366         public static double mps_to_fps(double mps) {
 367                 return meters_to_miles(mps) * 5280;
 368         }
 369
 370         public static double fps_to_mps(double mps) {
 371                 return miles_to_meters(mps) / 5280;
 372         }
 373
 374         public static double meters_to_mach(double meters) {
 375                 return meters / 343;            /* something close to mach at usual rocket sites */
 376         }
 377
 378         public static double meters_to_g(double meters) {
 379                 return meters / 9.80665;
 380         }
 381
 382         public static double c_to_f(double c) {
 383                 return c * 9/5 + 32;
 384         }
 385
 386         public static double f_to_c(double c) {
 387                 return (c - 32) * 5/9;
 388         }
 389
 390         public static double psi_to_pa(double psi) {
 391                 return psi * 6894.76;
 392         }
 393
 394         public static double pa_to_psi(double pa) {
 395                 return pa / 6894.76;
 396         }
 397
 398         public static double n_to_lb(double n) {
 399                 return n * 0.22480894;
 400         }
 401
 402         public static double lb_to_n(double lb) {
 403                 return lb / 0.22480894;
 404         }
 405
 406         public static double acceleration_from_sensor(double sensor, double plus_g, double minus_g, double ground) {
 407
 408                 if (sensor == AltosLib.MISSING)
 409                         return AltosLib.MISSING;
 410
 411                 if (plus_g == AltosLib.MISSING || minus_g == AltosLib.MISSING)
 412                         return AltosLib.MISSING;
 413
 414                 if (ground == AltosLib.MISSING)
 415                         ground = plus_g;
 416
 417                 double counts_per_g = (plus_g - minus_g) / 2.0;
 418                 double counts_per_mss = counts_per_g / gravity;
 419
 420                 if (counts_per_mss == 0)
 421                         return AltosLib.MISSING;
 422
 423                 return (sensor - ground) / counts_per_mss;
 424         }
 425
 426         public static boolean imperial_units = false;
 427
 428         public static AltosDistance distance = new AltosDistance();
 429
 430         public static AltosHeight height = new AltosHeight();
 431
 432         public static AltosPressure pressure = new AltosPressure();
 433
 434         public static AltosForce force = new AltosForce();
 435
 436         public static AltosSpeed speed = new AltosSpeed();
 437
 438         public static AltosAccel accel = new AltosAccel();
 439
 440         public static AltosTemperature temperature = new AltosTemperature();
 441
 442         public static AltosOrient orient = new AltosOrient();
 443
 444         public static AltosVoltage voltage = new AltosVoltage();
 445
 446         public static AltosLatitude latitude = new AltosLatitude();
 447
 448         public static AltosLongitude longitude = new AltosLongitude();
 449
 450         public static AltosRotationRate rotation_rate = new AltosRotationRate();
 451
 452         public static AltosStateName state_name = new AltosStateName();
 453
 454         public static AltosPyroName pyro_name = new AltosPyroName();
 455
 456         public static AltosUnits magnetic_field = null;
 457
 458         public static String show_gs(String format, double a) {
 459                 a = meters_to_g(a);
 460                 format = format.concat(" g");
 461                 return String.format(format, a);
 462         }
 463
 464         public static String say_gs(double a) {
 465                 return String.format("%6.0 gees", meters_to_g(a));
 466         }
 467
 468         public static int checksum(int[] data, int start, int length) {
 469                 int     csum = 0x5a;
 470                 for (int i = 0; i < length; i++)
 471                         csum += data[i + start];
 472                 return csum & 0xff;
 473         }
 474
 475         public static int checksum(List<Byte> data, int start, int length) {
 476                 int     csum = 0x5a;
 477                 for (int i = 0; i < length; i++)
 478                         csum += data.get(i+start);
 479                 return csum & 0xff;
 480         }
 481
 482         public static double beep_value_to_freq(int value) {
 483                 if (value == 0)
 484                         return 4000;
 485                 return 1.0/2.0 * (24.0e6/32.0) / (double) value;
 486         }
 487
 488         public static int beep_freq_to_value(double freq) {
 489                 if (freq == 0)
 490                         return 94;
 491                 return (int) Math.floor (1.0/2.0 * (24.0e6/32.0) / freq + 0.5);
 492         }
 493
 494         public static final int BEARING_LONG = 0;
 495         public static final int BEARING_SHORT = 1;
 496         public static final int BEARING_VOICE = 2;
 497
 498         public static String bearing_to_words(int length, double bearing) {
 499                 String [][] bearing_string = {
 500                         {
 501                                 "North", "North North East", "North East", "East North East",
 502                                 "East", "East South East", "South East", "South South East",
 503                                 "South", "South South West", "South West", "West South West",
 504                                 "West", "West North West", "North West", "North North West"
 505                         }, {
 506                                 "N", "NNE", "NE", "ENE",
 507                                 "E", "ESE", "SE", "SSE",
 508                                 "S", "SSW", "SW", "WSW",
 509                                 "W", "WNW", "NW", "NNW"
 510                         }, {
 511                                 "north", "nor nor east", "north east", "east nor east",
 512                                 "east", "east sow east", "south east", "sow sow east",
 513                                 "south", "sow sow west", "south west", "west sow west",
 514                                 "west", "west nor west", "north west", "nor nor west "
 515                         }
 516                 };
 517                 return bearing_string[length][(int)((bearing / 90 * 8 + 1) / 2)%16];
 518         }
 519 }