1/* 2 * refclock_wwv - clock driver for NIST WWV/H time/frequency station 3 */ 4#ifdef HAVE_CONFIG_H 5#include <config.h> 6#endif 7 8#if defined(REFCLOCK) && defined(CLOCK_WWV) 9 10#include "ntpd.h" 11#include "ntp_io.h" 12#include "ntp_refclock.h" 13#include "ntp_calendar.h" 14#include "ntp_stdlib.h" 15#include "audio.h" 16 17#include <stdio.h> 18#include <ctype.h> 19#include <math.h> 20#ifdef HAVE_SYS_IOCTL_H 21# include <sys/ioctl.h> 22#endif /* HAVE_SYS_IOCTL_H */ 23 24#define ICOM 1 25 26#ifdef ICOM 27#include "icom.h" 28#endif /* ICOM */ 29 30/* 31 * Audio WWV/H demodulator/decoder 32 * 33 * This driver synchronizes the computer time using data encoded in 34 * radio transmissions from NIST time/frequency stations WWV in Boulder, 35 * CO, and WWVH in Kauai, HI. Transmissions are made continuously on 36 * 2.5, 5, 10 and 15 MHz from WWV and WWVH, and 20 MHz from WWV. An 37 * ordinary AM shortwave receiver can be tuned manually to one of these 38 * frequencies or, in the case of ICOM receivers, the receiver can be 39 * tuned automatically using this program as propagation conditions 40 * change throughout the weasons, both day and night. 41 * 42 * The driver requires an audio codec or sound card with sampling rate 8 43 * kHz and mu-law companding. This is the same standard as used by the 44 * telephone industry and is supported by most hardware and operating 45 * systems, including Solaris, SunOS, FreeBSD, NetBSD and Linux. In this 46 * implementation, only one audio driver and codec can be supported on a 47 * single machine. 48 * 49 * The demodulation and decoding algorithms used in this driver are 50 * based on those developed for the TAPR DSP93 development board and the 51 * TI 320C25 digital signal processor described in: Mills, D.L. A 52 * precision radio clock for WWV transmissions. Electrical Engineering 53 * Report 97-8-1, University of Delaware, August 1997, 25 pp., available 54 * from www.eecis.udel.edu/~mills/reports.html. The algorithms described 55 * in this report have been modified somewhat to improve performance 56 * under weak signal conditions and to provide an automatic station 57 * identification feature. 58 * 59 * The ICOM code is normally compiled in the driver. It isn't used, 60 * unless the mode keyword on the server configuration command specifies 61 * a nonzero ICOM ID select code. The C-IV trace is turned on if the 62 * debug level is greater than one. 63 * 64 * Fudge factors 65 * 66 * Fudge flag4 causes the dubugging output described above to be 67 * recorded in the clockstats file. Fudge flag2 selects the audio input 68 * port, where 0 is the mike port (default) and 1 is the line-in port. 69 * It does not seem useful to select the compact disc player port. Fudge 70 * flag3 enables audio monitoring of the input signal. For this purpose, 71 * the monitor gain is set to a default value. 72 * 73 * CEVNT_BADTIME invalid date or time 74 * CEVNT_PROP propagation failure - no stations heard 75 * CEVNT_TIMEOUT timeout (see newgame() below) 76 */ 77/* 78 * General definitions. These ordinarily do not need to be changed. 79 */ 80#define DEVICE_AUDIO "/dev/audio" /* audio device name */ 81#define AUDIO_BUFSIZ 320 /* audio buffer size (50 ms) */ 82#define PRECISION (-10) /* precision assumed (about 1 ms) */ 83#define DESCRIPTION "WWV/H Audio Demodulator/Decoder" /* WRU */ 84#define SECOND 8000 /* second epoch (sample rate) (Hz) */ 85#define MINUTE (SECOND * 60) /* minute epoch */ 86#define OFFSET 128 /* companded sample offset */ 87#define SIZE 256 /* decompanding table size */ 88#define MAXAMP 6000. /* max signal level reference */ 89#define MAXCLP 100 /* max clips above reference per s */ 90#define MAXSNR 40. /* max SNR reference */ 91#define MAXFREQ 1.5 /* max frequency tolerance (187 PPM) */ 92#define DATCYC 170 /* data filter cycles */ 93#define DATSIZ (DATCYC * MS) /* data filter size */ 94#define SYNCYC 800 /* minute filter cycles */ 95#define SYNSIZ (SYNCYC * MS) /* minute filter size */ 96#define TCKCYC 5 /* tick filter cycles */ 97#define TCKSIZ (TCKCYC * MS) /* tick filter size */ 98#define NCHAN 5 /* number of radio channels */ 99#define AUDIO_PHI 5e-6 /* dispersion growth factor */ 100#define TBUF 128 /* max monitor line length */ 101 102/* 103 * Tunable parameters. The DGAIN parameter can be changed to fit the 104 * audio response of the radio at 100 Hz. The WWV/WWVH data subcarrier 105 * is transmitted at about 20 percent percent modulation; the matched 106 * filter boosts it by a factor of 17 and the receiver response does 107 * what it does. The compromise value works for ICOM radios. If the 108 * radio is not tunable, the DCHAN parameter can be changed to fit the 109 * expected best propagation frequency: higher if further from the 110 * transmitter, lower if nearer. The compromise value works for the US 111 * right coast. 112 */ 113#define DCHAN 3 /* default radio channel (15 Mhz) */ 114#define DGAIN 5. /* subcarrier gain */ 115 116/* 117 * General purpose status bits (status) 118 * 119 * SELV and/or SELH are set when WWV or WWVH have been heard and cleared 120 * on signal loss. SSYNC is set when the second sync pulse has been 121 * acquired and cleared by signal loss. MSYNC is set when the minute 122 * sync pulse has been acquired. DSYNC is set when the units digit has 123 * has reached the threshold and INSYNC is set when all nine digits have 124 * reached the threshold. The MSYNC, DSYNC and INSYNC bits are cleared 125 * only by timeout, upon which the driver starts over from scratch. 126 * 127 * DGATE is lit if the data bit amplitude or SNR is below thresholds and 128 * BGATE is lit if the pulse width amplitude or SNR is below thresolds. 129 * LEPSEC is set during the last minute of the leap day. At the end of 130 * this minute the driver inserts second 60 in the seconds state machine 131 * and the minute sync slips a second. 132 */ 133#define MSYNC 0x0001 /* minute epoch sync */ 134#define SSYNC 0x0002 /* second epoch sync */ 135#define DSYNC 0x0004 /* minute units sync */ 136#define INSYNC 0x0008 /* clock synchronized */ 137#define FGATE 0x0010 /* frequency gate */ 138#define DGATE 0x0020 /* data pulse amplitude error */ 139#define BGATE 0x0040 /* data pulse width error */ 140#define METRIC 0x0080 /* one or more stations heard */ 141#define LEPSEC 0x1000 /* leap minute */ 142 143/* 144 * Station scoreboard bits 145 * 146 * These are used to establish the signal quality for each of the five 147 * frequencies and two stations. 148 */ 149#define SELV 0x0100 /* WWV station select */ 150#define SELH 0x0200 /* WWVH station select */ 151 152/* 153 * Alarm status bits (alarm) 154 * 155 * These bits indicate various alarm conditions, which are decoded to 156 * form the quality character included in the timecode. 157 */ 158#define CMPERR 0x1 /* digit or misc bit compare error */ 159#define LOWERR 0x2 /* low bit or digit amplitude or SNR */ 160#define NINERR 0x4 /* less than nine digits in minute */ 161#define SYNERR 0x8 /* not tracking second sync */ 162 163/* 164 * Watchcat timeouts (watch) 165 * 166 * If these timeouts expire, the status bits are mashed to zero and the 167 * driver starts from scratch. Suitably more refined procedures may be 168 * developed in future. All these are in minutes. 169 */ 170#define ACQSN 6 /* station acquisition timeout */ 171#define DATA 15 /* unit minutes timeout */ 172#define SYNCH 40 /* station sync timeout */ 173#define PANIC (2 * 1440) /* panic timeout */ 174 175/* 176 * Thresholds. These establish the minimum signal level, minimum SNR and 177 * maximum jitter thresholds which establish the error and false alarm 178 * rates of the driver. The values defined here may be on the 179 * adventurous side in the interest of the highest sensitivity. 180 */ 181#define MTHR 13. /* minute sync gate (percent) */ 182#define TTHR 50. /* minute sync threshold (percent) */ 183#define AWND 20 /* minute sync jitter threshold (ms) */ 184#define ATHR 2500. /* QRZ minute sync threshold */ 185#define ASNR 20. /* QRZ minute sync SNR threshold (dB) */ 186#define QTHR 2500. /* QSY minute sync threshold */ 187#define QSNR 20. /* QSY minute sync SNR threshold (dB) */ 188#define STHR 2500. /* second sync threshold */ 189#define SSNR 15. /* second sync SNR threshold (dB) */ 190#define SCMP 10 /* second sync compare threshold */ 191#define DTHR 1000. /* bit threshold */ 192#define DSNR 10. /* bit SNR threshold (dB) */ 193#define AMIN 3 /* min bit count */ 194#define AMAX 6 /* max bit count */ 195#define BTHR 1000. /* digit threshold */ 196#define BSNR 3. /* digit likelihood threshold (dB) */ 197#define BCMP 3 /* digit compare threshold */ 198#define MAXERR 40 /* maximum error alarm */ 199 200/* 201 * Tone frequency definitions. The increments are for 4.5-deg sine 202 * table. 203 */ 204#define MS (SECOND / 1000) /* samples per millisecond */ 205#define IN100 ((100 * 80) / SECOND) /* 100 Hz increment */ 206#define IN1000 ((1000 * 80) / SECOND) /* 1000 Hz increment */ 207#define IN1200 ((1200 * 80) / SECOND) /* 1200 Hz increment */ 208 209/* 210 * Acquisition and tracking time constants 211 */ 212#define MINAVG 8 /* min averaging time */ 213#define MAXAVG 1024 /* max averaging time */ 214#define FCONST 3 /* frequency time constant */ 215#define TCONST 16 /* data bit/digit time constant */ 216 217/* 218 * Miscellaneous status bits (misc) 219 * 220 * These bits correspond to designated bits in the WWV/H timecode. The 221 * bit probabilities are exponentially averaged over several minutes and 222 * processed by a integrator and threshold. 223 */ 224#define DUT1 0x01 /* 56 DUT .1 */ 225#define DUT2 0x02 /* 57 DUT .2 */ 226#define DUT4 0x04 /* 58 DUT .4 */ 227#define DUTS 0x08 /* 50 DUT sign */ 228#define DST1 0x10 /* 55 DST1 leap warning */ 229#define DST2 0x20 /* 2 DST2 DST1 delayed one day */ 230#define SECWAR 0x40 /* 3 leap second warning */ 231 232/* 233 * The on-time synchronization point is the positive-going zero crossing 234 * of the first cycle of the 5-ms second pulse. The IIR baseband filter 235 * phase delay is 0.91 ms, while the receiver delay is approximately 4.7 236 * ms at 1000 Hz. The fudge value -0.45 ms due to the codec and other 237 * causes was determined by calibrating to a PPS signal from a GPS 238 * receiver. The additional propagation delay specific to each receiver 239 * location can be programmed in the fudge time1 and time2 values for 240 * WWV and WWVH, respectively. 241 * 242 * The resulting offsets with a 2.4-GHz P4 running FreeBSD 6.1 are 243 * generally within .02 ms short-term with .02 ms jitter. The long-term 244 * offsets vary up to 0.3 ms due to ionosperhic layer height variations. 245 * The processor load due to the driver is 5.8 percent. 246 */ 247#define PDELAY ((.91 + 4.7 - 0.45) / 1000) /* system delay (s) */ 248 249/* 250 * Table of sine values at 4.5-degree increments. This is used by the 251 * synchronous matched filter demodulators. 252 */ 253double sintab[] = { 254 0.000000e+00, 7.845910e-02, 1.564345e-01, 2.334454e-01, /* 0-3 */ 255 3.090170e-01, 3.826834e-01, 4.539905e-01, 5.224986e-01, /* 4-7 */ 256 5.877853e-01, 6.494480e-01, 7.071068e-01, 7.604060e-01, /* 8-11 */ 257 8.090170e-01, 8.526402e-01, 8.910065e-01, 9.238795e-01, /* 12-15 */ 258 9.510565e-01, 9.723699e-01, 9.876883e-01, 9.969173e-01, /* 16-19 */ 259 1.000000e+00, 9.969173e-01, 9.876883e-01, 9.723699e-01, /* 20-23 */ 260 9.510565e-01, 9.238795e-01, 8.910065e-01, 8.526402e-01, /* 24-27 */ 261 8.090170e-01, 7.604060e-01, 7.071068e-01, 6.494480e-01, /* 28-31 */ 262 5.877853e-01, 5.224986e-01, 4.539905e-01, 3.826834e-01, /* 32-35 */ 263 3.090170e-01, 2.334454e-01, 1.564345e-01, 7.845910e-02, /* 36-39 */ 264-0.000000e+00, -7.845910e-02, -1.564345e-01, -2.334454e-01, /* 40-43 */ 265-3.090170e-01, -3.826834e-01, -4.539905e-01, -5.224986e-01, /* 44-47 */ 266-5.877853e-01, -6.494480e-01, -7.071068e-01, -7.604060e-01, /* 48-51 */ 267-8.090170e-01, -8.526402e-01, -8.910065e-01, -9.238795e-01, /* 52-55 */ 268-9.510565e-01, -9.723699e-01, -9.876883e-01, -9.969173e-01, /* 56-59 */ 269-1.000000e+00, -9.969173e-01, -9.876883e-01, -9.723699e-01, /* 60-63 */ 270-9.510565e-01, -9.238795e-01, -8.910065e-01, -8.526402e-01, /* 64-67 */ 271-8.090170e-01, -7.604060e-01, -7.071068e-01, -6.494480e-01, /* 68-71 */ 272-5.877853e-01, -5.224986e-01, -4.539905e-01, -3.826834e-01, /* 72-75 */ 273-3.090170e-01, -2.334454e-01, -1.564345e-01, -7.845910e-02, /* 76-79 */ 274 0.000000e+00}; /* 80 */ 275 276/* 277 * Decoder operations at the end of each second are driven by a state 278 * machine. The transition matrix consists of a dispatch table indexed 279 * by second number. Each entry in the table contains a case switch 280 * number and argument. 281 */ 282struct progx { 283 int sw; /* case switch number */ 284 int arg; /* argument */ 285}; 286 287/* 288 * Case switch numbers 289 */ 290#define IDLE 0 /* no operation */ 291#define COEF 1 /* BCD bit */ 292#define COEF1 2 /* BCD bit for minute unit */ 293#define COEF2 3 /* BCD bit not used */ 294#define DECIM9 4 /* BCD digit 0-9 */ 295#define DECIM6 5 /* BCD digit 0-6 */ 296#define DECIM3 6 /* BCD digit 0-3 */ 297#define DECIM2 7 /* BCD digit 0-2 */ 298#define MSCBIT 8 /* miscellaneous bit */ 299#define MSC20 9 /* miscellaneous bit */ 300#define MSC21 10 /* QSY probe channel */ 301#define MIN1 11 /* latch time */ 302#define MIN2 12 /* leap second */ 303#define SYNC2 13 /* latch minute sync pulse */ 304#define SYNC3 14 /* latch data pulse */ 305 306/* 307 * Offsets in decoding matrix 308 */ 309#define MN 0 /* minute digits (2) */ 310#define HR 2 /* hour digits (2) */ 311#define DA 4 /* day digits (3) */ 312#define YR 7 /* year digits (2) */ 313 314struct progx progx[] = { 315 {SYNC2, 0}, /* 0 latch minute sync pulse */ 316 {SYNC3, 0}, /* 1 latch data pulse */ 317 {MSCBIT, DST2}, /* 2 dst2 */ 318 {MSCBIT, SECWAR}, /* 3 lw */ 319 {COEF, 0}, /* 4 1 year units */ 320 {COEF, 1}, /* 5 2 */ 321 {COEF, 2}, /* 6 4 */ 322 {COEF, 3}, /* 7 8 */ 323 {DECIM9, YR}, /* 8 */ 324 {IDLE, 0}, /* 9 p1 */ 325 {COEF1, 0}, /* 10 1 minute units */ 326 {COEF1, 1}, /* 11 2 */ 327 {COEF1, 2}, /* 12 4 */ 328 {COEF1, 3}, /* 13 8 */ 329 {DECIM9, MN}, /* 14 */ 330 {COEF, 0}, /* 15 10 minute tens */ 331 {COEF, 1}, /* 16 20 */ 332 {COEF, 2}, /* 17 40 */ 333 {COEF2, 3}, /* 18 80 (not used) */ 334 {DECIM6, MN + 1}, /* 19 p2 */ 335 {COEF, 0}, /* 20 1 hour units */ 336 {COEF, 1}, /* 21 2 */ 337 {COEF, 2}, /* 22 4 */ 338 {COEF, 3}, /* 23 8 */ 339 {DECIM9, HR}, /* 24 */ 340 {COEF, 0}, /* 25 10 hour tens */ 341 {COEF, 1}, /* 26 20 */ 342 {COEF2, 2}, /* 27 40 (not used) */ 343 {COEF2, 3}, /* 28 80 (not used) */ 344 {DECIM2, HR + 1}, /* 29 p3 */ 345 {COEF, 0}, /* 30 1 day units */ 346 {COEF, 1}, /* 31 2 */ 347 {COEF, 2}, /* 32 4 */ 348 {COEF, 3}, /* 33 8 */ 349 {DECIM9, DA}, /* 34 */ 350 {COEF, 0}, /* 35 10 day tens */ 351 {COEF, 1}, /* 36 20 */ 352 {COEF, 2}, /* 37 40 */ 353 {COEF, 3}, /* 38 80 */ 354 {DECIM9, DA + 1}, /* 39 p4 */ 355 {COEF, 0}, /* 40 100 day hundreds */ 356 {COEF, 1}, /* 41 200 */ 357 {COEF2, 2}, /* 42 400 (not used) */ 358 {COEF2, 3}, /* 43 800 (not used) */ 359 {DECIM3, DA + 2}, /* 44 */ 360 {IDLE, 0}, /* 45 */ 361 {IDLE, 0}, /* 46 */ 362 {IDLE, 0}, /* 47 */ 363 {IDLE, 0}, /* 48 */ 364 {IDLE, 0}, /* 49 p5 */ 365 {MSCBIT, DUTS}, /* 50 dut+- */ 366 {COEF, 0}, /* 51 10 year tens */ 367 {COEF, 1}, /* 52 20 */ 368 {COEF, 2}, /* 53 40 */ 369 {COEF, 3}, /* 54 80 */ 370 {MSC20, DST1}, /* 55 dst1 */ 371 {MSCBIT, DUT1}, /* 56 0.1 dut */ 372 {MSCBIT, DUT2}, /* 57 0.2 */ 373 {MSC21, DUT4}, /* 58 0.4 QSY probe channel */ 374 {MIN1, 0}, /* 59 p6 latch time */ 375 {MIN2, 0} /* 60 leap second */ 376}; 377 378/* 379 * BCD coefficients for maximum-likelihood digit decode 380 */ 381#define P15 1. /* max positive number */ 382#define N15 -1. /* max negative number */ 383 384/* 385 * Digits 0-9 386 */ 387#define P9 (P15 / 4) /* mark (+1) */ 388#define N9 (N15 / 4) /* space (-1) */ 389 390double bcd9[][4] = { 391 {N9, N9, N9, N9}, /* 0 */ 392 {P9, N9, N9, N9}, /* 1 */ 393 {N9, P9, N9, N9}, /* 2 */ 394 {P9, P9, N9, N9}, /* 3 */ 395 {N9, N9, P9, N9}, /* 4 */ 396 {P9, N9, P9, N9}, /* 5 */ 397 {N9, P9, P9, N9}, /* 6 */ 398 {P9, P9, P9, N9}, /* 7 */ 399 {N9, N9, N9, P9}, /* 8 */ 400 {P9, N9, N9, P9}, /* 9 */ 401 {0, 0, 0, 0} /* backstop */ 402}; 403 404/* 405 * Digits 0-6 (minute tens) 406 */ 407#define P6 (P15 / 3) /* mark (+1) */ 408#define N6 (N15 / 3) /* space (-1) */ 409 410double bcd6[][4] = { 411 {N6, N6, N6, 0}, /* 0 */ 412 {P6, N6, N6, 0}, /* 1 */ 413 {N6, P6, N6, 0}, /* 2 */ 414 {P6, P6, N6, 0}, /* 3 */ 415 {N6, N6, P6, 0}, /* 4 */ 416 {P6, N6, P6, 0}, /* 5 */ 417 {N6, P6, P6, 0}, /* 6 */ 418 {0, 0, 0, 0} /* backstop */ 419}; 420 421/* 422 * Digits 0-3 (day hundreds) 423 */ 424#define P3 (P15 / 2) /* mark (+1) */ 425#define N3 (N15 / 2) /* space (-1) */ 426 427double bcd3[][4] = { 428 {N3, N3, 0, 0}, /* 0 */ 429 {P3, N3, 0, 0}, /* 1 */ 430 {N3, P3, 0, 0}, /* 2 */ 431 {P3, P3, 0, 0}, /* 3 */ 432 {0, 0, 0, 0} /* backstop */ 433}; 434 435/* 436 * Digits 0-2 (hour tens) 437 */ 438#define P2 (P15 / 2) /* mark (+1) */ 439#define N2 (N15 / 2) /* space (-1) */ 440 441double bcd2[][4] = { 442 {N2, N2, 0, 0}, /* 0 */ 443 {P2, N2, 0, 0}, /* 1 */ 444 {N2, P2, 0, 0}, /* 2 */ 445 {0, 0, 0, 0} /* backstop */ 446}; 447 448/* 449 * DST decode (DST2 DST1) for prettyprint 450 */ 451char dstcod[] = { 452 'S', /* 00 standard time */ 453 'I', /* 01 set clock ahead at 0200 local */ 454 'O', /* 10 set clock back at 0200 local */ 455 'D' /* 11 daylight time */ 456}; 457 458/* 459 * The decoding matrix consists of nine row vectors, one for each digit 460 * of the timecode. The digits are stored from least to most significant 461 * order. The maximum-likelihood timecode is formed from the digits 462 * corresponding to the maximum-likelihood values reading in the 463 * opposite order: yy ddd hh:mm. 464 */ 465struct decvec { 466 int radix; /* radix (3, 4, 6, 10) */ 467 int digit; /* current clock digit */ 468 int count; /* match count */ 469 double digprb; /* max digit probability */ 470 double digsnr; /* likelihood function (dB) */ 471 double like[10]; /* likelihood integrator 0-9 */ 472}; 473 474/* 475 * The station structure (sp) is used to acquire the minute pulse from 476 * WWV and/or WWVH. These stations are distinguished by the frequency 477 * used for the second and minute sync pulses, 1000 Hz for WWV and 1200 478 * Hz for WWVH. Other than frequency, the format is the same. 479 */ 480struct sync { 481 double epoch; /* accumulated epoch differences */ 482 double maxeng; /* sync max energy */ 483 double noieng; /* sync noise energy */ 484 long pos; /* max amplitude position */ 485 long lastpos; /* last max position */ 486 long mepoch; /* minute synch epoch */ 487 488 double amp; /* sync signal */ 489 double syneng; /* sync signal max */ 490 double synmax; /* sync signal max latched at 0 s */ 491 double synsnr; /* sync signal SNR */ 492 double metric; /* signal quality metric */ 493 int reach; /* reachability register */ 494 int count; /* bit counter */ 495 int select; /* select bits */ 496 char refid[5]; /* reference identifier */ 497}; 498 499/* 500 * The channel structure (cp) is used to mitigate between channels. 501 */ 502struct chan { 503 int gain; /* audio gain */ 504 struct sync wwv; /* wwv station */ 505 struct sync wwvh; /* wwvh station */ 506}; 507 508/* 509 * WWV unit control structure (up) 510 */ 511struct wwvunit { 512 l_fp timestamp; /* audio sample timestamp */ 513 l_fp tick; /* audio sample increment */ 514 double phase, freq; /* logical clock phase and frequency */ 515 double monitor; /* audio monitor point */ 516 double pdelay; /* propagation delay (s) */ 517#ifdef ICOM 518 int fd_icom; /* ICOM file descriptor */ 519#endif /* ICOM */ 520 int errflg; /* error flags */ 521 int watch; /* watchcat */ 522 523 /* 524 * Audio codec variables 525 */ 526 double comp[SIZE]; /* decompanding table */ 527 int port; /* codec port */ 528 int gain; /* codec gain */ 529 int mongain; /* codec monitor gain */ 530 int clipcnt; /* sample clipped count */ 531 532 /* 533 * Variables used to establish basic system timing 534 */ 535 int avgint; /* master time constant */ 536 int yepoch; /* sync epoch */ 537 int repoch; /* buffered sync epoch */ 538 double epomax; /* second sync amplitude */ 539 double eposnr; /* second sync SNR */ 540 double irig; /* data I channel amplitude */ 541 double qrig; /* data Q channel amplitude */ 542 int datapt; /* 100 Hz ramp */ 543 double datpha; /* 100 Hz VFO control */ 544 int rphase; /* second sample counter */ 545 long mphase; /* minute sample counter */ 546 547 /* 548 * Variables used to mitigate which channel to use 549 */ 550 struct chan mitig[NCHAN]; /* channel data */ 551 struct sync *sptr; /* station pointer */ 552 int dchan; /* data channel */ 553 int schan; /* probe channel */ 554 int achan; /* active channel */ 555 556 /* 557 * Variables used by the clock state machine 558 */ 559 struct decvec decvec[9]; /* decoding matrix */ 560 int rsec; /* seconds counter */ 561 int digcnt; /* count of digits synchronized */ 562 563 /* 564 * Variables used to estimate signal levels and bit/digit 565 * probabilities 566 */ 567 double datsig; /* data signal max */ 568 double datsnr; /* data signal SNR (dB) */ 569 570 /* 571 * Variables used to establish status and alarm conditions 572 */ 573 int status; /* status bits */ 574 int alarm; /* alarm flashers */ 575 int misc; /* miscellaneous timecode bits */ 576 int errcnt; /* data bit error counter */ 577}; 578 579/* 580 * Function prototypes 581 */ 582static int wwv_start (int, struct peer *); 583static void wwv_shutdown (int, struct peer *); 584static void wwv_receive (struct recvbuf *); 585static void wwv_poll (int, struct peer *); 586 587/* 588 * More function prototypes 589 */ 590static void wwv_epoch (struct peer *); 591static void wwv_rf (struct peer *, double); 592static void wwv_endpoc (struct peer *, int); 593static void wwv_rsec (struct peer *, double); 594static void wwv_qrz (struct peer *, struct sync *, int); 595static void wwv_corr4 (struct peer *, struct decvec *, 596 double [], double [][4]); 597static void wwv_gain (struct peer *); 598static void wwv_tsec (struct peer *); 599static int timecode (struct wwvunit *, char *); 600static double wwv_snr (double, double); 601static int carry (struct decvec *); 602static int wwv_newchan (struct peer *); 603static void wwv_newgame (struct peer *); 604static double wwv_metric (struct sync *); 605static void wwv_clock (struct peer *); 606#ifdef ICOM 607static int wwv_qsy (struct peer *, int); 608#endif /* ICOM */ 609 610static double qsy[NCHAN] = {2.5, 5, 10, 15, 20}; /* frequencies (MHz) */ 611 612/* 613 * Transfer vector 614 */ 615struct refclock refclock_wwv = { 616 wwv_start, /* start up driver */ 617 wwv_shutdown, /* shut down driver */ 618 wwv_poll, /* transmit poll message */ 619 noentry, /* not used (old wwv_control) */ 620 noentry, /* initialize driver (not used) */ 621 noentry, /* not used (old wwv_buginfo) */ 622 NOFLAGS /* not used */ 623}; 624 625 626/* 627 * wwv_start - open the devices and initialize data for processing 628 */ 629static int 630wwv_start( 631 int unit, /* instance number (used by PCM) */ 632 struct peer *peer /* peer structure pointer */ 633 ) 634{ 635 struct refclockproc *pp; 636 struct wwvunit *up; 637#ifdef ICOM 638 int temp; 639#endif /* ICOM */ 640 641 /* 642 * Local variables 643 */ 644 int fd; /* file descriptor */ 645 int i; /* index */ 646 double step; /* codec adjustment */ 647 648 /* 649 * Open audio device 650 */ 651 fd = audio_init(DEVICE_AUDIO, AUDIO_BUFSIZ, unit); 652 if (fd < 0) 653 return (0); 654#ifdef DEBUG 655 if (debug) 656 audio_show(); 657#endif /* DEBUG */ 658 659 /* 660 * Allocate and initialize unit structure 661 */ 662 if (!(up = (struct wwvunit *)emalloc(sizeof(struct wwvunit)))) { 663 close(fd); 664 return (0); 665 } 666 memset(up, 0, sizeof(struct wwvunit)); 667 pp = peer->procptr; 668 pp->unitptr = (caddr_t)up; 669 pp->io.clock_recv = wwv_receive; 670 pp->io.srcclock = (caddr_t)peer; 671 pp->io.datalen = 0; 672 pp->io.fd = fd; 673 if (!io_addclock(&pp->io)) { 674 close(fd); 675 free(up); 676 return (0); 677 } 678 679 /* 680 * Initialize miscellaneous variables 681 */ 682 peer->precision = PRECISION; 683 pp->clockdesc = DESCRIPTION; 684 685 /* 686 * The companded samples are encoded sign-magnitude. The table 687 * contains all the 256 values in the interest of speed. 688 */ 689 up->comp[0] = up->comp[OFFSET] = 0.; 690 up->comp[1] = 1.; up->comp[OFFSET + 1] = -1.; 691 up->comp[2] = 3.; up->comp[OFFSET + 2] = -3.; 692 step = 2.; 693 for (i = 3; i < OFFSET; i++) { 694 up->comp[i] = up->comp[i - 1] + step; 695 up->comp[OFFSET + i] = -up->comp[i]; 696 if (i % 16 == 0) 697 step *= 2.; 698 } 699 DTOLFP(1. / SECOND, &up->tick); 700 701 /* 702 * Initialize the decoding matrix with the radix for each digit 703 * position. 704 */ 705 up->decvec[MN].radix = 10; /* minutes */ 706 up->decvec[MN + 1].radix = 6; 707 up->decvec[HR].radix = 10; /* hours */ 708 up->decvec[HR + 1].radix = 3; 709 up->decvec[DA].radix = 10; /* days */ 710 up->decvec[DA + 1].radix = 10; 711 up->decvec[DA + 2].radix = 4; 712 up->decvec[YR].radix = 10; /* years */ 713 up->decvec[YR + 1].radix = 10; 714 715#ifdef ICOM 716 /* 717 * Initialize autotune if available. Note that the ICOM select 718 * code must be less than 128, so the high order bit can be used 719 * to select the line speed 0 (9600 bps) or 1 (1200 bps). Note 720 * we don't complain if the ICOM device is not there; but, if it 721 * is, the radio better be working. 722 */ 723 temp = 0; 724#ifdef DEBUG 725 if (debug > 1) 726 temp = P_TRACE; 727#endif /* DEBUG */ 728 if (peer->ttl != 0) { 729 if (peer->ttl & 0x80) 730 up->fd_icom = icom_init("/dev/icom", B1200, 731 temp); 732 else 733 up->fd_icom = icom_init("/dev/icom", B9600, 734 temp); 735 } 736 if (up->fd_icom > 0) { 737 if (wwv_qsy(peer, DCHAN) != 0) { 738 msyslog(LOG_NOTICE, "icom: radio not found"); 739 close(up->fd_icom); 740 up->fd_icom = 0; 741 } else { 742 msyslog(LOG_NOTICE, "icom: autotune enabled"); 743 } 744 } 745#endif /* ICOM */ 746 747 /* 748 * Let the games begin. 749 */ 750 wwv_newgame(peer); 751 return (1); 752} 753 754 755/* 756 * wwv_shutdown - shut down the clock 757 */ 758static void 759wwv_shutdown( 760 int unit, /* instance number (not used) */ 761 struct peer *peer /* peer structure pointer */ 762 ) 763{ 764 struct refclockproc *pp; 765 struct wwvunit *up; 766 767 pp = peer->procptr; 768 up = (struct wwvunit *)pp->unitptr; 769 if (up == NULL) 770 return; 771 772 io_closeclock(&pp->io); 773#ifdef ICOM 774 if (up->fd_icom > 0) 775 close(up->fd_icom); 776#endif /* ICOM */ 777 free(up); 778} 779 780 781/* 782 * wwv_receive - receive data from the audio device 783 * 784 * This routine reads input samples and adjusts the logical clock to 785 * track the A/D sample clock by dropping or duplicating codec samples. 786 * It also controls the A/D signal level with an AGC loop to mimimize 787 * quantization noise and avoid overload. 788 */ 789static void 790wwv_receive( 791 struct recvbuf *rbufp /* receive buffer structure pointer */ 792 ) 793{ 794 struct peer *peer; 795 struct refclockproc *pp; 796 struct wwvunit *up; 797 798 /* 799 * Local variables 800 */ 801 double sample; /* codec sample */ 802 u_char *dpt; /* buffer pointer */ 803 int bufcnt; /* buffer counter */ 804 l_fp ltemp; 805 806 peer = (struct peer *)rbufp->recv_srcclock; 807 pp = peer->procptr; 808 up = (struct wwvunit *)pp->unitptr; 809 810 /* 811 * Main loop - read until there ain't no more. Note codec 812 * samples are bit-inverted. 813 */ 814 DTOLFP((double)rbufp->recv_length / SECOND, <emp); 815 L_SUB(&rbufp->recv_time, <emp); 816 up->timestamp = rbufp->recv_time; 817 dpt = rbufp->recv_buffer; 818 for (bufcnt = 0; bufcnt < rbufp->recv_length; bufcnt++) { 819 sample = up->comp[~*dpt++ & 0xff]; 820 821 /* 822 * Clip noise spikes greater than MAXAMP (6000) and 823 * record the number of clips to be used later by the 824 * AGC. 825 */ 826 if (sample > MAXAMP) { 827 sample = MAXAMP; 828 up->clipcnt++; 829 } else if (sample < -MAXAMP) { 830 sample = -MAXAMP; 831 up->clipcnt++; 832 } 833 834 /* 835 * Variable frequency oscillator. The codec oscillator 836 * runs at the nominal rate of 8000 samples per second, 837 * or 125 us per sample. A frequency change of one unit 838 * results in either duplicating or deleting one sample 839 * per second, which results in a frequency change of 840 * 125 PPM. 841 */ 842 up->phase += (up->freq + clock_codec) / SECOND; 843 if (up->phase >= .5) { 844 up->phase -= 1.; 845 } else if (up->phase < -.5) { 846 up->phase += 1.; 847 wwv_rf(peer, sample); 848 wwv_rf(peer, sample); 849 } else { 850 wwv_rf(peer, sample); 851 } 852 L_ADD(&up->timestamp, &up->tick); 853 } 854 855 /* 856 * Set the input port and monitor gain for the next buffer. 857 */ 858 if (pp->sloppyclockflag & CLK_FLAG2) 859 up->port = 2; 860 else 861 up->port = 1; 862 if (pp->sloppyclockflag & CLK_FLAG3) 863 up->mongain = MONGAIN; 864 else 865 up->mongain = 0; 866} 867 868 869/* 870 * wwv_poll - called by the transmit procedure 871 * 872 * This routine keeps track of status. If no offset samples have been 873 * processed during a poll interval, a timeout event is declared. If 874 * errors have have occurred during the interval, they are reported as 875 * well. 876 */ 877static void 878wwv_poll( 879 int unit, /* instance number (not used) */ 880 struct peer *peer /* peer structure pointer */ 881 ) 882{ 883 struct refclockproc *pp; 884 struct wwvunit *up; 885 886 pp = peer->procptr; 887 up = (struct wwvunit *)pp->unitptr; 888 if (up->errflg) 889 refclock_report(peer, up->errflg); 890 up->errflg = 0; 891 pp->polls++; 892} 893 894 895/* 896 * wwv_rf - process signals and demodulate to baseband 897 * 898 * This routine grooms and filters decompanded raw audio samples. The 899 * output signal is the 100-Hz filtered baseband data signal in 900 * quadrature phase. The routine also determines the minute synch epoch, 901 * as well as certain signal maxima, minima and related values. 902 * 903 * There are two 1-s ramps used by this program. Both count the 8000 904 * logical clock samples spanning exactly one second. The epoch ramp 905 * counts the samples starting at an arbitrary time. The rphase ramp 906 * counts the samples starting at the 5-ms second sync pulse found 907 * during the epoch ramp. 908 * 909 * There are two 1-m ramps used by this program. The mphase ramp counts 910 * the 480,000 logical clock samples spanning exactly one minute and 911 * starting at an arbitrary time. The rsec ramp counts the 60 seconds of 912 * the minute starting at the 800-ms minute sync pulse found during the 913 * mphase ramp. The rsec ramp drives the seconds state machine to 914 * determine the bits and digits of the timecode. 915 * 916 * Demodulation operations are based on three synthesized quadrature 917 * sinusoids: 100 Hz for the data signal, 1000 Hz for the WWV sync 918 * signal and 1200 Hz for the WWVH sync signal. These drive synchronous 919 * matched filters for the data signal (170 ms at 100 Hz), WWV minute 920 * sync signal (800 ms at 1000 Hz) and WWVH minute sync signal (800 ms 921 * at 1200 Hz). Two additional matched filters are switched in 922 * as required for the WWV second sync signal (5 cycles at 1000 Hz) and 923 * WWVH second sync signal (6 cycles at 1200 Hz). 924 */ 925static void 926wwv_rf( 927 struct peer *peer, /* peerstructure pointer */ 928 double isig /* input signal */ 929 ) 930{ 931 struct refclockproc *pp; 932 struct wwvunit *up; 933 struct sync *sp, *rp; 934 935 static double lpf[5]; /* 150-Hz lpf delay line */ 936 double data; /* lpf output */ 937 static double bpf[9]; /* 1000/1200-Hz bpf delay line */ 938 double syncx; /* bpf output */ 939 static double mf[41]; /* 1000/1200-Hz mf delay line */ 940 double mfsync; /* mf output */ 941 942 static int iptr; /* data channel pointer */ 943 static double ibuf[DATSIZ]; /* data I channel delay line */ 944 static double qbuf[DATSIZ]; /* data Q channel delay line */ 945 946 static int jptr; /* sync channel pointer */ 947 static int kptr; /* tick channel pointer */ 948 949 static int csinptr; /* wwv channel phase */ 950 static double cibuf[SYNSIZ]; /* wwv I channel delay line */ 951 static double cqbuf[SYNSIZ]; /* wwv Q channel delay line */ 952 static double ciamp; /* wwv I channel amplitude */ 953 static double cqamp; /* wwv Q channel amplitude */ 954 955 static double csibuf[TCKSIZ]; /* wwv I tick delay line */ 956 static double csqbuf[TCKSIZ]; /* wwv Q tick delay line */ 957 static double csiamp; /* wwv I tick amplitude */ 958 static double csqamp; /* wwv Q tick amplitude */ 959 960 static int hsinptr; /* wwvh channel phase */ 961 static double hibuf[SYNSIZ]; /* wwvh I channel delay line */ 962 static double hqbuf[SYNSIZ]; /* wwvh Q channel delay line */ 963 static double hiamp; /* wwvh I channel amplitude */ 964 static double hqamp; /* wwvh Q channel amplitude */ 965 966 static double hsibuf[TCKSIZ]; /* wwvh I tick delay line */ 967 static double hsqbuf[TCKSIZ]; /* wwvh Q tick delay line */ 968 static double hsiamp; /* wwvh I tick amplitude */ 969 static double hsqamp; /* wwvh Q tick amplitude */ 970 971 static double epobuf[SECOND]; /* second sync comb filter */ 972 static double epomax, nxtmax; /* second sync amplitude buffer */ 973 static int epopos; /* epoch second sync position buffer */ 974 975 static int iniflg; /* initialization flag */ 976 int epoch; /* comb filter index */ 977 double dtemp; 978 int i; 979 980 pp = peer->procptr; 981 up = (struct wwvunit *)pp->unitptr; 982 983 if (!iniflg) { 984 iniflg = 1; 985 memset((char *)lpf, 0, sizeof(lpf)); 986 memset((char *)bpf, 0, sizeof(bpf)); 987 memset((char *)mf, 0, sizeof(mf)); 988 memset((char *)ibuf, 0, sizeof(ibuf)); 989 memset((char *)qbuf, 0, sizeof(qbuf)); 990 memset((char *)cibuf, 0, sizeof(cibuf)); 991 memset((char *)cqbuf, 0, sizeof(cqbuf)); 992 memset((char *)csibuf, 0, sizeof(csibuf)); 993 memset((char *)csqbuf, 0, sizeof(csqbuf)); 994 memset((char *)hibuf, 0, sizeof(hibuf)); 995 memset((char *)hqbuf, 0, sizeof(hqbuf)); 996 memset((char *)hsibuf, 0, sizeof(hsibuf)); 997 memset((char *)hsqbuf, 0, sizeof(hsqbuf)); 998 memset((char *)epobuf, 0, sizeof(epobuf)); 999 } 1000 1001 /* 1002 * Baseband data demodulation. The 100-Hz subcarrier is 1003 * extracted using a 150-Hz IIR lowpass filter. This attenuates 1004 * the 1000/1200-Hz sync signals, as well as the 440-Hz and 1005 * 600-Hz tones and most of the noise and voice modulation 1006 * components. 1007 * 1008 * The subcarrier is transmitted 10 dB down from the carrier. 1009 * The DGAIN parameter can be adjusted for this and to 1010 * compensate for the radio audio response at 100 Hz. 1011 * 1012 * Matlab IIR 4th-order IIR elliptic, 150 Hz lowpass, 0.2 dB 1013 * passband ripple, -50 dB stopband ripple, phase delay 0.97 ms. 1014 */ 1015 data = (lpf[4] = lpf[3]) * 8.360961e-01; 1016 data += (lpf[3] = lpf[2]) * -3.481740e+00; 1017 data += (lpf[2] = lpf[1]) * 5.452988e+00; 1018 data += (lpf[1] = lpf[0]) * -3.807229e+00; 1019 lpf[0] = isig * DGAIN - data; 1020 data = lpf[0] * 3.281435e-03 1021 + lpf[1] * -1.149947e-02 1022 + lpf[2] * 1.654858e-02 1023 + lpf[3] * -1.149947e-02 1024 + lpf[4] * 3.281435e-03; 1025 1026 /* 1027 * The 100-Hz data signal is demodulated using a pair of 1028 * quadrature multipliers, matched filters and a phase lock 1029 * loop. The I and Q quadrature data signals are produced by 1030 * multiplying the filtered signal by 100-Hz sine and cosine 1031 * signals, respectively. The signals are processed by 170-ms 1032 * synchronous matched filters to produce the amplitude and 1033 * phase signals used by the demodulator. The signals are scaled 1034 * to produce unit energy at the maximum value. 1035 */ 1036 i = up->datapt; 1037 up->datapt = (up->datapt + IN100) % 80; 1038 dtemp = sintab[i] * data / (MS / 2. * DATCYC); 1039 up->irig -= ibuf[iptr]; 1040 ibuf[iptr] = dtemp; 1041 up->irig += dtemp; 1042 1043 i = (i + 20) % 80; 1044 dtemp = sintab[i] * data / (MS / 2. * DATCYC); 1045 up->qrig -= qbuf[iptr]; 1046 qbuf[iptr] = dtemp; 1047 up->qrig += dtemp; 1048 iptr = (iptr + 1) % DATSIZ; 1049 1050 /* 1051 * Baseband sync demodulation. The 1000/1200 sync signals are 1052 * extracted using a 600-Hz IIR bandpass filter. This removes 1053 * the 100-Hz data subcarrier, as well as the 440-Hz and 600-Hz 1054 * tones and most of the noise and voice modulation components. 1055 * 1056 * Matlab 4th-order IIR elliptic, 800-1400 Hz bandpass, 0.2 dB 1057 * passband ripple, -50 dB stopband ripple, phase delay 0.91 ms. 1058 */ 1059 syncx = (bpf[8] = bpf[7]) * 4.897278e-01; 1060 syncx += (bpf[7] = bpf[6]) * -2.765914e+00; 1061 syncx += (bpf[6] = bpf[5]) * 8.110921e+00; 1062 syncx += (bpf[5] = bpf[4]) * -1.517732e+01; 1063 syncx += (bpf[4] = bpf[3]) * 1.975197e+01; 1064 syncx += (bpf[3] = bpf[2]) * -1.814365e+01; 1065 syncx += (bpf[2] = bpf[1]) * 1.159783e+01; 1066 syncx += (bpf[1] = bpf[0]) * -4.735040e+00; 1067 bpf[0] = isig - syncx; 1068 syncx = bpf[0] * 8.203628e-03 1069 + bpf[1] * -2.375732e-02 1070 + bpf[2] * 3.353214e-02 1071 + bpf[3] * -4.080258e-02 1072 + bpf[4] * 4.605479e-02 1073 + bpf[5] * -4.080258e-02 1074 + bpf[6] * 3.353214e-02 1075 + bpf[7] * -2.375732e-02 1076 + bpf[8] * 8.203628e-03; 1077 1078 /* 1079 * The 1000/1200 sync signals are demodulated using a pair of 1080 * quadrature multipliers and matched filters. However, 1081 * synchronous demodulation at these frequencies is impractical, 1082 * so only the signal amplitude is used. The I and Q quadrature 1083 * sync signals are produced by multiplying the filtered signal 1084 * by 1000-Hz (WWV) and 1200-Hz (WWVH) sine and cosine signals, 1085 * respectively. The WWV and WWVH signals are processed by 800- 1086 * ms synchronous matched filters and combined to produce the 1087 * minute sync signal and detect which one (or both) the WWV or 1088 * WWVH signal is present. The WWV and WWVH signals are also 1089 * processed by 5-ms synchronous matched filters and combined to 1090 * produce the second sync signal. The signals are scaled to 1091 * produce unit energy at the maximum value. 1092 * 1093 * Note the master timing ramps, which run continuously. The 1094 * minute counter (mphase) counts the samples in the minute, 1095 * while the second counter (epoch) counts the samples in the 1096 * second. 1097 */ 1098 up->mphase = (up->mphase + 1) % MINUTE; 1099 epoch = up->mphase % SECOND; 1100 1101 /* 1102 * WWV 1103 */ 1104 i = csinptr; 1105 csinptr = (csinptr + IN1000) % 80; 1106 1107 dtemp = sintab[i] * syncx / (MS / 2.); 1108 ciamp -= cibuf[jptr]; 1109 cibuf[jptr] = dtemp; 1110 ciamp += dtemp; 1111 csiamp -= csibuf[kptr]; 1112 csibuf[kptr] = dtemp; 1113 csiamp += dtemp; 1114 1115 i = (i + 20) % 80; 1116 dtemp = sintab[i] * syncx / (MS / 2.); 1117 cqamp -= cqbuf[jptr]; 1118 cqbuf[jptr] = dtemp; 1119 cqamp += dtemp; 1120 csqamp -= csqbuf[kptr]; 1121 csqbuf[kptr] = dtemp; 1122 csqamp += dtemp; 1123 1124 sp = &up->mitig[up->achan].wwv; 1125 sp->amp = sqrt(ciamp * ciamp + cqamp * cqamp) / SYNCYC; 1126 if (!(up->status & MSYNC)) 1127 wwv_qrz(peer, sp, (int)(pp->fudgetime1 * SECOND)); 1128 1129 /* 1130 * WWVH 1131 */ 1132 i = hsinptr; 1133 hsinptr = (hsinptr + IN1200) % 80; 1134 1135 dtemp = sintab[i] * syncx / (MS / 2.); 1136 hiamp -= hibuf[jptr]; 1137 hibuf[jptr] = dtemp; 1138 hiamp += dtemp; 1139 hsiamp -= hsibuf[kptr]; 1140 hsibuf[kptr] = dtemp; 1141 hsiamp += dtemp; 1142 1143 i = (i + 20) % 80; 1144 dtemp = sintab[i] * syncx / (MS / 2.); 1145 hqamp -= hqbuf[jptr]; 1146 hqbuf[jptr] = dtemp; 1147 hqamp += dtemp; 1148 hsqamp -= hsqbuf[kptr]; 1149 hsqbuf[kptr] = dtemp; 1150 hsqamp += dtemp; 1151 1152 rp = &up->mitig[up->achan].wwvh; 1153 rp->amp = sqrt(hiamp * hiamp + hqamp * hqamp) / SYNCYC; 1154 if (!(up->status & MSYNC)) 1155 wwv_qrz(peer, rp, (int)(pp->fudgetime2 * SECOND)); 1156 jptr = (jptr + 1) % SYNSIZ; 1157 kptr = (kptr + 1) % TCKSIZ; 1158 1159 /* 1160 * The following section is called once per minute. It does 1161 * housekeeping and timeout functions and empties the dustbins. 1162 */ 1163 if (up->mphase == 0) { 1164 up->watch++; 1165 if (!(up->status & MSYNC)) { 1166 1167 /* 1168 * If minute sync has not been acquired before 1169 * ACQSN timeout (6 min), or if no signal is 1170 * heard, the program cycles to the next 1171 * frequency and tries again. 1172 */ 1173 if (!wwv_newchan(peer)) 1174 up->watch = 0; 1175 } else { 1176 1177 /* 1178 * If the leap bit is set, set the minute epoch 1179 * back one second so the station processes 1180 * don't miss a beat. 1181 */ 1182 if (up->status & LEPSEC) { 1183 up->mphase -= SECOND; 1184 if (up->mphase < 0) 1185 up->mphase += MINUTE; 1186 } 1187 } 1188 } 1189 1190 /* 1191 * When the channel metric reaches threshold and the second 1192 * counter matches the minute epoch within the second, the 1193 * driver has synchronized to the station. The second number is 1194 * the remaining seconds until the next minute epoch, while the 1195 * sync epoch is zero. Watch out for the first second; if 1196 * already synchronized to the second, the buffered sync epoch 1197 * must be set. 1198 * 1199 * Note the guard interval is 200 ms; if for some reason the 1200 * clock drifts more than that, it might wind up in the wrong 1201 * second. If the maximum frequency error is not more than about 1202 * 1 PPM, the clock can go as much as two days while still in 1203 * the same second. 1204 */ 1205 if (up->status & MSYNC) { 1206 wwv_epoch(peer); 1207 } else if (up->sptr != NULL) { 1208 sp = up->sptr; 1209 if (sp->metric >= TTHR && epoch == sp->mepoch % SECOND) 1210 { 1211 up->rsec = (60 - sp->mepoch / SECOND) % 60; 1212 up->rphase = 0; 1213 up->status |= MSYNC; 1214 up->watch = 0; 1215 if (!(up->status & SSYNC)) 1216 up->repoch = up->yepoch = epoch; 1217 else 1218 up->repoch = up->yepoch; 1219 1220 } 1221 } 1222 1223 /* 1224 * The second sync pulse is extracted using 5-ms (40 sample) FIR 1225 * matched filters at 1000 Hz for WWV or 1200 Hz for WWVH. This 1226 * pulse is used for the most precise synchronization, since if 1227 * provides a resolution of one sample (125 us). The filters run 1228 * only if the station has been reliably determined. 1229 */ 1230 if (up->status & SELV) 1231 mfsync = sqrt(csiamp * csiamp + csqamp * csqamp) / 1232 TCKCYC; 1233 else if (up->status & SELH) 1234 mfsync = sqrt(hsiamp * hsiamp + hsqamp * hsqamp) / 1235 TCKCYC; 1236 else 1237 mfsync = 0; 1238 1239 /* 1240 * Enhance the seconds sync pulse using a 1-s (8000-sample) comb 1241 * filter. Correct for the FIR matched filter delay, which is 5 1242 * ms for both the WWV and WWVH filters, and also for the 1243 * propagation delay. Once each second look for second sync. If 1244 * not in minute sync, fiddle the codec gain. Note the SNR is 1245 * computed from the maximum sample and the envelope of the 1246 * sample 6 ms before it, so if we slip more than a cycle the 1247 * SNR should plummet. The signal is scaled to produce unit 1248 * energy at the maximum value. 1249 */ 1250 dtemp = (epobuf[epoch] += (mfsync - epobuf[epoch]) / 1251 up->avgint); 1252 if (dtemp > epomax) { 1253 int j; 1254 1255 epomax = dtemp; 1256 epopos = epoch; 1257 j = epoch - 6 * MS; 1258 if (j < 0) 1259 j += SECOND; 1260 nxtmax = fabs(epobuf[j]); 1261 } 1262 if (epoch == 0) { 1263 up->epomax = epomax; 1264 up->eposnr = wwv_snr(epomax, nxtmax); 1265 epopos -= TCKCYC * MS; 1266 if (epopos < 0) 1267 epopos += SECOND; 1268 wwv_endpoc(peer, epopos); 1269 if (!(up->status & SSYNC)) 1270 up->alarm |= SYNERR; 1271 epomax = 0; 1272 if (!(up->status & MSYNC)) 1273 wwv_gain(peer); 1274 } 1275} 1276 1277 1278/* 1279 * wwv_qrz - identify and acquire WWV/WWVH minute sync pulse 1280 * 1281 * This routine implements a virtual station process used to acquire 1282 * minute sync and to mitigate among the ten frequency and station 1283 * combinations. During minute sync acquisition the process probes each 1284 * frequency and station in turn for the minute pulse, which 1285 * involves searching through the entire 480,000-sample minute. The 1286 * process finds the maximum signal and RMS noise plus signal. Then, the 1287 * actual noise is determined by subtracting the energy of the matched 1288 * filter. 1289 * 1290 * Students of radar receiver technology will discover this algorithm 1291 * amounts to a range-gate discriminator. A valid pulse must have peak 1292 * amplitude at least QTHR (2500) and SNR at least QSNR (20) dB and the 1293 * difference between the current and previous epoch must be less than 1294 * AWND (20 ms). Note that the discriminator peak occurs about 800 ms 1295 * into the second, so the timing is retarded to the previous second 1296 * epoch. 1297 */ 1298static void 1299wwv_qrz( 1300 struct peer *peer, /* peer structure pointer */ 1301 struct sync *sp, /* sync channel structure */ 1302 int pdelay /* propagation delay (samples) */ 1303 ) 1304{ 1305 struct refclockproc *pp; 1306 struct wwvunit *up; 1307 char tbuf[TBUF]; /* monitor buffer */ 1308 long epoch; 1309 1310 pp = peer->procptr; 1311 up = (struct wwvunit *)pp->unitptr; 1312 1313 /* 1314 * Find the sample with peak amplitude, which defines the minute 1315 * epoch. Accumulate all samples to determine the total noise 1316 * energy. 1317 */ 1318 epoch = up->mphase - pdelay - SYNSIZ; 1319 if (epoch < 0) 1320 epoch += MINUTE; 1321 if (sp->amp > sp->maxeng) { 1322 sp->maxeng = sp->amp; 1323 sp->pos = epoch; 1324 } 1325 sp->noieng += sp->amp; 1326 1327 /* 1328 * At the end of the minute, determine the epoch of the minute 1329 * sync pulse, as well as the difference between the current and 1330 * previous epoches due to the intrinsic frequency error plus 1331 * jitter. When calculating the SNR, subtract the pulse energy 1332 * from the total noise energy and then normalize. 1333 */ 1334 if (up->mphase == 0) { 1335 sp->synmax = sp->maxeng; 1336 sp->synsnr = wwv_snr(sp->synmax, (sp->noieng - 1337 sp->synmax) / MINUTE); 1338 if (sp->count == 0) 1339 sp->lastpos = sp->pos; 1340 epoch = (sp->pos - sp->lastpos) % MINUTE; 1341 sp->reach <<= 1; 1342 if (sp->reach & (1 << AMAX)) 1343 sp->count--; 1344 if (sp->synmax > ATHR && sp->synsnr > ASNR) { 1345 if (abs(epoch) < AWND * MS) { 1346 sp->reach |= 1; 1347 sp->count++; 1348 sp->mepoch = sp->lastpos = sp->pos; 1349 } else if (sp->count == 1) { 1350 sp->lastpos = sp->pos; 1351 } 1352 } 1353 if (up->watch > ACQSN) 1354 sp->metric = 0; 1355 else 1356 sp->metric = wwv_metric(sp); 1357 if (pp->sloppyclockflag & CLK_FLAG4) { 1358 sprintf(tbuf, 1359 "wwv8 %04x %3d %s %04x %.0f %.0f/%.1f %ld %ld", 1360 up->status, up->gain, sp->refid, 1361 sp->reach & 0xffff, sp->metric, sp->synmax, 1362 sp->synsnr, sp->pos % SECOND, epoch); 1363 record_clock_stats(&peer->srcadr, tbuf); 1364#ifdef DEBUG 1365 if (debug) 1366 printf("%s\n", tbuf); 1367#endif /* DEBUG */ 1368 } 1369 sp->maxeng = sp->noieng = 0; 1370 } 1371} 1372 1373 1374/* 1375 * wwv_endpoc - identify and acquire second sync pulse 1376 * 1377 * This routine is called at the end of the second sync interval. It 1378 * determines the second sync epoch position within the second and 1379 * disciplines the sample clock using a frequency-lock loop (FLL). 1380 * 1381 * Second sync is determined in the RF input routine as the maximum 1382 * over all 8000 samples in the second comb filter. To assure accurate 1383 * and reliable time and frequency discipline, this routine performs a 1384 * great deal of heavy-handed heuristic data filtering and grooming. 1385 */ 1386static void 1387wwv_endpoc( 1388 struct peer *peer, /* peer structure pointer */ 1389 int epopos /* epoch max position */ 1390 ) 1391{ 1392 struct refclockproc *pp; 1393 struct wwvunit *up; 1394 static int epoch_mf[3]; /* epoch median filter */ 1395 static int tepoch; /* current second epoch */ 1396 static int xepoch; /* last second epoch */ 1397 static int zepoch; /* last run epoch */ 1398 static int zcount; /* last run end time */ 1399 static int scount; /* seconds counter */ 1400 static int syncnt; /* run length counter */ 1401 static int maxrun; /* longest run length */ 1402 static int mepoch; /* longest run end epoch */ 1403 static int mcount; /* longest run end time */ 1404 static int avgcnt; /* averaging interval counter */ 1405 static int avginc; /* averaging ratchet */ 1406 static int iniflg; /* initialization flag */ 1407 char tbuf[TBUF]; /* monitor buffer */ 1408 double dtemp; 1409 int tmp2; 1410 1411 pp = peer->procptr; 1412 up = (struct wwvunit *)pp->unitptr; 1413 if (!iniflg) { 1414 iniflg = 1; 1415 memset((char *)epoch_mf, 0, sizeof(epoch_mf)); 1416 } 1417 1418 /* 1419 * If the signal amplitude or SNR fall below thresholds, dim the 1420 * second sync lamp and wait for hotter ions. If no stations are 1421 * heard, we are either in a probe cycle or the ions are really 1422 * cold. 1423 */ 1424 scount++; 1425 if (up->epomax < STHR || up->eposnr < SSNR) { 1426 up->status &= ~(SSYNC | FGATE); 1427 avgcnt = syncnt = maxrun = 0; 1428 return; 1429 } 1430 if (!(up->status & (SELV | SELH))) 1431 return; 1432 1433 /* 1434 * A three-stage median filter is used to help denoise the 1435 * second sync pulse. The median sample becomes the candidate 1436 * epoch. 1437 */ 1438 epoch_mf[2] = epoch_mf[1]; 1439 epoch_mf[1] = epoch_mf[0]; 1440 epoch_mf[0] = epopos; 1441 if (epoch_mf[0] > epoch_mf[1]) { 1442 if (epoch_mf[1] > epoch_mf[2]) 1443 tepoch = epoch_mf[1]; /* 0 1 2 */ 1444 else if (epoch_mf[2] > epoch_mf[0]) 1445 tepoch = epoch_mf[0]; /* 2 0 1 */ 1446 else 1447 tepoch = epoch_mf[2]; /* 0 2 1 */ 1448 } else { 1449 if (epoch_mf[1] < epoch_mf[2]) 1450 tepoch = epoch_mf[1]; /* 2 1 0 */ 1451 else if (epoch_mf[2] < epoch_mf[0]) 1452 tepoch = epoch_mf[0]; /* 1 0 2 */ 1453 else 1454 tepoch = epoch_mf[2]; /* 1 2 0 */ 1455 } 1456 1457 1458 /* 1459 * If the epoch candidate is the same as the last one, increment 1460 * the run counter. If not, save the length, epoch and end 1461 * time of the current run for use later and reset the counter. 1462 * The epoch is considered valid if the run is at least SCMP 1463 * (10) s, the minute is synchronized and the interval since the 1464 * last epoch is not greater than the averaging interval. Thus, 1465 * after a long absence, the program will wait a full averaging 1466 * interval while the comb filter charges up and noise 1467 * dissapates.. 1468 */ 1469 tmp2 = (tepoch - xepoch) % SECOND; 1470 if (tmp2 == 0) { 1471 syncnt++; 1472 if (syncnt > SCMP && up->status & MSYNC && (up->status & 1473 FGATE || scount - zcount <= up->avgint)) { 1474 up->status |= SSYNC; 1475 up->yepoch = tepoch; 1476 } 1477 } else if (syncnt >= maxrun) { 1478 maxrun = syncnt; 1479 mcount = scount; 1480 mepoch = xepoch; 1481 syncnt = 0; 1482 } 1483 if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status & 1484 MSYNC)) { 1485 sprintf(tbuf, 1486 "wwv1 %04x %3d %4d %5.0f %5.1f %5d %4d %4d %4d", 1487 up->status, up->gain, tepoch, up->epomax, 1488 up->eposnr, tmp2, avgcnt, syncnt, 1489 maxrun); 1490 record_clock_stats(&peer->srcadr, tbuf); 1491#ifdef DEBUG 1492 if (debug) 1493 printf("%s\n", tbuf); 1494#endif /* DEBUG */ 1495 } 1496 avgcnt++; 1497 if (avgcnt < up->avgint) { 1498 xepoch = tepoch; 1499 return; 1500 } 1501 1502 /* 1503 * The sample clock frequency is disciplined using a first-order 1504 * feedback loop with time constant consistent with the Allan 1505 * intercept of typical computer clocks. During each averaging 1506 * interval the candidate epoch at the end of the longest run is 1507 * determined. If the longest run is zero, all epoches in the 1508 * interval are different, so the candidate epoch is the current 1509 * epoch. The frequency update is computed from the candidate 1510 * epoch difference (125-us units) and time difference (seconds) 1511 * between updates. 1512 */ 1513 if (syncnt >= maxrun) { 1514 maxrun = syncnt; 1515 mcount = scount; 1516 mepoch = xepoch; 1517 } 1518 xepoch = tepoch; 1519 if (maxrun == 0) { 1520 mepoch = tepoch; 1521 mcount = scount; 1522 } 1523 1524 /* 1525 * The master clock runs at the codec sample frequency of 8000 1526 * Hz, so the intrinsic time resolution is 125 us. The frequency 1527 * resolution ranges from 18 PPM at the minimum averaging 1528 * interval of 8 s to 0.12 PPM at the maximum interval of 1024 1529 * s. An offset update is determined at the end of the longest 1530 * run in each averaging interval. The frequency adjustment is 1531 * computed from the difference between offset updates and the 1532 * interval between them. 1533 * 1534 * The maximum frequency adjustment ranges from 187 PPM at the 1535 * minimum interval to 1.5 PPM at the maximum. If the adjustment 1536 * exceeds the maximum, the update is discarded and the 1537 * hysteresis counter is decremented. Otherwise, the frequency 1538 * is incremented by the adjustment, but clamped to the maximum 1539 * 187.5 PPM. If the update is less than half the maximum, the 1540 * hysteresis counter is incremented. If the counter increments 1541 * to +3, the averaging interval is doubled and the counter set 1542 * to zero; if it decrements to -3, the interval is halved and 1543 * the counter set to zero. 1544 */ 1545 dtemp = (mepoch - zepoch) % SECOND; 1546 if (up->status & FGATE) { 1547 if (abs(dtemp) < MAXFREQ * MINAVG) { 1548 up->freq += (dtemp / 2.) / ((mcount - zcount) * 1549 FCONST); 1550 if (up->freq > MAXFREQ) 1551 up->freq = MAXFREQ; 1552 else if (up->freq < -MAXFREQ) 1553 up->freq = -MAXFREQ; 1554 if (abs(dtemp) < MAXFREQ * MINAVG / 2.) { 1555 if (avginc < 3) { 1556 avginc++; 1557 } else { 1558 if (up->avgint < MAXAVG) { 1559 up->avgint <<= 1; 1560 avginc = 0; 1561 } 1562 } 1563 } 1564 } else { 1565 if (avginc > -3) { 1566 avginc--; 1567 } else { 1568 if (up->avgint > MINAVG) { 1569 up->avgint >>= 1; 1570 avginc = 0; 1571 } 1572 } 1573 } 1574 } 1575 if (pp->sloppyclockflag & CLK_FLAG4) { 1576 sprintf(tbuf, 1577 "wwv2 %04x %5.0f %5.1f %5d %4d %4d %4d %4.0f %7.2f", 1578 up->status, up->epomax, up->eposnr, mepoch, 1579 up->avgint, maxrun, mcount - zcount, dtemp, 1580 up->freq * 1e6 / SECOND); 1581 record_clock_stats(&peer->srcadr, tbuf); 1582#ifdef DEBUG 1583 if (debug) 1584 printf("%s\n", tbuf); 1585#endif /* DEBUG */ 1586 } 1587 1588 /* 1589 * This is a valid update; set up for the next interval. 1590 */ 1591 up->status |= FGATE; 1592 zepoch = mepoch; 1593 zcount = mcount; 1594 avgcnt = syncnt = maxrun = 0; 1595} 1596 1597 1598/* 1599 * wwv_epoch - epoch scanner 1600 * 1601 * This routine extracts data signals from the 100-Hz subcarrier. It 1602 * scans the receiver second epoch to determine the signal amplitudes 1603 * and pulse timings. Receiver synchronization is determined by the 1604 * minute sync pulse detected in the wwv_rf() routine and the second 1605 * sync pulse detected in the wwv_epoch() routine. The transmitted 1606 * signals are delayed by the propagation delay, receiver delay and 1607 * filter delay of this program. Delay corrections are introduced 1608 * separately for WWV and WWVH. 1609 * 1610 * Most communications radios use a highpass filter in the audio stages, 1611 * which can do nasty things to the subcarrier phase relative to the 1612 * sync pulses. Therefore, the data subcarrier reference phase is 1613 * disciplined using the hardlimited quadrature-phase signal sampled at 1614 * the same time as the in-phase signal. The phase tracking loop uses 1615 * phase adjustments of plus-minus one sample (125 us). 1616 */ 1617static void 1618wwv_epoch( 1619 struct peer *peer /* peer structure pointer */ 1620 ) 1621{ 1622 struct refclockproc *pp; 1623 struct wwvunit *up; 1624 struct chan *cp; 1625 static double sigmin, sigzer, sigone, engmax, engmin; 1626 1627 pp = peer->procptr; 1628 up = (struct wwvunit *)pp->unitptr; 1629 1630 /* 1631 * Find the maximum minute sync pulse energy for both the 1632 * WWV and WWVH stations. This will be used later for channel 1633 * and station mitigation. Also set the seconds epoch at 800 ms 1634 * well before the end of the second to make sure we never set 1635 * the epoch backwards. 1636 */ 1637 cp = &up->mitig[up->achan]; 1638 if (cp->wwv.amp > cp->wwv.syneng) 1639 cp->wwv.syneng = cp->wwv.amp; 1640 if (cp->wwvh.amp > cp->wwvh.syneng) 1641 cp->wwvh.syneng = cp->wwvh.amp; 1642 if (up->rphase == 800 * MS) 1643 up->repoch = up->yepoch; 1644 1645 /* 1646 * Use the signal amplitude at epoch 15 ms as the noise floor. 1647 * This gives a guard time of +-15 ms from the beginning of the 1648 * second until the second pulse rises at 30 ms. There is a 1649 * compromise here; we want to delay the sample as long as 1650 * possible to give the radio time to change frequency and the 1651 * AGC to stabilize, but as early as possible if the second 1652 * epoch is not exact. 1653 */ 1654 if (up->rphase == 15 * MS) 1655 sigmin = sigzer = sigone = up->irig; 1656 1657 /* 1658 * Latch the data signal at 200 ms. Keep this around until the 1659 * end of the second. Use the signal energy as the peak to 1660 * compute the SNR. Use the Q sample to adjust the 100-Hz 1661 * reference oscillator phase. 1662 */ 1663 if (up->rphase == 200 * MS) { 1664 sigzer = up->irig; 1665 engmax = sqrt(up->irig * up->irig + up->qrig * 1666 up->qrig); 1667 up->datpha = up->qrig / up->avgint; 1668 if (up->datpha >= 0) { 1669 up->datapt++; 1670 if (up->datapt >= 80) 1671 up->datapt -= 80; 1672 } else { 1673 up->datapt--; 1674 if (up->datapt < 0) 1675 up->datapt += 80; 1676 } 1677 } 1678 1679 1680 /* 1681 * Latch the data signal at 500 ms. Keep this around until the 1682 * end of the second. 1683 */ 1684 else if (up->rphase == 500 * MS) 1685 sigone = up->irig; 1686 1687 /* 1688 * At the end of the second crank the clock state machine and 1689 * adjust the codec gain. Note the epoch is buffered from the 1690 * center of the second in order to avoid jitter while the 1691 * seconds synch is diddling the epoch. Then, determine the true 1692 * offset and update the median filter in the driver interface. 1693 * 1694 * Use the energy at the end of the second as the noise to 1695 * compute the SNR for the data pulse. This gives a better 1696 * measurement than the beginning of the second, especially when 1697 * returning from the probe channel. This gives a guard time of 1698 * 30 ms from the decay of the longest pulse to the rise of the 1699 * next pulse. 1700 */ 1701 up->rphase++; 1702 if (up->mphase % SECOND == up->repoch) { 1703 up->status &= ~(DGATE | BGATE); 1704 engmin = sqrt(up->irig * up->irig + up->qrig * 1705 up->qrig); 1706 up->datsig = engmax; 1707 up->datsnr = wwv_snr(engmax, engmin); 1708 1709 /* 1710 * If the amplitude or SNR is below threshold, average a 1711 * 0 in the the integrators; otherwise, average the 1712 * bipolar signal. This is done to avoid noise polution. 1713 */ 1714 if (engmax < DTHR || up->datsnr < DSNR) { 1715 up->status |= DGATE; 1716 wwv_rsec(peer, 0); 1717 } else { 1718 sigzer -= sigone; 1719 sigone -= sigmin; 1720 wwv_rsec(peer, sigone - sigzer); 1721 } 1722 if (up->status & (DGATE | BGATE)) 1723 up->errcnt++; 1724 if (up->errcnt > MAXERR) 1725 up->alarm |= LOWERR; 1726 wwv_gain(peer); 1727 cp = &up->mitig[up->achan]; 1728 cp->wwv.syneng = 0; 1729 cp->wwvh.syneng = 0; 1730 up->rphase = 0; 1731 } 1732} 1733 1734 1735/* 1736 * wwv_rsec - process receiver second 1737 * 1738 * This routine is called at the end of each receiver second to 1739 * implement the per-second state machine. The machine assembles BCD 1740 * digit bits, decodes miscellaneous bits and dances the leap seconds. 1741 * 1742 * Normally, the minute has 60 seconds numbered 0-59. If the leap 1743 * warning bit is set, the last minute (1439) of 30 June (day 181 or 182 1744 * for leap years) or 31 December (day 365 or 366 for leap years) is 1745 * augmented by one second numbered 60. This is accomplished by 1746 * extending the minute interval by one second and teaching the state 1747 * machine to ignore it. 1748 */ 1749static void 1750wwv_rsec( 1751 struct peer *peer, /* peer structure pointer */ 1752 double bit 1753 ) 1754{ 1755 static int iniflg; /* initialization flag */ 1756 static double bcddld[4]; /* BCD data bits */ 1757 static double bitvec[61]; /* bit integrator for misc bits */ 1758 struct refclockproc *pp; 1759 struct wwvunit *up; 1760 struct chan *cp; 1761 struct sync *sp, *rp; 1762 char tbuf[TBUF]; /* monitor buffer */ 1763 int sw, arg, nsec; 1764 1765 pp = peer->procptr; 1766 up = (struct wwvunit *)pp->unitptr; 1767 if (!iniflg) { 1768 iniflg = 1; 1769 memset((char *)bitvec, 0, sizeof(bitvec)); 1770 } 1771 1772 /* 1773 * The bit represents the probability of a hit on zero (negative 1774 * values), a hit on one (positive values) or a miss (zero 1775 * value). The likelihood vector is the exponential average of 1776 * these probabilities. Only the bits of this vector 1777 * corresponding to the miscellaneous bits of the timecode are 1778 * used, but it's easier to do them all. After that, crank the 1779 * seconds state machine. 1780 */ 1781 nsec = up->rsec; 1782 up->rsec++; 1783 bitvec[nsec] += (bit - bitvec[nsec]) / TCONST; 1784 sw = progx[nsec].sw; 1785 arg = progx[nsec].arg; 1786 1787 /* 1788 * The minute state machine. Fly off to a particular section as 1789 * directed by the transition matrix and second number. 1790 */ 1791 switch (sw) { 1792 1793 /* 1794 * Ignore this second. 1795 */ 1796 case IDLE: /* 9, 45-49 */ 1797 break; 1798 1799 /* 1800 * Probe channel stuff 1801 * 1802 * The WWV/H format contains data pulses in second 59 (position 1803 * identifier) and second 1, but not in second 0. The minute 1804 * sync pulse is contained in second 0. At the end of second 58 1805 * QSY to the probe channel, which rotates in turn over all 1806 * WWV/H frequencies. At the end of second 0 measure the minute 1807 * sync pulse. At the end of second 1 measure the data pulse and 1808 * QSY back to the data channel. Note that the actions commented 1809 * here happen at the end of the second numbered as shown. 1810 * 1811 * At the end of second 0 save the minute sync amplitude latched 1812 * at 800 ms as the signal later used to calculate the SNR. 1813 */ 1814 case SYNC2: /* 0 */ 1815 cp = &up->mitig[up->achan]; 1816 cp->wwv.synmax = cp->wwv.syneng; 1817 cp->wwvh.synmax = cp->wwvh.syneng; 1818 break; 1819 1820 /* 1821 * At the end of second 1 use the minute sync amplitude latched 1822 * at 800 ms as the noise to calculate the SNR. If the minute 1823 * sync pulse and SNR are above thresholds and the data pulse 1824 * amplitude and SNR are above thresolds, shift a 1 into the 1825 * station reachability register; otherwise, shift a 0. The 1826 * number of 1 bits in the last six intervals is a component of 1827 * the channel metric computed by the wwv_metric() routine. 1828 * Finally, QSY back to the data channel. 1829 */ 1830 case SYNC3: /* 1 */ 1831 cp = &up->mitig[up->achan]; 1832 1833 /* 1834 * WWV station 1835 */ 1836 sp = &cp->wwv; 1837 sp->synsnr = wwv_snr(sp->synmax, sp->amp); 1838 sp->reach <<= 1; 1839 if (sp->reach & (1 << AMAX)) 1840 sp->count--; 1841 if (sp->synmax >= QTHR && sp->synsnr >= QSNR && 1842 !(up->status & (DGATE | BGATE))) { 1843 sp->reach |= 1; 1844 sp->count++; 1845 } 1846 sp->metric = wwv_metric(sp); 1847 1848 /* 1849 * WWVH station 1850 */ 1851 rp = &cp->wwvh; 1852 rp->synsnr = wwv_snr(rp->synmax, rp->amp); 1853 rp->reach <<= 1; 1854 if (rp->reach & (1 << AMAX)) 1855 rp->count--; 1856 if (rp->synmax >= QTHR && rp->synsnr >= QSNR && 1857 !(up->status & (DGATE | BGATE))) { 1858 rp->reach |= 1; 1859 rp->count++; 1860 } 1861 rp->metric = wwv_metric(rp); 1862 if (pp->sloppyclockflag & CLK_FLAG4) { 1863 sprintf(tbuf, 1864 "wwv5 %04x %3d %4d %.0f/%.1f %.0f/%.1f %s %04x %.0f %.0f/%.1f %s %04x %.0f %.0f/%.1f", 1865 up->status, up->gain, up->yepoch, 1866 up->epomax, up->eposnr, up->datsig, 1867 up->datsnr, 1868 sp->refid, sp->reach & 0xffff, 1869 sp->metric, sp->synmax, sp->synsnr, 1870 rp->refid, rp->reach & 0xffff, 1871 rp->metric, rp->synmax, rp->synsnr); 1872 record_clock_stats(&peer->srcadr, tbuf); 1873#ifdef DEBUG 1874 if (debug) 1875 printf("%s\n", tbuf); 1876#endif /* DEBUG */ 1877 } 1878 up->errcnt = up->digcnt = up->alarm = 0; 1879 1880 /* 1881 * If synchronized to a station, restart if no stations 1882 * have been heard within the PANIC timeout (2 days). If 1883 * not and the minute digit has been found, restart if 1884 * not synchronized withing the SYNCH timeout (40 m). If 1885 * not, restart if the unit digit has not been found 1886 * within the DATA timeout (15 m). 1887 */ 1888 if (up->status & INSYNC) { 1889 if (up->watch > PANIC) { 1890 wwv_newgame(peer); 1891 return; 1892 } 1893 } else if (up->status & DSYNC) { 1894 if (up->watch > SYNCH) { 1895 wwv_newgame(peer); 1896 return; 1897 } 1898 } else if (up->watch > DATA) { 1899 wwv_newgame(peer); 1900 return; 1901 } 1902 wwv_newchan(peer); 1903 break; 1904 1905 /* 1906 * Save the bit probability in the BCD data vector at the index 1907 * given by the argument. Bits not used in the digit are forced 1908 * to zero. 1909 */ 1910 case COEF1: /* 4-7 */ 1911 bcddld[arg] = bit; 1912 break; 1913 1914 case COEF: /* 10-13, 15-17, 20-23, 25-26, 1915 30-33, 35-38, 40-41, 51-54 */ 1916 if (up->status & DSYNC) 1917 bcddld[arg] = bit; 1918 else 1919 bcddld[arg] = 0; 1920 break; 1921 1922 case COEF2: /* 18, 27-28, 42-43 */ 1923 bcddld[arg] = 0; 1924 break; 1925 1926 /* 1927 * Correlate coefficient vector with each valid digit vector and 1928 * save in decoding matrix. We step through the decoding matrix 1929 * digits correlating each with the coefficients and saving the 1930 * greatest and the next lower for later SNR calculation. 1931 */ 1932 case DECIM2: /* 29 */ 1933 wwv_corr4(peer, &up->decvec[arg], bcddld, bcd2); 1934 break; 1935 1936 case DECIM3: /* 44 */ 1937 wwv_corr4(peer, &up->decvec[arg], bcddld, bcd3); 1938 break; 1939 1940 case DECIM6: /* 19 */ 1941 wwv_corr4(peer, &up->decvec[arg], bcddld, bcd6); 1942 break; 1943 1944 case DECIM9: /* 8, 14, 24, 34, 39 */ 1945 wwv_corr4(peer, &up->decvec[arg], bcddld, bcd9); 1946 break; 1947 1948 /* 1949 * Miscellaneous bits. If above the positive threshold, declare 1950 * 1; if below the negative threshold, declare 0; otherwise 1951 * raise the BGATE bit. The design is intended to avoid 1952 * integrating noise under low SNR conditions. 1953 */ 1954 case MSC20: /* 55 */ 1955 wwv_corr4(peer, &up->decvec[YR + 1], bcddld, bcd9); 1956 /* fall through */ 1957 1958 case MSCBIT: /* 2-3, 50, 56-57 */ 1959 if (bitvec[nsec] > BTHR) { 1960 if (!(up->misc & arg)) 1961 up->alarm |= CMPERR; 1962 up->misc |= arg; 1963 } else if (bitvec[nsec] < -BTHR) { 1964 if (up->misc & arg) 1965 up->alarm |= CMPERR; 1966 up->misc &= ~arg; 1967 } else { 1968 up->status |= BGATE; 1969 } 1970 break; 1971 1972 /* 1973 * Save the data channel gain, then QSY to the probe channel and 1974 * dim the seconds comb filters. The www_newchan() routine will 1975 * light them back up. 1976 */ 1977 case MSC21: /* 58 */ 1978 if (bitvec[nsec] > BTHR) { 1979 if (!(up->misc & arg)) 1980 up->alarm |= CMPERR; 1981 up->misc |= arg; 1982 } else if (bitvec[nsec] < -BTHR) { 1983 if (up->misc & arg) 1984 up->alarm |= CMPERR; 1985 up->misc &= ~arg; 1986 } else { 1987 up->status |= BGATE; 1988 } 1989 up->status &= ~(SELV | SELH); 1990#ifdef ICOM 1991 if (up->fd_icom > 0) { 1992 up->schan = (up->schan + 1) % NCHAN; 1993 wwv_qsy(peer, up->schan); 1994 } else { 1995 up->mitig[up->achan].gain = up->gain; 1996 } 1997#else 1998 up->mitig[up->achan].gain = up->gain; 1999#endif /* ICOM */ 2000 break; 2001 2002 /* 2003 * The endgames 2004 * 2005 * During second 59 the receiver and codec AGC are settling 2006 * down, so the data pulse is unusable as quality metric. If 2007 * LEPSEC is set on the last minute of 30 June or 31 December, 2008 * the transmitter and receiver insert an extra second (60) in 2009 * the timescale and the minute sync repeats the second. Once 2010 * leaps occurred at intervals of about 18 months, but the last 2011 * leap before the most recent leap in 1995 was in 1998. 2012 */ 2013 case MIN1: /* 59 */ 2014 if (up->status & LEPSEC) 2015 break; 2016 2017 /* fall through */ 2018 2019 case MIN2: /* 60 */ 2020 up->status &= ~LEPSEC; 2021 wwv_tsec(peer); 2022 up->rsec = 0; 2023 wwv_clock(peer); 2024 break; 2025 } 2026 if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status & 2027 DSYNC)) { 2028 sprintf(tbuf, 2029 "wwv3 %2d %04x %3d %4d %5.0f %5.1f %5.0f %5.1f %5.0f", 2030 nsec, up->status, up->gain, up->yepoch, up->epomax, 2031 up->eposnr, up->datsig, up->datsnr, bit); 2032 record_clock_stats(&peer->srcadr, tbuf); 2033#ifdef DEBUG 2034 if (debug) 2035 printf("%s\n", tbuf); 2036#endif /* DEBUG */ 2037 } 2038 pp->disp += AUDIO_PHI; 2039} 2040 2041/* 2042 * The radio clock is set if the alarm bits are all zero. After that, 2043 * the time is considered valid if the second sync bit is lit. It should 2044 * not be a surprise, especially if the radio is not tunable, that 2045 * sometimes no stations are above the noise and the integrators 2046 * discharge below the thresholds. We assume that, after a day of signal 2047 * loss, the minute sync epoch will be in the same second. This requires 2048 * the codec frequency be accurate within 6 PPM. Practical experience 2049 * shows the frequency typically within 0.1 PPM, so after a day of 2050 * signal loss, the time should be within 8.6 ms.. 2051 */ 2052static void 2053wwv_clock( 2054 struct peer *peer /* peer unit pointer */ 2055 ) 2056{ 2057 struct refclockproc *pp; 2058 struct wwvunit *up; 2059 l_fp offset; /* offset in NTP seconds */ 2060 2061 pp = peer->procptr; 2062 up = (struct wwvunit *)pp->unitptr; 2063 if (!(up->status & SSYNC)) 2064 up->alarm |= SYNERR; 2065 if (up->digcnt < 9) 2066 up->alarm |= NINERR; 2067 if (!(up->alarm)) 2068 up->status |= INSYNC; 2069 if (up->status & INSYNC && up->status & SSYNC) { 2070 if (up->misc & SECWAR) 2071 pp->leap = LEAP_ADDSECOND; 2072 else 2073 pp->leap = LEAP_NOWARNING; 2074 pp->second = up->rsec; 2075 pp->minute = up->decvec[MN].digit + up->decvec[MN + 2076 1].digit * 10; 2077 pp->hour = up->decvec[HR].digit + up->decvec[HR + 2078 1].digit * 10; 2079 pp->day = up->decvec[DA].digit + up->decvec[DA + 2080 1].digit * 10 + up->decvec[DA + 2].digit * 100; 2081 pp->year = up->decvec[YR].digit + up->decvec[YR + 2082 1].digit * 10; 2083 pp->year += 2000; 2084 L_CLR(&offset); 2085 if (!clocktime(pp->day, pp->hour, pp->minute, 2086 pp->second, GMT, up->timestamp.l_ui, 2087 &pp->yearstart, &offset.l_ui)) { 2088 up->errflg = CEVNT_BADTIME; 2089 } else { 2090 up->watch = 0; 2091 pp->disp = 0; 2092 pp->lastref = up->timestamp; 2093 refclock_process_offset(pp, offset, 2094 up->timestamp, PDELAY + up->pdelay); 2095 refclock_receive(peer); 2096 } 2097 } 2098 pp->lencode = timecode(up, pp->a_lastcode); 2099 record_clock_stats(&peer->srcadr, pp->a_lastcode); 2100#ifdef DEBUG 2101 if (debug) 2102 printf("wwv: timecode %d %s\n", pp->lencode, 2103 pp->a_lastcode); 2104#endif /* DEBUG */ 2105} 2106 2107 2108/* 2109 * wwv_corr4 - determine maximum-likelihood digit 2110 * 2111 * This routine correlates the received digit vector with the BCD 2112 * coefficient vectors corresponding to all valid digits at the given 2113 * position in the decoding matrix. The maximum value corresponds to the 2114 * maximum-likelihood digit, while the ratio of this value to the next 2115 * lower value determines the likelihood function. Note that, if the 2116 * digit is invalid, the likelihood vector is averaged toward a miss. 2117 */ 2118static void 2119wwv_corr4( 2120 struct peer *peer, /* peer unit pointer */ 2121 struct decvec *vp, /* decoding table pointer */ 2122 double data[], /* received data vector */ 2123 double tab[][4] /* correlation vector array */ 2124 ) 2125{ 2126 struct refclockproc *pp; 2127 struct wwvunit *up; 2128 double topmax, nxtmax; /* metrics */ 2129 double acc; /* accumulator */ 2130 char tbuf[TBUF]; /* monitor buffer */ 2131 int mldigit; /* max likelihood digit */ 2132 int i, j; 2133 2134 pp = peer->procptr; 2135 up = (struct wwvunit *)pp->unitptr; 2136 2137 /* 2138 * Correlate digit vector with each BCD coefficient vector. If 2139 * any BCD digit bit is bad, consider all bits a miss. Until the 2140 * minute units digit has been resolved, don't to anything else. 2141 * Note the SNR is calculated as the ratio of the largest 2142 * likelihood value to the next largest likelihood value. 2143 */ 2144 mldigit = 0; 2145 topmax = nxtmax = -MAXAMP; 2146 for (i = 0; tab[i][0] != 0; i++) { 2147 acc = 0; 2148 for (j = 0; j < 4; j++) 2149 acc += data[j] * tab[i][j]; 2150 acc = (vp->like[i] += (acc - vp->like[i]) / TCONST); 2151 if (acc > topmax) { 2152 nxtmax = topmax; 2153 topmax = acc; 2154 mldigit = i; 2155 } else if (acc > nxtmax) { 2156 nxtmax = acc; 2157 } 2158 } 2159 vp->digprb = topmax; 2160 vp->digsnr = wwv_snr(topmax, nxtmax); 2161 2162 /* 2163 * The current maximum-likelihood digit is compared to the last 2164 * maximum-likelihood digit. If different, the compare counter 2165 * and maximum-likelihood digit are reset. When the compare 2166 * counter reaches the BCMP threshold (3), the digit is assumed 2167 * correct. When the compare counter of all nine digits have 2168 * reached threshold, the clock is assumed correct. 2169 * 2170 * Note that the clock display digit is set before the compare 2171 * counter has reached threshold; however, the clock display is 2172 * not considered correct until all nine clock digits have 2173 * reached threshold. This is intended as eye candy, but avoids 2174 * mistakes when the signal is low and the SNR is very marginal. 2175 */ 2176 if (vp->digprb < BTHR || vp->digsnr < BSNR) { 2177 up->status |= BGATE; 2178 } else { 2179 if (vp->digit != mldigit) { 2180 up->alarm |= CMPERR; 2181 if (vp->count > 0) 2182 vp->count--; 2183 if (vp->count == 0) 2184 vp->digit = mldigit; 2185 } else { 2186 if (vp->count < BCMP) 2187 vp->count++; 2188 if (vp->count == BCMP) { 2189 up->status |= DSYNC; 2190 up->digcnt++; 2191 } 2192 } 2193 } 2194 if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status & 2195 INSYNC)) { 2196 sprintf(tbuf, 2197 "wwv4 %2d %04x %3d %4d %5.0f %2d %d %d %d %5.0f %5.1f", 2198 up->rsec - 1, up->status, up->gain, up->yepoch, 2199 up->epomax, vp->radix, vp->digit, mldigit, 2200 vp->count, vp->digprb, vp->digsnr); 2201 record_clock_stats(&peer->srcadr, tbuf); 2202#ifdef DEBUG 2203 if (debug) 2204 printf("%s\n", tbuf); 2205#endif /* DEBUG */ 2206 } 2207} 2208 2209 2210/* 2211 * wwv_tsec - transmitter minute processing 2212 * 2213 * This routine is called at the end of the transmitter minute. It 2214 * implements a state machine that advances the logical clock subject to 2215 * the funny rules that govern the conventional clock and calendar. 2216 */ 2217static void 2218wwv_tsec( 2219 struct peer *peer /* driver structure pointer */ 2220 ) 2221{ 2222 struct refclockproc *pp; 2223 struct wwvunit *up; 2224 int minute, day, isleap; 2225 int temp; 2226 2227 pp = peer->procptr; 2228 up = (struct wwvunit *)pp->unitptr; 2229 2230 /* 2231 * Advance minute unit of the day. Don't propagate carries until 2232 * the unit minute digit has been found. 2233 */ 2234 temp = carry(&up->decvec[MN]); /* minute units */ 2235 if (!(up->status & DSYNC)) 2236 return; 2237 2238 /* 2239 * Propagate carries through the day. 2240 */ 2241 if (temp == 0) /* carry minutes */ 2242 temp = carry(&up->decvec[MN + 1]); 2243 if (temp == 0) /* carry hours */ 2244 temp = carry(&up->decvec[HR]); 2245 if (temp == 0) 2246 temp = carry(&up->decvec[HR + 1]); 2247 2248 /* 2249 * Decode the current minute and day. Set leap day if the 2250 * timecode leap bit is set on 30 June or 31 December. Set leap 2251 * minute if the last minute on leap day, but only if the clock 2252 * is syncrhronized. This code fails in 2400 AD. 2253 */ 2254 minute = up->decvec[MN].digit + up->decvec[MN + 1].digit * 2255 10 + up->decvec[HR].digit * 60 + up->decvec[HR + 2256 1].digit * 600; 2257 day = up->decvec[DA].digit + up->decvec[DA + 1].digit * 10 + 2258 up->decvec[DA + 2].digit * 100; 2259 2260 /* 2261 * Set the leap bit on the last minute of the leap day. 2262 */ 2263 isleap = up->decvec[YR].digit & 0x3; 2264 if (up->misc & SECWAR && up->status & INSYNC) { 2265 if ((day == (isleap ? 182 : 183) || day == (isleap ? 2266 365 : 366)) && minute == 1439) 2267 up->status |= LEPSEC; 2268 } 2269 2270 /* 2271 * Roll the day if this the first minute and propagate carries 2272 * through the year. 2273 */ 2274 if (minute != 1440) 2275 return; 2276 2277 minute = 0; 2278 while (carry(&up->decvec[HR]) != 0); /* advance to minute 0 */ 2279 while (carry(&up->decvec[HR + 1]) != 0); 2280 day++; 2281 temp = carry(&up->decvec[DA]); /* carry days */ 2282 if (temp == 0) 2283 temp = carry(&up->decvec[DA + 1]); 2284 if (temp == 0) 2285 temp = carry(&up->decvec[DA + 2]); 2286 2287 /* 2288 * Roll the year if this the first day and propagate carries 2289 * through the century. 2290 */ 2291 if (day != (isleap ? 365 : 366)) 2292 return; 2293 2294 day = 1; 2295 while (carry(&up->decvec[DA]) != 1); /* advance to day 1 */ 2296 while (carry(&up->decvec[DA + 1]) != 0); 2297 while (carry(&up->decvec[DA + 2]) != 0); 2298 temp = carry(&up->decvec[YR]); /* carry years */ 2299 if (temp == 0) 2300 carry(&up->decvec[YR + 1]); 2301} 2302 2303 2304/* 2305 * carry - process digit 2306 * 2307 * This routine rotates a likelihood vector one position and increments 2308 * the clock digit modulo the radix. It returns the new clock digit or 2309 * zero if a carry occurred. Once synchronized, the clock digit will 2310 * match the maximum-likelihood digit corresponding to that position. 2311 */ 2312static int 2313carry( 2314 struct decvec *dp /* decoding table pointer */ 2315 ) 2316{ 2317 int temp; 2318 int j; 2319 2320 dp->digit++; 2321 if (dp->digit == dp->radix) 2322 dp->digit = 0; 2323 temp = dp->like[dp->radix - 1]; 2324 for (j = dp->radix - 1; j > 0; j--) 2325 dp->like[j] = dp->like[j - 1]; 2326 dp->like[0] = temp; 2327 return (dp->digit); 2328} 2329 2330 2331/* 2332 * wwv_snr - compute SNR or likelihood function 2333 */ 2334static double 2335wwv_snr( 2336 double signal, /* signal */ 2337 double noise /* noise */ 2338 ) 2339{ 2340 double rval; 2341 2342 /* 2343 * This is a little tricky. Due to the way things are measured, 2344 * either or both the signal or noise amplitude can be negative 2345 * or zero. The intent is that, if the signal is negative or 2346 * zero, the SNR must always be zero. This can happen with the 2347 * subcarrier SNR before the phase has been aligned. On the 2348 * other hand, in the likelihood function the "noise" is the 2349 * next maximum down from the peak and this could be negative. 2350 * However, in this case the SNR is truly stupendous, so we 2351 * simply cap at MAXSNR dB (40). 2352 */ 2353 if (signal <= 0) { 2354 rval = 0; 2355 } else if (noise <= 0) { 2356 rval = MAXSNR; 2357 } else { 2358 rval = 20. * log10(signal / noise); 2359 if (rval > MAXSNR) 2360 rval = MAXSNR; 2361 } 2362 return (rval); 2363} 2364 2365 2366/* 2367 * wwv_newchan - change to new data channel 2368 * 2369 * The radio actually appears to have ten channels, one channel for each 2370 * of five frequencies and each of two stations (WWV and WWVH), although 2371 * if not tunable only the DCHAN channel appears live. While the radio 2372 * is tuned to the working data channel frequency and station for most 2373 * of the minute, during seconds 59, 0 and 1 the radio is tuned to a 2374 * probe frequency in order to search for minute sync pulse and data 2375 * subcarrier from other transmitters. 2376 * 2377 * The search for WWV and WWVH operates simultaneously, with WWV minute 2378 * sync pulse at 1000 Hz and WWVH at 1200 Hz. The probe frequency 2379 * rotates each minute over 2.5, 5, 10, 15 and 20 MHz in order and yes, 2380 * we all know WWVH is dark on 20 MHz, but few remember when WWV was lit 2381 * on 25 MHz. 2382 * 2383 * This routine selects the best channel using a metric computed from 2384 * the reachability register and minute pulse amplitude. Normally, the 2385 * award goes to the the channel with the highest metric; but, in case 2386 * of ties, the award goes to the channel with the highest minute sync 2387 * pulse amplitude and then to the highest frequency. 2388 * 2389 * The routine performs an important squelch function to keep dirty data 2390 * from polluting the integrators. In order to consider a station valid, 2391 * the metric must be at least MTHR (13); otherwise, the station select 2392 * bits are cleared so the second sync is disabled and the data bit 2393 * integrators averaged to a miss. 2394 */ 2395static int 2396wwv_newchan( 2397 struct peer *peer /* peer structure pointer */ 2398 ) 2399{ 2400 struct refclockproc *pp; 2401 struct wwvunit *up; 2402 struct sync *sp, *rp; 2403 double rank, dtemp; 2404 int i, j, rval; 2405 2406 pp = peer->procptr; 2407 up = (struct wwvunit *)pp->unitptr; 2408 2409 /* 2410 * Search all five station pairs looking for the channel with 2411 * maximum metric. 2412 */ 2413 sp = NULL; 2414 j = 0; 2415 rank = 0; 2416 for (i = 0; i < NCHAN; i++) { 2417 rp = &up->mitig[i].wwvh; 2418 dtemp = rp->metric; 2419 if (dtemp >= rank) { 2420 rank = dtemp; 2421 sp = rp; 2422 j = i; 2423 } 2424 rp = &up->mitig[i].wwv; 2425 dtemp = rp->metric; 2426 if (dtemp >= rank) { 2427 rank = dtemp; 2428 sp = rp; 2429 j = i; 2430 } 2431 } 2432 2433 /* 2434 * If the strongest signal is less than the MTHR threshold (13), 2435 * we are beneath the waves, so squelch the second sync and 2436 * advance to the next station. This makes sure all stations are 2437 * scanned when the ions grow dim. If the strongest signal is 2438 * greater than the threshold, tune to that frequency and 2439 * transmitter QTH. 2440 */ 2441 up->status &= ~(SELV | SELH); 2442 if (rank < MTHR) { 2443 up->dchan = (up->dchan + 1) % NCHAN; 2444 if (up->status & METRIC) { 2445 up->status &= ~METRIC; 2446 refclock_report(peer, CEVNT_PROP); 2447 } 2448 rval = FALSE; 2449 } else { 2450 up->dchan = j; 2451 up->sptr = sp; 2452 memcpy(&pp->refid, sp->refid, 4); 2453 peer->refid = pp->refid; 2454 up->status |= METRIC; 2455 if (sp->select & SELV) { 2456 up->status |= SELV; 2457 up->pdelay = pp->fudgetime1; 2458 } else if (sp->select & SELH) { 2459 up->status |= SELH; 2460 up->pdelay = pp->fudgetime2; 2461 } else { 2462 up->pdelay = 0; 2463 } 2464 rval = TRUE; 2465 } 2466#ifdef ICOM 2467 if (up->fd_icom > 0) 2468 wwv_qsy(peer, up->dchan); 2469#endif /* ICOM */ 2470 return (rval); 2471} 2472 2473 2474/* 2475 * wwv_newgame - reset and start over 2476 * 2477 * There are three conditions resulting in a new game: 2478 * 2479 * 1 After finding the minute pulse (MSYNC lit), going 15 minutes 2480 * (DATA) without finding the unit seconds digit. 2481 * 2482 * 2 After finding good data (DSYNC lit), going more than 40 minutes 2483 * (SYNCH) without finding station sync (INSYNC lit). 2484 * 2485 * 3 After finding station sync (INSYNC lit), going more than 2 days 2486 * (PANIC) without finding any station. 2487 */ 2488static void 2489wwv_newgame( 2490 struct peer *peer /* peer structure pointer */ 2491 ) 2492{ 2493 struct refclockproc *pp; 2494 struct wwvunit *up; 2495 struct chan *cp; 2496 int i; 2497 2498 pp = peer->procptr; 2499 up = (struct wwvunit *)pp->unitptr; 2500 2501 /* 2502 * Initialize strategic values. Note we set the leap bits 2503 * NOTINSYNC and the refid "NONE". 2504 */ 2505 if (up->status) 2506 up->errflg = CEVNT_TIMEOUT; 2507 peer->leap = LEAP_NOTINSYNC; 2508 up->watch = up->status = up->alarm = 0; 2509 up->avgint = MINAVG; 2510 up->freq = 0; 2511 up->gain = MAXGAIN / 2; 2512 2513 /* 2514 * Initialize the station processes for audio gain, select bit, 2515 * station/frequency identifier and reference identifier. Start 2516 * probing at the strongest channel or the default channel if 2517 * nothing heard. 2518 */ 2519 memset(up->mitig, 0, sizeof(up->mitig)); 2520 for (i = 0; i < NCHAN; i++) { 2521 cp = &up->mitig[i]; 2522 cp->gain = up->gain; 2523 cp->wwv.select = SELV; 2524 sprintf(cp->wwv.refid, "WV%.0f", floor(qsy[i])); 2525 cp->wwvh.select = SELH; 2526 sprintf(cp->wwvh.refid, "WH%.0f", floor(qsy[i])); 2527 } 2528 up->dchan = (DCHAN + NCHAN - 1) % NCHAN; 2529 wwv_newchan(peer); 2530 up->schan = up->dchan; 2531} 2532 2533/* 2534 * wwv_metric - compute station metric 2535 * 2536 * The most significant bits represent the number of ones in the 2537 * station reachability register. The least significant bits represent 2538 * the minute sync pulse amplitude. The combined value is scaled 0-100. 2539 */ 2540double 2541wwv_metric( 2542 struct sync *sp /* station pointer */ 2543 ) 2544{ 2545 double dtemp; 2546 2547 dtemp = sp->count * MAXAMP; 2548 if (sp->synmax < MAXAMP) 2549 dtemp += sp->synmax; 2550 else 2551 dtemp += MAXAMP - 1; 2552 dtemp /= (AMAX + 1) * MAXAMP; 2553 return (dtemp * 100.); 2554} 2555 2556 2557#ifdef ICOM 2558/* 2559 * wwv_qsy - Tune ICOM receiver 2560 * 2561 * This routine saves the AGC for the current channel, switches to a new 2562 * channel and restores the AGC for that channel. If a tunable receiver 2563 * is not available, just fake it. 2564 */ 2565static int 2566wwv_qsy( 2567 struct peer *peer, /* peer structure pointer */ 2568 int chan /* channel */ 2569 ) 2570{ 2571 int rval = 0; 2572 struct refclockproc *pp; 2573 struct wwvunit *up; 2574 2575 pp = peer->procptr; 2576 up = (struct wwvunit *)pp->unitptr; 2577 if (up->fd_icom > 0) { 2578 up->mitig[up->achan].gain = up->gain; 2579 rval = icom_freq(up->fd_icom, peer->ttl & 0x7f, 2580 qsy[chan]); 2581 up->achan = chan; 2582 up->gain = up->mitig[up->achan].gain; 2583 } 2584 return (rval); 2585} 2586#endif /* ICOM */ 2587 2588 2589/* 2590 * timecode - assemble timecode string and length 2591 * 2592 * Prettytime format - similar to Spectracom 2593 * 2594 * sq yy ddd hh:mm:ss ld dut lset agc iden sig errs freq avgt 2595 * 2596 * s sync indicator ('?' or ' ') 2597 * q error bits (hex 0-F) 2598 * yyyy year of century 2599 * ddd day of year 2600 * hh hour of day 2601 * mm minute of hour 2602 * ss second of minute) 2603 * l leap second warning (' ' or 'L') 2604 * d DST state ('S', 'D', 'I', or 'O') 2605 * dut DUT sign and magnitude (0.1 s) 2606 * lset minutes since last clock update 2607 * agc audio gain (0-255) 2608 * iden reference identifier (station and frequency) 2609 * sig signal quality (0-100) 2610 * errs bit errors in last minute 2611 * freq frequency offset (PPM) 2612 * avgt averaging time (s) 2613 */ 2614static int 2615timecode( 2616 struct wwvunit *up, /* driver structure pointer */ 2617 char *ptr /* target string */ 2618 ) 2619{ 2620 struct sync *sp; 2621 int year, day, hour, minute, second, dut; 2622 char synchar, leapchar, dst; 2623 char cptr[50]; 2624 2625 2626 /* 2627 * Common fixed-format fields 2628 */ 2629 synchar = (up->status & INSYNC) ? ' ' : '?'; 2630 year = up->decvec[YR].digit + up->decvec[YR + 1].digit * 10 + 2631 2000; 2632 day = up->decvec[DA].digit + up->decvec[DA + 1].digit * 10 + 2633 up->decvec[DA + 2].digit * 100; 2634 hour = up->decvec[HR].digit + up->decvec[HR + 1].digit * 10; 2635 minute = up->decvec[MN].digit + up->decvec[MN + 1].digit * 10; 2636 second = 0; 2637 leapchar = (up->misc & SECWAR) ? 'L' : ' '; 2638 dst = dstcod[(up->misc >> 4) & 0x3]; 2639 dut = up->misc & 0x7; 2640 if (!(up->misc & DUTS)) 2641 dut = -dut; 2642 sprintf(ptr, "%c%1X", synchar, up->alarm); 2643 sprintf(cptr, " %4d %03d %02d:%02d:%02d %c%c %+d", 2644 year, day, hour, minute, second, leapchar, dst, dut); 2645 strcat(ptr, cptr); 2646 2647 /* 2648 * Specific variable-format fields 2649 */ 2650 sp = up->sptr; 2651 sprintf(cptr, " %d %d %s %.0f %d %.1f %d", up->watch, 2652 up->mitig[up->dchan].gain, sp->refid, sp->metric, 2653 up->errcnt, up->freq / SECOND * 1e6, up->avgint); 2654 strcat(ptr, cptr); 2655 return (strlen(ptr)); 2656} 2657 2658 2659/* 2660 * wwv_gain - adjust codec gain 2661 * 2662 * This routine is called at the end of each second. During the second 2663 * the number of signal clips above the MAXAMP threshold (6000). If 2664 * there are no clips, the gain is bumped up; if there are more than 2665 * MAXCLP clips (100), it is bumped down. The decoder is relatively 2666 * insensitive to amplitude, so this crudity works just peachy. The 2667 * routine also jiggles the input port and selectively mutes the 2668 * monitor. 2669 */ 2670static void 2671wwv_gain( 2672 struct peer *peer /* peer structure pointer */ 2673 ) 2674{ 2675 struct refclockproc *pp; 2676 struct wwvunit *up; 2677 2678 pp = peer->procptr; 2679 up = (struct wwvunit *)pp->unitptr; 2680 2681 /* 2682 * Apparently, the codec uses only the high order bits of the 2683 * gain control field. Thus, it may take awhile for changes to 2684 * wiggle the hardware bits. 2685 */ 2686 if (up->clipcnt == 0) { 2687 up->gain += 4; 2688 if (up->gain > MAXGAIN) 2689 up->gain = MAXGAIN; 2690 } else if (up->clipcnt > MAXCLP) { 2691 up->gain -= 4; 2692 if (up->gain < 0) 2693 up->gain = 0; 2694 } 2695 audio_gain(up->gain, up->mongain, up->port); 2696 up->clipcnt = 0; 2697#if DEBUG 2698 if (debug > 1) 2699 audio_show(); 2700#endif 2701} 2702 2703 2704#else 2705int refclock_wwv_bs; 2706#endif /* REFCLOCK */ 2707