1/* $NetBSD: refclock_wwv.c,v 1.8 2020/05/25 20:47:26 christos Exp $ */ 2 3/* 4 * refclock_wwv - clock driver for NIST WWV/H time/frequency station 5 */ 6#ifdef HAVE_CONFIG_H 7#include <config.h> 8#endif 9 10#if defined(REFCLOCK) && defined(CLOCK_WWV) 11 12#include "ntpd.h" 13#include "ntp_io.h" 14#include "ntp_refclock.h" 15#include "ntp_calendar.h" 16#include "ntp_stdlib.h" 17#include "audio.h" 18 19#include <stdio.h> 20#include <ctype.h> 21#include <math.h> 22#ifdef HAVE_SYS_IOCTL_H 23# include <sys/ioctl.h> 24#endif /* HAVE_SYS_IOCTL_H */ 25 26#define ICOM 1 27 28#ifdef ICOM 29#include "icom.h" 30#endif /* ICOM */ 31 32/* 33 * Audio WWV/H demodulator/decoder 34 * 35 * This driver synchronizes the computer time using data encoded in 36 * radio transmissions from NIST time/frequency stations WWV in Boulder, 37 * CO, and WWVH in Kauai, HI. Transmissions are made continuously on 38 * 2.5, 5, 10 and 15 MHz from WWV and WWVH, and 20 MHz from WWV. An 39 * ordinary AM shortwave receiver can be tuned manually to one of these 40 * frequencies or, in the case of ICOM receivers, the receiver can be 41 * tuned automatically using this program as propagation conditions 42 * change throughout the weasons, both day and night. 43 * 44 * The driver requires an audio codec or sound card with sampling rate 8 45 * kHz and mu-law companding. This is the same standard as used by the 46 * telephone industry and is supported by most hardware and operating 47 * systems, including Solaris, SunOS, FreeBSD, NetBSD and Linux. In this 48 * implementation, only one audio driver and codec can be supported on a 49 * single machine. 50 * 51 * The demodulation and decoding algorithms used in this driver are 52 * based on those developed for the TAPR DSP93 development board and the 53 * TI 320C25 digital signal processor described in: Mills, D.L. A 54 * precision radio clock for WWV transmissions. Electrical Engineering 55 * Report 97-8-1, University of Delaware, August 1997, 25 pp., available 56 * from www.eecis.udel.edu/~mills/reports.html. The algorithms described 57 * in this report have been modified somewhat to improve performance 58 * under weak signal conditions and to provide an automatic station 59 * identification feature. 60 * 61 * The ICOM code is normally compiled in the driver. It isn't used, 62 * unless the mode keyword on the server configuration command specifies 63 * a nonzero ICOM ID select code. The C-IV trace is turned on if the 64 * debug level is greater than one. 65 * 66 * Fudge factors 67 * 68 * Fudge flag4 causes the debugging output described above to be 69 * recorded in the clockstats file. Fudge flag2 selects the audio input 70 * port, where 0 is the mike port (default) and 1 is the line-in port. 71 * It does not seem useful to select the compact disc player port. Fudge 72 * flag3 enables audio monitoring of the input signal. For this purpose, 73 * the monitor gain is set to a default value. 74 * 75 * CEVNT_BADTIME invalid date or time 76 * CEVNT_PROP propagation failure - no stations heard 77 * CEVNT_TIMEOUT timeout (see newgame() below) 78 */ 79/* 80 * General definitions. These ordinarily do not need to be changed. 81 */ 82#define DEVICE_AUDIO "/dev/audio" /* audio device name */ 83#define AUDIO_BUFSIZ 320 /* audio buffer size (50 ms) */ 84#define PRECISION (-10) /* precision assumed (about 1 ms) */ 85#define DESCRIPTION "WWV/H Audio Demodulator/Decoder" /* WRU */ 86#define WWV_SEC 8000 /* second epoch (sample rate) (Hz) */ 87#define WWV_MIN (WWV_SEC * 60) /* minute epoch */ 88#define OFFSET 128 /* companded sample offset */ 89#define SIZE 256 /* decompanding table size */ 90#define MAXAMP 6000. /* max signal level reference */ 91#define MAXCLP 100 /* max clips above reference per s */ 92#define MAXSNR 40. /* max SNR reference */ 93#define MAXFREQ 1.5 /* max frequency tolerance (187 PPM) */ 94#define DATCYC 170 /* data filter cycles */ 95#define DATSIZ (DATCYC * MS) /* data filter size */ 96#define SYNCYC 800 /* minute filter cycles */ 97#define SYNSIZ (SYNCYC * MS) /* minute filter size */ 98#define TCKCYC 5 /* tick filter cycles */ 99#define TCKSIZ (TCKCYC * MS) /* tick filter size */ 100#define NCHAN 5 /* number of radio channels */ 101#define AUDIO_PHI 5e-6 /* dispersion growth factor */ 102#define TBUF 128 /* max monitor line length */ 103 104/* 105 * Tunable parameters. The DGAIN parameter can be changed to fit the 106 * audio response of the radio at 100 Hz. The WWV/WWVH data subcarrier 107 * is transmitted at about 20 percent percent modulation; the matched 108 * filter boosts it by a factor of 17 and the receiver response does 109 * what it does. The compromise value works for ICOM radios. If the 110 * radio is not tunable, the DCHAN parameter can be changed to fit the 111 * expected best propagation frequency: higher if further from the 112 * transmitter, lower if nearer. The compromise value works for the US 113 * right coast. 114 */ 115#define DCHAN 3 /* default radio channel (15 Mhz) */ 116#define DGAIN 5. /* subcarrier gain */ 117 118/* 119 * General purpose status bits (status) 120 * 121 * SELV and/or SELH are set when WWV or WWVH have been heard and cleared 122 * on signal loss. SSYNC is set when the second sync pulse has been 123 * acquired and cleared by signal loss. MSYNC is set when the minute 124 * sync pulse has been acquired. DSYNC is set when the units digit has 125 * has reached the threshold and INSYNC is set when all nine digits have 126 * reached the threshold. The MSYNC, DSYNC and INSYNC bits are cleared 127 * only by timeout, upon which the driver starts over from scratch. 128 * 129 * DGATE is lit if the data bit amplitude or SNR is below thresholds and 130 * BGATE is lit if the pulse width amplitude or SNR is below thresolds. 131 * LEPSEC is set during the last minute of the leap day. At the end of 132 * this minute the driver inserts second 60 in the seconds state machine 133 * and the minute sync slips a second. 134 */ 135#define MSYNC 0x0001 /* minute epoch sync */ 136#define SSYNC 0x0002 /* second epoch sync */ 137#define DSYNC 0x0004 /* minute units sync */ 138#define INSYNC 0x0008 /* clock synchronized */ 139#define FGATE 0x0010 /* frequency gate */ 140#define DGATE 0x0020 /* data pulse amplitude error */ 141#define BGATE 0x0040 /* data pulse width error */ 142#define METRIC 0x0080 /* one or more stations heard */ 143#define LEPSEC 0x1000 /* leap minute */ 144 145/* 146 * Station scoreboard bits 147 * 148 * These are used to establish the signal quality for each of the five 149 * frequencies and two stations. 150 */ 151#define SELV 0x0100 /* WWV station select */ 152#define SELH 0x0200 /* WWVH station select */ 153 154/* 155 * Alarm status bits (alarm) 156 * 157 * These bits indicate various alarm conditions, which are decoded to 158 * form the quality character included in the timecode. 159 */ 160#define CMPERR 0x1 /* digit or misc bit compare error */ 161#define LOWERR 0x2 /* low bit or digit amplitude or SNR */ 162#define NINERR 0x4 /* less than nine digits in minute */ 163#define SYNERR 0x8 /* not tracking second sync */ 164 165/* 166 * Watchcat timeouts (watch) 167 * 168 * If these timeouts expire, the status bits are mashed to zero and the 169 * driver starts from scratch. Suitably more refined procedures may be 170 * developed in future. All these are in minutes. 171 */ 172#define ACQSN 6 /* station acquisition timeout */ 173#define DATA 15 /* unit minutes timeout */ 174#define SYNCH 40 /* station sync timeout */ 175#define PANIC (2 * 1440) /* panic timeout */ 176 177/* 178 * Thresholds. These establish the minimum signal level, minimum SNR and 179 * maximum jitter thresholds which establish the error and false alarm 180 * rates of the driver. The values defined here may be on the 181 * adventurous side in the interest of the highest sensitivity. 182 */ 183#define MTHR 13. /* minute sync gate (percent) */ 184#define TTHR 50. /* minute sync threshold (percent) */ 185#define AWND 20 /* minute sync jitter threshold (ms) */ 186#define ATHR 2500. /* QRZ minute sync threshold */ 187#define ASNR 20. /* QRZ minute sync SNR threshold (dB) */ 188#define QTHR 2500. /* QSY minute sync threshold */ 189#define QSNR 20. /* QSY minute sync SNR threshold (dB) */ 190#define STHR 2500. /* second sync threshold */ 191#define SSNR 15. /* second sync SNR threshold (dB) */ 192#define SCMP 10 /* second sync compare threshold */ 193#define DTHR 1000. /* bit threshold */ 194#define DSNR 10. /* bit SNR threshold (dB) */ 195#define AMIN 3 /* min bit count */ 196#define AMAX 6 /* max bit count */ 197#define BTHR 1000. /* digit threshold */ 198#define BSNR 3. /* digit likelihood threshold (dB) */ 199#define BCMP 3 /* digit compare threshold */ 200#define MAXERR 40 /* maximum error alarm */ 201 202/* 203 * Tone frequency definitions. The increments are for 4.5-deg sine 204 * table. 205 */ 206#define MS (WWV_SEC / 1000) /* samples per millisecond */ 207#define IN100 ((100 * 80) / WWV_SEC) /* 100 Hz increment */ 208#define IN1000 ((1000 * 80) / WWV_SEC) /* 1000 Hz increment */ 209#define IN1200 ((1200 * 80) / WWV_SEC) /* 1200 Hz increment */ 210 211/* 212 * Acquisition and tracking time constants 213 */ 214#define MINAVG 8 /* min averaging time */ 215#define MAXAVG 1024 /* max averaging time */ 216#define FCONST 3 /* frequency time constant */ 217#define TCONST 16 /* data bit/digit time constant */ 218 219/* 220 * Miscellaneous status bits (misc) 221 * 222 * These bits correspond to designated bits in the WWV/H timecode. The 223 * bit probabilities are exponentially averaged over several minutes and 224 * processed by a integrator and threshold. 225 */ 226#define DUT1 0x01 /* 56 DUT .1 */ 227#define DUT2 0x02 /* 57 DUT .2 */ 228#define DUT4 0x04 /* 58 DUT .4 */ 229#define DUTS 0x08 /* 50 DUT sign */ 230#define DST1 0x10 /* 55 DST1 leap warning */ 231#define DST2 0x20 /* 2 DST2 DST1 delayed one day */ 232#define SECWAR 0x40 /* 3 leap second warning */ 233 234/* 235 * The on-time synchronization point is the positive-going zero crossing 236 * of the first cycle of the 5-ms second pulse. The IIR baseband filter 237 * phase delay is 0.91 ms, while the receiver delay is approximately 4.7 238 * ms at 1000 Hz. The fudge value -0.45 ms due to the codec and other 239 * causes was determined by calibrating to a PPS signal from a GPS 240 * receiver. The additional propagation delay specific to each receiver 241 * location can be programmed in the fudge time1 and time2 values for 242 * WWV and WWVH, respectively. 243 * 244 * The resulting offsets with a 2.4-GHz P4 running FreeBSD 6.1 are 245 * generally within .02 ms short-term with .02 ms jitter. The long-term 246 * offsets vary up to 0.3 ms due to ionosperhic layer height variations. 247 * The processor load due to the driver is 5.8 percent. 248 */ 249#define PDELAY ((.91 + 4.7 - 0.45) / 1000) /* system delay (s) */ 250 251/* 252 * Table of sine values at 4.5-degree increments. This is used by the 253 * synchronous matched filter demodulators. 254 */ 255double sintab[] = { 256 0.000000e+00, 7.845910e-02, 1.564345e-01, 2.334454e-01, /* 0-3 */ 257 3.090170e-01, 3.826834e-01, 4.539905e-01, 5.224986e-01, /* 4-7 */ 258 5.877853e-01, 6.494480e-01, 7.071068e-01, 7.604060e-01, /* 8-11 */ 259 8.090170e-01, 8.526402e-01, 8.910065e-01, 9.238795e-01, /* 12-15 */ 260 9.510565e-01, 9.723699e-01, 9.876883e-01, 9.969173e-01, /* 16-19 */ 261 1.000000e+00, 9.969173e-01, 9.876883e-01, 9.723699e-01, /* 20-23 */ 262 9.510565e-01, 9.238795e-01, 8.910065e-01, 8.526402e-01, /* 24-27 */ 263 8.090170e-01, 7.604060e-01, 7.071068e-01, 6.494480e-01, /* 28-31 */ 264 5.877853e-01, 5.224986e-01, 4.539905e-01, 3.826834e-01, /* 32-35 */ 265 3.090170e-01, 2.334454e-01, 1.564345e-01, 7.845910e-02, /* 36-39 */ 266-0.000000e+00, -7.845910e-02, -1.564345e-01, -2.334454e-01, /* 40-43 */ 267-3.090170e-01, -3.826834e-01, -4.539905e-01, -5.224986e-01, /* 44-47 */ 268-5.877853e-01, -6.494480e-01, -7.071068e-01, -7.604060e-01, /* 48-51 */ 269-8.090170e-01, -8.526402e-01, -8.910065e-01, -9.238795e-01, /* 52-55 */ 270-9.510565e-01, -9.723699e-01, -9.876883e-01, -9.969173e-01, /* 56-59 */ 271-1.000000e+00, -9.969173e-01, -9.876883e-01, -9.723699e-01, /* 60-63 */ 272-9.510565e-01, -9.238795e-01, -8.910065e-01, -8.526402e-01, /* 64-67 */ 273-8.090170e-01, -7.604060e-01, -7.071068e-01, -6.494480e-01, /* 68-71 */ 274-5.877853e-01, -5.224986e-01, -4.539905e-01, -3.826834e-01, /* 72-75 */ 275-3.090170e-01, -2.334454e-01, -1.564345e-01, -7.845910e-02, /* 76-79 */ 276 0.000000e+00}; /* 80 */ 277 278/* 279 * Decoder operations at the end of each second are driven by a state 280 * machine. The transition matrix consists of a dispatch table indexed 281 * by second number. Each entry in the table contains a case switch 282 * number and argument. 283 */ 284struct progx { 285 int sw; /* case switch number */ 286 int arg; /* argument */ 287}; 288 289/* 290 * Case switch numbers 291 */ 292#define IDLE 0 /* no operation */ 293#define COEF 1 /* BCD bit */ 294#define COEF1 2 /* BCD bit for minute unit */ 295#define COEF2 3 /* BCD bit not used */ 296#define DECIM9 4 /* BCD digit 0-9 */ 297#define DECIM6 5 /* BCD digit 0-6 */ 298#define DECIM3 6 /* BCD digit 0-3 */ 299#define DECIM2 7 /* BCD digit 0-2 */ 300#define MSCBIT 8 /* miscellaneous bit */ 301#define MSC20 9 /* miscellaneous bit */ 302#define MSC21 10 /* QSY probe channel */ 303#define MIN1 11 /* latch time */ 304#define MIN2 12 /* leap second */ 305#define SYNC2 13 /* latch minute sync pulse */ 306#define SYNC3 14 /* latch data pulse */ 307 308/* 309 * Offsets in decoding matrix 310 */ 311#define MN 0 /* minute digits (2) */ 312#define HR 2 /* hour digits (2) */ 313#define DA 4 /* day digits (3) */ 314#define YR 7 /* year digits (2) */ 315 316struct progx progx[] = { 317 {SYNC2, 0}, /* 0 latch minute sync pulse */ 318 {SYNC3, 0}, /* 1 latch data pulse */ 319 {MSCBIT, DST2}, /* 2 dst2 */ 320 {MSCBIT, SECWAR}, /* 3 lw */ 321 {COEF, 0}, /* 4 1 year units */ 322 {COEF, 1}, /* 5 2 */ 323 {COEF, 2}, /* 6 4 */ 324 {COEF, 3}, /* 7 8 */ 325 {DECIM9, YR}, /* 8 */ 326 {IDLE, 0}, /* 9 p1 */ 327 {COEF1, 0}, /* 10 1 minute units */ 328 {COEF1, 1}, /* 11 2 */ 329 {COEF1, 2}, /* 12 4 */ 330 {COEF1, 3}, /* 13 8 */ 331 {DECIM9, MN}, /* 14 */ 332 {COEF, 0}, /* 15 10 minute tens */ 333 {COEF, 1}, /* 16 20 */ 334 {COEF, 2}, /* 17 40 */ 335 {COEF2, 3}, /* 18 80 (not used) */ 336 {DECIM6, MN + 1}, /* 19 p2 */ 337 {COEF, 0}, /* 20 1 hour units */ 338 {COEF, 1}, /* 21 2 */ 339 {COEF, 2}, /* 22 4 */ 340 {COEF, 3}, /* 23 8 */ 341 {DECIM9, HR}, /* 24 */ 342 {COEF, 0}, /* 25 10 hour tens */ 343 {COEF, 1}, /* 26 20 */ 344 {COEF2, 2}, /* 27 40 (not used) */ 345 {COEF2, 3}, /* 28 80 (not used) */ 346 {DECIM2, HR + 1}, /* 29 p3 */ 347 {COEF, 0}, /* 30 1 day units */ 348 {COEF, 1}, /* 31 2 */ 349 {COEF, 2}, /* 32 4 */ 350 {COEF, 3}, /* 33 8 */ 351 {DECIM9, DA}, /* 34 */ 352 {COEF, 0}, /* 35 10 day tens */ 353 {COEF, 1}, /* 36 20 */ 354 {COEF, 2}, /* 37 40 */ 355 {COEF, 3}, /* 38 80 */ 356 {DECIM9, DA + 1}, /* 39 p4 */ 357 {COEF, 0}, /* 40 100 day hundreds */ 358 {COEF, 1}, /* 41 200 */ 359 {COEF2, 2}, /* 42 400 (not used) */ 360 {COEF2, 3}, /* 43 800 (not used) */ 361 {DECIM3, DA + 2}, /* 44 */ 362 {IDLE, 0}, /* 45 */ 363 {IDLE, 0}, /* 46 */ 364 {IDLE, 0}, /* 47 */ 365 {IDLE, 0}, /* 48 */ 366 {IDLE, 0}, /* 49 p5 */ 367 {MSCBIT, DUTS}, /* 50 dut+- */ 368 {COEF, 0}, /* 51 10 year tens */ 369 {COEF, 1}, /* 52 20 */ 370 {COEF, 2}, /* 53 40 */ 371 {COEF, 3}, /* 54 80 */ 372 {MSC20, DST1}, /* 55 dst1 */ 373 {MSCBIT, DUT1}, /* 56 0.1 dut */ 374 {MSCBIT, DUT2}, /* 57 0.2 */ 375 {MSC21, DUT4}, /* 58 0.4 QSY probe channel */ 376 {MIN1, 0}, /* 59 p6 latch time */ 377 {MIN2, 0} /* 60 leap second */ 378}; 379 380/* 381 * BCD coefficients for maximum-likelihood digit decode 382 */ 383#define P15 1. /* max positive number */ 384#define N15 -1. /* max negative number */ 385 386/* 387 * Digits 0-9 388 */ 389#define P9 (P15 / 4) /* mark (+1) */ 390#define N9 (N15 / 4) /* space (-1) */ 391 392double bcd9[][4] = { 393 {N9, N9, N9, N9}, /* 0 */ 394 {P9, N9, N9, N9}, /* 1 */ 395 {N9, P9, N9, N9}, /* 2 */ 396 {P9, P9, N9, N9}, /* 3 */ 397 {N9, N9, P9, N9}, /* 4 */ 398 {P9, N9, P9, N9}, /* 5 */ 399 {N9, P9, P9, N9}, /* 6 */ 400 {P9, P9, P9, N9}, /* 7 */ 401 {N9, N9, N9, P9}, /* 8 */ 402 {P9, N9, N9, P9}, /* 9 */ 403 {0, 0, 0, 0} /* backstop */ 404}; 405 406/* 407 * Digits 0-6 (minute tens) 408 */ 409#define P6 (P15 / 3) /* mark (+1) */ 410#define N6 (N15 / 3) /* space (-1) */ 411 412double bcd6[][4] = { 413 {N6, N6, N6, 0}, /* 0 */ 414 {P6, N6, N6, 0}, /* 1 */ 415 {N6, P6, N6, 0}, /* 2 */ 416 {P6, P6, N6, 0}, /* 3 */ 417 {N6, N6, P6, 0}, /* 4 */ 418 {P6, N6, P6, 0}, /* 5 */ 419 {N6, P6, P6, 0}, /* 6 */ 420 {0, 0, 0, 0} /* backstop */ 421}; 422 423/* 424 * Digits 0-3 (day hundreds) 425 */ 426#define P3 (P15 / 2) /* mark (+1) */ 427#define N3 (N15 / 2) /* space (-1) */ 428 429double bcd3[][4] = { 430 {N3, N3, 0, 0}, /* 0 */ 431 {P3, N3, 0, 0}, /* 1 */ 432 {N3, P3, 0, 0}, /* 2 */ 433 {P3, P3, 0, 0}, /* 3 */ 434 {0, 0, 0, 0} /* backstop */ 435}; 436 437/* 438 * Digits 0-2 (hour tens) 439 */ 440#define P2 (P15 / 2) /* mark (+1) */ 441#define N2 (N15 / 2) /* space (-1) */ 442 443double bcd2[][4] = { 444 {N2, N2, 0, 0}, /* 0 */ 445 {P2, N2, 0, 0}, /* 1 */ 446 {N2, P2, 0, 0}, /* 2 */ 447 {0, 0, 0, 0} /* backstop */ 448}; 449 450/* 451 * DST decode (DST2 DST1) for prettyprint 452 */ 453char dstcod[] = { 454 'S', /* 00 standard time */ 455 'I', /* 01 set clock ahead at 0200 local */ 456 'O', /* 10 set clock back at 0200 local */ 457 'D' /* 11 daylight time */ 458}; 459 460/* 461 * The decoding matrix consists of nine row vectors, one for each digit 462 * of the timecode. The digits are stored from least to most significant 463 * order. The maximum-likelihood timecode is formed from the digits 464 * corresponding to the maximum-likelihood values reading in the 465 * opposite order: yy ddd hh:mm. 466 */ 467struct decvec { 468 int radix; /* radix (3, 4, 6, 10) */ 469 int digit; /* current clock digit */ 470 int count; /* match count */ 471 double digprb; /* max digit probability */ 472 double digsnr; /* likelihood function (dB) */ 473 double like[10]; /* likelihood integrator 0-9 */ 474}; 475 476/* 477 * The station structure (sp) is used to acquire the minute pulse from 478 * WWV and/or WWVH. These stations are distinguished by the frequency 479 * used for the second and minute sync pulses, 1000 Hz for WWV and 1200 480 * Hz for WWVH. Other than frequency, the format is the same. 481 */ 482struct sync { 483 double epoch; /* accumulated epoch differences */ 484 double maxeng; /* sync max energy */ 485 double noieng; /* sync noise energy */ 486 long pos; /* max amplitude position */ 487 long lastpos; /* last max position */ 488 long mepoch; /* minute synch epoch */ 489 490 double amp; /* sync signal */ 491 double syneng; /* sync signal max */ 492 double synmax; /* sync signal max latched at 0 s */ 493 double synsnr; /* sync signal SNR */ 494 double metric; /* signal quality metric */ 495 int reach; /* reachability register */ 496 int count; /* bit counter */ 497 int select; /* select bits */ 498 char refid[5]; /* reference identifier */ 499}; 500 501/* 502 * The channel structure (cp) is used to mitigate between channels. 503 */ 504struct chan { 505 int gain; /* audio gain */ 506 struct sync wwv; /* wwv station */ 507 struct sync wwvh; /* wwvh station */ 508}; 509 510/* 511 * WWV unit control structure (up) 512 */ 513struct wwvunit { 514 l_fp timestamp; /* audio sample timestamp */ 515 l_fp tick; /* audio sample increment */ 516 double phase, freq; /* logical clock phase and frequency */ 517 double monitor; /* audio monitor point */ 518 double pdelay; /* propagation delay (s) */ 519#ifdef ICOM 520 int fd_icom; /* ICOM file descriptor */ 521#endif /* ICOM */ 522 int errflg; /* error flags */ 523 int watch; /* watchcat */ 524 525 /* 526 * Audio codec variables 527 */ 528 double comp[SIZE]; /* decompanding table */ 529 int port; /* codec port */ 530 int gain; /* codec gain */ 531 int mongain; /* codec monitor gain */ 532 int clipcnt; /* sample clipped count */ 533 534 /* 535 * Variables used to establish basic system timing 536 */ 537 int avgint; /* master time constant */ 538 int yepoch; /* sync epoch */ 539 int repoch; /* buffered sync epoch */ 540 double epomax; /* second sync amplitude */ 541 double eposnr; /* second sync SNR */ 542 double irig; /* data I channel amplitude */ 543 double qrig; /* data Q channel amplitude */ 544 int datapt; /* 100 Hz ramp */ 545 double datpha; /* 100 Hz VFO control */ 546 int rphase; /* second sample counter */ 547 long mphase; /* minute sample counter */ 548 549 /* 550 * Variables used to mitigate which channel to use 551 */ 552 struct chan mitig[NCHAN]; /* channel data */ 553 struct sync *sptr; /* station pointer */ 554 int dchan; /* data channel */ 555 int schan; /* probe channel */ 556 int achan; /* active channel */ 557 558 /* 559 * Variables used by the clock state machine 560 */ 561 struct decvec decvec[9]; /* decoding matrix */ 562 int rsec; /* seconds counter */ 563 int digcnt; /* count of digits synchronized */ 564 565 /* 566 * Variables used to estimate signal levels and bit/digit 567 * probabilities 568 */ 569 double datsig; /* data signal max */ 570 double datsnr; /* data signal SNR (dB) */ 571 572 /* 573 * Variables used to establish status and alarm conditions 574 */ 575 int status; /* status bits */ 576 int alarm; /* alarm flashers */ 577 int misc; /* miscellaneous timecode bits */ 578 int errcnt; /* data bit error counter */ 579}; 580 581/* 582 * Function prototypes 583 */ 584static int wwv_start (int, struct peer *); 585static void wwv_shutdown (int, struct peer *); 586static void wwv_receive (struct recvbuf *); 587static void wwv_poll (int, struct peer *); 588 589/* 590 * More function prototypes 591 */ 592static void wwv_epoch (struct peer *); 593static void wwv_rf (struct peer *, double); 594static void wwv_endpoc (struct peer *, int); 595static void wwv_rsec (struct peer *, double); 596static void wwv_qrz (struct peer *, struct sync *, int); 597static void wwv_corr4 (struct peer *, struct decvec *, 598 double [], double [][4]); 599static void wwv_gain (struct peer *); 600static void wwv_tsec (struct peer *); 601static int timecode (struct wwvunit *, char *, size_t); 602static double wwv_snr (double, double); 603static int carry (struct decvec *); 604static int wwv_newchan (struct peer *); 605static void wwv_newgame (struct peer *); 606static double wwv_metric (struct sync *); 607static void wwv_clock (struct peer *); 608#ifdef ICOM 609static int wwv_qsy (struct peer *, int); 610#endif /* ICOM */ 611 612static double qsy[NCHAN] = {2.5, 5, 10, 15, 20}; /* frequencies (MHz) */ 613 614/* 615 * Transfer vector 616 */ 617struct refclock refclock_wwv = { 618 wwv_start, /* start up driver */ 619 wwv_shutdown, /* shut down driver */ 620 wwv_poll, /* transmit poll message */ 621 noentry, /* not used (old wwv_control) */ 622 noentry, /* initialize driver (not used) */ 623 noentry, /* not used (old wwv_buginfo) */ 624 NOFLAGS /* not used */ 625}; 626 627 628/* 629 * wwv_start - open the devices and initialize data for processing 630 */ 631static int 632wwv_start( 633 int unit, /* instance number (used by PCM) */ 634 struct peer *peer /* peer structure pointer */ 635 ) 636{ 637 struct refclockproc *pp; 638 struct wwvunit *up; 639#ifdef ICOM 640 int temp; 641#endif /* ICOM */ 642 643 /* 644 * Local variables 645 */ 646 int fd; /* file descriptor */ 647 int i; /* index */ 648 double step; /* codec adjustment */ 649 650 /* 651 * Open audio device 652 */ 653 fd = audio_init(DEVICE_AUDIO, AUDIO_BUFSIZ, unit); 654 if (fd < 0) 655 return (0); 656#ifdef DEBUG 657 if (debug) 658 audio_show(); 659#endif /* DEBUG */ 660 661 /* 662 * Allocate and initialize unit structure 663 */ 664 up = emalloc_zero(sizeof(*up)); 665 pp = peer->procptr; 666 pp->io.clock_recv = wwv_receive; 667 pp->io.srcclock = peer; 668 pp->io.datalen = 0; 669 pp->io.fd = fd; 670 if (!io_addclock(&pp->io)) { 671 close(fd); 672 free(up); 673 return (0); 674 } 675 pp->unitptr = up; 676 677 /* 678 * Initialize miscellaneous variables 679 */ 680 peer->precision = PRECISION; 681 pp->clockdesc = DESCRIPTION; 682 683 /* 684 * The companded samples are encoded sign-magnitude. The table 685 * contains all the 256 values in the interest of speed. 686 */ 687 up->comp[0] = up->comp[OFFSET] = 0.; 688 up->comp[1] = 1.; up->comp[OFFSET + 1] = -1.; 689 up->comp[2] = 3.; up->comp[OFFSET + 2] = -3.; 690 step = 2.; 691 for (i = 3; i < OFFSET; i++) { 692 up->comp[i] = up->comp[i - 1] + step; 693 up->comp[OFFSET + i] = -up->comp[i]; 694 if (i % 16 == 0) 695 step *= 2.; 696 } 697 DTOLFP(1. / WWV_SEC, &up->tick); 698 699 /* 700 * Initialize the decoding matrix with the radix for each digit 701 * position. 702 */ 703 up->decvec[MN].radix = 10; /* minutes */ 704 up->decvec[MN + 1].radix = 6; 705 up->decvec[HR].radix = 10; /* hours */ 706 up->decvec[HR + 1].radix = 3; 707 up->decvec[DA].radix = 10; /* days */ 708 up->decvec[DA + 1].radix = 10; 709 up->decvec[DA + 2].radix = 4; 710 up->decvec[YR].radix = 10; /* years */ 711 up->decvec[YR + 1].radix = 10; 712 713#ifdef ICOM 714 /* 715 * Initialize autotune if available. Note that the ICOM select 716 * code must be less than 128, so the high order bit can be used 717 * to select the line speed 0 (9600 bps) or 1 (1200 bps). Note 718 * we don't complain if the ICOM device is not there; but, if it 719 * is, the radio better be working. 720 */ 721 temp = 0; 722#ifdef DEBUG 723 if (debug > 1) 724 temp = P_TRACE; 725#endif /* DEBUG */ 726 if (peer->ttl != 0) { 727 if (peer->ttl & 0x80) 728 up->fd_icom = icom_init("/dev/icom", B1200, 729 temp); 730 else 731 up->fd_icom = icom_init("/dev/icom", B9600, 732 temp); 733 } 734 if (up->fd_icom > 0) { 735 if (wwv_qsy(peer, DCHAN) != 0) { 736 msyslog(LOG_NOTICE, "icom: radio not found"); 737 close(up->fd_icom); 738 up->fd_icom = 0; 739 } else { 740 msyslog(LOG_NOTICE, "icom: autotune enabled"); 741 } 742 } 743#endif /* ICOM */ 744 745 /* 746 * Let the games begin. 747 */ 748 wwv_newgame(peer); 749 return (1); 750} 751 752 753/* 754 * wwv_shutdown - shut down the clock 755 */ 756static void 757wwv_shutdown( 758 int unit, /* instance number (not used) */ 759 struct peer *peer /* peer structure pointer */ 760 ) 761{ 762 struct refclockproc *pp; 763 struct wwvunit *up; 764 765 pp = peer->procptr; 766 up = pp->unitptr; 767 if (up == NULL) 768 return; 769 770 io_closeclock(&pp->io); 771#ifdef ICOM 772 if (up->fd_icom > 0) 773 close(up->fd_icom); 774#endif /* ICOM */ 775 free(up); 776} 777 778 779/* 780 * wwv_receive - receive data from the audio device 781 * 782 * This routine reads input samples and adjusts the logical clock to 783 * track the A/D sample clock by dropping or duplicating codec samples. 784 * It also controls the A/D signal level with an AGC loop to mimimize 785 * quantization noise and avoid overload. 786 */ 787static void 788wwv_receive( 789 struct recvbuf *rbufp /* receive buffer structure pointer */ 790 ) 791{ 792 struct peer *peer; 793 struct refclockproc *pp; 794 struct wwvunit *up; 795 796 /* 797 * Local variables 798 */ 799 double sample; /* codec sample */ 800 u_char *dpt; /* buffer pointer */ 801 int bufcnt; /* buffer counter */ 802 l_fp ltemp; 803 804 peer = rbufp->recv_peer; 805 pp = peer->procptr; 806 up = pp->unitptr; 807 808 /* 809 * Main loop - read until there ain't no more. Note codec 810 * samples are bit-inverted. 811 */ 812 DTOLFP((double)rbufp->recv_length / WWV_SEC, <emp); 813 L_SUB(&rbufp->recv_time, <emp); 814 up->timestamp = rbufp->recv_time; 815 dpt = rbufp->recv_buffer; 816 for (bufcnt = 0; bufcnt < rbufp->recv_length; bufcnt++) { 817 sample = up->comp[~*dpt++ & 0xff]; 818 819 /* 820 * Clip noise spikes greater than MAXAMP (6000) and 821 * record the number of clips to be used later by the 822 * AGC. 823 */ 824 if (sample > MAXAMP) { 825 sample = MAXAMP; 826 up->clipcnt++; 827 } else if (sample < -MAXAMP) { 828 sample = -MAXAMP; 829 up->clipcnt++; 830 } 831 832 /* 833 * Variable frequency oscillator. The codec oscillator 834 * runs at the nominal rate of 8000 samples per second, 835 * or 125 us per sample. A frequency change of one unit 836 * results in either duplicating or deleting one sample 837 * per second, which results in a frequency change of 838 * 125 PPM. 839 */ 840 up->phase += (up->freq + clock_codec) / WWV_SEC; 841 if (up->phase >= .5) { 842 up->phase -= 1.; 843 } else if (up->phase < -.5) { 844 up->phase += 1.; 845 wwv_rf(peer, sample); 846 wwv_rf(peer, sample); 847 } else { 848 wwv_rf(peer, sample); 849 } 850 L_ADD(&up->timestamp, &up->tick); 851 } 852 853 /* 854 * Set the input port and monitor gain for the next buffer. 855 */ 856 if (pp->sloppyclockflag & CLK_FLAG2) 857 up->port = 2; 858 else 859 up->port = 1; 860 if (pp->sloppyclockflag & CLK_FLAG3) 861 up->mongain = MONGAIN; 862 else 863 up->mongain = 0; 864} 865 866 867/* 868 * wwv_poll - called by the transmit procedure 869 * 870 * This routine keeps track of status. If no offset samples have been 871 * processed during a poll interval, a timeout event is declared. If 872 * errors have have occurred during the interval, they are reported as 873 * well. 874 */ 875static void 876wwv_poll( 877 int unit, /* instance number (not used) */ 878 struct peer *peer /* peer structure pointer */ 879 ) 880{ 881 struct refclockproc *pp; 882 struct wwvunit *up; 883 884 pp = peer->procptr; 885 up = pp->unitptr; 886 if (up->errflg) 887 refclock_report(peer, up->errflg); 888 up->errflg = 0; 889 pp->polls++; 890} 891 892 893/* 894 * wwv_rf - process signals and demodulate to baseband 895 * 896 * This routine grooms and filters decompanded raw audio samples. The 897 * output signal is the 100-Hz filtered baseband data signal in 898 * quadrature phase. The routine also determines the minute synch epoch, 899 * as well as certain signal maxima, minima and related values. 900 * 901 * There are two 1-s ramps used by this program. Both count the 8000 902 * logical clock samples spanning exactly one second. The epoch ramp 903 * counts the samples starting at an arbitrary time. The rphase ramp 904 * counts the samples starting at the 5-ms second sync pulse found 905 * during the epoch ramp. 906 * 907 * There are two 1-m ramps used by this program. The mphase ramp counts 908 * the 480,000 logical clock samples spanning exactly one minute and 909 * starting at an arbitrary time. The rsec ramp counts the 60 seconds of 910 * the minute starting at the 800-ms minute sync pulse found during the 911 * mphase ramp. The rsec ramp drives the seconds state machine to 912 * determine the bits and digits of the timecode. 913 * 914 * Demodulation operations are based on three synthesized quadrature 915 * sinusoids: 100 Hz for the data signal, 1000 Hz for the WWV sync 916 * signal and 1200 Hz for the WWVH sync signal. These drive synchronous 917 * matched filters for the data signal (170 ms at 100 Hz), WWV minute 918 * sync signal (800 ms at 1000 Hz) and WWVH minute sync signal (800 ms 919 * at 1200 Hz). Two additional matched filters are switched in 920 * as required for the WWV second sync signal (5 cycles at 1000 Hz) and 921 * WWVH second sync signal (6 cycles at 1200 Hz). 922 */ 923static void 924wwv_rf( 925 struct peer *peer, /* peerstructure pointer */ 926 double isig /* input signal */ 927 ) 928{ 929 struct refclockproc *pp; 930 struct wwvunit *up; 931 struct sync *sp, *rp; 932 933 static double lpf[5]; /* 150-Hz lpf delay line */ 934 double data; /* lpf output */ 935 static double bpf[9]; /* 1000/1200-Hz bpf delay line */ 936 double syncx; /* bpf output */ 937 static double mf[41]; /* 1000/1200-Hz mf delay line */ 938 double mfsync; /* mf output */ 939 940 static int iptr; /* data channel pointer */ 941 static double ibuf[DATSIZ]; /* data I channel delay line */ 942 static double qbuf[DATSIZ]; /* data Q channel delay line */ 943 944 static int jptr; /* sync channel pointer */ 945 static int kptr; /* tick channel pointer */ 946 947 static int csinptr; /* wwv channel phase */ 948 static double cibuf[SYNSIZ]; /* wwv I channel delay line */ 949 static double cqbuf[SYNSIZ]; /* wwv Q channel delay line */ 950 static double ciamp; /* wwv I channel amplitude */ 951 static double cqamp; /* wwv Q channel amplitude */ 952 953 static double csibuf[TCKSIZ]; /* wwv I tick delay line */ 954 static double csqbuf[TCKSIZ]; /* wwv Q tick delay line */ 955 static double csiamp; /* wwv I tick amplitude */ 956 static double csqamp; /* wwv Q tick amplitude */ 957 958 static int hsinptr; /* wwvh channel phase */ 959 static double hibuf[SYNSIZ]; /* wwvh I channel delay line */ 960 static double hqbuf[SYNSIZ]; /* wwvh Q channel delay line */ 961 static double hiamp; /* wwvh I channel amplitude */ 962 static double hqamp; /* wwvh Q channel amplitude */ 963 964 static double hsibuf[TCKSIZ]; /* wwvh I tick delay line */ 965 static double hsqbuf[TCKSIZ]; /* wwvh Q tick delay line */ 966 static double hsiamp; /* wwvh I tick amplitude */ 967 static double hsqamp; /* wwvh Q tick amplitude */ 968 969 static double epobuf[WWV_SEC]; /* second sync comb filter */ 970 static double epomax, nxtmax; /* second sync amplitude buffer */ 971 static int epopos; /* epoch second sync position buffer */ 972 973 static int iniflg; /* initialization flag */ 974 int epoch; /* comb filter index */ 975 double dtemp; 976 int i; 977 978 pp = peer->procptr; 979 up = pp->unitptr; 980 981 if (!iniflg) { 982 iniflg = 1; 983 memset((char *)lpf, 0, sizeof(lpf)); 984 memset((char *)bpf, 0, sizeof(bpf)); 985 memset((char *)mf, 0, sizeof(mf)); 986 memset((char *)ibuf, 0, sizeof(ibuf)); 987 memset((char *)qbuf, 0, sizeof(qbuf)); 988 memset((char *)cibuf, 0, sizeof(cibuf)); 989 memset((char *)cqbuf, 0, sizeof(cqbuf)); 990 memset((char *)csibuf, 0, sizeof(csibuf)); 991 memset((char *)csqbuf, 0, sizeof(csqbuf)); 992 memset((char *)hibuf, 0, sizeof(hibuf)); 993 memset((char *)hqbuf, 0, sizeof(hqbuf)); 994 memset((char *)hsibuf, 0, sizeof(hsibuf)); 995 memset((char *)hsqbuf, 0, sizeof(hsqbuf)); 996 memset((char *)epobuf, 0, sizeof(epobuf)); 997 } 998 999 /* 1000 * Baseband data demodulation. The 100-Hz subcarrier is 1001 * extracted using a 150-Hz IIR lowpass filter. This attenuates 1002 * the 1000/1200-Hz sync signals, as well as the 440-Hz and 1003 * 600-Hz tones and most of the noise and voice modulation 1004 * components. 1005 * 1006 * The subcarrier is transmitted 10 dB down from the carrier. 1007 * The DGAIN parameter can be adjusted for this and to 1008 * compensate for the radio audio response at 100 Hz. 1009 * 1010 * Matlab IIR 4th-order IIR elliptic, 150 Hz lowpass, 0.2 dB 1011 * passband ripple, -50 dB stopband ripple, phase delay 0.97 ms. 1012 */ 1013 data = (lpf[4] = lpf[3]) * 8.360961e-01; 1014 data += (lpf[3] = lpf[2]) * -3.481740e+00; 1015 data += (lpf[2] = lpf[1]) * 5.452988e+00; 1016 data += (lpf[1] = lpf[0]) * -3.807229e+00; 1017 lpf[0] = isig * DGAIN - data; 1018 data = lpf[0] * 3.281435e-03 1019 + lpf[1] * -1.149947e-02 1020 + lpf[2] * 1.654858e-02 1021 + lpf[3] * -1.149947e-02 1022 + lpf[4] * 3.281435e-03; 1023 1024 /* 1025 * The 100-Hz data signal is demodulated using a pair of 1026 * quadrature multipliers, matched filters and a phase lock 1027 * loop. The I and Q quadrature data signals are produced by 1028 * multiplying the filtered signal by 100-Hz sine and cosine 1029 * signals, respectively. The signals are processed by 170-ms 1030 * synchronous matched filters to produce the amplitude and 1031 * phase signals used by the demodulator. The signals are scaled 1032 * to produce unit energy at the maximum value. 1033 */ 1034 i = up->datapt; 1035 up->datapt = (up->datapt + IN100) % 80; 1036 dtemp = sintab[i] * data / (MS / 2. * DATCYC); 1037 up->irig -= ibuf[iptr]; 1038 ibuf[iptr] = dtemp; 1039 up->irig += dtemp; 1040 1041 i = (i + 20) % 80; 1042 dtemp = sintab[i] * data / (MS / 2. * DATCYC); 1043 up->qrig -= qbuf[iptr]; 1044 qbuf[iptr] = dtemp; 1045 up->qrig += dtemp; 1046 iptr = (iptr + 1) % DATSIZ; 1047 1048 /* 1049 * Baseband sync demodulation. The 1000/1200 sync signals are 1050 * extracted using a 600-Hz IIR bandpass filter. This removes 1051 * the 100-Hz data subcarrier, as well as the 440-Hz and 600-Hz 1052 * tones and most of the noise and voice modulation components. 1053 * 1054 * Matlab 4th-order IIR elliptic, 800-1400 Hz bandpass, 0.2 dB 1055 * passband ripple, -50 dB stopband ripple, phase delay 0.91 ms. 1056 */ 1057 syncx = (bpf[8] = bpf[7]) * 4.897278e-01; 1058 syncx += (bpf[7] = bpf[6]) * -2.765914e+00; 1059 syncx += (bpf[6] = bpf[5]) * 8.110921e+00; 1060 syncx += (bpf[5] = bpf[4]) * -1.517732e+01; 1061 syncx += (bpf[4] = bpf[3]) * 1.975197e+01; 1062 syncx += (bpf[3] = bpf[2]) * -1.814365e+01; 1063 syncx += (bpf[2] = bpf[1]) * 1.159783e+01; 1064 syncx += (bpf[1] = bpf[0]) * -4.735040e+00; 1065 bpf[0] = isig - syncx; 1066 syncx = bpf[0] * 8.203628e-03 1067 + bpf[1] * -2.375732e-02 1068 + bpf[2] * 3.353214e-02 1069 + bpf[3] * -4.080258e-02 1070 + bpf[4] * 4.605479e-02 1071 + bpf[5] * -4.080258e-02 1072 + bpf[6] * 3.353214e-02 1073 + bpf[7] * -2.375732e-02 1074 + bpf[8] * 8.203628e-03; 1075 1076 /* 1077 * The 1000/1200 sync signals are demodulated using a pair of 1078 * quadrature multipliers and matched filters. However, 1079 * synchronous demodulation at these frequencies is impractical, 1080 * so only the signal amplitude is used. The I and Q quadrature 1081 * sync signals are produced by multiplying the filtered signal 1082 * by 1000-Hz (WWV) and 1200-Hz (WWVH) sine and cosine signals, 1083 * respectively. The WWV and WWVH signals are processed by 800- 1084 * ms synchronous matched filters and combined to produce the 1085 * minute sync signal and detect which one (or both) the WWV or 1086 * WWVH signal is present. The WWV and WWVH signals are also 1087 * processed by 5-ms synchronous matched filters and combined to 1088 * produce the second sync signal. The signals are scaled to 1089 * produce unit energy at the maximum value. 1090 * 1091 * Note the master timing ramps, which run continuously. The 1092 * minute counter (mphase) counts the samples in the minute, 1093 * while the second counter (epoch) counts the samples in the 1094 * second. 1095 */ 1096 up->mphase = (up->mphase + 1) % WWV_MIN; 1097 epoch = up->mphase % WWV_SEC; 1098 1099 /* 1100 * WWV 1101 */ 1102 i = csinptr; 1103 csinptr = (csinptr + IN1000) % 80; 1104 1105 dtemp = sintab[i] * syncx / (MS / 2.); 1106 ciamp -= cibuf[jptr]; 1107 cibuf[jptr] = dtemp; 1108 ciamp += dtemp; 1109 csiamp -= csibuf[kptr]; 1110 csibuf[kptr] = dtemp; 1111 csiamp += dtemp; 1112 1113 i = (i + 20) % 80; 1114 dtemp = sintab[i] * syncx / (MS / 2.); 1115 cqamp -= cqbuf[jptr]; 1116 cqbuf[jptr] = dtemp; 1117 cqamp += dtemp; 1118 csqamp -= csqbuf[kptr]; 1119 csqbuf[kptr] = dtemp; 1120 csqamp += dtemp; 1121 1122 sp = &up->mitig[up->achan].wwv; 1123 sp->amp = sqrt(ciamp * ciamp + cqamp * cqamp) / SYNCYC; 1124 if (!(up->status & MSYNC)) 1125 wwv_qrz(peer, sp, (int)(pp->fudgetime1 * WWV_SEC)); 1126 1127 /* 1128 * WWVH 1129 */ 1130 i = hsinptr; 1131 hsinptr = (hsinptr + IN1200) % 80; 1132 1133 dtemp = sintab[i] * syncx / (MS / 2.); 1134 hiamp -= hibuf[jptr]; 1135 hibuf[jptr] = dtemp; 1136 hiamp += dtemp; 1137 hsiamp -= hsibuf[kptr]; 1138 hsibuf[kptr] = dtemp; 1139 hsiamp += dtemp; 1140 1141 i = (i + 20) % 80; 1142 dtemp = sintab[i] * syncx / (MS / 2.); 1143 hqamp -= hqbuf[jptr]; 1144 hqbuf[jptr] = dtemp; 1145 hqamp += dtemp; 1146 hsqamp -= hsqbuf[kptr]; 1147 hsqbuf[kptr] = dtemp; 1148 hsqamp += dtemp; 1149 1150 rp = &up->mitig[up->achan].wwvh; 1151 rp->amp = sqrt(hiamp * hiamp + hqamp * hqamp) / SYNCYC; 1152 if (!(up->status & MSYNC)) 1153 wwv_qrz(peer, rp, (int)(pp->fudgetime2 * WWV_SEC)); 1154 jptr = (jptr + 1) % SYNSIZ; 1155 kptr = (kptr + 1) % TCKSIZ; 1156 1157 /* 1158 * The following section is called once per minute. It does 1159 * housekeeping and timeout functions and empties the dustbins. 1160 */ 1161 if (up->mphase == 0) { 1162 up->watch++; 1163 if (!(up->status & MSYNC)) { 1164 1165 /* 1166 * If minute sync has not been acquired before 1167 * ACQSN timeout (6 min), or if no signal is 1168 * heard, the program cycles to the next 1169 * frequency and tries again. 1170 */ 1171 if (!wwv_newchan(peer)) 1172 up->watch = 0; 1173 } else { 1174 1175 /* 1176 * If the leap bit is set, set the minute epoch 1177 * back one second so the station processes 1178 * don't miss a beat. 1179 */ 1180 if (up->status & LEPSEC) { 1181 up->mphase -= WWV_SEC; 1182 if (up->mphase < 0) 1183 up->mphase += WWV_MIN; 1184 } 1185 } 1186 } 1187 1188 /* 1189 * When the channel metric reaches threshold and the second 1190 * counter matches the minute epoch within the second, the 1191 * driver has synchronized to the station. The second number is 1192 * the remaining seconds until the next minute epoch, while the 1193 * sync epoch is zero. Watch out for the first second; if 1194 * already synchronized to the second, the buffered sync epoch 1195 * must be set. 1196 * 1197 * Note the guard interval is 200 ms; if for some reason the 1198 * clock drifts more than that, it might wind up in the wrong 1199 * second. If the maximum frequency error is not more than about 1200 * 1 PPM, the clock can go as much as two days while still in 1201 * the same second. 1202 */ 1203 if (up->status & MSYNC) { 1204 wwv_epoch(peer); 1205 } else if (up->sptr != NULL) { 1206 sp = up->sptr; 1207 if (sp->metric >= TTHR && epoch == sp->mepoch % WWV_SEC) 1208 { 1209 up->rsec = (60 - sp->mepoch / WWV_SEC) % 60; 1210 up->rphase = 0; 1211 up->status |= MSYNC; 1212 up->watch = 0; 1213 if (!(up->status & SSYNC)) 1214 up->repoch = up->yepoch = epoch; 1215 else 1216 up->repoch = up->yepoch; 1217 1218 } 1219 } 1220 1221 /* 1222 * The second sync pulse is extracted using 5-ms (40 sample) FIR 1223 * matched filters at 1000 Hz for WWV or 1200 Hz for WWVH. This 1224 * pulse is used for the most precise synchronization, since if 1225 * provides a resolution of one sample (125 us). The filters run 1226 * only if the station has been reliably determined. 1227 */ 1228 if (up->status & SELV) 1229 mfsync = sqrt(csiamp * csiamp + csqamp * csqamp) / 1230 TCKCYC; 1231 else if (up->status & SELH) 1232 mfsync = sqrt(hsiamp * hsiamp + hsqamp * hsqamp) / 1233 TCKCYC; 1234 else 1235 mfsync = 0; 1236 1237 /* 1238 * Enhance the seconds sync pulse using a 1-s (8000-sample) comb 1239 * filter. Correct for the FIR matched filter delay, which is 5 1240 * ms for both the WWV and WWVH filters, and also for the 1241 * propagation delay. Once each second look for second sync. If 1242 * not in minute sync, fiddle the codec gain. Note the SNR is 1243 * computed from the maximum sample and the envelope of the 1244 * sample 6 ms before it, so if we slip more than a cycle the 1245 * SNR should plummet. The signal is scaled to produce unit 1246 * energy at the maximum value. 1247 */ 1248 dtemp = (epobuf[epoch] += (mfsync - epobuf[epoch]) / 1249 up->avgint); 1250 if (dtemp > epomax) { 1251 int j; 1252 1253 epomax = dtemp; 1254 epopos = epoch; 1255 j = epoch - 6 * MS; 1256 if (j < 0) 1257 j += WWV_SEC; 1258 nxtmax = fabs(epobuf[j]); 1259 } 1260 if (epoch == 0) { 1261 up->epomax = epomax; 1262 up->eposnr = wwv_snr(epomax, nxtmax); 1263 epopos -= TCKCYC * MS; 1264 if (epopos < 0) 1265 epopos += WWV_SEC; 1266 wwv_endpoc(peer, epopos); 1267 if (!(up->status & SSYNC)) 1268 up->alarm |= SYNERR; 1269 epomax = 0; 1270 if (!(up->status & MSYNC)) 1271 wwv_gain(peer); 1272 } 1273} 1274 1275 1276/* 1277 * wwv_qrz - identify and acquire WWV/WWVH minute sync pulse 1278 * 1279 * This routine implements a virtual station process used to acquire 1280 * minute sync and to mitigate among the ten frequency and station 1281 * combinations. During minute sync acquisition the process probes each 1282 * frequency and station in turn for the minute pulse, which 1283 * involves searching through the entire 480,000-sample minute. The 1284 * process finds the maximum signal and RMS noise plus signal. Then, the 1285 * actual noise is determined by subtracting the energy of the matched 1286 * filter. 1287 * 1288 * Students of radar receiver technology will discover this algorithm 1289 * amounts to a range-gate discriminator. A valid pulse must have peak 1290 * amplitude at least QTHR (2500) and SNR at least QSNR (20) dB and the 1291 * difference between the current and previous epoch must be less than 1292 * AWND (20 ms). Note that the discriminator peak occurs about 800 ms 1293 * into the second, so the timing is retarded to the previous second 1294 * epoch. 1295 */ 1296static void 1297wwv_qrz( 1298 struct peer *peer, /* peer structure pointer */ 1299 struct sync *sp, /* sync channel structure */ 1300 int pdelay /* propagation delay (samples) */ 1301 ) 1302{ 1303 struct refclockproc *pp; 1304 struct wwvunit *up; 1305 char tbuf[TBUF]; /* monitor buffer */ 1306 long epoch; 1307 1308 pp = peer->procptr; 1309 up = pp->unitptr; 1310 1311 /* 1312 * Find the sample with peak amplitude, which defines the minute 1313 * epoch. Accumulate all samples to determine the total noise 1314 * energy. 1315 */ 1316 epoch = up->mphase - pdelay - SYNSIZ; 1317 if (epoch < 0) 1318 epoch += WWV_MIN; 1319 if (sp->amp > sp->maxeng) { 1320 sp->maxeng = sp->amp; 1321 sp->pos = epoch; 1322 } 1323 sp->noieng += sp->amp; 1324 1325 /* 1326 * At the end of the minute, determine the epoch of the minute 1327 * sync pulse, as well as the difference between the current and 1328 * previous epoches due to the intrinsic frequency error plus 1329 * jitter. When calculating the SNR, subtract the pulse energy 1330 * from the total noise energy and then normalize. 1331 */ 1332 if (up->mphase == 0) { 1333 sp->synmax = sp->maxeng; 1334 sp->synsnr = wwv_snr(sp->synmax, (sp->noieng - 1335 sp->synmax) / WWV_MIN); 1336 if (sp->count == 0) 1337 sp->lastpos = sp->pos; 1338 epoch = (sp->pos - sp->lastpos) % WWV_MIN; 1339 sp->reach <<= 1; 1340 if (sp->reach & (1 << AMAX)) 1341 sp->count--; 1342 if (sp->synmax > ATHR && sp->synsnr > ASNR) { 1343 if (labs(epoch) < AWND * MS) { 1344 sp->reach |= 1; 1345 sp->count++; 1346 sp->mepoch = sp->lastpos = sp->pos; 1347 } else if (sp->count == 1) { 1348 sp->lastpos = sp->pos; 1349 } 1350 } 1351 if (up->watch > ACQSN) 1352 sp->metric = 0; 1353 else 1354 sp->metric = wwv_metric(sp); 1355 if (pp->sloppyclockflag & CLK_FLAG4) { 1356 snprintf(tbuf, sizeof(tbuf), 1357 "wwv8 %04x %3d %s %04x %.0f %.0f/%.1f %ld %ld", 1358 up->status, up->gain, sp->refid, 1359 sp->reach & 0xffff, sp->metric, sp->synmax, 1360 sp->synsnr, sp->pos % WWV_SEC, epoch); 1361 record_clock_stats(&peer->srcadr, tbuf); 1362#ifdef DEBUG 1363 if (debug) 1364 printf("%s\n", tbuf); 1365#endif /* DEBUG */ 1366 } 1367 sp->maxeng = sp->noieng = 0; 1368 } 1369} 1370 1371 1372/* 1373 * wwv_endpoc - identify and acquire second sync pulse 1374 * 1375 * This routine is called at the end of the second sync interval. It 1376 * determines the second sync epoch position within the second and 1377 * disciplines the sample clock using a frequency-lock loop (FLL). 1378 * 1379 * Second sync is determined in the RF input routine as the maximum 1380 * over all 8000 samples in the second comb filter. To assure accurate 1381 * and reliable time and frequency discipline, this routine performs a 1382 * great deal of heavy-handed heuristic data filtering and grooming. 1383 */ 1384static void 1385wwv_endpoc( 1386 struct peer *peer, /* peer structure pointer */ 1387 int epopos /* epoch max position */ 1388 ) 1389{ 1390 struct refclockproc *pp; 1391 struct wwvunit *up; 1392 static int epoch_mf[3]; /* epoch median filter */ 1393 static int tepoch; /* current second epoch */ 1394 static int xepoch; /* last second epoch */ 1395 static int zepoch; /* last run epoch */ 1396 static int zcount; /* last run end time */ 1397 static int scount; /* seconds counter */ 1398 static int syncnt; /* run length counter */ 1399 static int maxrun; /* longest run length */ 1400 static int mepoch; /* longest run end epoch */ 1401 static int mcount; /* longest run end time */ 1402 static int avgcnt; /* averaging interval counter */ 1403 static int avginc; /* averaging ratchet */ 1404 static int iniflg; /* initialization flag */ 1405 char tbuf[TBUF]; /* monitor buffer */ 1406 double dtemp; 1407 int tmp2; 1408 1409 pp = peer->procptr; 1410 up = pp->unitptr; 1411 if (!iniflg) { 1412 iniflg = 1; 1413 ZERO(epoch_mf); 1414 } 1415 1416 /* 1417 * If the signal amplitude or SNR fall below thresholds, dim the 1418 * second sync lamp and wait for hotter ions. If no stations are 1419 * heard, we are either in a probe cycle or the ions are really 1420 * cold. 1421 */ 1422 scount++; 1423 if (up->epomax < STHR || up->eposnr < SSNR) { 1424 up->status &= ~(SSYNC | FGATE); 1425 avgcnt = syncnt = maxrun = 0; 1426 return; 1427 } 1428 if (!(up->status & (SELV | SELH))) 1429 return; 1430 1431 /* 1432 * A three-stage median filter is used to help denoise the 1433 * second sync pulse. The median sample becomes the candidate 1434 * epoch. 1435 */ 1436 epoch_mf[2] = epoch_mf[1]; 1437 epoch_mf[1] = epoch_mf[0]; 1438 epoch_mf[0] = epopos; 1439 if (epoch_mf[0] > epoch_mf[1]) { 1440 if (epoch_mf[1] > epoch_mf[2]) 1441 tepoch = epoch_mf[1]; /* 0 1 2 */ 1442 else if (epoch_mf[2] > epoch_mf[0]) 1443 tepoch = epoch_mf[0]; /* 2 0 1 */ 1444 else 1445 tepoch = epoch_mf[2]; /* 0 2 1 */ 1446 } else { 1447 if (epoch_mf[1] < epoch_mf[2]) 1448 tepoch = epoch_mf[1]; /* 2 1 0 */ 1449 else if (epoch_mf[2] < epoch_mf[0]) 1450 tepoch = epoch_mf[0]; /* 1 0 2 */ 1451 else 1452 tepoch = epoch_mf[2]; /* 1 2 0 */ 1453 } 1454 1455 1456 /* 1457 * If the epoch candidate is the same as the last one, increment 1458 * the run counter. If not, save the length, epoch and end 1459 * time of the current run for use later and reset the counter. 1460 * The epoch is considered valid if the run is at least SCMP 1461 * (10) s, the minute is synchronized and the interval since the 1462 * last epoch is not greater than the averaging interval. Thus, 1463 * after a long absence, the program will wait a full averaging 1464 * interval while the comb filter charges up and noise 1465 * dissapates.. 1466 */ 1467 tmp2 = (tepoch - xepoch) % WWV_SEC; 1468 if (tmp2 == 0) { 1469 syncnt++; 1470 if (syncnt > SCMP && up->status & MSYNC && (up->status & 1471 FGATE || scount - zcount <= up->avgint)) { 1472 up->status |= SSYNC; 1473 up->yepoch = tepoch; 1474 } 1475 } else if (syncnt >= maxrun) { 1476 maxrun = syncnt; 1477 mcount = scount; 1478 mepoch = xepoch; 1479 syncnt = 0; 1480 } 1481 if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status & 1482 MSYNC)) { 1483 snprintf(tbuf, sizeof(tbuf), 1484 "wwv1 %04x %3d %4d %5.0f %5.1f %5d %4d %4d %4d", 1485 up->status, up->gain, tepoch, up->epomax, 1486 up->eposnr, tmp2, avgcnt, syncnt, 1487 maxrun); 1488 record_clock_stats(&peer->srcadr, tbuf); 1489#ifdef DEBUG 1490 if (debug) 1491 printf("%s\n", tbuf); 1492#endif /* DEBUG */ 1493 } 1494 avgcnt++; 1495 if (avgcnt < up->avgint) { 1496 xepoch = tepoch; 1497 return; 1498 } 1499 1500 /* 1501 * The sample clock frequency is disciplined using a first-order 1502 * feedback loop with time constant consistent with the Allan 1503 * intercept of typical computer clocks. During each averaging 1504 * interval the candidate epoch at the end of the longest run is 1505 * determined. If the longest run is zero, all epoches in the 1506 * interval are different, so the candidate epoch is the current 1507 * epoch. The frequency update is computed from the candidate 1508 * epoch difference (125-us units) and time difference (seconds) 1509 * between updates. 1510 */ 1511 if (syncnt >= maxrun) { 1512 maxrun = syncnt; 1513 mcount = scount; 1514 mepoch = xepoch; 1515 } 1516 xepoch = tepoch; 1517 if (maxrun == 0) { 1518 mepoch = tepoch; 1519 mcount = scount; 1520 } 1521 1522 /* 1523 * The master clock runs at the codec sample frequency of 8000 1524 * Hz, so the intrinsic time resolution is 125 us. The frequency 1525 * resolution ranges from 18 PPM at the minimum averaging 1526 * interval of 8 s to 0.12 PPM at the maximum interval of 1024 1527 * s. An offset update is determined at the end of the longest 1528 * run in each averaging interval. The frequency adjustment is 1529 * computed from the difference between offset updates and the 1530 * interval between them. 1531 * 1532 * The maximum frequency adjustment ranges from 187 PPM at the 1533 * minimum interval to 1.5 PPM at the maximum. If the adjustment 1534 * exceeds the maximum, the update is discarded and the 1535 * hysteresis counter is decremented. Otherwise, the frequency 1536 * is incremented by the adjustment, but clamped to the maximum 1537 * 187.5 PPM. If the update is less than half the maximum, the 1538 * hysteresis counter is incremented. If the counter increments 1539 * to +3, the averaging interval is doubled and the counter set 1540 * to zero; if it decrements to -3, the interval is halved and 1541 * the counter set to zero. 1542 */ 1543 dtemp = (mepoch - zepoch) % WWV_SEC; 1544 if (up->status & FGATE) { 1545 if (fabs(dtemp) < MAXFREQ * MINAVG) { 1546 up->freq += (dtemp / 2.) / ((mcount - zcount) * 1547 FCONST); 1548 if (up->freq > MAXFREQ) 1549 up->freq = MAXFREQ; 1550 else if (up->freq < -MAXFREQ) 1551 up->freq = -MAXFREQ; 1552 if (fabs(dtemp) < MAXFREQ * MINAVG / 2.) { 1553 if (avginc < 3) { 1554 avginc++; 1555 } else { 1556 if (up->avgint < MAXAVG) { 1557 up->avgint <<= 1; 1558 avginc = 0; 1559 } 1560 } 1561 } 1562 } else { 1563 if (avginc > -3) { 1564 avginc--; 1565 } else { 1566 if (up->avgint > MINAVG) { 1567 up->avgint >>= 1; 1568 avginc = 0; 1569 } 1570 } 1571 } 1572 } 1573 if (pp->sloppyclockflag & CLK_FLAG4) { 1574 snprintf(tbuf, sizeof(tbuf), 1575 "wwv2 %04x %5.0f %5.1f %5d %4d %4d %4d %4.0f %7.2f", 1576 up->status, up->epomax, up->eposnr, mepoch, 1577 up->avgint, maxrun, mcount - zcount, dtemp, 1578 up->freq * 1e6 / WWV_SEC); 1579 record_clock_stats(&peer->srcadr, tbuf); 1580#ifdef DEBUG 1581 if (debug) 1582 printf("%s\n", tbuf); 1583#endif /* DEBUG */ 1584 } 1585 1586 /* 1587 * This is a valid update; set up for the next interval. 1588 */ 1589 up->status |= FGATE; 1590 zepoch = mepoch; 1591 zcount = mcount; 1592 avgcnt = syncnt = maxrun = 0; 1593} 1594 1595 1596/* 1597 * wwv_epoch - epoch scanner 1598 * 1599 * This routine extracts data signals from the 100-Hz subcarrier. It 1600 * scans the receiver second epoch to determine the signal amplitudes 1601 * and pulse timings. Receiver synchronization is determined by the 1602 * minute sync pulse detected in the wwv_rf() routine and the second 1603 * sync pulse detected in the wwv_epoch() routine. The transmitted 1604 * signals are delayed by the propagation delay, receiver delay and 1605 * filter delay of this program. Delay corrections are introduced 1606 * separately for WWV and WWVH. 1607 * 1608 * Most communications radios use a highpass filter in the audio stages, 1609 * which can do nasty things to the subcarrier phase relative to the 1610 * sync pulses. Therefore, the data subcarrier reference phase is 1611 * disciplined using the hardlimited quadrature-phase signal sampled at 1612 * the same time as the in-phase signal. The phase tracking loop uses 1613 * phase adjustments of plus-minus one sample (125 us). 1614 */ 1615static void 1616wwv_epoch( 1617 struct peer *peer /* peer structure pointer */ 1618 ) 1619{ 1620 struct refclockproc *pp; 1621 struct wwvunit *up; 1622 struct chan *cp; 1623 static double sigmin, sigzer, sigone, engmax, engmin; 1624 1625 pp = peer->procptr; 1626 up = pp->unitptr; 1627 1628 /* 1629 * Find the maximum minute sync pulse energy for both the 1630 * WWV and WWVH stations. This will be used later for channel 1631 * and station mitigation. Also set the seconds epoch at 800 ms 1632 * well before the end of the second to make sure we never set 1633 * the epoch backwards. 1634 */ 1635 cp = &up->mitig[up->achan]; 1636 if (cp->wwv.amp > cp->wwv.syneng) 1637 cp->wwv.syneng = cp->wwv.amp; 1638 if (cp->wwvh.amp > cp->wwvh.syneng) 1639 cp->wwvh.syneng = cp->wwvh.amp; 1640 if (up->rphase == 800 * MS) 1641 up->repoch = up->yepoch; 1642 1643 /* 1644 * Use the signal amplitude at epoch 15 ms as the noise floor. 1645 * This gives a guard time of +-15 ms from the beginning of the 1646 * second until the second pulse rises at 30 ms. There is a 1647 * compromise here; we want to delay the sample as long as 1648 * possible to give the radio time to change frequency and the 1649 * AGC to stabilize, but as early as possible if the second 1650 * epoch is not exact. 1651 */ 1652 if (up->rphase == 15 * MS) 1653 sigmin = sigzer = sigone = up->irig; 1654 1655 /* 1656 * Latch the data signal at 200 ms. Keep this around until the 1657 * end of the second. Use the signal energy as the peak to 1658 * compute the SNR. Use the Q sample to adjust the 100-Hz 1659 * reference oscillator phase. 1660 */ 1661 if (up->rphase == 200 * MS) { 1662 sigzer = up->irig; 1663 engmax = sqrt(up->irig * up->irig + up->qrig * 1664 up->qrig); 1665 up->datpha = up->qrig / up->avgint; 1666 if (up->datpha >= 0) { 1667 up->datapt++; 1668 if (up->datapt >= 80) 1669 up->datapt -= 80; 1670 } else { 1671 up->datapt--; 1672 if (up->datapt < 0) 1673 up->datapt += 80; 1674 } 1675 } 1676 1677 1678 /* 1679 * Latch the data signal at 500 ms. Keep this around until the 1680 * end of the second. 1681 */ 1682 else if (up->rphase == 500 * MS) 1683 sigone = up->irig; 1684 1685 /* 1686 * At the end of the second crank the clock state machine and 1687 * adjust the codec gain. Note the epoch is buffered from the 1688 * center of the second in order to avoid jitter while the 1689 * seconds synch is diddling the epoch. Then, determine the true 1690 * offset and update the median filter in the driver interface. 1691 * 1692 * Use the energy at the end of the second as the noise to 1693 * compute the SNR for the data pulse. This gives a better 1694 * measurement than the beginning of the second, especially when 1695 * returning from the probe channel. This gives a guard time of 1696 * 30 ms from the decay of the longest pulse to the rise of the 1697 * next pulse. 1698 */ 1699 up->rphase++; 1700 if (up->mphase % WWV_SEC == up->repoch) { 1701 up->status &= ~(DGATE | BGATE); 1702 engmin = sqrt(up->irig * up->irig + up->qrig * 1703 up->qrig); 1704 up->datsig = engmax; 1705 up->datsnr = wwv_snr(engmax, engmin); 1706 1707 /* 1708 * If the amplitude or SNR is below threshold, average a 1709 * 0 in the the integrators; otherwise, average the 1710 * bipolar signal. This is done to avoid noise polution. 1711 */ 1712 if (engmax < DTHR || up->datsnr < DSNR) { 1713 up->status |= DGATE; 1714 wwv_rsec(peer, 0); 1715 } else { 1716 sigzer -= sigone; 1717 sigone -= sigmin; 1718 wwv_rsec(peer, sigone - sigzer); 1719 } 1720 if (up->status & (DGATE | BGATE)) 1721 up->errcnt++; 1722 if (up->errcnt > MAXERR) 1723 up->alarm |= LOWERR; 1724 wwv_gain(peer); 1725 cp = &up->mitig[up->achan]; 1726 cp->wwv.syneng = 0; 1727 cp->wwvh.syneng = 0; 1728 up->rphase = 0; 1729 } 1730} 1731 1732 1733/* 1734 * wwv_rsec - process receiver second 1735 * 1736 * This routine is called at the end of each receiver second to 1737 * implement the per-second state machine. The machine assembles BCD 1738 * digit bits, decodes miscellaneous bits and dances the leap seconds. 1739 * 1740 * Normally, the minute has 60 seconds numbered 0-59. If the leap 1741 * warning bit is set, the last minute (1439) of 30 June (day 181 or 182 1742 * for leap years) or 31 December (day 365 or 366 for leap years) is 1743 * augmented by one second numbered 60. This is accomplished by 1744 * extending the minute interval by one second and teaching the state 1745 * machine to ignore it. 1746 */ 1747static void 1748wwv_rsec( 1749 struct peer *peer, /* peer structure pointer */ 1750 double bit 1751 ) 1752{ 1753 static int iniflg; /* initialization flag */ 1754 static double bcddld[4]; /* BCD data bits */ 1755 static double bitvec[61]; /* bit integrator for misc bits */ 1756 struct refclockproc *pp; 1757 struct wwvunit *up; 1758 struct chan *cp; 1759 struct sync *sp, *rp; 1760 char tbuf[TBUF]; /* monitor buffer */ 1761 int sw, arg, nsec; 1762 1763 pp = peer->procptr; 1764 up = pp->unitptr; 1765 if (!iniflg) { 1766 iniflg = 1; 1767 ZERO(bitvec); 1768 } 1769 1770 /* 1771 * The bit represents the probability of a hit on zero (negative 1772 * values), a hit on one (positive values) or a miss (zero 1773 * value). The likelihood vector is the exponential average of 1774 * these probabilities. Only the bits of this vector 1775 * corresponding to the miscellaneous bits of the timecode are 1776 * used, but it's easier to do them all. After that, crank the 1777 * seconds state machine. 1778 */ 1779 nsec = up->rsec; 1780 up->rsec++; 1781 bitvec[nsec] += (bit - bitvec[nsec]) / TCONST; 1782 sw = progx[nsec].sw; 1783 arg = progx[nsec].arg; 1784 1785 /* 1786 * The minute state machine. Fly off to a particular section as 1787 * directed by the transition matrix and second number. 1788 */ 1789 switch (sw) { 1790 1791 /* 1792 * Ignore this second. 1793 */ 1794 case IDLE: /* 9, 45-49 */ 1795 break; 1796 1797 /* 1798 * Probe channel stuff 1799 * 1800 * The WWV/H format contains data pulses in second 59 (position 1801 * identifier) and second 1, but not in second 0. The minute 1802 * sync pulse is contained in second 0. At the end of second 58 1803 * QSY to the probe channel, which rotates in turn over all 1804 * WWV/H frequencies. At the end of second 0 measure the minute 1805 * sync pulse. At the end of second 1 measure the data pulse and 1806 * QSY back to the data channel. Note that the actions commented 1807 * here happen at the end of the second numbered as shown. 1808 * 1809 * At the end of second 0 save the minute sync amplitude latched 1810 * at 800 ms as the signal later used to calculate the SNR. 1811 */ 1812 case SYNC2: /* 0 */ 1813 cp = &up->mitig[up->achan]; 1814 cp->wwv.synmax = cp->wwv.syneng; 1815 cp->wwvh.synmax = cp->wwvh.syneng; 1816 break; 1817 1818 /* 1819 * At the end of second 1 use the minute sync amplitude latched 1820 * at 800 ms as the noise to calculate the SNR. If the minute 1821 * sync pulse and SNR are above thresholds and the data pulse 1822 * amplitude and SNR are above thresolds, shift a 1 into the 1823 * station reachability register; otherwise, shift a 0. The 1824 * number of 1 bits in the last six intervals is a component of 1825 * the channel metric computed by the wwv_metric() routine. 1826 * Finally, QSY back to the data channel. 1827 */ 1828 case SYNC3: /* 1 */ 1829 cp = &up->mitig[up->achan]; 1830 1831 /* 1832 * WWV station 1833 */ 1834 sp = &cp->wwv; 1835 sp->synsnr = wwv_snr(sp->synmax, sp->amp); 1836 sp->reach <<= 1; 1837 if (sp->reach & (1 << AMAX)) 1838 sp->count--; 1839 if (sp->synmax >= QTHR && sp->synsnr >= QSNR && 1840 !(up->status & (DGATE | BGATE))) { 1841 sp->reach |= 1; 1842 sp->count++; 1843 } 1844 sp->metric = wwv_metric(sp); 1845 1846 /* 1847 * WWVH station 1848 */ 1849 rp = &cp->wwvh; 1850 rp->synsnr = wwv_snr(rp->synmax, rp->amp); 1851 rp->reach <<= 1; 1852 if (rp->reach & (1 << AMAX)) 1853 rp->count--; 1854 if (rp->synmax >= QTHR && rp->synsnr >= QSNR && 1855 !(up->status & (DGATE | BGATE))) { 1856 rp->reach |= 1; 1857 rp->count++; 1858 } 1859 rp->metric = wwv_metric(rp); 1860 if (pp->sloppyclockflag & CLK_FLAG4) { 1861 snprintf(tbuf, sizeof(tbuf), 1862 "wwv5 %04x %3d %4d %.0f/%.1f %.0f/%.1f %s %04x %.0f %.0f/%.1f %s %04x %.0f %.0f/%.1f", 1863 up->status, up->gain, up->yepoch, 1864 up->epomax, up->eposnr, up->datsig, 1865 up->datsnr, 1866 sp->refid, sp->reach & 0xffff, 1867 sp->metric, sp->synmax, sp->synsnr, 1868 rp->refid, rp->reach & 0xffff, 1869 rp->metric, rp->synmax, rp->synsnr); 1870 record_clock_stats(&peer->srcadr, tbuf); 1871#ifdef DEBUG 1872 if (debug) 1873 printf("%s\n", tbuf); 1874#endif /* DEBUG */ 1875 } 1876 up->errcnt = up->digcnt = up->alarm = 0; 1877 1878 /* 1879 * If synchronized to a station, restart if no stations 1880 * have been heard within the PANIC timeout (2 days). If 1881 * not and the minute digit has been found, restart if 1882 * not synchronized withing the SYNCH timeout (40 m). If 1883 * not, restart if the unit digit has not been found 1884 * within the DATA timeout (15 m). 1885 */ 1886 if (up->status & INSYNC) { 1887 if (up->watch > PANIC) { 1888 wwv_newgame(peer); 1889 return; 1890 } 1891 } else if (up->status & DSYNC) { 1892 if (up->watch > SYNCH) { 1893 wwv_newgame(peer); 1894 return; 1895 } 1896 } else if (up->watch > DATA) { 1897 wwv_newgame(peer); 1898 return; 1899 } 1900 wwv_newchan(peer); 1901 break; 1902 1903 /* 1904 * Save the bit probability in the BCD data vector at the index 1905 * given by the argument. Bits not used in the digit are forced 1906 * to zero. 1907 */ 1908 case COEF1: /* 4-7 */ 1909 bcddld[arg] = bit; 1910 break; 1911 1912 case COEF: /* 10-13, 15-17, 20-23, 25-26, 1913 30-33, 35-38, 40-41, 51-54 */ 1914 if (up->status & DSYNC) 1915 bcddld[arg] = bit; 1916 else 1917 bcddld[arg] = 0; 1918 break; 1919 1920 case COEF2: /* 18, 27-28, 42-43 */ 1921 bcddld[arg] = 0; 1922 break; 1923 1924 /* 1925 * Correlate coefficient vector with each valid digit vector and 1926 * save in decoding matrix. We step through the decoding matrix 1927 * digits correlating each with the coefficients and saving the 1928 * greatest and the next lower for later SNR calculation. 1929 */ 1930 case DECIM2: /* 29 */ 1931 wwv_corr4(peer, &up->decvec[arg], bcddld, bcd2); 1932 break; 1933 1934 case DECIM3: /* 44 */ 1935 wwv_corr4(peer, &up->decvec[arg], bcddld, bcd3); 1936 break; 1937 1938 case DECIM6: /* 19 */ 1939 wwv_corr4(peer, &up->decvec[arg], bcddld, bcd6); 1940 break; 1941 1942 case DECIM9: /* 8, 14, 24, 34, 39 */ 1943 wwv_corr4(peer, &up->decvec[arg], bcddld, bcd9); 1944 break; 1945 1946 /* 1947 * Miscellaneous bits. If above the positive threshold, declare 1948 * 1; if below the negative threshold, declare 0; otherwise 1949 * raise the BGATE bit. The design is intended to avoid 1950 * integrating noise under low SNR conditions. 1951 */ 1952 case MSC20: /* 55 */ 1953 wwv_corr4(peer, &up->decvec[YR + 1], bcddld, bcd9); 1954 /* fall through */ 1955 1956 case MSCBIT: /* 2-3, 50, 56-57 */ 1957 if (bitvec[nsec] > BTHR) { 1958 if (!(up->misc & arg)) 1959 up->alarm |= CMPERR; 1960 up->misc |= arg; 1961 } else if (bitvec[nsec] < -BTHR) { 1962 if (up->misc & arg) 1963 up->alarm |= CMPERR; 1964 up->misc &= ~arg; 1965 } else { 1966 up->status |= BGATE; 1967 } 1968 break; 1969 1970 /* 1971 * Save the data channel gain, then QSY to the probe channel and 1972 * dim the seconds comb filters. The www_newchan() routine will 1973 * light them back up. 1974 */ 1975 case MSC21: /* 58 */ 1976 if (bitvec[nsec] > BTHR) { 1977 if (!(up->misc & arg)) 1978 up->alarm |= CMPERR; 1979 up->misc |= arg; 1980 } else if (bitvec[nsec] < -BTHR) { 1981 if (up->misc & arg) 1982 up->alarm |= CMPERR; 1983 up->misc &= ~arg; 1984 } else { 1985 up->status |= BGATE; 1986 } 1987 up->status &= ~(SELV | SELH); 1988#ifdef ICOM 1989 if (up->fd_icom > 0) { 1990 up->schan = (up->schan + 1) % NCHAN; 1991 wwv_qsy(peer, up->schan); 1992 } else { 1993 up->mitig[up->achan].gain = up->gain; 1994 } 1995#else 1996 up->mitig[up->achan].gain = up->gain; 1997#endif /* ICOM */ 1998 break; 1999 2000 /* 2001 * The endgames 2002 * 2003 * During second 59 the receiver and codec AGC are settling 2004 * down, so the data pulse is unusable as quality metric. If 2005 * LEPSEC is set on the last minute of 30 June or 31 December, 2006 * the transmitter and receiver insert an extra second (60) in 2007 * the timescale and the minute sync repeats the second. Once 2008 * leaps occurred at intervals of about 18 months, but the last 2009 * leap before the most recent leap in 1995 was in 1998. 2010 */ 2011 case MIN1: /* 59 */ 2012 if (up->status & LEPSEC) 2013 break; 2014 2015 /* fall through */ 2016 2017 case MIN2: /* 60 */ 2018 up->status &= ~LEPSEC; 2019 wwv_tsec(peer); 2020 up->rsec = 0; 2021 wwv_clock(peer); 2022 break; 2023 } 2024 if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status & 2025 DSYNC)) { 2026 snprintf(tbuf, sizeof(tbuf), 2027 "wwv3 %2d %04x %3d %4d %5.0f %5.1f %5.0f %5.1f %5.0f", 2028 nsec, up->status, up->gain, up->yepoch, up->epomax, 2029 up->eposnr, up->datsig, up->datsnr, bit); 2030 record_clock_stats(&peer->srcadr, tbuf); 2031#ifdef DEBUG 2032 if (debug) 2033 printf("%s\n", tbuf); 2034#endif /* DEBUG */ 2035 } 2036 pp->disp += AUDIO_PHI; 2037} 2038 2039/* 2040 * The radio clock is set if the alarm bits are all zero. After that, 2041 * the time is considered valid if the second sync bit is lit. It should 2042 * not be a surprise, especially if the radio is not tunable, that 2043 * sometimes no stations are above the noise and the integrators 2044 * discharge below the thresholds. We assume that, after a day of signal 2045 * loss, the minute sync epoch will be in the same second. This requires 2046 * the codec frequency be accurate within 6 PPM. Practical experience 2047 * shows the frequency typically within 0.1 PPM, so after a day of 2048 * signal loss, the time should be within 8.6 ms.. 2049 */ 2050static void 2051wwv_clock( 2052 struct peer *peer /* peer unit pointer */ 2053 ) 2054{ 2055 struct refclockproc *pp; 2056 struct wwvunit *up; 2057 l_fp offset; /* offset in NTP seconds */ 2058 2059 pp = peer->procptr; 2060 up = pp->unitptr; 2061 if (!(up->status & SSYNC)) 2062 up->alarm |= SYNERR; 2063 if (up->digcnt < 9) 2064 up->alarm |= NINERR; 2065 if (!(up->alarm)) 2066 up->status |= INSYNC; 2067 if (up->status & INSYNC && up->status & SSYNC) { 2068 if (up->misc & SECWAR) 2069 pp->leap = LEAP_ADDSECOND; 2070 else 2071 pp->leap = LEAP_NOWARNING; 2072 pp->second = up->rsec; 2073 pp->minute = up->decvec[MN].digit + up->decvec[MN + 2074 1].digit * 10; 2075 pp->hour = up->decvec[HR].digit + up->decvec[HR + 2076 1].digit * 10; 2077 pp->day = up->decvec[DA].digit + up->decvec[DA + 2078 1].digit * 10 + up->decvec[DA + 2].digit * 100; 2079 pp->year = up->decvec[YR].digit + up->decvec[YR + 2080 1].digit * 10; 2081 pp->year += 2000; 2082 L_CLR(&offset); 2083 if (!clocktime(pp->day, pp->hour, pp->minute, 2084 pp->second, GMT, up->timestamp.l_ui, 2085 &pp->yearstart, &offset.l_ui)) { 2086 up->errflg = CEVNT_BADTIME; 2087 } else { 2088 up->watch = 0; 2089 pp->disp = 0; 2090 pp->lastref = up->timestamp; 2091 refclock_process_offset(pp, offset, 2092 up->timestamp, PDELAY + up->pdelay); 2093 refclock_receive(peer); 2094 } 2095 } 2096 pp->lencode = timecode(up, pp->a_lastcode, 2097 sizeof(pp->a_lastcode)); 2098 record_clock_stats(&peer->srcadr, pp->a_lastcode); 2099#ifdef DEBUG 2100 if (debug) 2101 printf("wwv: timecode %d %s\n", pp->lencode, 2102 pp->a_lastcode); 2103#endif /* DEBUG */ 2104} 2105 2106 2107/* 2108 * wwv_corr4 - determine maximum-likelihood digit 2109 * 2110 * This routine correlates the received digit vector with the BCD 2111 * coefficient vectors corresponding to all valid digits at the given 2112 * position in the decoding matrix. The maximum value corresponds to the 2113 * maximum-likelihood digit, while the ratio of this value to the next 2114 * lower value determines the likelihood function. Note that, if the 2115 * digit is invalid, the likelihood vector is averaged toward a miss. 2116 */ 2117static void 2118wwv_corr4( 2119 struct peer *peer, /* peer unit pointer */ 2120 struct decvec *vp, /* decoding table pointer */ 2121 double data[], /* received data vector */ 2122 double tab[][4] /* correlation vector array */ 2123 ) 2124{ 2125 struct refclockproc *pp; 2126 struct wwvunit *up; 2127 double topmax, nxtmax; /* metrics */ 2128 double acc; /* accumulator */ 2129 char tbuf[TBUF]; /* monitor buffer */ 2130 int mldigit; /* max likelihood digit */ 2131 int i, j; 2132 2133 pp = peer->procptr; 2134 up = pp->unitptr; 2135 2136 /* 2137 * Correlate digit vector with each BCD coefficient vector. If 2138 * any BCD digit bit is bad, consider all bits a miss. Until the 2139 * minute units digit has been resolved, don't to anything else. 2140 * Note the SNR is calculated as the ratio of the largest 2141 * likelihood value to the next largest likelihood value. 2142 */ 2143 mldigit = 0; 2144 topmax = nxtmax = -MAXAMP; 2145 for (i = 0; tab[i][0] != 0; i++) { 2146 acc = 0; 2147 for (j = 0; j < 4; j++) 2148 acc += data[j] * tab[i][j]; 2149 acc = (vp->like[i] += (acc - vp->like[i]) / TCONST); 2150 if (acc > topmax) { 2151 nxtmax = topmax; 2152 topmax = acc; 2153 mldigit = i; 2154 } else if (acc > nxtmax) { 2155 nxtmax = acc; 2156 } 2157 } 2158 vp->digprb = topmax; 2159 vp->digsnr = wwv_snr(topmax, nxtmax); 2160 2161 /* 2162 * The current maximum-likelihood digit is compared to the last 2163 * maximum-likelihood digit. If different, the compare counter 2164 * and maximum-likelihood digit are reset. When the compare 2165 * counter reaches the BCMP threshold (3), the digit is assumed 2166 * correct. When the compare counter of all nine digits have 2167 * reached threshold, the clock is assumed correct. 2168 * 2169 * Note that the clock display digit is set before the compare 2170 * counter has reached threshold; however, the clock display is 2171 * not considered correct until all nine clock digits have 2172 * reached threshold. This is intended as eye candy, but avoids 2173 * mistakes when the signal is low and the SNR is very marginal. 2174 */ 2175 if (vp->digprb < BTHR || vp->digsnr < BSNR) { 2176 up->status |= BGATE; 2177 } else { 2178 if (vp->digit != mldigit) { 2179 up->alarm |= CMPERR; 2180 if (vp->count > 0) 2181 vp->count--; 2182 if (vp->count == 0) 2183 vp->digit = mldigit; 2184 } else { 2185 if (vp->count < BCMP) 2186 vp->count++; 2187 if (vp->count == BCMP) { 2188 up->status |= DSYNC; 2189 up->digcnt++; 2190 } 2191 } 2192 } 2193 if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status & 2194 INSYNC)) { 2195 snprintf(tbuf, sizeof(tbuf), 2196 "wwv4 %2d %04x %3d %4d %5.0f %2d %d %d %d %5.0f %5.1f", 2197 up->rsec - 1, up->status, up->gain, up->yepoch, 2198 up->epomax, vp->radix, vp->digit, mldigit, 2199 vp->count, vp->digprb, vp->digsnr); 2200 record_clock_stats(&peer->srcadr, tbuf); 2201#ifdef DEBUG 2202 if (debug) 2203 printf("%s\n", tbuf); 2204#endif /* DEBUG */ 2205 } 2206} 2207 2208 2209/* 2210 * wwv_tsec - transmitter minute processing 2211 * 2212 * This routine is called at the end of the transmitter minute. It 2213 * implements a state machine that advances the logical clock subject to 2214 * the funny rules that govern the conventional clock and calendar. 2215 */ 2216static void 2217wwv_tsec( 2218 struct peer *peer /* driver structure pointer */ 2219 ) 2220{ 2221 struct refclockproc *pp; 2222 struct wwvunit *up; 2223 int minute, day, isleap; 2224 int temp; 2225 2226 pp = peer->procptr; 2227 up = pp->unitptr; 2228 2229 /* 2230 * Advance minute unit of the day. Don't propagate carries until 2231 * the unit minute digit has been found. 2232 */ 2233 temp = carry(&up->decvec[MN]); /* minute units */ 2234 if (!(up->status & DSYNC)) 2235 return; 2236 2237 /* 2238 * Propagate carries through the day. 2239 */ 2240 if (temp == 0) /* carry minutes */ 2241 temp = carry(&up->decvec[MN + 1]); 2242 if (temp == 0) /* carry hours */ 2243 temp = carry(&up->decvec[HR]); 2244 if (temp == 0) 2245 temp = carry(&up->decvec[HR + 1]); 2246 // XXX: Does temp have an expected value here? 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 // XXX: Is there an expected value of temp here? 2287 2288 /* 2289 * Roll the year if this the first day and propagate carries 2290 * through the century. 2291 */ 2292 if (day != (isleap ? 365 : 366)) 2293 return; 2294 2295 // day = 1; 2296 while (carry(&up->decvec[DA]) != 1); /* advance to day 1 */ 2297 while (carry(&up->decvec[DA + 1]) != 0); 2298 while (carry(&up->decvec[DA + 2]) != 0); 2299 temp = carry(&up->decvec[YR]); /* carry years */ 2300 if (temp == 0) 2301 carry(&up->decvec[YR + 1]); 2302} 2303 2304 2305/* 2306 * carry - process digit 2307 * 2308 * This routine rotates a likelihood vector one position and increments 2309 * the clock digit modulo the radix. It returns the new clock digit or 2310 * zero if a carry occurred. Once synchronized, the clock digit will 2311 * match the maximum-likelihood digit corresponding to that position. 2312 */ 2313static int 2314carry( 2315 struct decvec *dp /* decoding table pointer */ 2316 ) 2317{ 2318 int temp; 2319 int j; 2320 2321 dp->digit++; 2322 if (dp->digit == dp->radix) 2323 dp->digit = 0; 2324 temp = dp->like[dp->radix - 1]; 2325 for (j = dp->radix - 1; j > 0; j--) 2326 dp->like[j] = dp->like[j - 1]; 2327 dp->like[0] = temp; 2328 return (dp->digit); 2329} 2330 2331 2332/* 2333 * wwv_snr - compute SNR or likelihood function 2334 */ 2335static double 2336wwv_snr( 2337 double signal, /* signal */ 2338 double noise /* noise */ 2339 ) 2340{ 2341 double rval; 2342 2343 /* 2344 * This is a little tricky. Due to the way things are measured, 2345 * either or both the signal or noise amplitude can be negative 2346 * or zero. The intent is that, if the signal is negative or 2347 * zero, the SNR must always be zero. This can happen with the 2348 * subcarrier SNR before the phase has been aligned. On the 2349 * other hand, in the likelihood function the "noise" is the 2350 * next maximum down from the peak and this could be negative. 2351 * However, in this case the SNR is truly stupendous, so we 2352 * simply cap at MAXSNR dB (40). 2353 */ 2354 if (signal <= 0) { 2355 rval = 0; 2356 } else if (noise <= 0) { 2357 rval = MAXSNR; 2358 } else { 2359 rval = 20. * log10(signal / noise); 2360 if (rval > MAXSNR) 2361 rval = MAXSNR; 2362 } 2363 return (rval); 2364} 2365 2366 2367/* 2368 * wwv_newchan - change to new data channel 2369 * 2370 * The radio actually appears to have ten channels, one channel for each 2371 * of five frequencies and each of two stations (WWV and WWVH), although 2372 * if not tunable only the DCHAN channel appears live. While the radio 2373 * is tuned to the working data channel frequency and station for most 2374 * of the minute, during seconds 59, 0 and 1 the radio is tuned to a 2375 * probe frequency in order to search for minute sync pulse and data 2376 * subcarrier from other transmitters. 2377 * 2378 * The search for WWV and WWVH operates simultaneously, with WWV minute 2379 * sync pulse at 1000 Hz and WWVH at 1200 Hz. The probe frequency 2380 * rotates each minute over 2.5, 5, 10, 15 and 20 MHz in order and yes, 2381 * we all know WWVH is dark on 20 MHz, but few remember when WWV was lit 2382 * on 25 MHz. 2383 * 2384 * This routine selects the best channel using a metric computed from 2385 * the reachability register and minute pulse amplitude. Normally, the 2386 * award goes to the the channel with the highest metric; but, in case 2387 * of ties, the award goes to the channel with the highest minute sync 2388 * pulse amplitude and then to the highest frequency. 2389 * 2390 * The routine performs an important squelch function to keep dirty data 2391 * from polluting the integrators. In order to consider a station valid, 2392 * the metric must be at least MTHR (13); otherwise, the station select 2393 * bits are cleared so the second sync is disabled and the data bit 2394 * integrators averaged to a miss. 2395 */ 2396static int 2397wwv_newchan( 2398 struct peer *peer /* peer structure pointer */ 2399 ) 2400{ 2401 struct refclockproc *pp; 2402 struct wwvunit *up; 2403 struct sync *sp, *rp; 2404 double rank, dtemp; 2405 int i, j, rval; 2406 2407 pp = peer->procptr; 2408 up = pp->unitptr; 2409 2410 /* 2411 * Search all five station pairs looking for the channel with 2412 * maximum metric. 2413 */ 2414 sp = NULL; 2415 j = 0; 2416 rank = 0; 2417 for (i = 0; i < NCHAN; i++) { 2418 rp = &up->mitig[i].wwvh; 2419 dtemp = rp->metric; 2420 if (dtemp >= rank) { 2421 rank = dtemp; 2422 sp = rp; 2423 j = i; 2424 } 2425 rp = &up->mitig[i].wwv; 2426 dtemp = rp->metric; 2427 if (dtemp >= rank) { 2428 rank = dtemp; 2429 sp = rp; 2430 j = i; 2431 } 2432 } 2433 2434 /* 2435 * If the strongest signal is less than the MTHR threshold (13), 2436 * we are beneath the waves, so squelch the second sync and 2437 * advance to the next station. This makes sure all stations are 2438 * scanned when the ions grow dim. If the strongest signal is 2439 * greater than the threshold, tune to that frequency and 2440 * transmitter QTH. 2441 */ 2442 up->status &= ~(SELV | SELH); 2443 if (rank < MTHR) { 2444 up->dchan = (up->dchan + 1) % NCHAN; 2445 if (up->status & METRIC) { 2446 up->status &= ~METRIC; 2447 refclock_report(peer, CEVNT_PROP); 2448 } 2449 rval = FALSE; 2450 } else { 2451 up->dchan = j; 2452 up->sptr = sp; 2453 memcpy(&pp->refid, sp->refid, 4); 2454 peer->refid = pp->refid; 2455 up->status |= METRIC; 2456 if (sp->select & SELV) { 2457 up->status |= SELV; 2458 up->pdelay = pp->fudgetime1; 2459 } else if (sp->select & SELH) { 2460 up->status |= SELH; 2461 up->pdelay = pp->fudgetime2; 2462 } else { 2463 up->pdelay = 0; 2464 } 2465 rval = TRUE; 2466 } 2467#ifdef ICOM 2468 if (up->fd_icom > 0) 2469 wwv_qsy(peer, up->dchan); 2470#endif /* ICOM */ 2471 return (rval); 2472} 2473 2474 2475/* 2476 * wwv_newgame - reset and start over 2477 * 2478 * There are three conditions resulting in a new game: 2479 * 2480 * 1 After finding the minute pulse (MSYNC lit), going 15 minutes 2481 * (DATA) without finding the unit seconds digit. 2482 * 2483 * 2 After finding good data (DSYNC lit), going more than 40 minutes 2484 * (SYNCH) without finding station sync (INSYNC lit). 2485 * 2486 * 3 After finding station sync (INSYNC lit), going more than 2 days 2487 * (PANIC) without finding any station. 2488 */ 2489static void 2490wwv_newgame( 2491 struct peer *peer /* peer structure pointer */ 2492 ) 2493{ 2494 struct refclockproc *pp; 2495 struct wwvunit *up; 2496 struct chan *cp; 2497 int i; 2498 2499 pp = peer->procptr; 2500 up = pp->unitptr; 2501 2502 /* 2503 * Initialize strategic values. Note we set the leap bits 2504 * NOTINSYNC and the refid "NONE". 2505 */ 2506 if (up->status) 2507 up->errflg = CEVNT_TIMEOUT; 2508 peer->leap = LEAP_NOTINSYNC; 2509 up->watch = up->status = up->alarm = 0; 2510 up->avgint = MINAVG; 2511 up->freq = 0; 2512 up->gain = MAXGAIN / 2; 2513 2514 /* 2515 * Initialize the station processes for audio gain, select bit, 2516 * station/frequency identifier and reference identifier. Start 2517 * probing at the strongest channel or the default channel if 2518 * nothing heard. 2519 */ 2520 memset(up->mitig, 0, sizeof(up->mitig)); 2521 for (i = 0; i < NCHAN; i++) { 2522 cp = &up->mitig[i]; 2523 cp->gain = up->gain; 2524 cp->wwv.select = SELV; 2525 snprintf(cp->wwv.refid, sizeof(cp->wwv.refid), "WV%.0f", 2526 floor(qsy[i])); 2527 cp->wwvh.select = SELH; 2528 snprintf(cp->wwvh.refid, sizeof(cp->wwvh.refid), "WH%.0f", 2529 floor(qsy[i])); 2530 } 2531 up->dchan = (DCHAN + NCHAN - 1) % NCHAN; 2532 wwv_newchan(peer); 2533 up->schan = up->dchan; 2534} 2535 2536/* 2537 * wwv_metric - compute station metric 2538 * 2539 * The most significant bits represent the number of ones in the 2540 * station reachability register. The least significant bits represent 2541 * the minute sync pulse amplitude. The combined value is scaled 0-100. 2542 */ 2543double 2544wwv_metric( 2545 struct sync *sp /* station pointer */ 2546 ) 2547{ 2548 double dtemp; 2549 2550 dtemp = sp->count * MAXAMP; 2551 if (sp->synmax < MAXAMP) 2552 dtemp += sp->synmax; 2553 else 2554 dtemp += MAXAMP - 1; 2555 dtemp /= (AMAX + 1) * MAXAMP; 2556 return (dtemp * 100.); 2557} 2558 2559 2560#ifdef ICOM 2561/* 2562 * wwv_qsy - Tune ICOM receiver 2563 * 2564 * This routine saves the AGC for the current channel, switches to a new 2565 * channel and restores the AGC for that channel. If a tunable receiver 2566 * is not available, just fake it. 2567 */ 2568static int 2569wwv_qsy( 2570 struct peer *peer, /* peer structure pointer */ 2571 int chan /* channel */ 2572 ) 2573{ 2574 int rval = 0; 2575 struct refclockproc *pp; 2576 struct wwvunit *up; 2577 2578 pp = peer->procptr; 2579 up = pp->unitptr; 2580 if (up->fd_icom > 0) { 2581 up->mitig[up->achan].gain = up->gain; 2582 rval = icom_freq(up->fd_icom, peer->ttl & 0x7f, 2583 qsy[chan]); 2584 up->achan = chan; 2585 up->gain = up->mitig[up->achan].gain; 2586 } 2587 return (rval); 2588} 2589#endif /* ICOM */ 2590 2591 2592/* 2593 * timecode - assemble timecode string and length 2594 * 2595 * Prettytime format - similar to Spectracom 2596 * 2597 * sq yy ddd hh:mm:ss ld dut lset agc iden sig errs freq avgt 2598 * 2599 * s sync indicator ('?' or ' ') 2600 * q error bits (hex 0-F) 2601 * yyyy year of century 2602 * ddd day of year 2603 * hh hour of day 2604 * mm minute of hour 2605 * ss second of minute) 2606 * l leap second warning (' ' or 'L') 2607 * d DST state ('S', 'D', 'I', or 'O') 2608 * dut DUT sign and magnitude (0.1 s) 2609 * lset minutes since last clock update 2610 * agc audio gain (0-255) 2611 * iden reference identifier (station and frequency) 2612 * sig signal quality (0-100) 2613 * errs bit errors in last minute 2614 * freq frequency offset (PPM) 2615 * avgt averaging time (s) 2616 */ 2617static int 2618timecode( 2619 struct wwvunit *up, /* driver structure pointer */ 2620 char * tc, /* target string */ 2621 size_t tcsiz /* target max chars */ 2622 ) 2623{ 2624 struct sync *sp; 2625 int year, day, hour, minute, second, dut; 2626 char synchar, leapchar, dst; 2627 char cptr[50]; 2628 2629 2630 /* 2631 * Common fixed-format fields 2632 */ 2633 synchar = (up->status & INSYNC) ? ' ' : '?'; 2634 year = up->decvec[YR].digit + up->decvec[YR + 1].digit * 10 + 2635 2000; 2636 day = up->decvec[DA].digit + up->decvec[DA + 1].digit * 10 + 2637 up->decvec[DA + 2].digit * 100; 2638 hour = up->decvec[HR].digit + up->decvec[HR + 1].digit * 10; 2639 minute = up->decvec[MN].digit + up->decvec[MN + 1].digit * 10; 2640 second = 0; 2641 leapchar = (up->misc & SECWAR) ? 'L' : ' '; 2642 dst = dstcod[(up->misc >> 4) & 0x3]; 2643 dut = up->misc & 0x7; 2644 if (!(up->misc & DUTS)) 2645 dut = -dut; 2646 snprintf(tc, tcsiz, "%c%1X", synchar, up->alarm); 2647 snprintf(cptr, sizeof(cptr), 2648 " %4d %03d %02d:%02d:%02d %c%c %+d", 2649 year, day, hour, minute, second, leapchar, dst, dut); 2650 strlcat(tc, cptr, tcsiz); 2651 2652 /* 2653 * Specific variable-format fields 2654 */ 2655 sp = up->sptr; 2656 snprintf(cptr, sizeof(cptr), " %d %d %s %.0f %d %.1f %d", 2657 up->watch, up->mitig[up->dchan].gain, sp->refid, 2658 sp->metric, up->errcnt, up->freq / WWV_SEC * 1e6, 2659 up->avgint); 2660 strlcat(tc, cptr, tcsiz); 2661 2662 return strlen(tc); 2663} 2664 2665 2666/* 2667 * wwv_gain - adjust codec gain 2668 * 2669 * This routine is called at the end of each second. During the second 2670 * the number of signal clips above the MAXAMP threshold (6000). If 2671 * there are no clips, the gain is bumped up; if there are more than 2672 * MAXCLP clips (100), it is bumped down. The decoder is relatively 2673 * insensitive to amplitude, so this crudity works just peachy. The 2674 * routine also jiggles the input port and selectively mutes the 2675 * monitor. 2676 */ 2677static void 2678wwv_gain( 2679 struct peer *peer /* peer structure pointer */ 2680 ) 2681{ 2682 struct refclockproc *pp; 2683 struct wwvunit *up; 2684 2685 pp = peer->procptr; 2686 up = pp->unitptr; 2687 2688 /* 2689 * Apparently, the codec uses only the high order bits of the 2690 * gain control field. Thus, it may take awhile for changes to 2691 * wiggle the hardware bits. 2692 */ 2693 if (up->clipcnt == 0) { 2694 up->gain += 4; 2695 if (up->gain > MAXGAIN) 2696 up->gain = MAXGAIN; 2697 } else if (up->clipcnt > MAXCLP) { 2698 up->gain -= 4; 2699 if (up->gain < 0) 2700 up->gain = 0; 2701 } 2702 audio_gain(up->gain, up->mongain, up->port); 2703 up->clipcnt = 0; 2704#if DEBUG 2705 if (debug > 1) 2706 audio_show(); 2707#endif 2708} 2709 2710 2711#else 2712int refclock_wwv_bs; 2713#endif /* REFCLOCK */ 2714