/contrib/ntp/ntpd/refclock_chu.c
https://bitbucket.org/freebsd/freebsd-head/ · C · 1687 lines · 1044 code · 124 blank · 519 comment · 187 complexity · 80c4a4fc3e837b9804bf43bab4d88afd MD5 · raw file
- /*
- * refclock_chu - clock driver for Canadian CHU time/frequency station
- */
- #ifdef HAVE_CONFIG_H
- #include <config.h>
- #endif
- #if defined(REFCLOCK) && defined(CLOCK_CHU)
- #include "ntpd.h"
- #include "ntp_io.h"
- #include "ntp_refclock.h"
- #include "ntp_calendar.h"
- #include "ntp_stdlib.h"
- #include <stdio.h>
- #include <ctype.h>
- #include <math.h>
- #ifdef HAVE_AUDIO
- #include "audio.h"
- #endif /* HAVE_AUDIO */
- #define ICOM 1 /* undefine to suppress ICOM code */
- #ifdef ICOM
- #include "icom.h"
- #endif /* ICOM */
- /*
- * Audio CHU demodulator/decoder
- *
- * This driver synchronizes the computer time using data encoded in
- * radio transmissions from Canadian time/frequency station CHU in
- * Ottawa, Ontario. Transmissions are made continuously on 3330 kHz,
- * 7335 kHz and 14670 kHz in upper sideband, compatible AM mode. An
- * ordinary shortwave receiver can be tuned manually to one of these
- * frequencies or, in the case of ICOM receivers, the receiver can be
- * tuned automatically using this program as propagation conditions
- * change throughout the day and night.
- *
- * The driver receives, demodulates and decodes the radio signals when
- * connected to the audio codec of a suported workstation hardware and
- * operating system. These include Solaris, SunOS, FreeBSD, NetBSD and
- * Linux. In this implementation, only one audio driver and codec can be
- * supported on a single machine.
- *
- * The driver can be compiled to use a Bell 103 compatible modem or
- * modem chip to receive the radio signal and demodulate the data.
- * Alternatively, the driver can be compiled to use the audio codec of
- * the Sun workstation or another with compatible audio drivers. In the
- * latter case, the driver implements the modem using DSP routines, so
- * the radio can be connected directly to either the microphone on line
- * input port. In either case, the driver decodes the data using a
- * maximum likelihood technique which exploits the considerable degree
- * of redundancy available to maximize accuracy and minimize errors.
- *
- * The CHU time broadcast includes an audio signal compatible with the
- * Bell 103 modem standard (mark = 2225 Hz, space = 2025 Hz). It consist
- * of nine, ten-character bursts transmitted at 300 bps and beginning
- * each second from second 31 to second 39 of the minute. Each character
- * consists of eight data bits plus one start bit and two stop bits to
- * encode two hex digits. The burst data consist of five characters (ten
- * hex digits) followed by a repeat of these characters. In format A,
- * the characters are repeated in the same polarity; in format B, the
- * characters are repeated in the opposite polarity.
- *
- * Format A bursts are sent at seconds 32 through 39 of the minute in
- * hex digits
- *
- * 6dddhhmmss6dddhhmmss
- *
- * The first ten digits encode a frame marker (6) followed by the day
- * (ddd), hour (hh in UTC), minute (mm) and the second (ss). Since
- * format A bursts are sent during the third decade of seconds the tens
- * digit of ss is always 3. The driver uses this to determine correct
- * burst synchronization. These digits are then repeated with the same
- * polarity.
- *
- * Format B bursts are sent at second 31 of the minute in hex digits
- *
- * xdyyyyttaaxdyyyyttaa
- *
- * The first ten digits encode a code (x described below) followed by
- * the DUT1 (d in deciseconds), Gregorian year (yyyy), difference TAI -
- * UTC (tt) and daylight time indicator (aa) peculiar to Canada. These
- * digits are then repeated with inverted polarity.
- *
- * The x is coded
- *
- * 1 Sign of DUT (0 = +)
- * 2 Leap second warning. One second will be added.
- * 4 Leap second warning. One second will be subtracted.
- * 8 Even parity bit for this nibble.
- *
- * By design, the last stop bit of the last character in the burst
- * coincides with 0.5 second. Since characters have 11 bits and are
- * transmitted at 300 bps, the last stop bit of the first character
- * coincides with 0.5 - 10 * 11/300 = 0.133 second. Depending on the
- * UART, character interrupts can vary somewhere between the beginning
- * of bit 9 and end of bit 11. These eccentricities can be corrected
- * along with the radio propagation delay using fudge time 1.
- *
- * Debugging aids
- *
- * The timecode format used for debugging and data recording includes
- * data helpful in diagnosing problems with the radio signal and serial
- * connections. With debugging enabled (-d on the ntpd command line),
- * the driver produces one line for each burst in two formats
- * corresponding to format A and B. Following is format A:
- *
- * n b f s m code
- *
- * where n is the number of characters in the burst (0-11), b the burst
- * distance (0-40), f the field alignment (-1, 0, 1), s the
- * synchronization distance (0-16), m the burst number (2-9) and code
- * the burst characters as received. Note that the hex digits in each
- * character are reversed, so the burst
- *
- * 10 38 0 16 9 06851292930685129293
- *
- * is interpreted as containing 11 characters with burst distance 38,
- * field alignment 0, synchronization distance 16 and burst number 9.
- * The nibble-swapped timecode shows day 58, hour 21, minute 29 and
- * second 39.
- *
- * When the audio driver is compiled, format A is preceded by
- * the current gain (0-255) and relative signal level (0-9999). The
- * receiver folume control should be set so that the gain is somewhere
- * near the middle of the range 0-255, which results in a signal level
- * near 1000.
- *
- * Following is format B:
- *
- * n b s code
- *
- * where n is the number of characters in the burst (0-11), b the burst
- * distance (0-40), s the synchronization distance (0-40) and code the
- * burst characters as received. Note that the hex digits in each
- * character are reversed and the last ten digits inverted, so the burst
- *
- * 11 40 1091891300ef6e76ecff
- *
- * is interpreted as containing 11 characters with burst distance 40.
- * The nibble-swapped timecode shows DUT1 +0.1 second, year 1998 and TAI
- * - UTC 31 seconds.
- *
- * In addition to the above, the reference timecode is updated and
- * written to the clockstats file and debug score after the last burst
- * received in the minute. The format is
- *
- * qq yyyy ddd hh:mm:ss nn dd tt
- *
- * where qq are the error flags, as described below, yyyy is the year,
- * ddd the day, hh:mm:ss the time of day, nn the number of format A
- * bursts received during the previous minute, dd the decoding distance
- * and tt the number of timestamps. The error flags are cleared after
- * every update.
- *
- * Fudge factors
- *
- * For accuracies better than the low millisceconds, fudge time1 can be
- * set to the radio propagation delay from CHU to the receiver. This can
- * be done conviently using the minimuf program.
- *
- * Fudge flag4 causes the dubugging output described above to be
- * recorded in the clockstats file. When the audio driver is compiled,
- * fudge flag2 selects the audio input port, where 0 is the mike port
- * (default) and 1 is the line-in port. It does not seem useful to
- * select the compact disc player port. Fudge flag3 enables audio
- * monitoring of the input signal. For this purpose, the monitor gain is
- * set to a default value.
- *
- * The audio codec code is normally compiled in the driver if the
- * architecture supports it (HAVE_AUDIO defined), but is used only if
- * the link /dev/chu_audio is defined and valid. The serial port code is
- * always compiled in the driver, but is used only if the autdio codec
- * is not available and the link /dev/chu%d is defined and valid.
- *
- * The ICOM code is normally compiled in the driver if selected (ICOM
- * defined), but is used only if the link /dev/icom%d is defined and
- * valid and the mode keyword on the server configuration command
- * specifies a nonzero mode (ICOM ID select code). The C-IV speed is
- * 9600 bps if the high order 0x80 bit of the mode is zero and 1200 bps
- * if one. The C-IV trace is turned on if the debug level is greater
- * than one.
- */
- /*
- * Interface definitions
- */
- #define SPEED232 B300 /* uart speed (300 baud) */
- #define PRECISION (-10) /* precision assumed (about 1 ms) */
- #define REFID "CHU" /* reference ID */
- #define DEVICE "/dev/chu%d" /* device name and unit */
- #define SPEED232 B300 /* UART speed (300 baud) */
- #ifdef ICOM
- #define TUNE .001 /* offset for narrow filter (kHz) */
- #define DWELL 5 /* minutes in a probe cycle */
- #define NCHAN 3 /* number of channels */
- #define ISTAGE 3 /* number of integrator stages */
- #endif /* ICOM */
- #ifdef HAVE_AUDIO
- /*
- * Audio demodulator definitions
- */
- #define SECOND 8000 /* nominal sample rate (Hz) */
- #define BAUD 300 /* modulation rate (bps) */
- #define OFFSET 128 /* companded sample offset */
- #define SIZE 256 /* decompanding table size */
- #define MAXAMP 6000. /* maximum signal level */
- #define MAXCLP 100 /* max clips above reference per s */
- #define LIMIT 1000. /* soft limiter threshold */
- #define AGAIN 6. /* baseband gain */
- #define LAG 10 /* discriminator lag */
- #define DEVICE_AUDIO "/dev/audio" /* device name */
- #define DESCRIPTION "CHU Audio/Modem Receiver" /* WRU */
- #define AUDIO_BUFSIZ 240 /* audio buffer size (30 ms) */
- #else
- #define DESCRIPTION "CHU Modem Receiver" /* WRU */
- #endif /* HAVE_AUDIO */
- /*
- * Decoder definitions
- */
- #define CHAR (11. / 300.) /* character time (s) */
- #define FUDGE .185 /* offset to first stop bit (s) */
- #define BURST 11 /* max characters per burst */
- #define MINCHAR 9 /* min characters per burst */
- #define MINDIST 28 /* min burst distance (of 40) */
- #define MINBURST 4 /* min bursts in minute */
- #define MINSYNC 8 /* min sync distance (of 16) */
- #define MINSTAMP 20 /* min timestamps (of 60) */
- #define METRIC 50. /* min channel metric */
- #define PANIC 1440 /* panic timeout (m) */
- #define HOLD 30 /* reach hold (m) */
- /*
- * Hex extension codes (>= 16)
- */
- #define HEX_MISS 16 /* miss _ */
- #define HEX_SOFT 17 /* soft error * */
- #define HEX_HARD 18 /* hard error = */
- /*
- * Status bits (status)
- */
- #define RUNT 0x0001 /* runt burst */
- #define NOISE 0x0002 /* noise burst */
- #define BFRAME 0x0004 /* invalid format B frame sync */
- #define BFORMAT 0x0008 /* invalid format B data */
- #define AFRAME 0x0010 /* invalid format A frame sync */
- #define AFORMAT 0x0020 /* invalid format A data */
- #define DECODE 0x0040 /* invalid data decode */
- #define STAMP 0x0080 /* too few timestamps */
- #define AVALID 0x0100 /* valid A frame */
- #define BVALID 0x0200 /* valid B frame */
- #define INSYNC 0x0400 /* clock synchronized */
- /*
- * Alarm status bits (alarm)
- *
- * These alarms are set at the end of a minute in which at least one
- * burst was received. SYNERR is raised if the AFRAME or BFRAME status
- * bits are set during the minute, FMTERR is raised if the AFORMAT or
- * BFORMAT status bits are set, DECERR is raised if the DECODE status
- * bit is set and TSPERR is raised if the STAMP status bit is set.
- */
- #define SYNERR 0x01 /* frame sync error */
- #define FMTERR 0x02 /* data format error */
- #define DECERR 0x04 /* data decoding error */
- #define TSPERR 0x08 /* insufficient data */
- #ifdef HAVE_AUDIO
- /*
- * Maximum likelihood UART structure. There are eight of these
- * corresponding to the number of phases.
- */
- struct surv {
- double shift[12]; /* mark register */
- double es_max, es_min; /* max/min envelope signals */
- double dist; /* sample distance */
- int uart; /* decoded character */
- };
- #endif /* HAVE_AUDIO */
- #ifdef ICOM
- /*
- * CHU station structure. There are three of these corresponding to the
- * three frequencies.
- */
- struct xmtr {
- double integ[ISTAGE]; /* circular integrator */
- double metric; /* integrator sum */
- int iptr; /* integrator pointer */
- int probe; /* dwells since last probe */
- };
- #endif /* ICOM */
- /*
- * CHU unit control structure
- */
- struct chuunit {
- u_char decode[20][16]; /* maximum likelihood decoding matrix */
- l_fp cstamp[BURST]; /* character timestamps */
- l_fp tstamp[MAXSTAGE]; /* timestamp samples */
- l_fp timestamp; /* current buffer timestamp */
- l_fp laststamp; /* last buffer timestamp */
- l_fp charstamp; /* character time as a l_fp */
- int errflg; /* error flags */
- int status; /* status bits */
- char ident[5]; /* station ID and channel */
- #ifdef ICOM
- int fd_icom; /* ICOM file descriptor */
- int chan; /* data channel */
- int achan; /* active channel */
- int dwell; /* dwell cycle */
- struct xmtr xmtr[NCHAN]; /* station metric */
- #endif /* ICOM */
- /*
- * Character burst variables
- */
- int cbuf[BURST]; /* character buffer */
- int ntstamp; /* number of timestamp samples */
- int ndx; /* buffer start index */
- int prevsec; /* previous burst second */
- int burdist; /* burst distance */
- int syndist; /* sync distance */
- int burstcnt; /* format A bursts this minute */
- /*
- * Format particulars
- */
- int leap; /* leap/dut code */
- int dut; /* UTC1 correction */
- int tai; /* TAI - UTC correction */
- int dst; /* Canadian DST code */
- #ifdef HAVE_AUDIO
- /*
- * Audio codec variables
- */
- int fd_audio; /* audio port file descriptor */
- double comp[SIZE]; /* decompanding table */
- int port; /* codec port */
- int gain; /* codec gain */
- int mongain; /* codec monitor gain */
- int clipcnt; /* sample clip count */
- int seccnt; /* second interval counter */
- /*
- * Modem variables
- */
- l_fp tick; /* audio sample increment */
- double bpf[9]; /* IIR bandpass filter */
- double disc[LAG]; /* discriminator shift register */
- double lpf[27]; /* FIR lowpass filter */
- double monitor; /* audio monitor */
- double maxsignal; /* signal level */
- int discptr; /* discriminator pointer */
- /*
- * Maximum likelihood UART variables
- */
- double baud; /* baud interval */
- struct surv surv[8]; /* UART survivor structures */
- int decptr; /* decode pointer */
- int dbrk; /* holdoff counter */
- #endif /* HAVE_AUDIO */
- };
- /*
- * Function prototypes
- */
- static int chu_start P((int, struct peer *));
- static void chu_shutdown P((int, struct peer *));
- static void chu_receive P((struct recvbuf *));
- static void chu_poll P((int, struct peer *));
- /*
- * More function prototypes
- */
- static void chu_decode P((struct peer *, int));
- static void chu_burst P((struct peer *));
- static void chu_clear P((struct peer *));
- static void chu_a P((struct peer *, int));
- static void chu_b P((struct peer *, int));
- static int chu_dist P((int, int));
- static double chu_major P((struct peer *));
- #ifdef HAVE_AUDIO
- static void chu_uart P((struct surv *, double));
- static void chu_rf P((struct peer *, double));
- static void chu_gain P((struct peer *));
- static void chu_audio_receive P((struct recvbuf *rbufp));
- #endif /* HAVE_AUDIO */
- #ifdef ICOM
- static int chu_newchan P((struct peer *, double));
- #endif /* ICOM */
- static void chu_serial_receive P((struct recvbuf *rbufp));
- /*
- * Global variables
- */
- static char hexchar[] = "0123456789abcdef_*=";
- #ifdef ICOM
- /*
- * Note the tuned frequencies are 1 kHz higher than the carrier. CHU
- * transmits on USB with carrier so we can use AM and the narrow SSB
- * filter.
- */
- static double qsy[NCHAN] = {3.330, 7.335, 14.670}; /* freq (MHz) */
- #endif /* ICOM */
- /*
- * Transfer vector
- */
- struct refclock refclock_chu = {
- chu_start, /* start up driver */
- chu_shutdown, /* shut down driver */
- chu_poll, /* transmit poll message */
- noentry, /* not used (old chu_control) */
- noentry, /* initialize driver (not used) */
- noentry, /* not used (old chu_buginfo) */
- NOFLAGS /* not used */
- };
- /*
- * chu_start - open the devices and initialize data for processing
- */
- static int
- chu_start(
- int unit, /* instance number (not used) */
- struct peer *peer /* peer structure pointer */
- )
- {
- struct chuunit *up;
- struct refclockproc *pp;
- char device[20]; /* device name */
- int fd; /* file descriptor */
- #ifdef ICOM
- int temp;
- #endif /* ICOM */
- #ifdef HAVE_AUDIO
- int fd_audio; /* audio port file descriptor */
- int i; /* index */
- double step; /* codec adjustment */
- /*
- * Open audio device.
- */
- fd_audio = audio_init(DEVICE_AUDIO, AUDIO_BUFSIZ, unit);
- #ifdef DEBUG
- if (fd_audio > 0 && debug)
- audio_show();
- #endif
- /*
- * Open serial port in raw mode.
- */
- if (fd_audio > 0) {
- fd = fd_audio;
- } else {
- sprintf(device, DEVICE, unit);
- fd = refclock_open(device, SPEED232, LDISC_RAW);
- }
- #else /* HAVE_AUDIO */
- /*
- * Open serial port in raw mode.
- */
- sprintf(device, DEVICE, unit);
- fd = refclock_open(device, SPEED232, LDISC_RAW);
- #endif /* HAVE_AUDIO */
- if (fd <= 0)
- return (0);
- /*
- * Allocate and initialize unit structure
- */
- if (!(up = (struct chuunit *)
- emalloc(sizeof(struct chuunit)))) {
- close(fd);
- return (0);
- }
- memset((char *)up, 0, sizeof(struct chuunit));
- pp = peer->procptr;
- pp->unitptr = (caddr_t)up;
- pp->io.clock_recv = chu_receive;
- pp->io.srcclock = (caddr_t)peer;
- pp->io.datalen = 0;
- pp->io.fd = fd;
- if (!io_addclock(&pp->io)) {
- close(fd);
- free(up);
- return (0);
- }
- /*
- * Initialize miscellaneous variables
- */
- peer->precision = PRECISION;
- pp->clockdesc = DESCRIPTION;
- strcpy(up->ident, "CHU");
- memcpy(&peer->refid, up->ident, 4);
- DTOLFP(CHAR, &up->charstamp);
- #ifdef HAVE_AUDIO
- /*
- * The companded samples are encoded sign-magnitude. The table
- * contains all the 256 values in the interest of speed. We do
- * this even if the audio codec is not available. C'est la lazy.
- */
- up->fd_audio = fd_audio;
- up->gain = 127;
- up->comp[0] = up->comp[OFFSET] = 0.;
- up->comp[1] = 1; up->comp[OFFSET + 1] = -1.;
- up->comp[2] = 3; up->comp[OFFSET + 2] = -3.;
- step = 2.;
- for (i = 3; i < OFFSET; i++) {
- up->comp[i] = up->comp[i - 1] + step;
- up->comp[OFFSET + i] = -up->comp[i];
- if (i % 16 == 0)
- step *= 2.;
- }
- DTOLFP(1. / SECOND, &up->tick);
- #endif /* HAVE_AUDIO */
- #ifdef ICOM
- temp = 0;
- #ifdef DEBUG
- if (debug > 1)
- temp = P_TRACE;
- #endif
- if (peer->ttl > 0) {
- if (peer->ttl & 0x80)
- up->fd_icom = icom_init("/dev/icom", B1200,
- temp);
- else
- up->fd_icom = icom_init("/dev/icom", B9600,
- temp);
- }
- if (up->fd_icom > 0) {
- if (chu_newchan(peer, 0) != 0) {
- NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT)
- msyslog(LOG_NOTICE,
- "icom: radio not found");
- up->errflg = CEVNT_FAULT;
- close(up->fd_icom);
- up->fd_icom = 0;
- } else {
- NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT)
- msyslog(LOG_NOTICE,
- "icom: autotune enabled");
- }
- }
- #endif /* ICOM */
- return (1);
- }
- /*
- * chu_shutdown - shut down the clock
- */
- static void
- chu_shutdown(
- int unit, /* instance number (not used) */
- struct peer *peer /* peer structure pointer */
- )
- {
- struct chuunit *up;
- struct refclockproc *pp;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- if (up == NULL)
- return;
- io_closeclock(&pp->io);
- #ifdef ICOM
- if (up->fd_icom > 0)
- close(up->fd_icom);
- #endif /* ICOM */
- free(up);
- }
- /*
- * chu_receive - receive data from the audio or serial device
- */
- static void
- chu_receive(
- struct recvbuf *rbufp /* receive buffer structure pointer */
- )
- {
- #ifdef HAVE_AUDIO
- struct chuunit *up;
- struct refclockproc *pp;
- struct peer *peer;
- peer = (struct peer *)rbufp->recv_srcclock;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * If the audio codec is warmed up, the buffer contains codec
- * samples which need to be demodulated and decoded into CHU
- * characters using the software UART. Otherwise, the buffer
- * contains CHU characters from the serial port, so the software
- * UART is bypassed. In this case the CPU will probably run a
- * few degrees cooler.
- */
- if (up->fd_audio > 0)
- chu_audio_receive(rbufp);
- else
- chu_serial_receive(rbufp);
- #else
- chu_serial_receive(rbufp);
- #endif /* HAVE_AUDIO */
- }
- #ifdef HAVE_AUDIO
- /*
- * chu_audio_receive - receive data from the audio device
- */
- static void
- chu_audio_receive(
- struct recvbuf *rbufp /* receive buffer structure pointer */
- )
- {
- struct chuunit *up;
- struct refclockproc *pp;
- struct peer *peer;
- double sample; /* codec sample */
- u_char *dpt; /* buffer pointer */
- int bufcnt; /* buffer counter */
- l_fp ltemp; /* l_fp temp */
- peer = (struct peer *)rbufp->recv_srcclock;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * Main loop - read until there ain't no more. Note codec
- * samples are bit-inverted.
- */
- DTOLFP((double)rbufp->recv_length / SECOND, <emp);
- L_SUB(&rbufp->recv_time, <emp);
- up->timestamp = rbufp->recv_time;
- dpt = rbufp->recv_buffer;
- for (bufcnt = 0; bufcnt < rbufp->recv_length; bufcnt++) {
- sample = up->comp[~*dpt++ & 0xff];
- /*
- * Clip noise spikes greater than MAXAMP. If no clips,
- * increase the gain a tad; if the clips are too high,
- * decrease a tad.
- */
- if (sample > MAXAMP) {
- sample = MAXAMP;
- up->clipcnt++;
- } else if (sample < -MAXAMP) {
- sample = -MAXAMP;
- up->clipcnt++;
- }
- chu_rf(peer, sample);
- L_ADD(&up->timestamp, &up->tick);
- /*
- * Once each second ride gain.
- */
- up->seccnt = (up->seccnt + 1) % SECOND;
- if (up->seccnt == 0) {
- pp->second = (pp->second + 1) % 60;
- chu_gain(peer);
- }
- }
- /*
- * Set the input port and monitor gain for the next buffer.
- */
- if (pp->sloppyclockflag & CLK_FLAG2)
- up->port = 2;
- else
- up->port = 1;
- if (pp->sloppyclockflag & CLK_FLAG3)
- up->mongain = MONGAIN;
- else
- up->mongain = 0;
- }
- /*
- * chu_rf - filter and demodulate the FSK signal
- *
- * This routine implements a 300-baud Bell 103 modem with mark 2225 Hz
- * and space 2025 Hz. It uses a bandpass filter followed by a soft
- * limiter, FM discriminator and lowpass filter. A maximum likelihood
- * decoder samples the baseband signal at eight times the baud rate and
- * detects the start bit of each character.
- *
- * The filters are built for speed, which explains the rather clumsy
- * code. Hopefully, the compiler will efficiently implement the move-
- * and-muiltiply-and-add operations.
- */
- static void
- chu_rf(
- struct peer *peer, /* peer structure pointer */
- double sample /* analog sample */
- )
- {
- struct refclockproc *pp;
- struct chuunit *up;
- struct surv *sp;
- /*
- * Local variables
- */
- double signal; /* bandpass signal */
- double limit; /* limiter signal */
- double disc; /* discriminator signal */
- double lpf; /* lowpass signal */
- double span; /* UART signal span */
- double dist; /* UART signal distance */
- int i, j;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * Bandpass filter. 4th-order elliptic, 500-Hz bandpass centered
- * at 2125 Hz. Passband ripple 0.3 dB, stopband ripple 50 dB.
- */
- signal = (up->bpf[8] = up->bpf[7]) * 5.844676e-01;
- signal += (up->bpf[7] = up->bpf[6]) * 4.884860e-01;
- signal += (up->bpf[6] = up->bpf[5]) * 2.704384e+00;
- signal += (up->bpf[5] = up->bpf[4]) * 1.645032e+00;
- signal += (up->bpf[4] = up->bpf[3]) * 4.644557e+00;
- signal += (up->bpf[3] = up->bpf[2]) * 1.879165e+00;
- signal += (up->bpf[2] = up->bpf[1]) * 3.522634e+00;
- signal += (up->bpf[1] = up->bpf[0]) * 7.315738e-01;
- up->bpf[0] = sample - signal;
- signal = up->bpf[0] * 6.176213e-03
- + up->bpf[1] * 3.156599e-03
- + up->bpf[2] * 7.567487e-03
- + up->bpf[3] * 4.344580e-03
- + up->bpf[4] * 1.190128e-02
- + up->bpf[5] * 4.344580e-03
- + up->bpf[6] * 7.567487e-03
- + up->bpf[7] * 3.156599e-03
- + up->bpf[8] * 6.176213e-03;
- up->monitor = signal / 4.; /* note monitor after filter */
- /*
- * Soft limiter/discriminator. The 11-sample discriminator lag
- * interval corresponds to three cycles of 2125 Hz, which
- * requires the sample frequency to be 2125 * 11 / 3 = 7791.7
- * Hz. The discriminator output varies +-0.5 interval for input
- * frequency 2025-2225 Hz. However, we don't get to sample at
- * this frequency, so the discriminator output is biased. Life
- * at 8000 Hz sucks.
- */
- limit = signal;
- if (limit > LIMIT)
- limit = LIMIT;
- else if (limit < -LIMIT)
- limit = -LIMIT;
- disc = up->disc[up->discptr] * -limit;
- up->disc[up->discptr] = limit;
- up->discptr = (up->discptr + 1 ) % LAG;
- if (disc >= 0)
- disc = SQRT(disc);
- else
- disc = -SQRT(-disc);
- /*
- * Lowpass filter. Raised cosine, Ts = 1 / 300, beta = 0.1.
- */
- lpf = (up->lpf[26] = up->lpf[25]) * 2.538771e-02;
- lpf += (up->lpf[25] = up->lpf[24]) * 1.084671e-01;
- lpf += (up->lpf[24] = up->lpf[23]) * 2.003159e-01;
- lpf += (up->lpf[23] = up->lpf[22]) * 2.985303e-01;
- lpf += (up->lpf[22] = up->lpf[21]) * 4.003697e-01;
- lpf += (up->lpf[21] = up->lpf[20]) * 5.028552e-01;
- lpf += (up->lpf[20] = up->lpf[19]) * 6.028795e-01;
- lpf += (up->lpf[19] = up->lpf[18]) * 6.973249e-01;
- lpf += (up->lpf[18] = up->lpf[17]) * 7.831828e-01;
- lpf += (up->lpf[17] = up->lpf[16]) * 8.576717e-01;
- lpf += (up->lpf[16] = up->lpf[15]) * 9.183463e-01;
- lpf += (up->lpf[15] = up->lpf[14]) * 9.631951e-01;
- lpf += (up->lpf[14] = up->lpf[13]) * 9.907208e-01;
- lpf += (up->lpf[13] = up->lpf[12]) * 1.000000e+00;
- lpf += (up->lpf[12] = up->lpf[11]) * 9.907208e-01;
- lpf += (up->lpf[11] = up->lpf[10]) * 9.631951e-01;
- lpf += (up->lpf[10] = up->lpf[9]) * 9.183463e-01;
- lpf += (up->lpf[9] = up->lpf[8]) * 8.576717e-01;
- lpf += (up->lpf[8] = up->lpf[7]) * 7.831828e-01;
- lpf += (up->lpf[7] = up->lpf[6]) * 6.973249e-01;
- lpf += (up->lpf[6] = up->lpf[5]) * 6.028795e-01;
- lpf += (up->lpf[5] = up->lpf[4]) * 5.028552e-01;
- lpf += (up->lpf[4] = up->lpf[3]) * 4.003697e-01;
- lpf += (up->lpf[3] = up->lpf[2]) * 2.985303e-01;
- lpf += (up->lpf[2] = up->lpf[1]) * 2.003159e-01;
- lpf += (up->lpf[1] = up->lpf[0]) * 1.084671e-01;
- lpf += up->lpf[0] = disc * 2.538771e-02;
- /*
- * Maximum likelihood decoder. The UART updates each of the
- * eight survivors and determines the span, slice level and
- * tentative decoded character. Valid 11-bit characters are
- * framed so that bit 1 and bit 11 (stop bits) are mark and bit
- * 2 (start bit) is space. When a valid character is found, the
- * survivor with maximum distance determines the final decoded
- * character.
- */
- up->baud += 1. / SECOND;
- if (up->baud > 1. / (BAUD * 8.)) {
- up->baud -= 1. / (BAUD * 8.);
- sp = &up->surv[up->decptr];
- span = sp->es_max - sp->es_min;
- up->maxsignal += (span - up->maxsignal) / 80.;
- if (up->dbrk > 0) {
- up->dbrk--;
- } else if ((sp->uart & 0x403) == 0x401 && span > 1000.)
- {
- dist = 0;
- j = 0;
- for (i = 0; i < 8; i++) {
- if (up->surv[i].dist > dist) {
- dist = up->surv[i].dist;
- j = i;
- }
- }
- chu_decode(peer, (up->surv[j].uart >> 2) &
- 0xff);
- up->dbrk = 80;
- }
- up->decptr = (up->decptr + 1) % 8;
- chu_uart(sp, -lpf * AGAIN);
- }
- }
- /*
- * chu_uart - maximum likelihood UART
- *
- * This routine updates a shift register holding the last 11 envelope
- * samples. It then computes the slice level and span over these samples
- * and determines the tentative data bits and distance. The calling
- * program selects over the last eight survivors the one with maximum
- * distance to determine the decoded character.
- */
- static void
- chu_uart(
- struct surv *sp, /* survivor structure pointer */
- double sample /* baseband signal */
- )
- {
- double es_max, es_min; /* max/min envelope */
- double slice; /* slice level */
- double dist; /* distance */
- double dtemp;
- int i;
- /*
- * Save the sample and shift right. At the same time, measure
- * the maximum and minimum over all eleven samples.
- */
- es_max = -1e6;
- es_min = 1e6;
- sp->shift[0] = sample;
- for (i = 11; i > 0; i--) {
- sp->shift[i] = sp->shift[i - 1];
- if (sp->shift[i] > es_max)
- es_max = sp->shift[i];
- if (sp->shift[i] < es_min)
- es_min = sp->shift[i];
- }
- /*
- * Determine the slice level midway beteen the maximum and
- * minimum and the span as the maximum less the minimum. Compute
- * the distance on the assumption the first and last bits must
- * be mark, the second space and the rest either mark or space.
- */
- slice = (es_max + es_min) / 2.;
- dist = 0;
- sp->uart = 0;
- for (i = 1; i < 12; i++) {
- sp->uart <<= 1;
- dtemp = sp->shift[i];
- if (dtemp > slice)
- sp->uart |= 0x1;
- if (i == 1 || i == 11) {
- dist += dtemp - es_min;
- } else if (i == 10) {
- dist += es_max - dtemp;
- } else {
- if (dtemp > slice)
- dist += dtemp - es_min;
- else
- dist += es_max - dtemp;
- }
- }
- sp->es_max = es_max;
- sp->es_min = es_min;
- sp->dist = dist / (11 * (es_max - es_min));
- }
- #endif /* HAVE_AUDIO */
- /*
- * chu_serial_receive - receive data from the serial device
- */
- static void
- chu_serial_receive(
- struct recvbuf *rbufp /* receive buffer structure pointer */
- )
- {
- struct chuunit *up;
- struct refclockproc *pp;
- struct peer *peer;
- u_char *dpt; /* receive buffer pointer */
- peer = (struct peer *)rbufp->recv_srcclock;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * Initialize pointers and read the timecode and timestamp.
- */
- up->timestamp = rbufp->recv_time;
- dpt = (u_char *)&rbufp->recv_space;
- chu_decode(peer, *dpt);
- }
- /*
- * chu_decode - decode the character data
- */
- static void
- chu_decode(
- struct peer *peer, /* peer structure pointer */
- int hexhex /* data character */
- )
- {
- struct refclockproc *pp;
- struct chuunit *up;
- l_fp tstmp; /* timestamp temp */
- double dtemp;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * If the interval since the last character is greater than the
- * longest burst, process the last burst and start a new one. If
- * the interval is less than this but greater than two
- * characters, consider this a noise burst and reject it.
- */
- tstmp = up->timestamp;
- if (L_ISZERO(&up->laststamp))
- up->laststamp = up->timestamp;
- L_SUB(&tstmp, &up->laststamp);
- up->laststamp = up->timestamp;
- LFPTOD(&tstmp, dtemp);
- if (dtemp > BURST * CHAR) {
- chu_burst(peer);
- up->ndx = 0;
- } else if (dtemp > 2.5 * CHAR) {
- up->ndx = 0;
- }
- /*
- * Append the character to the current burst and append the
- * timestamp to the timestamp list.
- */
- if (up->ndx < BURST) {
- up->cbuf[up->ndx] = hexhex & 0xff;
- up->cstamp[up->ndx] = up->timestamp;
- up->ndx++;
- }
- }
- /*
- * chu_burst - search for valid burst format
- */
- static void
- chu_burst(
- struct peer *peer
- )
- {
- struct chuunit *up;
- struct refclockproc *pp;
- int i;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * Correlate a block of five characters with the next block of
- * five characters. The burst distance is defined as the number
- * of bits that match in the two blocks for format A and that
- * match the inverse for format B.
- */
- if (up->ndx < MINCHAR) {
- up->status |= RUNT;
- return;
- }
- up->burdist = 0;
- for (i = 0; i < 5 && i < up->ndx - 5; i++)
- up->burdist += chu_dist(up->cbuf[i], up->cbuf[i + 5]);
- /*
- * If the burst distance is at least MINDIST, this must be a
- * format A burst; if the value is not greater than -MINDIST, it
- * must be a format B burst. If the B burst is perfect, we
- * believe it; otherwise, it is a noise burst and of no use to
- * anybody.
- */
- if (up->burdist >= MINDIST) {
- chu_a(peer, up->ndx);
- } else if (up->burdist <= -MINDIST) {
- chu_b(peer, up->ndx);
- } else {
- up->status |= NOISE;
- return;
- }
- /*
- * If this is a valid burst, wait a guard time of ten seconds to
- * allow for more bursts, then arm the poll update routine to
- * process the minute. Don't do this if this is called from the
- * timer interrupt routine.
- */
- if (peer->outdate != current_time)
- peer->nextdate = current_time + 10;
- }
- /*
- * chu_b - decode format B burst
- */
- static void
- chu_b(
- struct peer *peer,
- int nchar
- )
- {
- struct refclockproc *pp;
- struct chuunit *up;
- u_char code[11]; /* decoded timecode */
- char tbuf[80]; /* trace buffer */
- l_fp offset; /* timestamp offset */
- int i;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * In a format B burst, a character is considered valid only if
- * the first occurrence matches the last occurrence. The burst
- * is considered valid only if all characters are valid; that
- * is, only if the distance is 40. Note that once a valid frame
- * has been found errors are ignored.
- */
- sprintf(tbuf, "chuB %04x %2d %2d ", up->status, nchar,
- -up->burdist);
- for (i = 0; i < nchar; i++)
- sprintf(&tbuf[strlen(tbuf)], "%02x", up->cbuf[i]);
- if (pp->sloppyclockflag & CLK_FLAG4)
- record_clock_stats(&peer->srcadr, tbuf);
- #ifdef DEBUG
- if (debug)
- printf("%s\n", tbuf);
- #endif
- if (up->burdist > -40) {
- up->status |= BFRAME;
- return;
- }
- up->status |= BVALID;
- /*
- * Convert the burst data to internal format. If this succeeds,
- * save the timestamps for later.
- */
- for (i = 0; i < 5; i++) {
- code[2 * i] = hexchar[up->cbuf[i] & 0xf];
- code[2 * i + 1] = hexchar[(up->cbuf[i] >>
- 4) & 0xf];
- }
- if (sscanf((char *)code, "%1x%1d%4d%2d%2x", &up->leap, &up->dut,
- &pp->year, &up->tai, &up->dst) != 5) {
- up->status |= BFORMAT;
- return;
- }
- if (up->leap & 0x8)
- up->dut = -up->dut;
- offset.l_ui = 31;
- offset.l_f = 0;
- for (i = 0; i < nchar && i < 10; i++) {
- up->tstamp[up->ntstamp] = up->cstamp[i];
- L_SUB(&up->tstamp[up->ntstamp], &offset);
- L_ADD(&offset, &up->charstamp);
- if (up->ntstamp < MAXSTAGE - 1)
- up->ntstamp++;
- }
- }
- /*
- * chu_a - decode format A burst
- */
- static void
- chu_a(
- struct peer *peer,
- int nchar
- )
- {
- struct refclockproc *pp;
- struct chuunit *up;
- char tbuf[80]; /* trace buffer */
- l_fp offset; /* timestamp offset */
- int val; /* distance */
- int temp;
- int i, j, k;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * Determine correct burst phase. There are three cases
- * corresponding to in-phase, one character early or one
- * character late. These cases are distinguished by the position
- * of the framing digits x6 at positions 0 and 5 and x3 at
- * positions 4 and 9. The correct phase is when the distance
- * relative to the framing digits is maximum. The burst is valid
- * only if the maximum distance is at least MINSYNC.
- */
- up->syndist = k = 0;
- val = -16;
- for (i = -1; i < 2; i++) {
- temp = up->cbuf[i + 4] & 0xf;
- if (i >= 0)
- temp |= (up->cbuf[i] & 0xf) << 4;
- val = chu_dist(temp, 0x63);
- temp = (up->cbuf[i + 5] & 0xf) << 4;
- if (i + 9 < nchar)
- temp |= up->cbuf[i + 9] & 0xf;
- val += chu_dist(temp, 0x63);
- if (val > up->syndist) {
- up->syndist = val;
- k = i;
- }
- }
- temp = (up->cbuf[k + 4] >> 4) & 0xf;
- if (temp > 9 || k + 9 >= nchar || temp != ((up->cbuf[k + 9] >>
- 4) & 0xf))
- temp = 0;
- #ifdef HAVE_AUDIO
- if (up->fd_audio)
- sprintf(tbuf, "chuA %04x %4.0f %2d %2d %2d %2d %1d ",
- up->status, up->maxsignal, nchar, up->burdist, k,
- up->syndist, temp);
- else
- sprintf(tbuf, "chuA %04x %2d %2d %2d %2d %1d ",
- up->status, nchar, up->burdist, k, up->syndist,
- temp);
- #else
- sprintf(tbuf, "chuA %04x %2d %2d %2d %2d %1d ", up->status,
- nchar, up->burdist, k, up->syndist, temp);
- #endif /* HAVE_AUDIO */
- for (i = 0; i < nchar; i++)
- sprintf(&tbuf[strlen(tbuf)], "%02x",
- up->cbuf[i]);
- if (pp->sloppyclockflag & CLK_FLAG4)
- record_clock_stats(&peer->srcadr, tbuf);
- #ifdef DEBUG
- if (debug)
- printf("%s\n", tbuf);
- #endif
- if (up->syndist < MINSYNC) {
- up->status |= AFRAME;
- return;
- }
- /*
- * A valid burst requires the first seconds number to match the
- * last seconds number. If so, the burst timestamps are
- * corrected to the current minute and saved for later
- * processing. In addition, the seconds decode is advanced from
- * the previous burst to the current one.
- */
- if (temp != 0) {
- pp->second = 30 + temp;
- offset.l_ui = 30 + temp;
- offset.l_f = 0;
- i = 0;
- if (k < 0)
- offset = up->charstamp;
- else if (k > 0)
- i = 1;
- for (; i < nchar && i < k + 10; i++) {
- up->tstamp[up->ntstamp] = up->cstamp[i];
- L_SUB(&up->tstamp[up->ntstamp], &offset);
- L_ADD(&offset, &up->charstamp);
- if (up->ntstamp < MAXSTAGE - 1)
- up->ntstamp++;
- }
- while (temp > up->prevsec) {
- for (j = 15; j > 0; j--) {
- up->decode[9][j] = up->decode[9][j - 1];
- up->decode[19][j] =
- up->decode[19][j - 1];
- }
- up->decode[9][j] = up->decode[19][j] = 0;
- up->prevsec++;
- }
- }
- i = -(2 * k);
- for (j = 0; j < nchar; j++) {
- if (i < 0 || i > 18) {
- i += 2;
- continue;
- }
- up->decode[i][up->cbuf[j] & 0xf]++;
- i++;
- up->decode[i][(up->cbuf[j] >> 4) & 0xf]++;
- i++;
- }
- up->status |= AVALID;
- up->burstcnt++;
- }
- /*
- * chu_poll - called by the transmit procedure
- */
- static void
- chu_poll(
- int unit,
- struct peer *peer /* peer structure pointer */
- )
- {
- struct refclockproc *pp;
- struct chuunit *up;
- l_fp offset;
- char synchar, qual, leapchar;
- int minset, i;
- double dtemp;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- if (pp->coderecv == pp->codeproc)
- up->errflg = CEVNT_TIMEOUT;
- else
- pp->polls++;
- /*
- * If once in sync and the radio has not been heard for awhile
- * (30 m), it is no longer reachable. If not heard in a long
- * while (one day), turn out the lights and start from scratch.
- */
- minset = ((current_time - peer->update) + 30) / 60;
- if (up->status & INSYNC) {
- if (minset > PANIC)
- up->status = 0;
- else if (minset <= HOLD)
- peer->reach |= 1;
- }
- /*
- * Process the last burst, if still in the burst buffer.
- * Don't mess with anything if nothing has been heard. If the
- * minute contains a valid A frame and valid B frame, assume
- * synchronized; however, believe the time only if within metric
- * threshold. Note the quality indicator is only for
- * diagnostics; the data are used only if in sync and above
- * metric threshold.
- */
- chu_burst(peer);
- if (up->burstcnt == 0) {
- #ifdef ICOM
- chu_newchan(peer, 0);
- #endif /* ICOM */
- return;
- }
- dtemp = chu_major(peer);
- qual = 0;
- if (up->status & (BFRAME | AFRAME))
- qual |= SYNERR;
- if (up->status & (BFORMAT | AFORMAT))
- qual |= FMTERR;
- if (up->status & DECODE)
- qual |= DECERR;
- if (up->status & STAMP)
- qual |= TSPERR;
- if (up->status & AVALID && up->status & BVALID)
- up->status |= INSYNC;
- synchar = leapchar = ' ';
- if (!(up->status & INSYNC)) {
- pp->leap = LEAP_NOTINSYNC;
- synchar = '?';
- } else if (up->leap & 0x2) {
- pp->leap = LEAP_ADDSECOND;
- leapchar = 'L';
- } else if (up->leap & 0x4) {
- pp->leap = LEAP_DELSECOND;
- leapchar = 'l';
- } else {
- pp->leap = LEAP_NOWARNING;
- }
- #ifdef HAVE_AUDIO
- if (up->fd_audio)
- sprintf(pp->a_lastcode,
- "%c%1X %04d %3d %02d:%02d:%02d %c%x %+d %d %d %s %.0f %d",
- synchar, qual, pp->year, pp->day, pp->hour,
- pp->minute, pp->second, leapchar, up->dst, up->dut,
- minset, up->gain, up->ident, dtemp, up->ntstamp);
- else
- sprintf(pp->a_lastcode,
- "%c%1X %04d %3d %02d:%02d:%02d %c%x %+d %d %s %.0f %d",
- synchar, qual, pp->year, pp->day, pp->hour,
- pp->minute, pp->second, leapchar, up->dst, up->dut,
- minset, up->ident, dtemp, up->ntstamp);
- #else
- sprintf(pp->a_lastcode,
- "%c%1X %04d %3d %02d:%02d:%02d %c%x %+d %d %s %.0f %d",
- synchar, qual, pp->year, pp->day, pp->hour, pp->minute,
- pp->second, leapchar, up->dst, up->dut, minset, up->ident,
- dtemp, up->ntstamp);
- #endif /* HAVE_AUDIO */
- pp->lencode = strlen(pp->a_lastcode);
- /*
- * If in sync and the signal metric is above threshold, the
- * timecode is ipso fatso valid and can be selected to
- * discipline the clock. Be sure not to leave stray timestamps
- * around if signals are too weak or the clock time is invalid.
- */
- if (up->status & INSYNC && dtemp > METRIC) {
- if (!clocktime(pp->day, pp->hour, pp->minute, 0, GMT,
- up->tstamp[0].l_ui, &pp->yearstart, &offset.l_ui)) {
- up->errflg = CEVNT_BADTIME;
- } else {
- offset.l_uf = 0;
- for (i = 0; i < up->ntstamp; i++)
- refclock_process_offset(pp, offset,
- up->tstamp[i], FUDGE +
- pp->fudgetime1);
- pp->lastref = up->timestamp;
- refclock_receive(peer);
- }
- record_clock_stats(&peer->srcadr, pp->a_lastcode);
- } else if (pp->sloppyclockflag & CLK_FLAG4) {
- record_clock_stats(&peer->srcadr, pp->a_lastcode);
- }
- #ifdef DEBUG
- if (debug)
- printf("chu: timecode %d %s\n", pp->lencode,
- pp->a_lastcode);
- #endif
- #ifdef ICOM
- chu_newchan(peer, dtemp);
- #endif /* ICOM */
- chu_clear(peer);
- if (up->errflg)
- refclock_report(peer, up->errflg);
- up->errflg = 0;
- }
- /*
- * chu_major - majority decoder
- */
- static double
- chu_major(
- struct peer *peer /* peer structure pointer */
- )
- {
- struct refclockproc *pp;
- struct chuunit *up;
- u_char code[11]; /* decoded timecode */
- int mindist; /* minimum distance */
- int val1, val2; /* maximum distance */
- int synchar; /* stray cat */
- int temp;
- int i, j, k;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * Majority decoder. Each burst encodes two replications at each
- * digit position in the timecode. Each row of the decoding
- * matrix encodes the number of occurrences of each digit found
- * at the corresponding position. The maximum over all
- * occurrences at each position is the distance for this
- * position and the corresponding digit is the maximum
- * likelihood candidate. If the distance is zero, assume a miss
- * '_'; if the distance is not more than half the total number
- * of occurrences, assume a soft error '*'; if two different
- * digits with the same distance are found, assume a hard error
- * '='. These will later cause a format error when the timecode
- * is interpreted. The decoding distance is defined as the
- * minimum distance over the first nine digits. The tenth digit
- * varies over the seconds, so we don't count it.
- */
- mindist = 16;
- for (i = 0; i < 9; i++) {
- val1 = val2 = 0;
- k = 0;
- for (j = 0; j < 16; j++) {
- temp = up->decode[i][j] + up->decode[i + 10][j];
- if (temp > val1) {
- val2 = val1;
- val1 = temp;
- k = j;
- }
- }
- if (val1 == 0)
- code[i] = HEX_MISS;
- else if (val1 == val2)
- code[i] = HEX_HARD;
- else if (val1 <= up->burstcnt)
- code[i] = HEX_SOFT;
- else
- code[i] = k;
- if (val1 < mindist)
- mindist = val1;
- code[i] = hexchar[code[i]];
- }
- code[i] = 0;
- /*
- * A valid timecode requires a minimum distance at least half
- * the total number of occurrences. A valid timecode also
- * requires at least 20 valid timestamps.
- */
- if (up->burstcnt < MINBURST || mindist < up->burstcnt)
- up->status |= DECODE;
- if (up->ntstamp < MINSTAMP)
- up->status |= STAMP;
- /*
- * Compute the timecode timestamp from the days, hours and
- * minutes of the timecode. Use clocktime() for the aggregate
- * minutes and the minute offset computed from the burst
- * seconds. Note that this code relies on the filesystem time
- * for the years and does not use the years of the timecode.
- */
- if (sscanf((char *)code, "%1x%3d%2d%2d", &synchar, &pp->day,
- &pp->hour, &pp->minute) != 4) {
- up->status |= AFORMAT;
- return (0);
- }
- if (up->status & (DECODE | STAMP)) {
- up->errflg = CEVNT_BADREPLY;
- return (0);
- }
- return (mindist * 100. / (2. * up->burstcnt));
- }
- /*
- * chu_clear - clear decoding matrix
- */
- static void
- chu_clear(
- struct peer *peer /* peer structure pointer */
- )
- {
- struct refclockproc *pp;
- struct chuunit *up;
- int i, j;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * Clear stuff for the minute.
- */
- up->ndx = up->prevsec = 0;
- up->burstcnt = up->ntstamp = 0;
- up->status &= INSYNC;
- for (i = 0; i < 20; i++) {
- for (j = 0; j < 16; j++)
- up->decode[i][j] = 0;
- }
- }
- #ifdef ICOM
- /*
- * chu_newchan - called once per minute to find the best channel;
- * returns zero on success, nonzero if ICOM error.
- */
- static int
- chu_newchan(
- struct peer *peer,
- double met
- )
- {
- struct chuunit *up;
- struct refclockproc *pp;
- struct xmtr *sp;
- char tbuf[80]; /* trace buffer */
- int rval;
- double metric;
- int i, j;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * The radio can be tuned to three channels: 0 (3330 kHz), 1
- * (7335 kHz) and 2 (14670 kHz). There are five one-minute
- * dwells in each cycle. During the first dwell the radio is
- * tuned to one of three probe channels; during the remaining
- * four dwells the radio is tuned to the data channel. The probe
- * channel is selects as the least recently used. At the end of
- * each dwell the channel metrics are measured and the highest
- * one is selected as the data channel.
- */
- if (up->fd_icom <= 0)
- return (0);
- sp = &up->xmtr[up->achan];
- sp->metric -= sp->integ[sp->iptr];
- sp->integ[sp->iptr] = met;
- sp->metric += sp->integ[sp->iptr];
- sp->iptr = (sp->iptr + 1) % ISTAGE;
- metric = 0;
- j = 0;
- for (i = 0; i < NCHAN; i++) {
- up->xmtr[i].probe++;
- if (i == up->achan)
- up->xmtr[i].probe = 0;
- if (up->xmtr[i].metric < metric)
- continue;
- metric = up->xmtr[i].metric;
- j = i;
- }
- if (j != up->chan && metric > 0) {
- up->chan = j;
- sprintf(tbuf, "chu: QSY to %.3f MHz metric %.0f",
- qsy[up->chan], metric);
- if (pp->sloppyclockflag & CLK_FLAG4)
- record_clock_stats(&peer->srcadr, tbuf);
- #ifdef DEBUG
- if (debug)
- printf("%s\n", tbuf);
- #endif
- }
- /*
- * Start the next dwell. We speed up the initial sync a little.
- * If not in sync and no bursts were heard the previous dwell,
- * restart the probe.
- */
- rval = 0;
- if (up->burstcnt == 0 && !(up->status & INSYNC))
- up->dwell = 0;
- #ifdef DEBUG
- if (debug)
- printf(
- "chu: at %ld dwell %d achan %d metric %.0f chan %d\n",
- current_time, up->dwell, up->achan, sp->metric,
- up->chan);
- #endif
- if (up->dwell == 0) {
- rval = 0;
- for (i = 0; i < NCHAN; i++) {
- if (up->xmtr[i].probe < rval)
- continue;
- rval = up->xmtr[i].probe;
- up->achan = i;
- }
- rval = icom_freq(up->fd_icom, peer->ttl & 0x7f,
- qsy[up->achan] + TUNE);
- #ifdef DEBUG
- if (debug)
- printf("chu: at %ld probe channel %d\n",
- current_time, up->achan);
- #endif
- } else {
- if (up->achan != up->chan) {
- rval = icom_freq(up->fd_icom, peer->ttl & 0x7f,
- qsy[up->chan] + TUNE);
- up->achan = up->chan;
- }
- }
- sprintf(up->ident, "CHU%d", up->achan);
- memcpy(&peer->refid, up->ident, 4);
- up->dwell = (up->dwell + 1) % DWELL;
- return (rval);
- }
- #endif /* ICOM */
- /*
- * chu_dist - determine the distance of two octet arguments
- */
- static int
- chu_dist(
- int x, /* an octet of bits */
- int y /* another octet of bits */
- )
- {
- int val; /* bit count */
- int temp;
- int i;
- /*
- * The distance is determined as the weight of the exclusive OR
- * of the two arguments. The weight is determined by the number
- * of one bits in the result. Each one bit increases the weight,
- * while each zero bit decreases it.
- */
- temp = x ^ y;
- val = 0;
- for (i = 0; i < 8; i++) {
- if ((temp & 0x1) == 0)
- val++;
- else
- val--;
- temp >>= 1;
- }
- return (val);
- }
- #ifdef HAVE_AUDIO
- /*
- * chu_gain - adjust codec gain
- *
- * This routine is called once each second. If the signal envelope
- * amplitude is too low, the codec gain is bumped up by four units; if
- * too high, it is bumped down. The decoder is relatively insensitive to
- * amplitude, so this crudity works just fine. The input port is set and
- * the error flag is cleared, mostly to be ornery.
- */
- static void
- chu_gain(
- struct peer *peer /* peer structure pointer */
- )
- {
- struct refclockproc *pp;
- struct chuunit *up;
- pp = peer->procptr;
- up = (struct chuunit *)pp->unitptr;
- /*
- * Apparently, the codec uses only the high order bits of the
- * gain control field. Thus, it may take awhile for changes to
- * wiggle the hardware bits.
- */
- if (up->clipcnt == 0) {
- up->gain += 4;
- if (up->gain > MAXGAIN)
- up->gain = MAXGAIN;
- } else if (up->clipcnt > MAXCLP) {
- up->gain -= 4;
- if (up->gain < 0)
- up->gain = 0;
- }
- audio_gain(up->gain, up->mongain, up->port);
- up->clipcnt = 0;
- }
- #endif /* HAVE_AUDIO */
- #else
- int refclock_chu_bs;
- #endif /* REFCLOCK */