1688 lines
46 KiB
C
1688 lines
46 KiB
C
/*
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* refclock_chu - clock driver for Canadian CHU time/frequency station
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#if defined(REFCLOCK) && defined(CLOCK_CHU)
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#include "ntpd.h"
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#include "ntp_io.h"
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#include "ntp_refclock.h"
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#include "ntp_calendar.h"
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#include "ntp_stdlib.h"
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#include <stdio.h>
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#include <ctype.h>
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#include <math.h>
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#ifdef HAVE_AUDIO
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#include "audio.h"
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#endif /* HAVE_AUDIO */
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#define ICOM 1 /* undefine to suppress ICOM code */
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#ifdef ICOM
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#include "icom.h"
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#endif /* ICOM */
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/*
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* Audio CHU demodulator/decoder
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*
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* This driver synchronizes the computer time using data encoded in
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* radio transmissions from Canadian time/frequency station CHU in
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* Ottawa, Ontario. Transmissions are made continuously on 3330 kHz,
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* 7335 kHz and 14670 kHz in upper sideband, compatible AM mode. An
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* ordinary shortwave receiver can be tuned manually to one of these
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* frequencies or, in the case of ICOM receivers, the receiver can be
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* tuned automatically using this program as propagation conditions
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* change throughout the day and night.
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*
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* The driver receives, demodulates and decodes the radio signals when
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* connected to the audio codec of a suported workstation hardware and
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* operating system. These include Solaris, SunOS, FreeBSD, NetBSD and
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* Linux. In this implementation, only one audio driver and codec can be
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* supported on a single machine.
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*
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* The driver can be compiled to use a Bell 103 compatible modem or
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* modem chip to receive the radio signal and demodulate the data.
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* Alternatively, the driver can be compiled to use the audio codec of
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* the Sun workstation or another with compatible audio drivers. In the
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* latter case, the driver implements the modem using DSP routines, so
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* the radio can be connected directly to either the microphone on line
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* input port. In either case, the driver decodes the data using a
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* maximum likelihood technique which exploits the considerable degree
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* of redundancy available to maximize accuracy and minimize errors.
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*
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* The CHU time broadcast includes an audio signal compatible with the
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* Bell 103 modem standard (mark = 2225 Hz, space = 2025 Hz). It consist
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* of nine, ten-character bursts transmitted at 300 bps and beginning
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* each second from second 31 to second 39 of the minute. Each character
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* consists of eight data bits plus one start bit and two stop bits to
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* encode two hex digits. The burst data consist of five characters (ten
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* hex digits) followed by a repeat of these characters. In format A,
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* the characters are repeated in the same polarity; in format B, the
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* characters are repeated in the opposite polarity.
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*
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* Format A bursts are sent at seconds 32 through 39 of the minute in
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* hex digits
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*
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* 6dddhhmmss6dddhhmmss
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*
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* The first ten digits encode a frame marker (6) followed by the day
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* (ddd), hour (hh in UTC), minute (mm) and the second (ss). Since
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* format A bursts are sent during the third decade of seconds the tens
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* digit of ss is always 3. The driver uses this to determine correct
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* burst synchronization. These digits are then repeated with the same
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* polarity.
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*
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* Format B bursts are sent at second 31 of the minute in hex digits
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*
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* xdyyyyttaaxdyyyyttaa
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*
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* The first ten digits encode a code (x described below) followed by
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* the DUT1 (d in deciseconds), Gregorian year (yyyy), difference TAI -
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* UTC (tt) and daylight time indicator (aa) peculiar to Canada. These
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* digits are then repeated with inverted polarity.
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*
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* The x is coded
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*
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* 1 Sign of DUT (0 = +)
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* 2 Leap second warning. One second will be added.
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* 4 Leap second warning. One second will be subtracted.
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* 8 Even parity bit for this nibble.
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*
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* By design, the last stop bit of the last character in the burst
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* coincides with 0.5 second. Since characters have 11 bits and are
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* transmitted at 300 bps, the last stop bit of the first character
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* coincides with 0.5 - 10 * 11/300 = 0.133 second. Depending on the
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* UART, character interrupts can vary somewhere between the beginning
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* of bit 9 and end of bit 11. These eccentricities can be corrected
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* along with the radio propagation delay using fudge time 1.
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*
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* Debugging aids
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*
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* The timecode format used for debugging and data recording includes
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* data helpful in diagnosing problems with the radio signal and serial
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* connections. With debugging enabled (-d on the ntpd command line),
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* the driver produces one line for each burst in two formats
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* corresponding to format A and B. Following is format A:
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*
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* n b f s m code
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*
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* where n is the number of characters in the burst (0-11), b the burst
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* distance (0-40), f the field alignment (-1, 0, 1), s the
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* synchronization distance (0-16), m the burst number (2-9) and code
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* the burst characters as received. Note that the hex digits in each
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* character are reversed, so the burst
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*
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* 10 38 0 16 9 06851292930685129293
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*
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* is interpreted as containing 11 characters with burst distance 38,
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* field alignment 0, synchronization distance 16 and burst number 9.
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* The nibble-swapped timecode shows day 58, hour 21, minute 29 and
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* second 39.
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*
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* When the audio driver is compiled, format A is preceded by
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* the current gain (0-255) and relative signal level (0-9999). The
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* receiver folume control should be set so that the gain is somewhere
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* near the middle of the range 0-255, which results in a signal level
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* near 1000.
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*
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* Following is format B:
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*
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* n b s code
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*
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* where n is the number of characters in the burst (0-11), b the burst
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* distance (0-40), s the synchronization distance (0-40) and code the
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* burst characters as received. Note that the hex digits in each
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* character are reversed and the last ten digits inverted, so the burst
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*
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* 11 40 1091891300ef6e76ecff
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*
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* is interpreted as containing 11 characters with burst distance 40.
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* The nibble-swapped timecode shows DUT1 +0.1 second, year 1998 and TAI
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* - UTC 31 seconds.
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*
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* In addition to the above, the reference timecode is updated and
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* written to the clockstats file and debug score after the last burst
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* received in the minute. The format is
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*
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* qq yyyy ddd hh:mm:ss nn dd tt
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*
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* where qq are the error flags, as described below, yyyy is the year,
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* ddd the day, hh:mm:ss the time of day, nn the number of format A
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* bursts received during the previous minute, dd the decoding distance
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* and tt the number of timestamps. The error flags are cleared after
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* every update.
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*
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* Fudge factors
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*
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* For accuracies better than the low millisceconds, fudge time1 can be
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* set to the radio propagation delay from CHU to the receiver. This can
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* be done conviently using the minimuf program.
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*
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* Fudge flag4 causes the dubugging output described above to be
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* recorded in the clockstats file. When the audio driver is compiled,
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* fudge flag2 selects the audio input port, where 0 is the mike port
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* (default) and 1 is the line-in port. It does not seem useful to
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* select the compact disc player port. Fudge flag3 enables audio
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* monitoring of the input signal. For this purpose, the monitor gain is
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* set to a default value.
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*
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* The audio codec code is normally compiled in the driver if the
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* architecture supports it (HAVE_AUDIO defined), but is used only if
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* the link /dev/chu_audio is defined and valid. The serial port code is
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* always compiled in the driver, but is used only if the autdio codec
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* is not available and the link /dev/chu%d is defined and valid.
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*
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* The ICOM code is normally compiled in the driver if selected (ICOM
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* defined), but is used only if the link /dev/icom%d is defined and
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* valid and the mode keyword on the server configuration command
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* specifies a nonzero mode (ICOM ID select code). The C-IV speed is
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* 9600 bps if the high order 0x80 bit of the mode is zero and 1200 bps
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* if one. The C-IV trace is turned on if the debug level is greater
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* than one.
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*/
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/*
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* Interface definitions
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*/
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#define SPEED232 B300 /* uart speed (300 baud) */
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#define PRECISION (-10) /* precision assumed (about 1 ms) */
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#define REFID "CHU" /* reference ID */
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#define DEVICE "/dev/chu%d" /* device name and unit */
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#define SPEED232 B300 /* UART speed (300 baud) */
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#ifdef ICOM
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#define TUNE .001 /* offset for narrow filter (kHz) */
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#define DWELL 5 /* minutes in a probe cycle */
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#define NCHAN 3 /* number of channels */
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#define ISTAGE 3 /* number of integrator stages */
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#endif /* ICOM */
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#ifdef HAVE_AUDIO
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/*
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* Audio demodulator definitions
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*/
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#define SECOND 8000 /* nominal sample rate (Hz) */
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#define BAUD 300 /* modulation rate (bps) */
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#define OFFSET 128 /* companded sample offset */
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#define SIZE 256 /* decompanding table size */
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#define MAXAMP 6000. /* maximum signal level */
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#define MAXCLP 100 /* max clips above reference per s */
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#define LIMIT 1000. /* soft limiter threshold */
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#define AGAIN 6. /* baseband gain */
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#define LAG 10 /* discriminator lag */
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#define DEVICE_AUDIO "/dev/audio" /* device name */
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#define DESCRIPTION "CHU Audio/Modem Receiver" /* WRU */
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#define AUDIO_BUFSIZ 240 /* audio buffer size (30 ms) */
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#else
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#define DESCRIPTION "CHU Modem Receiver" /* WRU */
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#endif /* HAVE_AUDIO */
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/*
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* Decoder definitions
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*/
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#define CHAR (11. / 300.) /* character time (s) */
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#define FUDGE .185 /* offset to first stop bit (s) */
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#define BURST 11 /* max characters per burst */
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#define MINCHAR 9 /* min characters per burst */
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#define MINDIST 28 /* min burst distance (of 40) */
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#define MINBURST 4 /* min bursts in minute */
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#define MINSYNC 8 /* min sync distance (of 16) */
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#define MINSTAMP 20 /* min timestamps (of 60) */
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#define METRIC 50. /* min channel metric */
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#define PANIC 1440 /* panic timeout (m) */
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#define HOLD 30 /* reach hold (m) */
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/*
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* Hex extension codes (>= 16)
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*/
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#define HEX_MISS 16 /* miss _ */
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#define HEX_SOFT 17 /* soft error * */
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#define HEX_HARD 18 /* hard error = */
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/*
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* Status bits (status)
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*/
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#define RUNT 0x0001 /* runt burst */
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#define NOISE 0x0002 /* noise burst */
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#define BFRAME 0x0004 /* invalid format B frame sync */
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#define BFORMAT 0x0008 /* invalid format B data */
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#define AFRAME 0x0010 /* invalid format A frame sync */
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#define AFORMAT 0x0020 /* invalid format A data */
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#define DECODE 0x0040 /* invalid data decode */
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#define STAMP 0x0080 /* too few timestamps */
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#define AVALID 0x0100 /* valid A frame */
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#define BVALID 0x0200 /* valid B frame */
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#define INSYNC 0x0400 /* clock synchronized */
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/*
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* Alarm status bits (alarm)
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*
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* These alarms are set at the end of a minute in which at least one
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* burst was received. SYNERR is raised if the AFRAME or BFRAME status
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* bits are set during the minute, FMTERR is raised if the AFORMAT or
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* BFORMAT status bits are set, DECERR is raised if the DECODE status
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* bit is set and TSPERR is raised if the STAMP status bit is set.
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*/
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#define SYNERR 0x01 /* frame sync error */
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#define FMTERR 0x02 /* data format error */
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#define DECERR 0x04 /* data decoding error */
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#define TSPERR 0x08 /* insufficient data */
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#ifdef HAVE_AUDIO
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/*
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* Maximum likelihood UART structure. There are eight of these
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* corresponding to the number of phases.
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*/
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struct surv {
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double shift[12]; /* mark register */
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double es_max, es_min; /* max/min envelope signals */
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double dist; /* sample distance */
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int uart; /* decoded character */
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};
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#endif /* HAVE_AUDIO */
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#ifdef ICOM
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/*
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* CHU station structure. There are three of these corresponding to the
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* three frequencies.
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*/
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struct xmtr {
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double integ[ISTAGE]; /* circular integrator */
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double metric; /* integrator sum */
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int iptr; /* integrator pointer */
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int probe; /* dwells since last probe */
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};
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#endif /* ICOM */
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/*
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* CHU unit control structure
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*/
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struct chuunit {
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u_char decode[20][16]; /* maximum likelihood decoding matrix */
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l_fp cstamp[BURST]; /* character timestamps */
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l_fp tstamp[MAXSTAGE]; /* timestamp samples */
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l_fp timestamp; /* current buffer timestamp */
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l_fp laststamp; /* last buffer timestamp */
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l_fp charstamp; /* character time as a l_fp */
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int errflg; /* error flags */
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int status; /* status bits */
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char ident[5]; /* station ID and channel */
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#ifdef ICOM
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int fd_icom; /* ICOM file descriptor */
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int chan; /* data channel */
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int achan; /* active channel */
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int dwell; /* dwell cycle */
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struct xmtr xmtr[NCHAN]; /* station metric */
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#endif /* ICOM */
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/*
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* Character burst variables
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*/
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int cbuf[BURST]; /* character buffer */
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int ntstamp; /* number of timestamp samples */
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int ndx; /* buffer start index */
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int prevsec; /* previous burst second */
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int burdist; /* burst distance */
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int syndist; /* sync distance */
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int burstcnt; /* format A bursts this minute */
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/*
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* Format particulars
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*/
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int leap; /* leap/dut code */
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int dut; /* UTC1 correction */
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int tai; /* TAI - UTC correction */
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int dst; /* Canadian DST code */
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#ifdef HAVE_AUDIO
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/*
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* Audio codec variables
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*/
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int fd_audio; /* audio port file descriptor */
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double comp[SIZE]; /* decompanding table */
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int port; /* codec port */
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int gain; /* codec gain */
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int mongain; /* codec monitor gain */
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int clipcnt; /* sample clip count */
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int seccnt; /* second interval counter */
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/*
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* Modem variables
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*/
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l_fp tick; /* audio sample increment */
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double bpf[9]; /* IIR bandpass filter */
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double disc[LAG]; /* discriminator shift register */
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double lpf[27]; /* FIR lowpass filter */
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double monitor; /* audio monitor */
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double maxsignal; /* signal level */
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int discptr; /* discriminator pointer */
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/*
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* Maximum likelihood UART variables
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*/
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double baud; /* baud interval */
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struct surv surv[8]; /* UART survivor structures */
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int decptr; /* decode pointer */
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int dbrk; /* holdoff counter */
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#endif /* HAVE_AUDIO */
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};
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/*
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* Function prototypes
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*/
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static int chu_start P((int, struct peer *));
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static void chu_shutdown P((int, struct peer *));
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static void chu_receive P((struct recvbuf *));
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static void chu_poll P((int, struct peer *));
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/*
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* More function prototypes
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*/
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static void chu_decode P((struct peer *, int));
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static void chu_burst P((struct peer *));
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static void chu_clear P((struct peer *));
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static void chu_a P((struct peer *, int));
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static void chu_b P((struct peer *, int));
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static int chu_dist P((int, int));
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static double chu_major P((struct peer *));
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#ifdef HAVE_AUDIO
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static void chu_uart P((struct surv *, double));
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static void chu_rf P((struct peer *, double));
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static void chu_gain P((struct peer *));
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static void chu_audio_receive P((struct recvbuf *rbufp));
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#endif /* HAVE_AUDIO */
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#ifdef ICOM
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static int chu_newchan P((struct peer *, double));
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#endif /* ICOM */
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static void chu_serial_receive P((struct recvbuf *rbufp));
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/*
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* Global variables
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*/
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static char hexchar[] = "0123456789abcdef_*=";
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#ifdef ICOM
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/*
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* Note the tuned frequencies are 1 kHz higher than the carrier. CHU
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* transmits on USB with carrier so we can use AM and the narrow SSB
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* filter.
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*/
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static double qsy[NCHAN] = {3.330, 7.335, 14.670}; /* freq (MHz) */
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#endif /* ICOM */
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/*
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* Transfer vector
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*/
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struct refclock refclock_chu = {
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chu_start, /* start up driver */
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chu_shutdown, /* shut down driver */
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chu_poll, /* transmit poll message */
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noentry, /* not used (old chu_control) */
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noentry, /* initialize driver (not used) */
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noentry, /* not used (old chu_buginfo) */
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NOFLAGS /* not used */
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};
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/*
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* chu_start - open the devices and initialize data for processing
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*/
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static int
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chu_start(
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int unit, /* instance number (not used) */
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struct peer *peer /* peer structure pointer */
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)
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{
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struct chuunit *up;
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struct refclockproc *pp;
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char device[20]; /* device name */
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int fd; /* file descriptor */
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#ifdef ICOM
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int temp;
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#endif /* ICOM */
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#ifdef HAVE_AUDIO
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int fd_audio; /* audio port file descriptor */
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int i; /* index */
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double step; /* codec adjustment */
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/*
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* Open audio device.
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*/
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fd_audio = audio_init(DEVICE_AUDIO, AUDIO_BUFSIZ, unit);
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#ifdef DEBUG
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if (fd_audio > 0 && debug)
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audio_show();
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#endif
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/*
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* Open serial port in raw mode.
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*/
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if (fd_audio > 0) {
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fd = fd_audio;
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} else {
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sprintf(device, DEVICE, unit);
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fd = refclock_open(device, SPEED232, LDISC_RAW);
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}
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#else /* HAVE_AUDIO */
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/*
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* Open serial port in raw mode.
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*/
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sprintf(device, DEVICE, unit);
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fd = refclock_open(device, SPEED232, LDISC_RAW);
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#endif /* HAVE_AUDIO */
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if (fd <= 0)
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return (0);
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/*
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* Allocate and initialize unit structure
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*/
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if (!(up = (struct chuunit *)
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emalloc(sizeof(struct chuunit)))) {
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close(fd);
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return (0);
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}
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memset((char *)up, 0, sizeof(struct chuunit));
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pp = peer->procptr;
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pp->unitptr = (caddr_t)up;
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pp->io.clock_recv = chu_receive;
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pp->io.srcclock = (caddr_t)peer;
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pp->io.datalen = 0;
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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 */
|