* decompanded input signal amplitude must be greater than 100 units and
* the codec sample frequency error less than 250 PPM (.025 percent).
*
- * The program performs a number of error checks to protect against
- * overdriven or underdriven input signal levels, incorrect signal
- * format or improper hardware configuration. Specifically, if any of
- * the following errors occur for a time measurement, the data are
- * rejected.
+ * Monitor Data
*
- * o The peak carrier amplitude is less than DRPOUT (100). This usually
- * means dead IRIG signal source, broken cable or wrong input port.
- *
- * o The frequency error is greater than MAXFREQ +-250 PPM (.025%). This
- * usually means broken codec hardware or wrong codec configuration.
- *
- * o The modulation index is less than MODMIN (0.5). This usually means
- * overdriven IRIG signal or wrong IRIG format.
- *
- * o A frame synchronization error has occurred. This usually means
- * wrong IRIG signal format or the IRIG signal source has lost
- * synchronization (signature control).
- *
- * o A data decoding error has occurred. This usually means wrong IRIG
- * signal format.
- *
- * o The current second of the day is not exactly one greater than the
- * previous one. This usually means a very noisy IRIG signal or
- * insufficient CPU resources.
- *
- * o An audio codec error (overrun) occurred. This usually means
- * insufficient CPU resources, as sometimes happens with Sun SPARC
- * IPCs when doing something useful.
+ * The timecode format used for debugging and data recording includes
+ * data helpful in diagnosing problems with the IRIG signal and codec
+ * connections. The driver produces one line for each timecode in the
+ * following format:
*
- * Note that additional checks are done elsewhere in the reference clock
- * interface routines.
+ * 00 00 98 23 19:26:52 2782 143 0.694 10 0.3 66.5 3094572411.00027
*
- * Debugging aids
+ * If clockstats is enabled, the most recent line is written to the
+ * clockstats file every 64 s. If verbose recording is enabled (fudge
+ * flag 4) each line is written as generated.
*
- * The timecode format used for debugging and data recording includes
- * data helpful in diagnosing problems with the IRIG signal and codec
- * connections. With debugging enabled (-d on the ntpd command line),
- * the driver produces one line for each timecode in the following
- * format:
+ * The first field containes the error flags in hex, where the hex bits
+ * are interpreted as below. This is followed by the year of century,
+ * day of year and time of day. Note that the time of day is for the
+ * previous minute, not the current time. The status indicator and year
+ * are not produced by some IRIG devices and appear as zeros. Following
+ * these fields are the carrier amplitude (0-3000), codec gain (0-255),
+ * modulation index (0-1), time constant (4-10), carrier phase error
+ * +-.5) and carrier frequency error (PPM). The last field is the on-
+ * time timestamp in NTP format.
*
- * 00 1 98 23 19:26:52 721 143 0.694 20 0.1 66.5 3094572411.00027
+ * The error flags are defined as follows in hex:
*
- * The most recent line is also written to the clockstats file at 64-s
- * intervals.
+ * x01 Low signal. The carrier amplitude is less than 100 units. This
+ * is usually the result of no signal or wrong input port.
+ * x02 Frequency error. The codec frequency error is greater than 250
+ * PPM. This may be due to wrong signal format or (rarely)
+ * defective codec.
+ * x04 Modulation error. The IRIG modulation index is less than 0.5.
+ * This is usually the result of an overdriven codec, wrong signal
+ * format or wrong input port.
+ * x08 Frame synch error. The decoder frame does not match the IRIG
+ * frame. This is usually the result of an overdriven codec, wrong
+ * signal format or noisy IRIG signal. It may also be the result of
+ * an IRIG signature check which indicates a failure of the IRIG
+ * signal synchronization source.
+ * x10 Data bit error. The data bit length is out of tolerance. This is
+ * usually the result of an overdriven codec, wrong signal format
+ * or noisy IRIG signal.
+ * x20 Seconds numbering discrepancy. The decoder second does not match
+ * the IRIG second. This is usually the result of an overdriven
+ * codec, wrong signal format or noisy IRIG signal.
+ * x40 Codec error (overrun). The machine is not fast enough to keep up
+ * with the codec.
+ * x80 Device status error (Spectracom).
*
- * The first field contains the error flags in hex, where the hex bits
- * are interpreted as below. This is followed by the IRIG status
- * indicator, year of century, day of year and time of day. The status
- * indicator and year are not produced by some IRIG devices. Following
- * these fields are the signal amplitude (0-8100), codec gain (0-255),
- * modulation index (0-1), time constant (2-20), carrier phase error
- * (us) and carrier frequency error (PPM). The last field is the on-time
- * timestamp in NTP format.
*
- * The fraction part of the on-time timestamp is a good indicator of how
- * well the driver is doing. Once upon a time, an UltrSPARC 30 and
- * Solaris 2.7 kept the clock within a few tens of microseconds relative
- * to the IRIG-B signal. Accuracy with IRIG-E was about ten times worse.
- * Unfortunately, Sun broke the 2.7 audio driver in 2.8, which has a 10-
- * ms sawtooth modulation. The driver attempts to remove the modulation
- * by some clever estimation techniques which mostly work. With the
- * "mixerctl -o" command before starting the daemon, the jitter is down
- * to about 100 microseconds. Your experience may vary.
+ * Once upon a time, an UltrSPARC 30 and Solaris 2.7 kept the clock
+ * within a few tens of microseconds relative to the IRIG-B signal.
+ * Accuracy with IRIG-E was about ten times worse. Unfortunately, Sun
+ * broke the 2.7 audio driver in 2.8, which has a 10-ms sawtooth
+ * modulation.
*
* Unlike other drivers, which can have multiple instantiations, this
* one supports only one. It does not seem likely that more than one
#define FIELD 100 /* bits per second */
#define MINTC 2 /* min PLL time constant */
#define MAXTC 10 /* max PLL time constant max */
-#define MAXAMP 5000. /* maximum signal amplitude */
-#define MINAMP 4000. /* minimum signal amplitude */
+#define MAXAMP 3000. /* maximum signal amplitude */
+#define MINAMP 2000. /* minimum signal amplitude */
#define DRPOUT 100. /* dropout signal amplitude */
#define MODMIN 0.5 /* minimum modulation index */
#define MAXFREQ (250e-6 * SECOND) /* freq tolerance (.025%) */
* decoded second, which happens with a garbled
* IRIG signal. We are very particular.
*/
- if (pp->day == 0 || pp->year != 0 && syncdig ==
- 0)
+ if (pp->day == 0 || (pp->year != 0 && syncdig ==
+ 0))
up->errflg |= IRIG_ERR_SIGERR;
if (pp->second != up->second)
up->errflg |= IRIG_ERR_CHECK;
projects / thirdparty / ntp.git / commitdiff
