[Git][NTPsec/ntpsec][master] refclock_nmea: provisional fix for issue #62.

[Gary E. Miller]

Gary E. Miller pushed to branch master at NTPsec / ntpsec


Commits:
7d49f80d by Gary E. Miller at 2017-09-14T02:08:13Z
refclock_nmea: provisional fix for issue #62.

In the NMEA refclock, when PPS is lost, the peer jitter was left at the
low value calculated for PPS.  This jitter is now used for NMEA.  So
the NMEA time is wrongly thought to be PPS precise.  This caused the
selection algorithm to wrongly pick NMEA over other better sources.

The fix is to reset the jitter when PPS is lost.

- - - - -


1 changed file:

- ntpd/refclock_nmea.c


Changes:

=====================================
ntpd/refclock_nmea.c
=====================================
--- a/ntpd/refclock_nmea.c
+++ b/ntpd/refclock_nmea.c
@@ -1136,6 +1136,15 @@ nmea_poll(
 	 * for now.
 	 */
 	if (!up->ppsapi_gate) {
+		if ( FLAG_PPS & peer->cfg.flags ) {
+                    /*
+                     * PPS just turned off, reset jitter to prevent
+                     * thinking the NMEA is PPS precise and thus
+                     * being wrongly seelcted when better time is
+                     * available elsewhere
+                     */
+                    peer->jitter = LOGTOD(PRECISION);
+                }
 		peer->cfg.flags &= ~FLAG_PPS;
 		peer->precision = PRECISION;
 	} else {



View it on GitLab: https://gitlab.com/NTPsec/ntpsec/commit/7d49f80d0b6eda195443353f2db84fc7bea30f28

---
View it on GitLab: https://gitlab.com/NTPsec/ntpsec/commit/7d49f80d0b6eda195443353f2db84fc7bea30f28
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