diff -uNrBbd ntp-dev-4.2.5p158.org/ntpd/refclock_nmea.c ntp-dev-4.2.5p158/ntpd/refclock_nmea.c
--- ntp-dev-4.2.5p158.org/ntpd/refclock_nmea.c	2008-06-07 01:13:46.000000000 +0200
+++ ntp-dev-4.2.5p158/ntpd/refclock_nmea.c	2009-02-13 10:19:24.000000000 +0100
@@ -74,6 +74,7 @@
 # define DEVICE "COM%d:" 	/* COM 1 - 3 supported */
 #else
 # define DEVICE	"/dev/gps%d"	/* name of radio device */
+# define DEVICEPPS "/dev/pps%d" /* name of alternate PPS radio device */
 #endif
 #define	SPEED232	B4800	/* uart speed (4800 bps) */
 #define	PRECISION	(-9)	/* precision assumed (about 2 ms) */
@@ -265,17 +266,37 @@
 	gps_send(pp->io.fd,"$PMOTG,RMC,0000*1D\r\n", peer);
 
 #ifdef HAVE_PPSAPI
-	/*
-	 * Start the PPSAPI interface if it is there. Default to use
-	 * the assert edge and do not enable the kernel hardpps.
-	 */
-	if (time_pps_create(fd, &up->handle) < 0) {
-		up->handle = 0;
-		msyslog(LOG_ERR,
-		    "refclock_nmea: time_pps_create failed: %m");
-		return (1);
+	msyslog(LOG_ERR, "refclock_nmea: found GPS source \"%s\"", device);
+	if (time_pps_create(pp->io.fd, &up->handle) == 0)
+	{
+		msyslog(LOG_INFO, "refclock_nmea: found PPS source \"%s\"", device);
+		return(nmea_ppsapi(peer, 0, 0, &(pp->fudgetime1)));
 	}
-	return(nmea_ppsapi(peer, 0, 0, NULL));
+
+	/* Try the alternate PPS device */
+	(void) snprintf(device, sizeof(device), DEVICEPPS, unit);
+	fd = open(device, O_RDWR);
+	if (fd >= 0)  /* /dev/pps0 exists */
+	{
+		msyslog(LOG_ERR, "refclock_nmea: try \"%s\" for PPS", device);
+
+		if (time_pps_create(fd, &up->handle) == 0)
+		{
+			msyslog(LOG_INFO, "refclock_nmea: found PPS source \"%s\"", device);
+			return(nmea_ppsapi(peer, 0, 0, &(pp->fudgetime1)));
+		}
+
+		close(fd); 
+	} 
+	else if (errno != EEXIST)
+	{
+		msyslog(LOG_ERR, "refclock_nmea: error opening %s: %m", device);
+	}
+
+	/* No luck, no PPS unit available! */
+	up->handle = -1;
+	msyslog(LOG_ERR, "refclock_nmea: no PPS devices found at %s", device);
+	return (1);
 #else
 	return (1);
 #endif /* HAVE_PPSAPI */
@@ -296,7 +317,6 @@
 	pp = peer->procptr;
 	up = (struct nmeaunit *)pp->unitptr;
 #ifdef HAVE_PPSAPI
-	if (up->handle != 0)
 		time_pps_destroy(up->handle);
 #endif /* HAVE_PPSAPI */
 	io_closeclock(&pp->io);
@@ -314,20 +334,20 @@
 	struct refclockstat *out, /* output parameters (not used) */
 	struct peer *peer	/* peer structure pointer */
 	)
-{
+		{
 	struct refclockproc *pp;
 
 	pp = peer->procptr;
 	nmea_ppsapi(peer, pp->sloppyclockflag & CLK_FLAG2,
 	    pp->sloppyclockflag & CLK_FLAG3, &(pp->fudgetime1));
-}
+		}
 
 
-/*
+		/*
  * Initialize PPSAPI
  */
-int
-nmea_ppsapi(
+		int
+		nmea_ppsapi(
 	struct peer *peer,	/* peer structure pointer */
 	int enb_clear,		/* clear enable */
 	int enb_hardpps,	/* hardpps enable */
@@ -422,7 +442,7 @@
 	/*
 	 * Convert the timespec nanoseconds field to ntp l_fp units.
 	 */ 
-	if (up->handle == 0)
+	if (up->handle == -1)
 		return (0);
 	timeout.tv_sec = 0;
 	timeout.tv_nsec = 0;