I am using Kernel :2.6.23rc2, PPS patch: ntp -pps-2.6.23rc2.diff NTP version: ntp-4.2.4P4.I have complied the Kernel with Serial Driver,PPS support as a module.Under the PPS SUPPORT I have selected PPS debugging message,UART serial support. I am using GPS Receiver TRIMBLE ACE 3 . The Receiver is Configured forTSIP Output and PPS.Data and PPS from GPS receiver is fed to MAX232 and output of MAX232 is fed to DCD pin of serial port.The serial port I have used is ttyS3. I complied Ntp-4.2.4p4 with USE="parse_clocks". Any body can help me out. And i have also enabled

ln -s /dev/ttyS3 /dev/refclock-3
ln -s /dev/pps0 /dev/refclockpps-3