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  • Keith VE7GDH
    Scott - does the time used by time stamps in a OT / OT2m etc. take into account leap seconds and TAI? I was trying to track down some delayed packets and
    Message 1 of 5 , Feb 16, 2009
      Scott - does the time used by time stamps in a OT / OT2m etc. take
      into account leap seconds and TAI? I was trying to track down some
      delayed packets and noticed the discrepancy. I'm seeing my beacons
      gated before they were sent - hi! The beacons seem to be time stamped
      about 14 seconds before the actual time according to UTC.

      I've compared WWV, a yellow eTrex, the Nuvi 350 that is being used
      with the T2-301 and the time on my computer which was just calibrated.
      They all agree on the time. I just checked the eTrex in VisualGPS and
      the time in $GPRMC agrees with WWV. The clock in a TNC that I'm
      monitoring the transmitted packets with is also calibrated to within a
      fraction of a second and disagrees with the time stamps. The time stamps
      in beacons from the T2-301 are 14 seconds BEFORE the actual time
      from all of those sources.

      I did some digging and there are apparently 24 leap seconds to date
      and a 10 second offset from TAI or International Atomic Time. That
      seems to add up to the 14 second difference that I'm seeing.

      73 es cul - Keith VE7GDH
      --
      "I may be lost, but I know exactly where I am!"
    • Mike Fenske
      Hi Keith, Have a look at this previous posting by Scott: http://groups.yahoo.com/group/tracker2/message/1998 Looks like when using a GPS in Garmin mode, leap
      Message 2 of 5 , Feb 16, 2009
        Hi Keith,

        Have a look at this previous posting by Scott:

        http://groups.yahoo.com/group/tracker2/message/1998

        Looks like when using a GPS in Garmin mode, leap seconds are not taken into account, but they are when in NMEA mode.

        Mike
        VE7MKF

        Keith VE7GDH wrote:
        > Scott - does the time used by time stamps in a OT / OT2m etc. take
        > into account leap seconds and TAI? I was trying to track down some
        > delayed packets and noticed the discrepancy. I'm seeing my beacons
        > gated before they were sent - hi! The beacons seem to be time stamped
        > about 14 seconds before the actual time according to UTC.
        >
        > I've compared WWV, a yellow eTrex, the Nuvi 350 that is being used
        > with the T2-301 and the time on my computer which was just calibrated.
        > They all agree on the time. I just checked the eTrex in VisualGPS and
        > the time in $GPRMC agrees with WWV. The clock in a TNC that I'm
        > monitoring the transmitted packets with is also calibrated to within a
        > fraction of a second and disagrees with the time stamps. The time stamps
        > in beacons from the T2-301 are 14 seconds BEFORE the actual time
        > from all of those sources.
        >
        > I did some digging and there are apparently 24 leap seconds to date
        > and a 10 second offset from TAI or International Atomic Time. That
        > seems to add up to the 14 second difference that I'm seeing.
        >
        > 73 es cul - Keith VE7GDH
        > --
        > "I may be lost, but I know exactly where I am!"
      • Keith VE7GDH
        Mike VE7MKF wrote... ... Thanks Mike - it looks like I m guilty of not checking the archives before posting - hi! Hopefully Scott has freed up some code space
        Message 3 of 5 , Feb 16, 2009
          Mike VE7MKF wrote...

          > Have a look at this previous posting by Scott:
          > http://groups.yahoo.com/group/tracker2/message/1998
          > Looks like when using a GPS in Garmin mode, leap seconds are
          > not taken into account, but they are when in NMEA mode.

          Thanks Mike - it looks like I'm guilty of not checking the archives
          before posting - hi! Hopefully Scott has freed up some code space
          since so the issue can be addressed.

          73 es cul - Keith VE7GDH
          --
          "I may be lost, but I know exactly where I am!"
        • Scott Miller
          Right, no leap-second compensation. I did add that to the Garmin code in the GTRANS, I ve just got to check if I can fit the changes into the T2. Scott
          Message 4 of 5 , Feb 16, 2009
            Right, no leap-second compensation. I did add that to the Garmin code
            in the GTRANS, I've just got to check if I can fit the changes into the T2.

            Scott

            Keith VE7GDH wrote:
            >
            >
            > Scott - does the time used by time stamps in a OT / OT2m etc. take
            > into account leap seconds and TAI? I was trying to track down some
            > delayed packets and noticed the discrepancy. I'm seeing my beacons
            > gated before they were sent - hi! The beacons seem to be time stamped
            > about 14 seconds before the actual time according to UTC.
            >
            > I've compared WWV, a yellow eTrex, the Nuvi 350 that is being used
            > with the T2-301 and the time on my computer which was just calibrated.
            > They all agree on the time. I just checked the eTrex in VisualGPS and
            > the time in $GPRMC agrees with WWV. The clock in a TNC that I'm
            > monitoring the transmitted packets with is also calibrated to within a
            > fraction of a second and disagrees with the time stamps. The time stamps
            > in beacons from the T2-301 are 14 seconds BEFORE the actual time
            > from all of those sources.
            >
            > I did some digging and there are apparently 24 leap seconds to date
            > and a 10 second offset from TAI or International Atomic Time. That
            > seems to add up to the 14 second difference that I'm seeing.
            >
            > 73 es cul - Keith VE7GDH
            > --
            > "I may be lost, but I know exactly where I am!"
            >
            >
          • Keith VE7GDH
            Scott N1VG wrote... ... Thanks - that would be great if you can make it fit! 73 es cul - Keith VE7GDH -- I may be lost, but I know exactly where I am!
            Message 5 of 5 , Feb 16, 2009
              Scott N1VG wrote...

              > Right, no leap-second compensation. I did add that to the Garmin code
              > in the GTRANS, I've just got to check if I can fit the changes into
              > the T2.

              Thanks - that would be great if you can make it fit!

              73 es cul - Keith VE7GDH
              --
              "I may be lost, but I know exactly where I am!"
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