Re: Using mode byte for Accord GPS Clock (venugopal) - NTP

This is a discussion on Re: Using mode byte for Accord GPS Clock (venugopal) - NTP ; Hi all, After going through the NMEA ref.clock driver, it seems that the original author has choosen values 0(GPXXX), 1(GPRMC), 2(GPGGA) and 4(GPGLL) for mode field so that multiple sentences can be selected. As posted earlier reg. using the mode ...

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Thread: Re: Using mode byte for Accord GPS Clock (venugopal)

  1. Re: Using mode byte for Accord GPS Clock (venugopal)

    Hi all,

    After going through the NMEA ref.clock driver, it seems that the
    original author has choosen values 0(GPXXX), 1(GPRMC), 2(GPGGA) and
    4(GPGLL) for mode field so that multiple sentences can be selected. As
    posted earlier reg. using the mode byte/field to support Accord GPS
    Clock, fourth bit cannot be used to denote the baudrate.

    Fourth bit can denote GPZDG(8) (custom NMEA format) while the fifth
    bit can be used for baudrate 0(4800) and 1(9600). But in this case
    multiple sentences may be allowed only if the value of last four bits
    is less than 8, because GPZDG gives GPS time and not UTC like rest of
    them. So if GPZDG is selected, others sentences should not be
    selected.

    Venu

  2. Re: Using mode byte for Accord GPS Clock (venugopal)

    Hi all,

    I need comments from folks who have been maintining reference clk
    drivers reg. using extra bits of the mode field to accomodate support
    for Accord GPS Clock. Please see the pervious posting on the same
    topic.

    As Dave Sir has suggested we need to have some agreement reg. this so
    that I can proceed to sumbit the modified NMEA driver for approval.

    Venu

    On 12/5/07, venu gopal wrote:
    > Hi all,
    >
    > After going through the NMEA ref.clock driver, it seems that the
    > original author has choosen values 0(GPXXX), 1(GPRMC), 2(GPGGA) and
    > 4(GPGLL) for mode field so that multiple sentences can be selected. As
    > posted earlier reg. using the mode byte/field to support Accord GPS
    > Clock, fourth bit cannot be used to denote the baudrate.
    >
    > Fourth bit can denote GPZDG(8) (custom NMEA format) while the fifth
    > bit can be used for baudrate 0(4800) and 1(9600). But in this case
    > multiple sentences may be allowed only if the value of last four bits
    > is less than 8, because GPZDG gives GPS time and not UTC like rest of
    > them. So if GPZDG is selected, others sentences should not be
    > selected.
    >
    > Venu
    >


  3. Re: Using mode byte for Accord GPS Clock (venu gopal)

    Venu,

    venu gopal wrote:
    > Hi all,
    >
    > I need comments from folks who have been maintining reference clk
    > drivers reg. using extra bits of the mode field to accomodate support
    > for Accord GPS Clock. Please see the pervious posting on the same
    > topic.
    >
    > As Dave Sir has suggested we need to have some agreement reg. this so
    > that I can proceed to sumbit the modified NMEA driver for approval.


    I think Frank Kardel (kardel@ntp.org) would be a good starting point. Frank
    is pretty familiar with the NTP driver concept, and NTP in general.

    Unfortunately he is still on holidays until mid December, but I think it's
    worth waiting for his comments ...

    Martin
    --
    Martin Burnicki

    Meinberg Funkuhren
    Bad Pyrmont
    Germany

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