GPS clock for Linux - NTP

This is a discussion on GPS clock for Linux - NTP ; Hello, I am interested in getting a GPS clock to synchronize our internal test network. I am curious to hear about relativley cheap and Linux friendly GPS clock. (Less than $100 would be great) Thanks in advance...

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  1. GPS clock for Linux

    Hello,
    I am interested in getting a GPS clock to synchronize our internal
    test network. I am curious to hear about relativley cheap and Linux
    friendly GPS clock. (Less than $100 would be great)

    Thanks in advance

  2. Re: GPS clock for Linux


    > I am interested in getting a GPS clock to synchronize our internal
    >test network. I am curious to hear about relativley cheap and Linux
    >friendly GPS clock. (Less than $100 would be great)


    The Garmin GPS 18 LVC is popular. "Some assembly required."
    (aka soldering) No big deal if somebody has a soldering iron
    handy. There are a couple of links from here:
    http://support.ntp.org/bin/view/Supp...xpensiveOemGps

    Bewares:
    You don't want the GPS 18 USB version.

    There are a lot of low cost USB GPS gizmos that use the
    SiRF Star III. They suck for timekeeping.

    --
    These are my opinions, not necessarily my employer's. I hate spam.


  3. Re: GPS clock for Linux

    Hal Murray wrote:
    >> I am interested in getting a GPS clock to synchronize our internal
    >> test network. I am curious to hear about relativley cheap and Linux
    >> friendly GPS clock. (Less than $100 would be great)

    >
    > The Garmin GPS 18 LVC is popular. "Some assembly required."
    > (aka soldering) No big deal if somebody has a soldering iron
    > handy. There are a couple of links from here:
    > http://support.ntp.org/bin/view/Supp...xpensiveOemGps


    You will need a 5VDC power supply and a DB-9 or DB-25 connector that
    will connect to a serial or parallel port. The serial port DCD line is
    frequently used. Also some hookup wire, solder, and perhaps other goodies.

  4. Re: GPS clock for Linux

    On Sep 11, 4:54 pm, hal-use...@ip-64-139-1-69.sjc.megapath.net (Hal
    Murray) wrote:
    > > I am interested in getting a GPS clock to synchronize our internal
    > >test network. I am curious to hear about relativley cheap and Linux
    > >friendly GPS clock. (Less than $100 would be great)

    >
    > The Garmin GPS 18 LVC is popular. "Some assembly required."
    > (aka soldering) No big deal if somebody has a soldering iron
    > handy. There are a couple of links from here:
    > http://support.ntp.org/bin/view/Supp...xpensiveOemGps
    >
    > Bewares:
    > You don't want the GPS 18 USB version.
    >
    > There are a lot of low cost USB GPS gizmos that use the
    > SiRF Star III. They suck for timekeeping.
    >
    > --
    > These are my opinions, not necessarily my employer's. I hate spam.

    Thanks. Although, I would prefer something to be just ready to go, as
    we have a paper deadline coming up.

  5. Re: GPS clock for Linux

    On 2008-09-12, rochertov@gmail.com wrote:

    > On Sep 11, 4:54 pm, (Hal Murray) wrote:
    >
    >> > I am interested in getting a GPS clock to synchronize our
    >> >internal test network. I am curious to hear about relativley cheap
    >> >and Linux friendly GPS clock. (Less than $100 would be great)


    http://www.google.com/search?q=gps+clock
    http://www.google.com/search?q=gps+clock+linux
    http://www.google.com/search?q=gps+timing+receiver

    Any timing GPS which ouputs NMEA sentences and a PPS signal is supported
    by the Generic NMEA driver in ntpd. You do need to have LinuxPPS support
    in your kernel or use a helper such as gpsd.

    If you want a drop-in solution you'll need something like

    http://www.ntp-systems.com/products.asp
    or
    http://www.endruntechnologies.com/time-servers.htm

    >> The Garmin GPS 18 LVC is popular. "Some assembly required."
    >> (aka soldering) No big deal if somebody has a soldering
    >> iron handy. There are a couple of links from here:
    >> http://support.ntp.org/bin/view/Supp...xpensiveOemGps

    >
    > Thanks. Although, I would prefer something to be just ready to go, as
    > we have a paper deadline coming up.


    The GPS 18 LVC costs less than $70. Add to that the time for someone to
    work out the wiring and solder up the connector (well under an hour for
    a competant tech).

    Any other solution is likely to cost more.

    --
    Steve Kostecke
    NTP Public Services Project - http://support.ntp.org/

  6. Re: GPS clock for Linux

    Steve Kostecke wrote:

    > The GPS 18 LVC costs less than $70. Add to that the time for someone to
    > work out the wiring and solder up the connector (well under an hour for
    > a competant tech).


    If you ask Garmin Europe for a quote : ~190Euro + VAT Grrrrrrr.

    uwe

  7. Re: GPS clock for Linux

    Uwe Klein wrote:
    > Steve Kostecke wrote:
    >
    >> The GPS 18 LVC costs less than $70. Add to that the time for someone to
    >> work out the wiring and solder up the connector (well under an hour for
    >> a competant tech).

    >
    > If you ask Garmin Europe for a quote : ~190Euro + VAT Grrrrrrr.


    Huh???

    I bought (i.e. ordered) one from a local dealer here in Oslo, I paid
    about $120 at the time, a few years ago.

    Anyway it is so small and cheap that I'd simply order one from the US:
    Even if you have to pay freight and customs, you're still far below that
    Euro price!

    Terje

    --
    -
    "almost all programming can be viewed as an exercise in caching"

  8. Re: GPS clock for Linux

    Richard B. Gilbert wrote:
    > Hal Murray wrote:
    >> The Garmin GPS 18 LVC is popular. "Some assembly required."
    >> (aka soldering) No big deal if somebody has a soldering iron
    >> handy. There are a couple of links from here:
    >> http://support.ntp.org/bin/view/Supp...xpensiveOemGps

    >
    > You will need a 5VDC power supply and a DB-9 or DB-25 connector that
    > will connect to a serial or parallel port. The serial port DCD line is
    > frequently used. Also some hookup wire, solder, and perhaps other goodies.


    Using a USB port for the +5V line is the canonical solution: Very cheap,
    dependable, and no extra wall warts.

    Terje

    --
    -
    "almost all programming can be viewed as an exercise in caching"

  9. Re: GPS clock for Linux

    Terje Mathisen wrote:
    > Uwe Klein wrote:
    >
    >> Steve Kostecke wrote:
    >>
    >>> The GPS 18 LVC costs less than $70. Add to that the time for someone to
    >>> work out the wiring and solder up the connector (well under an hour for
    >>> a competant tech).

    >>
    >>
    >> If you ask Garmin Europe for a quote : ~190Euro + VAT Grrrrrrr.

    >
    >
    > Huh???
    >
    > I bought (i.e. ordered) one from a local dealer here in Oslo, I paid
    > about $120 at the time, a few years ago.
    >
    > Anyway it is so small and cheap that I'd simply order one from the US:
    > Even if you have to pay freight and customs, you're still far below that
    > Euro price!


    YES
    friend of mine is a reseller for garmin. I had him ask for the price
    at Garmin DE about a year ago. I was quite astonished.

    uwe

  10. Re: GPS clock for Linux

    Terje Mathisen wrote:
    > Richard B. Gilbert wrote:
    >> Hal Murray wrote:
    >>> The Garmin GPS 18 LVC is popular. "Some assembly required."
    >>> (aka soldering) No big deal if somebody has a soldering iron
    >>> handy. There are a couple of links from here:
    >>> http://support.ntp.org/bin/view/Supp...xpensiveOemGps

    >>
    >> You will need a 5VDC power supply and a DB-9 or DB-25 connector that
    >> will connect to a serial or parallel port. The serial port DCD line
    >> is frequently used. Also some hookup wire, solder, and perhaps other
    >> goodies.

    >
    > Using a USB port for the +5V line is the canonical solution: Very cheap,
    > dependable, and no extra wall warts.
    >
    > Terje
    >


    I have read claims here that the high and unpredictable latencies in USB
    render it useless for time keeping!

  11. Re: GPS clock for Linux

    hal-usenet@ip-64-139-1-69.sjc.megapath.net (Hal Murray) writes:


    >> I am interested in getting a GPS clock to synchronize our internal
    >>test network. I am curious to hear about relativley cheap and Linux
    >>friendly GPS clock. (Less than $100 would be great)


    >The Garmin GPS 18 LVC is popular. "Some assembly required."
    >(aka soldering) No big deal if somebody has a soldering iron
    >handy. There are a couple of links from here:
    > http://support.ntp.org/bin/view/Supp...xpensiveOemGps


    >Bewares:
    > You don't want the GPS 18 USB version.


    You also do not want the GPS 18 PC serial port version either. Neither has
    a PPS ( pulse per second) output.



    > There are a lot of low cost USB GPS gizmos that use the
    >SiRF Star III. They suck for timekeeping.


    >--
    >These are my opinions, not necessarily my employer's. I hate spam.



  12. Re: GPS clock for Linux

    Uwe Klein writes:

    >Steve Kostecke wrote:


    >> The GPS 18 LVC costs less than $70. Add to that the time for someone to
    >> work out the wiring and solder up the connector (well under an hour for
    >> a competant tech).


    >If you ask Garmin Europe for a quote : ~190Euro + VAT Grrrrrrr.


    Wow! Order from the US. The shipping will not be 150 euros ( the price
    difference between 190 E and the cost in the US)


    >uwe


  13. Re: GPS clock for Linux

    "Richard B. Gilbert" writes:

    >Terje Mathisen wrote:
    >> Richard B. Gilbert wrote:
    >>> Hal Murray wrote:
    >>>> The Garmin GPS 18 LVC is popular. "Some assembly required."
    >>>> (aka soldering) No big deal if somebody has a soldering iron
    >>>> handy. There are a couple of links from here:
    >>>> http://support.ntp.org/bin/view/Supp...xpensiveOemGps
    >>>
    >>> You will need a 5VDC power supply and a DB-9 or DB-25 connector that
    >>> will connect to a serial or parallel port. The serial port DCD line
    >>> is frequently used. Also some hookup wire, solder, and perhaps other
    >>> goodies.

    >>
    >> Using a USB port for the +5V line is the canonical solution: Very cheap,
    >> dependable, and no extra wall warts.
    >>
    >> Terje
    >>


    >I have read claims here that the high and unpredictable latencies in USB
    >render it useless for time keeping!


    Yes. That is why you ONLY use it for the 5V. The usb output is +5V, Signal
    +, Signal -, Power ground. Ignore the signal lines and just use the +5V and
    ground to power your Garmin GPS.


  14. Re: GPS clock for Linux

    Hal Murray wrote:

    > There are a lot of low cost USB GPS gizmos that use the
    > SiRF Star III. They suck for timekeeping.
    >

    Is there a reason known for this?

    uwe

  15. Re: GPS clock for Linux

    Richard B. Gilbert wrote:
    > Terje Mathisen wrote:
    >> Using a USB port for the +5V line is the canonical solution: Very
    >> cheap, dependable, and no extra wall warts.
    >>
    >> Terje
    >>

    >
    > I have read claims here that the high and unpredictable latencies in USB
    > render it useless for time keeping!


    Sure, but +5V DC is _perfect_ for powering said GSP. :-)

    Terje

    --
    -
    "almost all programming can be viewed as an exercise in caching"

  16. Re: GPS clock for Linux

    Uwe Klein wrote:
    > Hal Murray wrote:
    >
    >> There are a lot of low cost USB GPS gizmos that use the
    >> SiRF Star III. They suck for timekeeping.
    >>

    > Is there a reason known for this?


    No PPS signal.

    Terje

    --
    -
    "almost all programming can be viewed as an exercise in caching"

  17. Re: GPS clock for Linux

    In article ,
    Uwe Klein writes:
    >Hal Murray wrote:
    >
    >> There are a lot of low cost USB GPS gizmos that use the
    >> SiRF Star III. They suck for timekeeping.
    >>

    >Is there a reason known for this?


    I assume it's a software bug/feature. The problem is drift/wander
    in the offset. The offset changes too slowly for normal
    jitter filters to work on it.
    http://www.megapathdsl.net/~hmurray/ntp/GPSSiRF-off.gif

    I forgot to mention another problem with those chipsets.
    They have a leap second bug.
    http://www.megapathdsl.net/~hmurray/ntp/leap-gps.gif


    --
    These are my opinions, not necessarily my employer's. I hate spam.


  18. Re: GPS clock for Linux

    On Thu, 11 Sep 2008 18:54:25 -0500, Hal Murray wrote:

    >> I am interested in getting a GPS clock to synchronize our internal
    >>test network. I am curious to hear about relativley cheap and Linux
    >>friendly GPS clock. (Less than $100 would be great)

    >
    > The Garmin GPS 18 LVC is popular.


    The above has been superseded by Garmin model: GPS 18x LVC
    Physically identical, but having a more "sensitive" receiver.
    Note the "x" in the model number when shopping for one.

    > "Some assembly required." (aka
    > soldering) No big deal if somebody has a soldering iron handy. There
    > are a couple of links from here:
    > http://support.ntp.org/bin/view/Supp...xpensiveOemGps
    >
    > Bewares:
    > You don't want the GPS 18 USB version.
    >
    > There are a lot of low cost USB GPS gizmos that use the
    > SiRF Star III. They suck for timekeeping.



  19. Re: GPS clock for Linux

    Hal Murray wrote:
    > In article ,
    > Uwe Klein writes:
    >
    >>Hal Murray wrote:
    >>
    >>
    >>> There are a lot of low cost USB GPS gizmos that use the
    >>>SiRF Star III. They suck for timekeeping.
    >>>

    >>
    >>Is there a reason known for this?

    >
    >
    > I assume it's a software bug/feature. The problem is drift/wander
    > in the offset. The offset changes too slowly for normal
    > jitter filters to work on it.
    > http://www.megapathdsl.net/~hmurray/ntp/GPSSiRF-off.gif

    connected via serial/nmea or pps?

    that looks like some beat frequency effect.
    But it is much too slow/time too big
    to be sender and/or receiver uart clocking.

    >
    > I forgot to mention another problem with those chipsets.
    > They have a leap second bug.
    > http://www.megapathdsl.net/~hmurray/ntp/leap-gps.gif

    Hmpf
    >

    uwe

    >


  20. Re: GPS clock for Linux

    >> I assume it's a software bug/feature. The problem is drift/wander
    >> in the offset. The offset changes too slowly for normal
    >> jitter filters to work on it.
    >> http://www.megapathdsl.net/~hmurray/ntp/GPSSiRF-off.gif


    >connected via serial/nmea or pps?


    Direct USB.

    I have another one (using the SiRF chips) that is serial
    via a serial-USB adapter. Same thing.


    >that looks like some beat frequency effect.
    >But it is much too slow/time too big
    > to be sender and/or receiver uart clocking.


    Yes. But I don't think it's a USB problem. I get much better
    results with a Garmin GPS 18 USB. (Of course, what I don't know
    about USB could fill ...)

    --
    These are my opinions, not necessarily my employer's. I hate spam.


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