[time-nuts] Fwd: GPS NTP update on Mac OS-X 10.7.4

[Ross T61AA]

Thanks Hal

On 13/06/2012, at 10:08 AM, Hal Murray wrote:

> 
>> I recently connected up a USB GPS to my Linux box and found it quite easy to
>> get NTP to up from the GPS. I was hoping to get the same GPS to update the
>> Mac running Lion 10.7.4, however, it has been a very frustrating uphill
>> battle.
> 
>> Has anybody managed to get GPS NTP update working on OS-X? 
> 
> You will probably get much better answers to NTP questions over on the NTP 
> lists.
> http://lists.ntp.org/listinfo
> Down near the bottom is questions
> 
I'll look at ntp.org

> GPS over USB generally doesn't work very well.  You will probably get better 
> results over the net.
> 
I will be in an entirely stand alone situation and therefore GPS is my best timekeeping option for WSPR and WSJT - EME ops.

> The problem isn't USB polling, it's firmware that adds about 100 ms of 
> wander.  By wander I mean low frequency drift.  It's too slow to filter out.
> 
> Here is a graph from a SiRF III, the most common chipset in low cost USB GPS 
> devices.  Most others are similar.
> http://www.megapathdsl.net/~hmurray/ntp/GPSSiRF-off.gif
> If anybody finds a good one, please let me know.
> 
I've had a UBLox chip on a board working with my Linux laptop perfectly well, however OSX will just not allow the setup to work.

> 
>> I did a sum link to /dev/gps0 and can cat the output and see the NMEA stream
>> of alternate $GPRMC and $GPZDA messages, 
> 
>> I just cannot get it to accept the gps as a peer.
> 
> The GPRMC sentence has a flag to tell you if it is seeing enough satellites.  
> Are you seeing A or V?  I think A is good and V is bad.
> 
I am seeing satellites and can cat the output of the device OS X will just not allow to to connect to 127.127.20.0, same device plugged into the Linux laptop works very well - just cannot get NTP in OS X to add it as a peer

> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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