[ntp:questions] GPS clock for Linux

Unruh unruh-spam at physics.ubc.ca
Fri Sep 12 13:40:00 UTC 2008

"Richard B. Gilbert" <rgilbert88 at comcast.net> 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/Support/InexpensiveOemGps
>>> 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.

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