Bluetooth GPS for timekeeping?
David Gilbert
dgilbert at dclg.ca
Tue Aug 9 19:19:57 GMT 2005
>>>>> "Frank" == Frank Mayhar <frank at exit.com> writes:
Frank> On Tue, 2005-08-09 at 14:51 -0400, David Gilbert wrote:
>> But ... since there are long patches of time where I'm not mobile,
>> I was wondering if anyone had looked at using a Bluetooth GPS for
>> timekeeping. Has anyone also ever had an ntp server sometimes use
>> a GPS and othertimes use other servers ... depending on the
>> availability of the GPS?
Frank> The former would depend strongly on the characteristics of the
Frank> Bluetooth protocols, at least when it comes to accuracy.
Frank> Keeping time to the half-second or so would be pretty easy, I
Frank> would guess.
Frank> The latter is the way it already works. Just configure other
Frank> peers in your ntp.conf along with your GPS, viz:
How might you determine the accuracy of the GPS ... or the
"characteristics of the Bluetooth protocols" ?
The GPS docs "say" that the GPS chipset keep time to within 100ns.
However (and I assume this is to save power) they also say that the
position indication is only sent once per second.
In my case, the Bluetooth GPS would be talking to a Bluetooth dongle
hanging directly out a port of the server in question.
Dave.
--
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|David Gilbert, Independent Contractor. | Two things can only be |
|Mail: dave at daveg.ca | equal if and only if they |
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