[Lazarus] Portable way to get accurate timestamps?

[Bo Berglund]

On Wed, 23 Feb 2011 10:20:19 +0100, Sven Barth
<pascaldragon at googlemail.com> wrote:

>Am 23.02.2011 10:04, schrieb Graeme Geldenhuys:
>> Op 2011-02-23 10:50, Sven Barth het geskryf:
>>>
>>> I don't know of a suitable hardware though (I haven't yet done anything
>>> related to such accurate timings).
>>
>> I have heard of users using something as simple as GPS devices. What
>> accuracy that gives, I am not sure - but I do know each GPS syncs with
>> 9–12 atomic clocks [depending or reception].
>
>Right, that would be an idea (and Bo is using that already to check the 
>accuracy of the system time ;) )
>

Yeah, but my efforts are not successful in using a USB connected GPS
sensor and trying to get accuracy from the telegrams sent by it. I
think much of the time wobble I see is caused by USB latency in the
track from the GPS sensor to the USB hub to the next USB hub and then
into the laptop.
Add to this the way the device driover (Prolific USB2Serial) might
buffer up the data before it reaches the Windows serial system and
there are lots of places time can be lost.

As I posted just a minute ago I found the perfect solution in a Garmin
device with microsecond accurate pulse output.

Have just ordered one for testing.

-- 
Bo Berglund
Developer in Sweden