[ale] Re: WWVB to computer

[Michael H. Warfield]

On Tue, 2007-12-18 at 12:26 -0500, Michael B. Trausch wrote:
> On Tue, 2007-12-18 at 11:39 -0500, Christopher Fowler wrote:
> > I started doing a bit of research in ways to tie 60kHz WWVB source
> > into
> > a computer as requested on this list.  I have some devices out in the
> > filed that are dial-up only and they could benefit from this solution.

> I would like to get away without buying the tuner component.  I really
> want to do it "from scratch", but I lack the knowledge to know how to do
> so or even where to look to find out what I need to know to learn how to
> do so.

	Just out of curiosity, why resort to WWVB and not simply go with a GPS
receiver?  Both constitute an appropriate source for an ntp stratum 1
time server and the ntp package directly supports talking to GPS
receivers.  I'm not sure if ntpd will talk directly to a SiRF receiver
but gpsd can handle the translation to NMEA if not.  Propagation delay
is most likely no worse coming down from a constellation of satellites
than the 60KHz ground wave signal from WWVB.

	GPS receivers (serial, USB, and bluetooth) are reasonably cheap and
will plug right into a Linux system and be supported off stock packages.
Plug and play.  I've got some serial and some USB and one bluetooth (for
the laptop in the car - the Delorme Blue Logger).  All work like a dream
under Linux.

	If you want to get fancy, there are even timeserver-optimized OEM GPS
receiver modules some with as many as 16 channels and some under $50.
The timerserver optimized ones have the algorithm tuned to give the best
time precision and accuracy at some slight expense in positional
accuracy.  The OEM modules are cute little things and some even have
built in USB interfaces and are powered off the USB.

	In this day and age of cheap GPS modules, I wouldn't even consider
going the WWVB route.

> I suppose it probably isn't something I can do, anyway.  I really want
> to have the tuner device in a small housing like a USB flash
> drive/stick.  My thoughts would be to build two of them; one for my
> server, and one that I could keep with me to use to sync computers to
> the correct time.  I think it would be kind of cool, but then again,
> that is just me.

> I think what I need is to perhaps find some books on electronics or
> something.

> 	-- Mike

	Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
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