Re: What time is it, really?
On Fri 10 Aug 2018 at 09:20:42 (-0700), Fred wrote:
> On 08/10/2018 08:18 AM, David Wright wrote:
> >On Thu 09 Aug 2018 at 14:26:30 (-0700), Fred wrote:
> >>Several years ago I built a "network clock" that receives WWVB time
> >>signals, has a clock display and an Ethernet interface so computers
> >>on the local network can ask for the time. The hardware works and
> >>the software is able to decode the WWVB time code. I am interested
> >>in finishing it now. The computers on the network can use a Perl
> >>program to get the time.
> >Interesting. I played around with a Wireless World design in the
> >early 70's (TTL) where the "Rugby" time code (the slow one) was
> >decoded in hardware.
Correction: it was the fast code I was using. I was confused by the
fact that we also used a BCD-encoded slow code on some of our clocks
around the same time; the latter was necessarily slow because there
were mechanical relays that had to be able to follow it.
> I haven't tried chrony as I have renewed interest in completing the
> "network clock" project I started some time ago. There are far more
> interesting "home projects" than you can shake a stick at. I ran
> ntpdate once as root and it did correct the time.
>
> WWVB supposedly covers the continental US. but I am sure there are
> areas that don't get useful signal strength. The software for my
> clock is to the point of changing the signal time intervals into
> bits so the next step is doing something with the bits.
Best of luck with this, and far better done in software. I turned up
a reference to the one I played with:
http://www.keith-snook.info/wireless-world-magazine/Wireless-World-1976/Self-setting%20time%20code%20clock.pdf
and its lifetime would have lasted until 1998 when they turned off
the fast code at MSF. But 1976 was about the time that microprocessors
were becoming affordable for this kind of work.
AFAIK signal strength is not an issue for us as there's not a lot
between here and CO. The only radio clock I've known to have an issue
was one that wouldn't synchronise in a UK church vestry. I swapped it
for an ancient electric wall clock, and the radio one worked perfectly
in our basement.
Cheers,
David.
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