In article ,
"Geoffrey S. Mendelson" wrote:

Jeff Liebermann wrote:
Building a store and forward repeater for WWVB (or the EU equivalent)
60Khz is a waste of time. The storage delay needed to regenerate the
signal will result in the sync pulses arriving too late. However, a
system that uses GPS, GLONASS, or Galileo as a reference, and
generates a simulated time code format will work. The problem is that
at 60Khz, the necessary antenna farm would be huge and the
transmitters rather power hungry. WWVB runs at an EIRP of about 70kW.

That's sort of what I was thinking of. Get the time from NTP, generate
a fresh time code signal, which would not be accurate enough for someone who
wanted truely accurate time code, but to keep a clock that displays to the
minute, or even to the second on time, it would be good enough.

It would be *very good* because it would never drift. The rate
(long-term) would be spot on, and the epoch (the name for "what time is
it right now"?) would be only slightly in error.

As for the transmitter, how much power do you need to transmit a signal from
a time code generator to a receiver next to it, connected via a coax cable?

A microwatt? A milliwatt?

limited abilities of a commodity router. Methinks you would be better
off with a SBC (single board computer) or common PC (ITX, Mini-ITX,
etc).

It depends. A cheap router, such as the Linksys WRTG-54L (note the L at the
end it's the enhanced model that runs Linux) would do it. It sells new for
not much money, will be obosolete as the 802.11N routers come into general
useage, has an ARM processor, two ethernet interfaces (one connected to a
4 port hub), a WiFi radio and a bunch of status LEDs. The advantage of it
is that there are several alternate Linux packages for it and you can easily
compile your own programs, build your own "flash" (firmware image) and load
it.

There are also distributions for other routers, I recently bought a $30
EDIMAX
wired router that had a distribution for it.

Actually, a 60KHz xmitter is fairly easy to design. The problem is
that all the components would be huge.

You could synthesize the whole signal in software and drive a D-to-A
converter to create the modulated carrier. Any commodity video D-A would
be more than fast enough.

I'm sure that nearby users that went through the trouble of obtaining
large antennas, will not be thrilled with your transmissions. Even a
"local" transmitter can carry a substantial distance at 60KHz.

But very probably not, unless a very long antenna were attached to it.


Isaac