Tom, thank you for those links!

Yes, my employer used successive generations of GOES satellite clock
receivers that generated IRIG signals piped around the company. Even though
my company started in revenue service in 1976 I don't think we had our
first GOES clock until a few years later.

The IRIG signals were not just used for internal displays. In the 1980's
each passenger station got public facing LED clocks that were standard
NatSemi LED display chips but "force synchronized" at top of each hour and
at midnight via audio tones driving relay contacts that stimulated the set
pushbutton inputs of the NatSemi chips.

When GOES was turned off in 2004, then we switched to NTP controlled IRIG
generator and only in the past month have we removed the last internal IRIG
clock displays. All the passenger facing LED clocks had been removed in the
past decade too.

I am building a miniature reproduction of the bicentennial clock although
it will obviously not be run through GOES or use a 4004. Current prototype
uses a ESP8266 and NTP over WiFi.

Tim N3QE

On Fri, Aug 10, 2018 at 10:18 AM, Tom Van Baak <> wrote:

> Tim,
> Thanks for posting that photo. That space age 1976 GOES clock caught our
> eyes when the paper came out in 2005 (see also pages 11, 12, 13):
> There was quite a bit of traffic on time-nuts around 2005 when the GOES
> satellite time service was turned off (and back on, and off, and on, and
> finally off for good). That left many of us with piles of 468 MHz GOES
> receivers, antennae, clocks and led to efforts to re-create the RF signals
> in-home so that GOES clocks would still work. There was even a commercial
> G2G (GPS to GOES) translator.
> Anyway, I asked around about that one-off bicentennial clock in the photo
> and neither the authors, NIST, or Smithsonian knows where it ended up.
> There's tons of information on the GOES satellite system and GOES clocks in
> the NIST T&F archives:
> Best to search title for GOES, or search author for Hanson. It's a
> fascinating glimpse into the recent past. Yes, it's sad that GOES (and
> Omega, and Loran-C) aren't operational anymore, but GPS does such a better
> job. Plus we now have cable, WiFi, cell phones, the internet, Iridium, etc.
> If you wanted to build your own Bicentennial GOES Clock, the design was
> published, including source code -- for its i4004 (!!) CPU. If you have
> even one minute to spare, see attached image and click on these two PDF's:
> "Satellite Controlled Digital Clock System (patent)"
> "A Satellite-Controlled Digital Clock (NBS TN-681)"
> /tvb
> ----- Original Message -----
> From: "Tim Shoppa" <>
> To: "Discussion of precise time and frequency measurement" <
> Sent: Wednesday, August 08, 2018 7:29 PM
> Subject: [time-nuts] Bicentennial GOES satellite clock
> > See the groovy picture at
> >
> figure/f9-j110-2lom/
> >
> > If anyone knows the whereabouts or history of the bicentennial GOES time
> > clock display, please let me know!
> >
> > Tim N3QE
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