[time-nuts] GPS for Nixie Clock

Clint Jay cjaysharp at gmail.com
Tue Jul 12 15:23:56 EDT 2016

I've used the wiznet module,  these days I'd consider the esp8266,
powerful little module that can be had for a couple of dollars complete
with WiFi capabilities and enough GPIO to interface GPS and some sort of
serial nixie interface.
On 12 Jul 2016 20:11, "Vlad" <time at patoka.org> wrote:

> In addition, even MCU has not enough resources to handle TCP/IP, DHCP and
> NTP, it is some solutions available to outsource it to dedicated chips. I
> was using WIZ5100 (assembled as a modules) with great success.
> Regards,
> Vlad
> On 2016-07-12 12:01, Chris Albertson wrote:
>> What kind of micro processor are you using to run the Nixie tube clock?
>> If
>> that processor could run NTP you would not need GPS.   But of course you
>> could always do both.   GPS requires a view of the sky and maybe that is
>> not available in a multi story building unless near a window.  NTP would
>> be
>> available any place there is WiFi.     Even without network connection,
>> NTP
>> is a good way to interface the GPS as it knows how to talk to most GPSes
>> made. can handle GPS outages (like when the clock is moved away from a
>> window)
>> That said, you are likely not using a uP big enough to run NTP as a setup
>> like that is about $40 vs. using a bare AVR chip for about $3.  But even
>> with the smaller uP you might think about having the chip keep it's own
>> internal time and using GPS to discipline that internal time, much like
>> the
>> way NTP works.   Basically the uP has a flywheel and GPS regulates it's
>> speed.  Let's you handle holdover gracefully.
>> If using NMEA sentences from GPS, remember that the NMEA standard allows
>> those senates to come out at any time during the second to which they
>> apply.  In other words the sentence itself can be up to almost a second
>> "off".
>> If you are looking for a GPS for use indoors I think you don't care about
>> anything other then receiver sensitivity.  Without that you have nothing,
>> no signal.  It is more important than a few less nanoseconds of
>> uncertainty
>> in the time solution.   So those ublox receivers look good.   I'm looking
>> to buy some for another application, mobile robots, I'll use GPS for gross
>> level navigation and it would be nice if it still worked indoors
>> On Sun, Jul 10, 2016 at 10:24 PM, Mark Sims <holrum at hotmail.com> wrote:
>> The Jupiter receiver defaults to Motorola output, but can be switched to
>>> Zodiac.  It talks at 9600:8:N:1
>>> Frankly, it is the wrong receiver to use, particularly with an indoor
>>> antenna.  I would go with a modern GPS receiver with standard NMEA output
>>> and a 1PPS signal.   They are MUCH more sensitive and usually work
>>> indoors
>>> and can be had for dirt cheap.   Most have an on-board ceramic patch
>>> antenna.  Ublox receivers seem to work well indoors.
>>> NAVSPARK makes a tiny little GPS board with 1PPS output.  6 for $36 or
>>> one
>>> free for $10 shipping (no antenna supplied, has a U.FL connector).  It
>>> speaks NMEA at 115,200:8:N:1  or can be setup for 9600 baud.
>>> The delay between message and 1PPS is receiver dependent.  Usually it is
>>> small enough to not be noticeable.  Some receivers send the message
>>> before
>>> the 1PPS, others after it.   You can compensate for the
>>> differences/delays
>>> in software.
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> --
> WBW,
> V.P.
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