Re: Time question on GPS TIME and leap second.

[Larry McDavid]

While I am truly fond of analog clocks, certainly including sundials, I 
also have a place in my heart for interesting digital clocks. Hence, I 
still have two Heathkit "Most Accurate Clocks," model GC-1000, that run 
24/7 and have done for 30 years. This red LED digital clock sets its 
time from WWV (not WWVB) using the two-tone, seconds-tick tone; that 
seconds-tick tone digitally encodes the time of day, DST and more. The 
Heath clock decodes it, displaying hours, minutes, seconds and tenths of 
seconds. For its era, this Heath clock has many innovative features, 
including learning and correcting the frequency error of its internal 
crystal. Originally a relatively expensive Heathkit product selling for 
about $250, it now sells for $400-$600 on eBay!


Bet you did not know the WWV seconds-tick tone actually shifts between 
two different tones to allow this encoding! No, I can't hear the difference.


But, that was before GPS time. I recently found a kit for a red LED 
digital clock that uses GPS and displays hours, minutes, seconds and 
also tenths of seconds. Try that with a sundial! Of course, you don't 
need to plug in your sundial...


Look here for the $60 GPS Clock:

https://www.tindie.com/products/nsayer/gps-clock/

I've had one of these GPS Clocks running for about a month and it has 
been absolutely reliable, syncing quickly to GPS upon power-up from a 5 
volt wall wart power supply.


Larry


On 1/31/2017 11:46 PM, rodwall1...@gmail.com wrote:

A recent article on the GPS analog clock driver. A better description;

http://archive.siliconchip.com.au/cms/A_92/article.html

Roderick Wall.

...

--
Best wishes,

Larry McDavid W6FUB
Anaheim, California  (SE of Los Angeles, near Disneyland)
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Time question on GPS TIME and leap second.

[rodwall1...@gmail.com]

Hi Brooke,
The radio controlled clock that you described that uses  WWVB is very good. If 
you live in Canada, America or Mexico.

But I don't think it would work in Australia or some other parts in the world.

Where the GPS signals can be received anywhere. 

For the Silicon Chip GPS controlled clock. The firmware is written in the C 
programming language. And is available if you want to make it work the way you 
want it to.

Have fun,

Roderick Wall.

- Reply message -
From: "Brooke Clarke" 
To: "rodwall1...@gmail.com" , "sundial list" 

Subject: Time question on GPS TIME and leap second.
Date: Fri, Feb 3, 2017 6:06 AM

Hi Rod:

OK, that allows you to set the clock., but it's not a stand alone self setting 
clock.
I was disappointed with the Heathkit GC-1000 when I found that it was off by an 
hour at the changes of daylight savings 
in displaying my local time.  (It changed time when the transmitter in Colorado 
changed it's time rather than when it 
should.)  As far as I know that was never fixed.

GPS does not know about the date or daylight savings, but does have a way to 
get to UTC by using the accumulated offset 
between GPS and UTC.

So the only way to have an accurate and self setting clock is to make use of a 
"time" station like WWV or WWVB.  I've 
only heard of one clock model that makes use of the phase modulation that's 
been on WWVB for many years and it's the La 
Crosse 404-1235UA-SS.

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

 Original Message 
> Hi Brooke,
>
> True, GPS doesn't know about daylight saving.
>
> To set the clock up after building it. You use a RS232 Com terminal program, 
> to talk to the clock driver 
> microprocessor. And set up the month and which Sunday daylight saving starts 
> and finishes.
>
> You need to:
> Set your time zone.
> Daylight saving ON or OFF.
> Start daylight saving month.
> Start daylight saving Sunday.
> End daylight saving month.
> End daylight saving Sunday.
> Set clock pulse mSeconds.
> Set GPS update (hours).
>
> Q = quit.
>
> Command:_
>
> The firmware is written in the C language. Source code can be downloaded and 
> you can play around with it if you want.
>
> Article also gives a web link for the free Hi-Tech C Compiler.
>
> I'm waiting to see if a local electronic supplier produces a kit of parts for 
> it.
>
> Looks like fun,
>
> Roderick Wall.
>
> - Reply message -
> From: "Brooke Clarke" 
> To: "sundial list" 
> Subject: Time question on GPS TIME and leap second.
> Date: Thu, Feb 2, 2017 9:26 AM
>
> Hi Roderick:
>
> GPS knows about neither daylight savings nor the date.
> The article mentions "understands the rules of daylight saving (DST)" which 
> are a political thing so this will only work
> until the rules change.
> This happened to VCR players and after the rules change they are always wrong.
> The only time source that knows about these things are the time stations, 
> like WWV & WWVB.
> http://www.prc68.com/I/timefreq.shtml#RSL
>
> -- 
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
>
>  Original Message 
> > A recent article on the GPS analog clock driver. A better description;
> >
> >http://archive.siliconchip.com.au/cms/A_92/article.html
> >
> > Roderick Wall.
> >
> > - Reply message -
> > From: "Richard Langley" 
> > To: "Brooke Clarke" , "sundial list" 
> > 
> > Subject: Time question on GPS TIME and leap second.
> > Date: Tue, Jan 31, 2017 10:33 AM
> >
> > "This causes problems for GPS receivers that are more than a few years old 
> > since they have no idea what year it is."
> >
> >
> > Not quite true. One of the continuously operating receivers at UNB is more 
> > than 15 years old. Please see:
> >
> >http://gauss2.gge.unb.ca/gpsworld/gpsworld.november98.pdf​ 
>   
> > 
> >
> >
> > -- Richard Langley
> >
> >
> > -
> > | Richard B. LangleyE-mail: l...@unb.ca 
> > |
> > | Geodetic Research Laboratory  
> > Web:http://gge.unb.ca  |
> > | Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   
> > |
> > | University of New Brunswick   Fax:  +1 506 453-4943   
> > |
> > | Fredericton, N.B., Canada  E3B 5A3
> > |
> > |Fredericton?  Where's that?  
> > 

Re: Time question on GPS TIME and leap second.

[Brooke Clarke]

Hi Rod:

OK, that allows you to set the clock., but it's not a stand alone self setting 
clock.
I was disappointed with the Heathkit GC-1000 when I found that it was off by an hour at the changes of daylight savings 
in displaying my local time.  (It changed time when the transmitter in Colorado changed it's time rather than when it 
should.)  As far as I know that was never fixed.


GPS does not know about the date or daylight savings, but does have a way to get to UTC by using the accumulated offset 
between GPS and UTC.


So the only way to have an accurate and self setting clock is to make use of a "time" station like WWV or WWVB.  I've 
only heard of one clock model that makes use of the phase modulation that's been on WWVB for many years and it's the La 
Crosse 404-1235UA-SS.


--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

 Original Message 

Hi Brooke,

True, GPS doesn't know about daylight saving.

To set the clock up after building it. You use a RS232 Com terminal program, to talk to the clock driver 
microprocessor. And set up the month and which Sunday daylight saving starts and finishes.


You need to:
Set your time zone.
Daylight saving ON or OFF.
Start daylight saving month.
Start daylight saving Sunday.
End daylight saving month.
End daylight saving Sunday.
Set clock pulse mSeconds.
Set GPS update (hours).

Q = quit.

Command:_

The firmware is written in the C language. Source code can be downloaded and 
you can play around with it if you want.

Article also gives a web link for the free Hi-Tech C Compiler.

I'm waiting to see if a local electronic supplier produces a kit of parts for 
it.

Looks like fun,

Roderick Wall.

- Reply message -
From: "Brooke Clarke" 
To: "sundial list" 
Subject: Time question on GPS TIME and leap second.
Date: Thu, Feb 2, 2017 9:26 AM

Hi Roderick:

GPS knows about neither daylight savings nor the date.
The article mentions "understands the rules of daylight saving (DST)" which are 
a political thing so this will only work
until the rules change.
This happened to VCR players and after the rules change they are always wrong.
The only time source that knows about these things are the time stations, like WWV 
& WWVB.
http://www.prc68.com/I/timefreq.shtml#RSL

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

 Original Message 
> A recent article on the GPS analog clock driver. A better description;
>
>http://archive.siliconchip.com.au/cms/A_92/article.html
>
> Roderick Wall.
>
> - Reply message -
> From: "Richard Langley" 
> To: "Brooke Clarke" , "sundial list" 

> Subject: Time question on GPS TIME and leap second.
> Date: Tue, Jan 31, 2017 10:33 AM
>
> "This causes problems for GPS receivers that are more than a few years old since 
they have no idea what year it is."
>
>
> Not quite true. One of the continuously operating receivers at UNB is more 
than 15 years old. Please see:
>
>http://gauss2.gge.unb.ca/gpsworld/gpsworld.november98.pdf​ 
  
> 

>
>
> -- Richard Langley
>
>
> -
> | Richard B. LangleyE-mail: l...@unb.ca |
> | Geodetic Research Laboratory  
Web:http://gge.unb.ca  |
> | Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
> | University of New Brunswick   Fax:  +1 506 453-4943   |
> | Fredericton, N.B., Canada  E3B 5A3|
> |Fredericton?  Where's that?  
See:http://www.fredericton.ca/
   |
> -
> 
> From: sundial  on behalf of Brooke Clarke 

> Sent: Monday, January 30, 2017 4:29 PM
> To: sundial list
> Subject: Re: Time question on GPS TIME and leap second.
>
> Hi Roderick:
>
> GPS time is continuous, that's to say there are no leap seconds or other 
changes to it since it started.  It uses a 10 bit binary week counter so the week 
number rolls over after 1024 weeks.  This causes problems for GPS receivers that 
are more than a few years old since they have no idea what year it is.
> The total number of seconds offset from UTC is transmitted separately so that 
a GPS receiver can display either GPS time or UTC.
> Note that the time and position are independent from the year.
>