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'[EE] MSF Clock Chips was Using clock mechanisms'
2005\04\01@112530 by Alan B. Pearce

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>And I discovered (by reading the instructions! :-)
>that when it has to go back an hour in the Autumn, it
>just freezes for an hour, rather than going forwards
>23 hours (actually 11, since most traditional clocks
>are inherently 12-hour).  Not ideal, but if you can put
>up with a rogue hour once a year, it's usable,  If not,
>then you'd have to get one of the signal decoders that
>aer designed for passing the data on to other equipment,
>rather than just telling people the time.

I seem to recall reading somewhere the amusement that people have with
travelling between the UK and Europe on the Chunnel, with MSF controlled
clocks on their cars see the them rapidly go forwards or backwards as the
receiver picks up the transmitter in the different time zone. I guess these
must have some form of stepper motor.

I just went looking at the MSF document I have, and it specifies a bit time
of 100mS. I also have a data sheet for a chip designed as a radio clock
receiver from a company called Gunter Semiconductor Gmbh, for a chip
catalogue number AK2124, but it is quite complex with at least 2 tuned
circuits. Looks like I got it from here http://www.gsg-asia.com/wpl_ic.htm.
I thought I had other bits I had saved off the web as well.

Just went googling, found an Okisemi chip, ML6190A, for which there are
block diagrams and an "introduction sheet" available. See
http://www.oki.com/semi/english/pis/pi-ml6190.pdf

Couple of interesting looking chips here
http://www.hkw-elektronik.de/produkte/ (English on RHS of page). Scroll down
to components. also looks like they have everything in the way of modules
and antennae for those not wanting to make a receiver themselves.

Right, my colleague has returned now, and I find the receiver he built uses
a telefunken or Temic (or possibly other manufacturers) U4224, datasheet
available here http://www.asmeltec.de/dl0az/datasheets/u4224.pdf



Bottom of this page has an interesting variation on the Propeller Clock
idea, but instead using a pendulum as the scanning mechanism. I know that
the pendulum variation is not new, but this is interesting for the driving
method. http://www.genre.fsnet.co.uk/museum/clocks/


While searching found this interesting looking article about TCP/IP on a PIC
http://www.eix.co.uk/Ethernet/WWarticle.htm which describes using an ISA
Ethernet board with a PIC, and looks like it has a fair dose on the software
needed, for those not experienced with TCP/IP.

2005\04\01@120235 by olin_piclist

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Alan B. Pearce wrote:
> I seem to recall reading somewhere the amusement that people have with
> travelling between the UK and Europe on the Chunnel, with MSF controlled
> clocks on their cars see the them rapidly go forwards or backwards as
> the receiver picks up the transmitter in the different time zone. I
> guess these must have some form of stepper motor.

How would the receiver know it got moved to a new time zone?  If it had GPS,
then it wouldn't need to also pick up the low frequency time signal.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\04\01@122510 by James Newton, Host

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THANK YOU! For changing the tag!

---
James.



> -----Original Message-----
> From: spam_OUTpiclist-bouncesTakeThisOuTspammit.edu
> [.....piclist-bouncesKILLspamspam@spam@mit.edu] On Behalf Of Alan B. Pearce
> Sent: 2005 Apr 01, Fri 08:25
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] MSF Clock Chips was Using clock mechanisms

<SNIP>


2005\04\01@151620 by Howard Winter

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Olin,

On Fri, 1 Apr 2005 12:02:17 -0500, Olin Lathrop wrote:

> Alan B. Pearce wrote:
> > I seem to recall reading somewhere the amusement that people have with
> > travelling between the UK and Europe on the Chunnel, with MSF controlled
> > clocks on their cars see the them rapidly go forwards or backwards as
> > the receiver picks up the transmitter in the different time zone. I
> > guess these must have some form of stepper motor.
>
> How would the receiver know it got moved to a new time zone?  If it had GPS,
> then it wouldn't need to also pick up the low frequency time signal.

It doesn't know - MSF is a UK time service, and doesn't get involved in timezones.  I think the cars involved
are actually using GPS rather than MSF.

Cheers,




Howard Winter
St.Albans, England


2005\04\04@124125 by Alan B. Pearce

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Someone was asking what LF clock time signals are available. This link gives
a fair number, including some Russian ones, and at least one East European.

http://www.cl.cam.ac.uk/~mgk25/lf-clocks.html

2005\04\08@182032 by Robert Rolf

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The listed URL also has a listing of suitable chips and kits.

"Low-cost receiver components

A receiver consists of

    * a tuned ferrite core antenna (e.g., from HKW, 60 kHz version sold
by Maplin order no MK72P, 77.5 kHz version sold by Conrad order number
641138-62)
    * a receiver IC for amplification, selection, AM detection and
automatic gain control (e.g., Atmel T4227 40-120 kHz or U4223B 40-80
kHz, HKW UE6002/UE6005, GSG Semicon AK2124, AK2125 or AK2127, MAS
MAS1016 or MAS1017)
    * a microcontroller with ADC input for decoding the time signal and
phase-locking a software-controlled local clock to it

Low-cost time-code receiver ICs, prebuild modules and units, antennas
and test equipment for DCF77/MSF/WWVB are available e.g. from HKW
Elektronik.

Complete WWVB receivers are also available from Ultralink. MSF and DCF77
wrist watches are distributed in the UK for example by watch-heaven.com.
"
Alan B. Pearce wrote:
> Someone was asking what LF clock time signals are available. This link gives
> a fair number, including some Russian ones, and at least one East European.
>
> http://www.cl.cam.ac.uk/~mgk25/lf-clocks.html
>

2005\04\09@084627 by Martin McCormick

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Robert Rolf writes:
>The listed URL also has a listing of suitable chips and kits.
>Complete WWVB receivers are also available from Ultralink.

       I have a few questions for anyone who has built WWVB
receivers.  http://www.ultralink.com or .net don't appear to go to anything
related to this topic.

       Is there a neat modular approach to receiving the WWVB signal?
The tuned detector with AGC is the critical part along with a suitable
antenna.  As one who has seen how much less trouble receiving IR
remote signals are with one of those little modules one can buy or
salvage compared with trying to do the same thing from scratch, I know
the wisdom of standing on the shoulders of giants.

       I want two or three WWVB modules for building various projects
that need to know the time so I need to find somebody like Digikey or
Jameco who sells small quantities.

       Here in the Central USA, most WWVB clock devices I have heard of
seem to work well as long as the decoding software is smart enough
to not misread a marginal frame of data.  Some seem to work flawlessly
as long as they get a usable signal part of the day and others just
are too easily confused by bad reception to be of much use.

       I suspect the kind of detector I need either has a logic-level
output that delivers the varying-width pulse or delivers an analog DC
voltage related to signal strength.  Due to the number of PIC's with
A/D and or comparator inputs, either signal is fine with me.  The
advantage of a logic-level input is that WWV on short wave uses a
100-HZ sub carrier to send the same information that way.  One could
decode that signal as a redundant second channel in to the same
processor that normally reads the WWVB signal.

       Thanks for any ideas or caveats.

Martin McCormick WB5AGZ  Stillwater, OK
OSU Information Technology Division Network Operations Group

2005\04\09@095022 by Russell McMahon

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> Is there a neat modular approach to receiving the WWVB signal?


Completely different suggestion - would GPS meet your need?
Limited indoor use due to shielding by buildings may be a killer.
Modules getting very cheap.
Extremely easy to interface to.


       RM

2005\04\09@182846 by Martin McCormick

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Russell McMahon writes:
>Completely different suggestion - would GPS meet your need?
>Limited indoor use due to shielding by buildings may be a killer.
>Modules getting very cheap.
>Extremely easy to interface to.

       That is a great suggestion.  If it wasn't for the indoor
signal reception problem, I wouldn't even consider the LF radio
solution.  Maybe I should buy a module and see if enough signal leaks
in to our house through the windows or walls to be reliable.

Martin McCormick WB5AGZ  Stillwater, OK
OSU Information Technology Division Network Operations Group

2005\04\09@214238 by Russell McMahon

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> That is a great suggestion.  If it wasn't for the indoor
> signal reception problem, I wouldn't even consider the LF radio
> solution.  Maybe I should buy a module and see if enough signal
> leaks
> in to our house through the windows or walls to be reliable.

As an alternative to an outdoor antenna you could place the whole GPS
unit somewhere suitable and relay the output with a short range
transmitter - probably RF but even IR would do. AFAIR you get time
signal as soon as you acquire a single satellite - maybe not as
accurately but probably good enough for many purposes.


       RM

2005\04\10@044141 by Howard Winter

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Martin,

On Sat, 09 Apr 2005 17:28:45 -0500, Martin McCormick wrote:

{Quote hidden}

I'm afraid that's incredibly unlikely!  Even outdoors, being under a thick canopy of trees can stop it.  
Remember it needs to "see" more than one satelite at once to be able to work, and the darned things are moving
so you may get patchy operation through windows at best.  You could get a separate antenna and mount it
outside, but you may not want the wire trailing about.

Cheers,


Howard Winter
St.Albans, England


2005\04\10@044353 by Howard Winter

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Russell,

On Sun, 10 Apr 2005 13:36:14 +1200, Russell McMahon
wrote:

>  AFAIR you get time  signal as soon as you acquire a
single satellite - maybe not as
> accurately but probably good enough for many purposes.

I don't think you do with "ordinary" GPS navigation
receivers - it may be different with some of the
cut-down ones that are being discussed, but I have a
feeling you need at least two because of the way the
signal is formatted.

Cheers,


Howard Winter
St.Albans, England


2005\04\10@061254 by Vic Fraenckel

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You might want to check into the sci.geo.satellite-nav newsgroup. This sort
of thing has been discussed widely there and some of the regulars just might
have some words of widom for you.

HTH

Vic
________________________________________________________

Victor Fraenckel - The Windman
victorf ATSIGN windreader DOTcom
KC2GUI


2005\04\10@105724 by George Smith

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On 10 Apr 2005, at 9:41, Howard Winter wrote:

>  Remember it needs to "see" more than one satelite
> at once to be able to work, and the darned things are moving so you may get
> patchy operation through windows at best.

To get location - yes - but are three necessary for time?

George Smith

2005\04\10@110440 by Bob Axtell

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George Smith wrote:

>On 10 Apr 2005, at 9:41, Howard Winter wrote:
>
>  
>
>> Remember it needs to "see" more than one satelite
>>at once to be able to work, and the darned things are moving so you may get
>>patchy operation through windows at best.
>>    
>>
>
>To get location - yes - but are three necessary for time?
>
>George Smith
>  
>
Just need one for time.

--Bob

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2005\04\10@123347 by Brooke Clarke

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Hi:

When done correctly GPS is good for about 30 nano seconds on a 1 Pulse
Per Second basis.  Average these and you can easily get to a nano second.
Olin's concerns are correct, you need to account for all the cable
propagation delays and you need to know exactly where the antenna is
located, each foot of error translates to a nano second of error in the
UTC second tick.  But for many applications a fixed offset in UTC is not
a concern, like when setting the frequency of a standard.

The best GPS receivers for reasonably priced timing applications are the
Motorola units specified for timing.  These are operated in the timing
mode where the receiver location is already known (or can be determined
by a day's worth of averaging).  The current 12 channel model is the
M12+T and includes a number of timing related functions, like automatic
averaging to get position and then switch over to zero-D mode.  Also a
function that compares the time based on each satellite to see if they
all agree and if not turns off the 1 PPS output for that second and sets
an alarm, and others.

I've found that to get the best results you also need set the elevation
mask angle high enough to eliminate multipath.  In my case living in a
forest that angle is 50 degrees.  But since only one satellite is needed
in position fix mode it works well.

There's a new GPS time transfer method based on what's called carrier
phase that's good for about 3 nano seconds on a 1 Pulse Per Second
bases, but it requires the use of an Ashtech Z12 receiver and now is
very expensive.

The time transfer method that's second best after GPS is LORAN-C.  This
system had a questionable future after GPS came out and after the Omega
radio navigation system was shut down, and a few months ago the GEOS
satellite based time service was shut down, but LORAN-C has recently
been selected as a backup to GPS and the system will survive and is in
the process of being modernized.  It's a pulse transmission on 100 kHz
and has much better time transfer capability than the 60 kHz type
systems (MSF, WWVB, etc.), but has a disadvantage in that you can not
set the date, hours, minutes or seconds using LORAN-C, but you can set
the exact second boundary using what's called Time Of Coincidence.

Have Fun,

Brooke Clarke, N6GCE

http://www.precisionclock.com


2005\04\11@054432 by Howard Winter

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Brooke,

On Sun, 10 Apr 2005 09:33:35 -0700, Brooke Clarke wrote:

> The time transfer method that's second best after GPS is LORAN-C.  This
> system had a questionable future after GPS came out and after the Omega
> radio navigation system was shut down, and a few months ago the GEOS
> satellite based time service was shut down, but LORAN-C has recently
> been selected as a backup to GPS and the system will survive and is in
> the process of being modernized.

Maybe in the US, but over this side of the pond LORAN-C is dying out - see http://home.online.no/~loran-c/ :

***********
31.12.2004
The Norwegian Government has desided to shut down the Norwegian Loran-C stations at Bø (7001M - 9007X), Jan-Mayen (7001X - 9007W),Berlevåg(7001Y) and Værlandet(9007Y -7499Y) from January 1. 2006
The desission is based on the facts that Loran-C is no longer in use by boats and planes, and that, in an emergency, the GPS users can use lighthouses and sea-markers.
***********

Cheers,


Howard Winter
St.Albans, England

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