[time-nuts] LF time signal emulation

Brooke Clarke brooke at pacific.net
Mon Apr 30 11:00:27 EDT 2007


Hi Jim:

I thought JJY was in Japan?
http://www.pacificsites.com/~brooke/timefreq.shtml#RSL

I think the crew from what was called Temic has formed a new company called 
C-MAX.  The C-MAX LF time signal receiver chips support automatic tuning to 3 
frequencies using the same loop antenna by switching caps.  The ICs also know 
the protocol for the various LF time stations, so products that use the C-MAX 
chip will work world wide (if there's a signal), but older products are 
typically specific to one frequency and protocol.
http://www.pacificsites.com/~brooke/timefreq.shtml#VL

They have app notes on how to design the loop.
http://www.pacificsites.com/~brooke/Loop.shtml
Larger loops are more sensitive than smaller loops.

Joseph's suggestion of making a resonating loop is worth a try.  Remember to 
orient the vertical loop both in azimuth and maybe tilt.  Maybe just wind it 
around you house top to bottom.

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com



Palfreyman, Jim L wrote:
> Folks,
> 
> Living in Australia we are generally out of range of the LF time signals
> (WWVB, JJY etc). However I recently purchased a multi-band travel clock
> off ebay for $30 and found I could get JJY in Tasmania.
> 
> Excitedly I purchased a Casio multi band G-Shock wristwatch (which I
> really like), but have had little luck in getting it to pick up an LF
> time signal.
> 
> Since I already have tenth of millisecond accuracy locally in my house
> based on a GPSDO, what I would like to do is build my own local LF
> transmitter (reception within say 100m) and emulate the time codes of
> one of the stations so my watch (and any future similar purchases) lock
> on to the local signal each night.
> 
> Because I like to stand on the shoulders of giants, has anyone actually
> done something like this? My skills are more in software development and
> hardware digital logic rather than in LF radio transmitters - so any
> help or pointing in the right direction would be appreciated.
> 
> Regards,
> 
> 
> Jim Palfreyman
> 
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