LF time signal emulation
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
I wonder if building a passive loop antenna would suffice? This trick is
used with AM BCB radios.
----- Original Message -----
From: "Palfreyman, Jim L" Jim.Palfreyman@team.telstra.com
To: time-nuts@febo.com
Sent: Monday, April 30, 2007 1:13 AM
Subject: [time-nuts] LF time signal emulation
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
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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
Yes, the following examples will generate a subcode:
http://www.leapsecond.com/notes/wwvb1.htm
http://www.leapsecond.com/notes/wwvb2.htm
Then use one of these TCO (time code output):
http://www.leapsecond.com/tools/tco1.c
http://www.leapsecond.com/tools/tco2.c
Then gate the output of a 60 kHz signal generator. I found
any piece of dangling wire was a sufficiently good antenna
to trigger reception in a WWVB radio clock.
I have untested versions for DCF77 also.
/tvb
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
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
On Monday 30 April 2007 11:00, Brooke Clarke wrote:
I think the crew from what was called Temic has formed a new company called
C-MAX.
Here is their web site:
http://www.c-maxgroup.com/home/index.php
Their parts, and ~$30 evaluation module, are available from
DigiKey.
They do sell a simulation transmitter, don't know if you
can get that from DigiKey.
--
http://www.wearablesmartsensors.com/
http://www.softwaresafety.net/ http://www.designer-iii.com/
http://www.unusualresearch.com/
This just came in, thought it might be of interest to those
discussing the effect of the flare.
John