Consider the following:
1) I have a lot of clocks which can set themselves automatically based
on the WWV time signal - cf.
http://tf.nist.gov/timefreq/stations/wwv.html
2) Where I live this WWV signal is very weak to non-existant.
3) I have multiple computers connected to the internet through an
always-on Cable Model connection (Windows and Linux)
4) I have those computers stay synchronized with NTP time servers

The thought occured to me that I could solve my problems with my
out-of-sync WWV clocks in my house if I were able somehow to
rebroadcast (at low power) the WWV time signal, controlled by one of my
NTP-synced computers.

Has anybody done such a thing? Do radios exist for transmitting the WWV
signal?

Where can I find the specs on the format of the WWV signal? What I
found initially is that it is in the 60Hz range.

My purpose is not to become some WWV station; I just want my clocks to
stay synched!

Thanks - Steven

Hi Steven

The URL you gave has info on the signal itself....

http://tf.nist.gov/timefreq/stations/iform.html

I havent come accross software to do it but I'd suspect that it would be
pretty wasy to write a batch/shell job that outputs a series of linked
wav (sound) files) to a small transmitter. (eg using aplay under linux.
Use Audactity etc to create the raw files) You would need to pre-empt
the timing somewhat with (say) a 10 second offset. If you applications
are very time critical the async nature of your OS could lead to small
time errors.

You could also obviously write code directly to output to the soundcard.

Then amplitude modulate a very low powered TX. Make sure you dont
interfere with any other users! (Not to mention the legal aspect!) Might
be worth running the signal close to each RX with coax. AM TX's are
pretty simple. You might even find a single chip that will do it. If you
want it in discrete components, one of those chip size xtal oscillators
on the right frequency (5, 10 or 15Mhz) followed by a single transistor
biased AB and the soundcard output as the (decoupled) collector power
supply might do it. I shd describe that a little better but it really is
simple!

Cheers Bob VK2YQA

wrote:


Has anybody done such a thing? Do radios exist for transmitting the WWV
signal?

Where can I find the specs on the format of the WWV signal? What I
found initially is that it is in the 60Hz range.

In article ,
Bob Bob wrote:

| The URL you gave has info on the signal itself....
|
| http://tf.nist.gov/timefreq/stations/iform.html

Though of course you probably want WWVB, not WWV, and if so,
http://tf.nist.gov/timefreq/stations/wwvbtimecode.htm is better.

WWV and WWVB are different. WWV is what you pick up on your HF/SW rig
and is AM. WWVB is at 60 KHz and is what is used by most of the
`atomic clocks' out there, and is not meant for human listening.
Looks like it's CW (but not Morse Code -- instead, the encoding scheme
is described on the page I gave.)

| I havent come accross software to do it but I'd suspect that it would be
| pretty wasy to write a batch/shell job that outputs a series of linked
| wav (sound) files) to a small transmitter.

That wouldn't work for WWVB. Instead, you'd make a 60 KHz CW
transmitter that you could click on and off at appropriate times. It
would have to be very low power to avoid interfering with other people
around you who may be able to pick up the real WWVB signal.

| Then amplitude modulate a very low powered TX. Make sure you dont
| interfere with any other users! (Not to mention the legal aspect!)

I do believe that FCC regulations would permit such a transmitter as
long as the power was low enough, and the antenna was small enough.
(I guess that 2500 meter 1/2 wave resonant dipole is out.)

| AM TX's are pretty simple.

And CW TX's are even simpler

And the bit rate is very slow -- looks like one bit per second. You
could probably rig up something to control that via a serial or
parallel port very simply.

Could be a fun project. Not very practical, but fun

| Where can I find the specs on the format of the WWV signal? What I
| found initially is that it is in the 60Hz range.

As before, it's WWVB you want, and it's at 60 KHz. (60 Hz = your
power lines.)

AD5RH

--
Doug McLaren,
You can get there from here, but why on earth would you want to?

In article ,
Doug McLaren wrote:

| Looks like it's CW (but not Morse Code -- instead, the encoding scheme
| is described on the page I gave.)

Ok, that's wrong. It's pulse width modulation -- close, but not
quite.

http://tf.nist.gov/timefreq/stations/wwvb.htm tells more.

Still, would be an interesting project.

--
Doug McLaren,
`When all you've got is a hammer, every problem looks like a nail.'

rig it to your car and drive around resetting everyone's clocks! that would
be a hoot!

In article ,
Falky foo wrote:

| rig it to your car and drive around resetting everyone's clocks!
| that would be a hoot!

It would, but there's a few problems --

1) It would probably qualify as harmful interference and would
probably annoy the FCC, no matter how low your power. (On the other
hand, it would be next to impossible to pin it on you unless your car
had some massive antenna array on top.)

(Sidenote: with an appropriate antenna and 100 watts, you could
probably reprogram the clocks in the entire city. Though a sutiable
antenna could be very difficult to come by, since 1/4 wavelength =
1250 meters.)

2) most of those clocks only sync up a few times per day (and often
only at night), and almost all of them require several `cycles' (and
each cycle lasts a minute) to do so. So you'd have to catch them
right when they're syncing up, and they'd have to receive your signal
the entire time.)

And if the clock does continuously re-sync, then it will go back to
the correct time signal the moment it stops picking up your signal.

But yes, it could qualify as a good `hack' if done properly.

--
Doug McLaren,
"It's got a cop motor, a 440 cubic inch plant, it's got cop tires, cop
suspension, cop shocks. It's a model made before catalytic converters so it'll
run good on regular gas. What do you say, is it the new Bluesmobile or what?"

On 15/11/2005 11:15 PM, Doug McLaren wrote:
In article ,
Falky foo wrote:

| rig it to your car and drive around resetting everyone's clocks!
| that would be a hoot!

It would, but there's a few problems --

1) It would probably qualify as harmful interference and would
probably annoy the FCC, no matter how low your power. (On the other
hand, it would be next to impossible to pin it on you unless your car
had some massive antenna array on top.)

(Sidenote: with an appropriate antenna and 100 watts, you could
probably reprogram the clocks in the entire city. Though a sutiable
antenna could be very difficult to come by, since 1/4 wavelength =
1250 meters.)

2) most of those clocks only sync up a few times per day (and often
only at night), and almost all of them require several `cycles' (and
each cycle lasts a minute) to do so. So you'd have to catch them
right when they're syncing up, and they'd have to receive your signal
the entire time.)

And if the clock does continuously re-sync, then it will go back to
the correct time signal the moment it stops picking up your signal.

But yes, it could qualify as a good `hack' if done properly.


Yup, this is a good example of a "data poisoning" hack. For those
receivers that only sync up to a single source (and with the caveats you
mention regarding when and how such receivers sync up) this is a
definite hack.

For those of us who rely on upstream NTP sources for their computers,
that protocol is relatively more robust. Even if some of the so-called
upper strata servers use WWV (or local equivalent) to get their time,
the protocol is designed to rejects times that obviously out of sync
with others. So those coincidental upper strata sources would have to
sync up at the same time to these radio sources for it propagate. I've
seen my local NTP server reject entire subnets because it was a few
seconds off. Eventually those subnets are trusted again.

Recently, wasn't there a problem with some of these signals? I recall
that folks who have those fancy set-themselves watches did not have
accurate time for a few weeks.

On 15/11/2005 11:15 PM, Doug McLaren wrote:
"It's got a cop motor, a 440 cubic inch plant, it's got cop tires, cop
suspension, cop shocks. It's a model made before catalytic converters so it'll
run good on regular gas. What do you say, is it the new Bluesmobile or what?"

Fix the lighter.

Steven:

Where are you located that they won't sync?

When propagation is good, they should sync from anywhere on the US
mainland.

I should know, I'm located in Hawaii, and my wife bought one of the damn
things and it would reset itself about every other day. This is a problem,
as the clock doesn't have a selection for Hawaii Standard Time, only for
the time zones on the mainland US. The typical scenario was: Set the
clock to local time, set the alarm, go to sleep. Sometime during the
night, clock resets itself to Pacific Time, and the alarm goes off two or
three hours early (depending on daylight savings time). As malfunctions of
any electronic item in the house are assumed to be my fault, I was
typically blamed for the problem.

I finally opened it up and disconnected it's antenna, so it can't resync
any more. The actual timekeeping is pretty good, no large amount of drift
noted so far, so it is still a decent "stand alone" clock. The display
showing it trying to get the time signal is comical at times, though. Of
course, the bog box store she bought it from should have never sold it
here, because I'd guess most of them eventually get returned because they
keep changing time....

Given we are over 2300 miles from the west coast, plus the distance to
Boulder, you shouldn't have any problem anywhere on the mainland unless you
live in the back of a cave or under water. If the clocks are just bitching
about not having sync'd, I'd just ignore them. If they are drifting so
much it matters, I'd get rid of them if they won't sync.

Good Luck
--Rick AH7H

wrote:

Consider the following:
1) I have a lot of clocks which can set themselves automatically based
on the WWV time signal - cf.
http://tf.nist.gov/timefreq/stations/wwv.html
2) Where I live this WWV signal is very weak to non-existant.
3) I have multiple computers connected to the internet through an
always-on Cable Model connection (Windows and Linux)
4) I have those computers stay synchronized with NTP time servers

The thought occured to me that I could solve my problems with my
out-of-sync WWV clocks in my house if I were able somehow to
rebroadcast (at low power) the WWV time signal, controlled by one of my
NTP-synced computers.

Has anybody done such a thing? Do radios exist for transmitting the WWV
signal?

Where can I find the specs on the format of the WWV signal? What I
found initially is that it is in the 60Hz range.

My purpose is not to become some WWV station; I just want my clocks to
stay synched!

Thanks - Steven

wrote:
Consider the following:
1) I have a lot of clocks which can set themselves automatically based
on the WWV time signal - cf.
http://tf.nist.gov/timefreq/stations/wwv.html
2) Where I live this WWV signal is very weak to non-existant.
3) I have multiple computers connected to the internet through an
always-on Cable Model connection (Windows and Linux)
4) I have those computers stay synchronized with NTP time servers

The thought occured to me that I could solve my problems with my
out-of-sync WWV clocks in my house if I were able somehow to
rebroadcast (at low power) the WWV time signal, controlled by one of my
NTP-synced computers.

Has anybody done such a thing? Do radios exist for transmitting the WWV
signal?

Where can I find the specs on the format of the WWV signal? What I
found initially is that it is in the 60Hz range.

My purpose is not to become some WWV station; I just want my clocks to
stay synched!

Thanks - Steven


This is a late followup, but I do believe that this would be legal under
"Part 15". See http://www.arrl.org/tis/info/part15.html