Prev: If you had one what would you use it for
Next: Interesting TIA design
From: Hal Murray on 25 Oct 2009 03:33

>The usual method is to use WWVB at 60 kHz, with a ferrite loopstick
>antenna, a crystal filter, and a PLL. You can get nice 2400 mu ferrite
>from Amidon. The ground wave delay is more stable than the sky wave
>from the 10 MHz stations.

"Usual" is an interesting word. I think it depends on what sort of
quality you want.

WWVB at 60 kHz is common for watches and battery powered wall clocks.
It lets them set themselves to better than a second each night.
It's inexpensive. There are similar signals from other countries.

Somebody asked for a chip. (I think.) Feed CME6005 to Digikey.
Others may carry similar toys. $11 includes an antenna. (Not
watch size.)

For higher quality, GPS disciplining a good quartz crystal
is the current sweet spot. It's widely used for cell phones
and 911 type time-stamping. A lot of it is available surplus.
You can also use GPS with a Rubidium oscillator.

--
These are my opinions, not necessarily my employer's. I hate spam.

From: E on 25 Oct 2009 04:35

"Jim Yanik" <jyanik(a)abuse.gov> kirjoitti
viestiss�:Xns9CAEBF8A4257Fjyaniklocalnetcom(a)216.168.3.44...
>
> I'm surprised there isn't some receiver IC that would do this job,and
> maybe
> a companion IC to do the PLL/dividing.
>

There are for example Micro Analog Systems
MAS6180 Stand-alone AM Receiver IC with Differential Input for
WWVB, JJY, MSF and DCF Time Code Formats

http://www.mas-oy.com/

Available as 150 mm tested wafer or TSSOP-16 from nowhere

-ek


From: Martin Brown on 25 Oct 2009 05:23
Hal Murray wrote:
>> The usual method is to use WWVB at 60 kHz, with a ferrite loopstick
>> antenna, a crystal filter, and a PLL. You can get nice 2400 mu ferrite
>>from Amidon. The ground wave delay is more stable than the sky wave
>>from the 10 MHz stations.
>
> "Usual" is an interesting word. I think it depends on what sort of
> quality you want.
>
> WWVB at 60 kHz is common for watches and battery powered wall clocks.
> It lets them set themselves to better than a second each night.
> It's inexpensive. There are similar signals from other countries.

It was used to discipline Rubidium atomic clocks for low frequency
continental VLBI in the early 80's. The transmitter - Rubgy in this case
has a very good stable carrier wave that covers most of Europe. ISTR the
remote VLBI stations could detect dew on the ground at Rugby causing a
few us shift in rise time on the seconds pulses.
>
> Somebody asked for a chip. (I think.) Feed CME6005 to Digikey.
> Others may carry similar toys. $11 includes an antenna. (Not
> watch size.)
>
> For higher quality, GPS disciplining a good quartz crystal
> is the current sweet spot. It's widely used for cell phones
> and 911 type time-stamping. A lot of it is available surplus.
> You can also use GPS with a Rubidium oscillator.

GPS is probably better these days, but 60kHz may still be cheaper.
Unlcear to me why a hobbyist would want such an accurate frequency
standard apart from for the challenge of making one. For VLBI it makes
life a lot easier having precise timestamps when searching for fringes
when the observations are combined at correlator stations.

Regards,
Martin Brown
First  |  Prev  | 
Pages: 1 2 3
Prev: If you had one what would you use it for
Next: Interesting TIA design