[time-nuts] WWVB Measurements
semiflex at comcast.net
Mon Mar 28 16:33:29 UTC 2011
There is a method to recover a very weak signal
out of the mud that is fairly easy to build. It uses
a multiplying DAC run by a local reference look
up table that is phase locked into the noise. BW
can be effectively 1 Hz. Output of the DAC would
be integrated to a DC value to control the LO.
Once lock is achieved then the LO can be used
to look at the modulated signal in a wider BW.
Maybe some useful modulation maybe not.
An 8 bit MDAC with 256 or 512 samples per wave
would work ok, no problem to go to 12 14 16 bits
to polish the idea if desired.
Reference LO would be 30M72 for 512 or 15M36
for 256. Other ratios could be made using some
extra logic to make whole ratios better suited for
10M0 final detected values.
On 3/28/2011 4:51 AM, EWKehren at aol.com wrote:
> Living in Miami probably as far away as possible in the continental US I
> have no problem receiving WWVB. When I moved here in 1993, 60 KHz was my main
> reference source. I used a Tracor 599 and a HP 117 along with a 4 foot
> commercial loop. The 599 showed clearly superior performance. Later Austron
> Loran C was added. The 117 was put on the shelf because without paper it was
> not conducive for long term tracking.When $5 Million homes where build
> directly next to me the loop had to go, plus the homes where in the direct pass
> with the transmitting site. Homes here are built because of code with
> concrete cinder blocks and vertical 1" rebar every one or two feet. I did
> replace the loop with a commercial 60 KHz ferrite rod unit that also does an
> excellent job. With the new location of the antenna I try to peak between the
> two houses but there is also a power transformer on a pole within a 10
> degree window. During the time I relied on 60 KHz the 599 worked flawless and
> as soon as I have room in my lab again I will run it against a tbolt.
> I am presently cleaning house in preparation for a next year move and it is
> depressing to throw out stuff that at one time I paid good money for. No
> room to move in the lab right now.
> In the nineties Junghans came to Miami to do some field strength
> measurements in preparation with their product roll out. Knowing their senior
> management I had an opportunity to host them. I ended up with four Junghans MEGA
> clocks and two MEGA watches. The watches have the antenna in the leather
> watch bands (their patent). All work well in a house with steel rebar and two
> houses next to me in the signal pass. The same is true of the receiver in
> my La Crosse weather station I bought three years ago. The only way I can
> really tell when we change daylight time and I make it a point to check the
> following morning. With out exception they all change.
> Bert Kehren
> In a message dated 3/28/2011 12:11:15 A.M. Eastern Daylight Time,
> hmurray at megapathdsl.net writes:
>> Pretty much before all these switching power supplies and cpfls etc.
> Does anybody know what frequency CPFLs are using today?
> I remember that we had some (non-compact) ceiling fluorescents at work
> "electronic" ballasts that were in the 50-60 KHz range. That was 5 years
> I wonder if all that junk will eventually migrate to well above 60 KHz to
> take advantage of the smaller magnetics and open up WWVB again.
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