[ntp:questions] Re: improving WWVB reception

David L. Mills mills at udel.edu
Tue Aug 5 16:36:30 UTC 2003


George,

It is well known that Newark DE is in a radio-free zone. I have had 
problems over the last 17 years with WWVB, both because of conductive 
interference from industrial switching power supplies and most recently 
apparent blockage of signals due new campus buildings. I have three WWVB 
receivers, two on campus and one at home, all with the same problem more 
or less. The antennas for these receivers are well situated on top of 
buildings and away from possible re-radiators.

Some time ago I called the FCC about the interference problem and they 
lit up the Maine and Maryland monitoring stations to find the cause. 
Now, I've personally seen the monitoring station equipment and don't 
have much faith in that gear, but they did triangulate on a source in 
Quebec and then told me it was an international issue for the State 
Department.

I did indeed survey the local area for power line interference and did 
verify that was the source at least of some problems, probably the auto 
assembly plant on the edge of town. I can't bitch about that, since the 
conductive interference is less than the 15 microvolts per meter at 
wavelength over 2 PI limit of FCC Part 15. The wavelength at 60 kHz is 
rather large.

Nevertheless, my pals near Boston told me they have no such problems. I 
have to conclude the problem is local to this area and that the FCC 
monitoring stations have no idea what is going on. Something like this 
may be affecting the reported problem, but if so there is not much you 
can do about it other than the usual workarounds familiar to radio hams.

The WWVB transmitter plant has recently been augmented by 6 dB using 
gear from an old Navy longwave transmitter and antenna from the old WWVL 
station. Frankly, that has made no difference in my experience. The 
local problem is immediatelyi apparent with a communications receiver 
and oscilloscope.

Dave

George R. Gonzalez wrote:

> You may have a RFI problem.  The 60KHz signal is pretty weak compared to a
> lot of the signals floating around in the average civilized office.   Light
> dimmers, flourescent lights, CRT's, switching-mode power supplies all  put
> out lots of RF in that part of the spectrum.  Your best bet might be to just
> receive WWV on a SW radio and use it to set your clocks.  Low-tech but
> usually works, unless propagation is just shot.
> 
> 
> 
> 
> "Chris Campbell" <chris-google at pobox.com> wrote in message
> news:bglodn$qgr$1 at xuxa.iecc.com...
> 
>>I recently bought this clock:
>>
>>   http://store.yahoo.com/atomictime/attimsildigw.html
>>
>>for use in a radio studio.  We're going to do a fancier timekeeping
>>solution after our studio move next year but for now this is good
>>enough.
>>
>>Well, it would be if it worked.  The clock synchronizes with WWVB
>>every night, and I had it working on my engineering bench.  But with
>>it mounted on my air studio wall, it won't sync.  I've tried three
>>different positions -- mounted flat on west, north and east walls.  In
>>each position, I left it there for about a week to see if it would
>>sync.
>>
>>I'm in Atlanta, so WWVB is generally west from me.  I don't know how
>>the internal antenna element is oriented, but I assume it's parallel
>>to the big flat dimension of the clock, so either east or west should
>>have worked best.  Obviously the building is attenuating the signal,
>>but I really want it to work in that room, so I've got to find a way
>>to improve the signal reception without moving the clock much from
>>where it's at.
>>
>>So, does anyone have any experience with opening these clocks up and
>>adding an antenna?  What kind of antenna should I use, and how should
>>I orient it?
>>
>>- Chris
>>
> 
> 
> 
> 




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