[time-nuts] David Welch's 3 block signal

WB6BNQ wb6bnq at cox.net
Wed Feb 13 20:14:49 EST 2008


Hi David,

I am not sure where you are at, but your mail server appears to be on the East
Coast of the US.  I seriously doubt that it is your "in house" 10 MHz that is
traveling 3 blocks.  If it is then there are some serious issues to contend
with.  The first being, if you are in the US, that you are exceeding the FCC
limits for unintentional radiators as defined under Part 15 of the FCC rules.
For what would be considered a more or less sealed system (i.e., your
equipment/cables), it is NOT normal to hear "the" signal beyond the first
neighbor in any direction from the equipment location.

Are you sure your "old Radio Shack" receiver is working properly ?  I can still
copy 10 MHz WWV mixed in with the local house standards at my location in the San
Diego, California area.  Of course I am using much higher quality receiver
designed for the Amateur radio market.

First I would turn everything off and then see what you hear.  Then i would turn
on & off each individual item and see how much (if any) contribution the item
makes to noise floor in the receiver.  After that I would turn on, in succession,
the most important to the least significant and see who might be generating the
strong signal.  Something in that process should give you a clue as to which item
may have a serious problem.

In the end, if you have a real need to receive WWV on the HF frequencies, I would
consider a much better receiver and, of course, an outside antenna.  If I may
suggest, the is a software defined receiver that appears to be of quality design
covering from 500 Hz to 30 MHz for $499.99 that may interest you.  Go to
http://www.rfspace.com and look at the SDR-IQ model.  I talked to someone who has
one to test and he thought quite highly of it.  It is of a very interesting
design and includes software to run it.  It plugs into the computer via a USB
cable and is powered from that USB cable.  The software includes bandwidth
settings, a FFT spectrum and a waterfall type display as well.  In addition, it
handles CW, AM, LSB, USB, wide and narrow FM and perhaps other modes.

Don't forget that WWV also transmits on 2.5, 5 and 15 MHz.  15 MHz is good during
mid day and 5 MHz is quite good at night time.  2.5 MHz is only good at night and
a little tough to copy unless you have a good antenna or are living quite close
to it.

Bill....WB6BNQ

David Welch wrote:

> I was wondering with so many 10 mhz sources running.or even a single cesium
> and gps receiver running, as I have now..and the 10 mhz is also routed to a
> clock driver system (leitch).I cannot receive 10mhz wwv broadcasts at all
> anytime,I am using a old radio shack sw radio on batt power..I tried even
> almost 3 blocks away and all I get is my 10 mhz carrier..so even a rooftop
> ant will not work ..I must have a lot of leakage somewhere to travel for the
> signal to peg the radios meter blocks away..
>
> ----- Original Message -----
> From: "Matt Ettus" <boyscout at gmail.com>
> To: "Tom Van Baak" <tvb at leapsecond.com>; "Discussion of precise time and
> frequency measurement" <time-nuts at febo.com>
> Sent: Wednesday, February 13, 2008 3:17 AM
> Subject: Re: [time-nuts] GPS Locked and Unlocked Performance Comparison
>
> > On Feb 13, 2008 1:03 AM, Tom Van Baak <tvb at leapsecond.com> wrote:
> > > To prevent, or at least detect, this effect I allow my 10 MHz
> > > house reference to drift off-frequency by quite a bit (last
> > > month it was 1.7e-12 off). That way there are no on-time
> > > or on-frequency sources near the test setup.
> >
> > Tom,
> >
> > I think you might be the only person in the world who would consider
> > 1.7 parts per trillion to be "quite a bit off" :)
> >
> > Matt
> >
> > _______________________________________________
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