Lets talk about WWV as a calibration source

Discussion in 'Wireless & RF Design' started by Wendy, May 17, 2019.

  1. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    Anyone that follows my ramblings know my Lets talk about series. It's master index can be found here:
    Wendy's Index

    Wikipedia has a marvelous article on WWV.For those whom are unaware WWV is broadcast at 10Mhz as an AM signal with lots of sidebands, and the broadcast carrier signal is derived from an atomic clock. The National Institute of Time Standards (AKA NITS) provides the service as a public service and is sponsored by the federal government There was a rumor its funding had been cut but it seems to be just a rumor. If you are wanting to know more see "Is WWV going away?". We could theoretically use the 10Mhz signal to fine tune a time base to an atomic clock. How cool is that? I will attempt to design a circuit along with a 10Mhz time base to be used in things like home brewed freq counter. Notice I am not talking about using WWV as a time base.. Being a shortwave signal, Reception is spotty pretty much anywhere you live unless you happen to live close to Ft. Collins, Colorado. in which case you could probably use it as an excellent time base as is.

    BTW, the internet web site is pretty cool too.

    I am going to do something a little different on this article, While I will post my ideas and show how I would do this, this thread is open to anyone to show how they would accomplish this. So lets get started!

    Since I just started this thread. It will take a couple of hours/days to develop and draw my ideas.
     
    Last edited: May 18, 2019 at 12:06 AM
  2. MrAl

    AAC Fanatic!

    Jun 17, 2014
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    Hi,

    I think it was back as early as the 1960's that was my favorite radio station :)

    I used to set my watch by that and other things using a short wave radio.
    Now i can get i think on 5MHz or 10Mhz but havent done that for over a year now.
     
  3. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    I was 13 when I got a 100 in 1 projects sold by Radio Shack for Christmas. I was a shared gift for both of me and my brother, he was 8. It was a life changer for both of us.. I started building breadboards of various circuits on spare chunks of lumber I scrounged. A lot of it RF projects. My Dad developed a new order for me "Turn it off!" Most of the time our TV reception promptly cleared up too, We lived deep in East Oklahoma country near some very tall hills(mountains?). But receivers were always fair game. Especially crystal sets, I used to buy 100' spools of wire and attach it to trees and bring it in through the bedroom window. I tried building crystal shortwave receiver then with some success. Then I borrowed my Dad's Wide band receiver which included shortwave and a whole world opened up before me, If their had been any amateur radio clubs I would have been in one. But I was a techie nerd in redneck country, no luck there. A good shortwave radio can receive WWV intermittently with a 3' telescoping antenna.I would suggest having a shortwave radio as a check to see if conditions. Allow reception in the first place. Occasionally it just won't be there for you to receive. But the ionispher moves from day to night, there is a very good chance it will occasionally not be there for you to use.

    This might be an exercise in futility. A crystal oscillator will likely radiate enough to jam out any signal WWV can provide. But, nothing tried nothing gained. When building the crystal oscillator A metal box and coax will be your friend.
     
    Last edited: May 19, 2019 at 9:43 PM
  4. MrAl

    AAC Fanatic!

    Jun 17, 2014
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    Hi,

    Sounds cool and reminds me of my early days in CB radio when i built a home made full dipole CB antenna and installed it vertically on the peak of the roof of our house. I used heavy fishing line for guy wire ha ha but it stayed up there for years. I got much better reception and transmit range than my store bought antenna which was smaller of course.
    Back then EVERYBODY in my town and many other towns in the area had a CB radio. It was the 'in' thing back then.
     
  5. DickCappels

    Moderator

    Aug 21, 2008
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    Before leaving the U.S. the last time, I wired up a circuit board with a 4 MHz crystal and a long chain of
    CMOS frequency dividers. I zero beat the 5th harmonic of the 1 MHz output against WWV (living in Arizona) by padding the load capacitors. Here in North East Thailand I cannot find standard time and frequency broadcasts on the radio but I have a poor man's secondary standard to check against.

    Back around 1975 a friend and I designed and manufactured shutter meters for testing film cameras. I used the same idea to get our calibration light source. An oscillator was zero beat against WWV then that output was divided down to drive an LED to produce a precision timed flash of light against which we calibrated the meter.

    Perhaps 10 years before that I visited a friend who had moved out of the area, and spent a couple of nights at his home since visiting was such a long trip. One night we stayed up through the whole night listening to WWV. Great memories.
     
  6. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    One of the assumed resource I would expect people to have is an oscilloscope. It needs to go to a least 100Mhz or 50Mhz. With that and the shortwave radio you can actually see the WWV signal.I had not thought of beating harmonics, It works and is simple enough it would work with a wide range of crystal oscillators.

    Since WWV is a relatively low freq AM signal, Many of the same techniques that work for 1Mhz crystal radios will work for it. One of the thing super hetrodyne radios do is drop the radio frequency to 455Khz to amplify and demodulate This also has the advantage of bringing the frequency low enough that transistors with a lower frequency cutoff value can be used.

    Since I am thinking of amplifying 10Mhz directly we will have to use a better quality transistor. Specifically I am thinking of a PN2222, I can buy a bag of unlabeled transistor for a $1 in this flavor. and occationally, do.
     
    Last edited: May 20, 2019 at 8:58 AM
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