WWV & WWVB Ground Wave!

Discussion in 'Amateur Radio News' started by KA0KA, Oct 1, 2019.

Tags:
ad: L-HROutlet
ad: l-rl
ad: Left-3
ad: MessiPaoloni-1
ad: Subscribe
ad: L-MFJ
ad: Left-2
  1. WQ2H

    WQ2H QRZ Lifetime Member #214 Platinum Subscriber Life Member QRZ Page

    Tyler - great video captures ! Thanks for sharing these ! :)

    By the way - love the mounting feet on your tuner. :eek:

    73
    Jim, WQ2H / WK2XAH
     
    KA0KA likes this.
  2. K0YQ

    K0YQ Ham Member QRZ Page

    I imagine the flux capacitor in your shack powers everything but you must get some overload from the un-shielded 1.21GW?
     
    KA0KA likes this.
  3. AJ4LN

    AJ4LN Ham Member QRZ Page

    I've listened to the 60.Khz WWVB signal, and decoded it, in VA on my Kenwood TS-590S and my G5RV. I used the CLOCK app for decode from http://f6cte.free.fr/index_anglais.htm
     
    KC5MO likes this.
  4. KA0KA

    KA0KA Ham Member QRZ Page

    I just posted the 'WWV removed weather service announcements' and the 'WWV Splatter' video if interested. See URL video page link.
    ~Tyler, KA0KA
     
  5. KA9Q

    KA9Q Ham Member QRZ Page

    Thanks for these recordings. Did you get any of the other frequencies?

    I've been studying WWV's HF transmitters for a while, and I see significant AM-to-PM distortion on their 5, 10 and 15 MHz signals -- especially 10 MHz. This does not affect ordinary envelope AM detection but adds considerable audible distortion to synchronous (coherent) AM detection. You can also see the distortion on an I/Q signal plot. A clean AM signal should appear as a flat line on the +I axis; the distorted signal appears banana-shaped.

    The 5, 10 and 15 MHz transmitters use high level plate modulation. The 2.5, 20 and 25 MHz transmitters use linear amplifiers and appear clean.
     
  6. K6CLS

    K6CLS Ham Member QRZ Page

    Hi, thanks for your post. I'm curious about this. Could you post a couple pictures, I/Q plots I guess?

    I'll try tuning in with synchronous AM, never tried that mode. Very curious!
     
    KA9Q likes this.
  7. KA0KA

    KA0KA Ham Member QRZ Page

    I have to agree with your listening as well, from here in Fort Collins, the worst sounding signal is by far the 10 MHz signal as you saw the splatter video I posted. They do fix it, after about a week or so of problems when it happens. The best sounding transmitters are 2.5;20;25 MHz. That is also why I took my 'master' recordings from 2.5 MHz! If anyone wants a sample of a different frequency I can do that, they are all ground wave here so SAM is not needed for me as you can imagine.
     
  8. W0PV

    W0PV Ham Member QRZ Page

    A few years ago, when we had a higher average MUF, I was frequently on 12m. Of course WWV at 25 Mhz is VERY close to the edge of that amateur band. Afternoons they would often have a BIG signal into FL, often S9+20, or more.

    One day I was tuning at the top of the 12m phone band segment and I heard a strange xmsn, a voice, on 24984 kHz, just above the band edge. It sounded familiar. I realized it was coming from WWV!

    It had a very weird sound, suppressed carrier (!) and DSB, on both USB and LSB. I wondered if there was more to it and also found the same phenomenon at 16 kHz above the fundamental, or 25016 kHz.

    The following links are audio clips. They start out listening on the fundamental freq, 25 MHz, then you will hear a "beep" as I flip to one of the spurious frequencies, where you will hear the fainter voice of the spurious signal. More beeps is more flipping to other sideband or to the other spur frequency, and then back to the fundamental.

    WWV 25 MHz clip 1 - https://vocaroo.com/i/s0jCjW2zTP9a
    WWV 25 MHz clip 2 - https://vocaroo.com/i/s0UxIPP9ViuC

    Note these spurs ONLY happened during the vocal "special announcements", like solar indices or sea WX, and NOT during the normal top of the minute time posts. Apparently the level of audio sent to the xmtr or some other parameter varies between those sources.

    I emailed WWV with a description and these clips to alert them of this incident. Eventually I received the following reply and confirmation. (I redacted the name of the responder to not create any trouble.)

    I don't hear WWV much on 25 MHz any more these days, so you may want to see if this is still occurring.

    73, John, WØPV

    ------------------------------
    wwv <wwv@nist.gov>
    Tue 12/8/2015 10:05 AM

    Hello Mr. Rech,
    Thank you for your report on the spurious emissions around the 25MHz. I was able to confirm your report of a modulated emission at 24.984 but found nothing at 25.946. I’m surprised you were able to receive it. The signal is 60 db down and is originating in a phase lock loop section of our modulator. I’ve backed off the modulation level on the special announcements so this may minimize the issue during those minutes but if conditions are right and you look closely I think you will find the spurious carrier still there and still modulated. I’m currently looking into a long term solution.

    Thanks for the report.

    Sincerely,
    XXXX XXXXX
    Technician, WWV

    From: John Rech [mailto:johnrech@hotmail.com]
    Sent: Sunday, December 06, 2015 1:19 PM
    To: wwv <wwv@nist.gov>

    Subject: 25 mhz - possible spurious adjacent channel emissions

    To Whom It May Concern,

    First, thank you very much for the QSL card I received for my signal report in February of this year.

    However, I want to report that today while listening in the 12m amateur band, I heard a very curious signal. It was a female voice coming from what appeared to be a double-sideband modulated (!) signal centered about on 24.984 mhz. The content of her message was solar index information, and looking at the time, I realized this could be the usual solar report broadcast by WWV.

    I tuned up to 25 mhz and could hear WWV with a very strong signal, peaking S9+2- db with QSB fading down to S8, on my Icom IC-781 and wire dipole at 30 ft AGL. The voice message interval had passed, and I did not hear any more spurious signals during normal time ticks or tones, nor during the on-the-minute male voice announcements.

    But, later, when there were more special broadcasts (sea states?) with a male announcer, I tuned and heard similar modulation artifacts, this time mostly above the primary 25 mhz frequency. These were not intelligible like the female announcement though, just distorted noises.

    I thought perhaps this was a fault in my receiver front end. After all, the IC-781 is an old gal now. So I switched to a FT-817 portable radio and waited for the next solar index announcement at 1918-19 UTC. To my astonishment, I heard the DSB modulated female voice distinctly on 24.984 and on 25.916 mhz! These signals were not strong, in my judgement at least minus 50-60db down from the primary carrier, but very clearly intelligible here.

    Anyway, this is NOT a complaint for me, but I thought it might be of interest to you.

    Best regards,

    John Rech - WØPV
    Bradenton Florida
     
  9. KA0KA

    KA0KA Ham Member QRZ Page

    You are not going to believe this, but I actually listen to the solar forecast 18 mins after the hour +16 kHz from center, basically the level of IMD the signal produces allows for the exact same signal to be heard and seen +- 16 kHz center. I thought about making a 1 min video showing the event but never did thinking that only a few people would care to see it or even understand what I as showing but I think it is really neat. Perhaps, I will whip this out and post that as well John. If you did not do so, check out the additional WWV videos I posted. You will love the Splatter one.
     
    W0PV likes this.
  10. AB1KR

    AB1KR Ham Member QRZ Page

    Classic!


    Nice work Tyler! Last year I made a cycling voyage to see the antenna farm at WWV. Loved it! Not least was the private hexbeam located literally just over the fence line...
     

    Attached Files:

Share This Page