[HN Gopher] Receiving the WWVB time signal in Portugal (by accid...
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Receiving the WWVB time signal in Portugal (by accident)
Author : jgrahamc
Score : 55 points
Date : 2021-07-08 08:11 UTC (14 hours ago)
(HTM) web link (blog.jgc.org)
(TXT) w3m dump (blog.jgc.org)
| ttul wrote:
| This appears to be JGC's first post since 2010. Perhaps the
| Cloudflare IPO has finally enabled him to take a holiday! Well
| done, John!
| jgrahamc wrote:
| What makes you say that? I've posted lots of things. Such as
| this: https://blog.jgc.org/2021/04/aeronear-ambient-device-
| showing...
| kube-system wrote:
| You're looking at the "popular posts" section at the bottom of
| the page, not a list of all articles.
| supernova87a wrote:
| I agree with above commenter -- must have been some really
| exceptional ionosphere conditions or something!
|
| By the way, what's the latest on the retirement/phasing out of
| these time signal stations? I was under the impression from years
| ago that they were on the way out / being defunded with some kind
| of decade-long timescale (in favor of GPS).
| throw0101a wrote:
| > _I was under the impression from years ago that they were on
| the way out / being defunded with some kind of decade-long
| timescale (in favor of GPS)._
|
| There's actually an effort to get more systems _in addition to_
| GPS going, as it is a SPoF. eLoran is one option, and has an
| advantage of actually being in production in other countries
| already. There are others. The US DoT published a study in
| January 2021 (PDF):
|
| *
| https://www.transportation.gov/sites/dot.gov/files/2021-01/F...
|
| So I doubt reducing time signals generally is really on the
| menu.
| Stratoscope wrote:
| There was a 2019 NIST budget proposal to shut down WWV, WWVB,
| and WWVH, but this was reversed in the final budget. The
| Wikipedia page has some details. See the last paragraph under
| "Time signal transmissions", especially the two footnotes.
|
| https://en.wikipedia.org/wiki/WWV_(radio_station)
|
| That said, no one knows what the future holds.
| FredPret wrote:
| Sometimes I can't even get it on the East Coast!
| TMWNN wrote:
| I couldn't even get it on the West Coast. When I owned a
| wristwatch that synced to the time signal, twice a year I'd
| have to put it in on the windowsill the night of the daylight
| savings change; otherwise, it _never_ received the signal.
| FredPret wrote:
| I'm in the same boat - my WWVB wristwatch needs a nightly
| spot near a window to make it work
| jmcphers wrote:
| It's kind of miraculous that wristwatches can pick it up at
| all given how little space they can dedicate to an antenna. I
| live at the very outer Northwestern edge of WWVB's coverage,
| in the Seattle area, and my similarly equipped wristwatch
| reliably gets the signal -- but only at night, and,
| curiously, only if I'm wearing it! My theory, which I've
| never done any research on, is that the conductive metal
| backing of the watch allows some of my own body to serve as
| an antenna.
| jgrahamc wrote:
| Take a look at NIST's propagation charts for WWVB. You can
| clearly see the US East Coast getting little signal at certain
| times during the day: https://www.nist.gov/pml/time-and-
| frequency-division/radio-s... You're actually getting the best
| coverage at about the same time my clock was hearing its first
| signal in 15 years.
| politelemon wrote:
| Why is the propagation different during different times of
| day?
|
| On that page, it says
|
| > WWVB radio controlled clocks should be able to work in most
| places in North America. The red areas on the coverage maps
| below show where a WWVB radio controlled clock should be able
| to synchronize. Note that the red area is largest at night,
| and smallest in the daytime (click on the map to see a larger
| image). For example, 0600 UTC is about midnight in the
| central United States.
| jgrahamc wrote:
| _Why is the propagation different during different times of
| day?_
|
| Welcome to the wonderful world of radio propagation.
| Different radio signals at different frequencies "bounce
| around" the world in different ways. LF (low frequency)
| which is where the WWVB beacon operates bounces off the
| ionosphere (refracts) and can bounce very long distances.
|
| But the bouncing depends on conditions in the ionosphere
| which are affected by day/night cycles and sun cycles.
|
| Start here for some information: http://rsgb.org/main/files
| /2012/10/Understanding_LF_and_HF_p...
| [deleted]
| ggm wrote:
| Ntp synced emulator for rpi which I use in Australia to sync my
| citizen skymaster
|
| I didn't write this code. It has about 10-20cm of useful
| propagation distance (this is a transmitter and may breach local
| RF regulations)
|
| We're outside the footprint of jjy, wwvb or dcf
|
| https://github.com/hzeller/txtempus
| kube-system wrote:
| That is really cool. I wonder if there were any extraordinary
| atmospheric conditions going on.
| segfaultbuserr wrote:
| I find long distance reception of longwave radio signals (LW DX)
| fascinating, there are still a few interesting high-power
| stations that can be heard internationally. The radio is also
| easy to build - low-noise audio frequency amplifiers and 24-bit
| ADCs should do. Unfortunately it's extremely impractical for us
| city dwellers due to the huge antenna required for DXing and the
| deafening noise from switched-mode or digital devices. It only
| takes a single bad PSU to trash the LW spectrum.
| dragontamer wrote:
| I'm no antenna expert, but it was my understanding that the
| WWVB signal could be received on a homecrafted Ferrite Rod
| antenna.
|
| http://prc68.com/I/Loop.shtml
|
| Antenna of this type are a large ferrite rod, with a number of
| copper loops forming an effective inductor. With some
| capacitors, you can filter out other signals (forming a notch
| at the 60,000 Hz signal to get the WWVB)
|
| Not that I've done this before nor am I any kind of expert on
| radio. But... its not an especially large antenna from my
| understanding.
|
| --------
|
| I can appreciate the issues of noise. The 60,000 Hz signal is a
| 1-baud (lol) signal, one-bit every second. So you need
| 60-seconds to transfer the 60-bits of time information to the
| receiver.
|
| Any noise within that 60 seconds could destroy the signal and
| make it inaccurate.
| segfaultbuserr wrote:
| A simple ferrite rod antenna is the standard if you're in a
| covered zone. If you want to pick up distant signals you'll
| need something better. I've previously heard some amateur
| radio operators use many meters of random wires around one's
| backyard, that was what I imagined to be a "large antenna,"
| so I didn't look further. But I just found an ARRL article
| [0],
|
| > _A long wire sometimes works if directly connected to the
| antenna jack on the transceiver. In reality, a 500 foot long
| wire is a very short wire (less than 0.1 l) on 2200 meters. A
| preferable option is to use a small loop antenna and a
| preamp. These loops are generally about 2 meters in diameter,
| and a number of designs can be found on the LF Web sites.
| Unlike any practical wire antenna an amateur can erect, a
| loop will not take up much real estate and can be made
| directional to reduce interference. Once you have your
| antenna up and can receive commercial longwave stations such
| as CFH and DCF39, you have sufficient receiver sensitivity
| and you are now well on your way to receiving amateur signals
| on LF._
|
| Looks like a small, 2-meter magnetic loop antenna paired with
| a preamp should work well. Perhaps I should give it a shot
| one day.
|
| Of course, to transmit a signal (2200 meter is 136 kHz, which
| is an amateur band), it's a completely different story.
|
| [0] http://www.arrl.org/files/file/Technology/pdf/craig.pdf
| dzhiurgis wrote:
| Dad bought a similar clock few years back in west coast of
| Lithuania. Apparently it always resets by one hour back which I
| assume is a time signal from Sweden. No way to disable it so he
| just lives with it lol.
| Stratoscope wrote:
| For the curious, the National Institute of Standards and
| Technology (NIST) has a really interesting PDF with the history
| and technology of WWV, WWVB, and WWVH:
|
| https://tf.nist.gov/general/pdf/1969.pdf
| hoytech wrote:
| Alternate possibility: Your neighbour was messing with something
| like this: https://www.instructables.com/WWVB-radio-time-signal-
| generat...
|
| Just kidding, that's some nice propagation. One of my favourite
| websites is: https://www.pskreporter.info/pskmap.html
|
| When I want to test an antenna or anything I just call CQ a few
| times on FT8 and within seconds I get dozens/hundreds of reports
| and can see how far/what direction my signal is going.
| jgrahamc wrote:
| If it's the neighbour I'd be happy to meet them!
|
| The one advantage of this is that my wife told me that she felt
| bad for the little clock that had been waiting 15 years to
| receive that signal which gave me the opportunity to get out
| some of my ham gear and show her.
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(page generated 2021-07-08 23:01 UTC)