[time-nuts] WWV receivers?

[paul swed]

Good thread. Thanks for the clue on the kiwiSDR. I went to the sites and
lots of fun playing with the receivers. As an example hearing LORAN C in
the Asia region.
Certainly seems the receiver is pretty sensitive and capable. Went hunting
for various low frequency timing signals such as JJY and the submarine
crusher signals. All were heard.
I agree with Bobs comments that the signal at WWV range can be all over the
place and though seasonal effects can be a somewhat accounted for the
reality is, its still pretty random. The changes can occur slowly or
rapidly.
Regards
Paul
WB8TSL

On Sat, Oct 29, 2016 at 9:03 AM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
> Let’s see…. WWV (not WWVB) gets here via a variety of propagation
> mechanisms
> that vary over the day. According to NIST (who probably know :) that puts
> a random timing
> variation of ~1 ms on the signal. Since some modes get me a signal and
> others don’t, there
> is no real reason to assume it is random. It can easily be an offset that
> varies month to month.
>
> Net result, forget about the chip delays. The signal already has a bunch
> of built in variability
> that will swamp anything in the silicon.
>
> https://www.nist.gov/pml/time-and-frequency-division/nist-
> radio-broadcasts-frequently-asked-questions-faq
>
> Also in the same data is the fact that the “as transmitted” signal is good
> to 100 ns. That’s plenty good
> enough for the system as described. It also is a pretty modest number for
> a GPS timing module. One
> would guess that the number is a bit better than 100 ns (it is NIST after
> all). It also does not directly
> compare to the GPS number since there are UTC offset numbers there as
> well. Bottom line is that
> there inevitably *are* numbers like that buried in the system once you get
> past the 1 ms.
>
> Bob
>
> > On Oct 29, 2016, at 1:36 AM, Nick Sayer via time-nuts <
> time-nuts at febo.com> wrote:
> >
> > That single-chip version is going to have a *LOT* less (and less
> variable) latency than an SDR.
> >
> >> On Oct 27, 2016, at 12:20 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>
> wrote:
> >>
> >> --------
> >> In message <5A002554-8D90-4C75-95DA-21DB45D61E95 at kfu.com>, Nick Sayer
> via time-
> >> nuts writes:
> >>
> >>> If you’re in North America, a CHU receiver is a lot easier to make
> >>> than WWV/WWVH. The CHU timecode is just BEL 103 AFSK at 300 baud -
> >>> it was a one-chip solution 20 years ago when I made one in college.
> >>
> >> We have CPUs and sounds-cards these days...
> >>
> >> Also: The KiwiSDR is nearly perfect hardware, no matter which VLF/HF
> >> station you want:  You can track GPS and four (possibly 8) VLF/HF
> >> stations at the same time.
> >>
> >> --
> >> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> >> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> >> FreeBSD committer       | BSD since 4.3-tahoe
> >> Never attribute to malice what can adequately be explained by
> incompetence.
> >
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