[time-nuts] WWVB: measuring local 60 KHz noise
kb8tq at n1k.org
Sat May 5 11:49:10 EDT 2018
If you want delay ( hardware delay and not propagation), calibrating a SDR should not
be to nutty. Some boards ( the Lime SDR comes to mind) will generate a signal as well
as receive one. That could be piped into a scope to make the measurement fairly
easy. Once you know what is going into the receiver and what is coming out, it’s just
twiddling the knobs ….
> On May 5, 2018, at 5:50 AM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> Some SDRs can tune that low and should provide a means to determine
> if noise is really the problem as well as give some clues as to the
> of said noise. But they are much less likely to help with delay
> unless you can figure out a practical way to ascertain the latency in both
> SDR's HW and its SW. The latter component will also vary considerable
> depending on what computer you are using with the SDR, as well as with
> random variations due to the vagrancy of typical operating systems.
> I recently did a crude delay estimation for WWV (not WWVB) using my
> Sony ICF-2010 receiver, a 2-channel DSO, and an Adafruit "Ultimate GPS"
> module's PPS output. The combined (receiver + propagation) delay was
> very close to 5 msec in Kerrville, TX. The precision was mostly limited by
> my inability to decide precisely where each WWV tick started on the 'scope's
> display due to distortion arising from multipath and the receiver's
> The actual received waveform varied considerably from second to second.
> On Sat, May 5, 2018 at 3:08 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
>> Review/background: I have an UltraLink 333 WWVB receiver. It didn't
>> Several weeks ago. a discussion here mentioned that the phone cable
>> the main box and antenna needs to be straight through rather than the
>> reversed. That was my problem. With the correct cable, the meter shows
>> signal and bounces around such that with practice, I could probably read
>> bit pattern. But it didn't lock up.
>> That was several weeks ago. I left it running. When I looked last night,
>> had figured out that it is 2018. I wasn't watching or monitoring, so I
>> know how long it took.
>> I assume the problem is noise. Is there any simple way to measure the
>> around 60 KHz? How about not so simple?
>> Extra credit for a way that others nuts can reproduce so we can compare
>> noise at my location with other locations.
>> Can any audio cards be pushed that high? I see sample rates of 192K, but
>> don't know if that is useful.
>> I'd also like to measure the propagation delays on WWV so a setup for HF
>> also works down to 60 KHz would be interesting.
>> The UltraLink documentation says the display has a slot for a C or H. The
>> C is for Colorado and the H is for Hawaii. Did WWVH have a low frequency
>> transmitter many years ago? The NIST history of WWVH doesn't mention it.
>> My guess is a cut+paste from a version that listened to WWV/WWVH.
>> These are my opinions. I hate spam.
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