Years ago I needed to lock a 16.777216 MHz oscillator to a 10 MHz
reference for a "Williams" DDS synthesizer.
Because 32768 is a subharmonic of 2^24 Hz, this same sort of scheme
should be adaptable.
I will quote my own posting to this group from Feb 2, 2012:
Clint wrote:
> Years ago (in
Hi Bob,
The use of the PIC for WWVB carrier/data detection was only ever
intended for use with a visual clock, thus uncertainty (e.g. lag, delay
or whatever you want to call it) was par for the course in the
implementation that I described.
On 8/7/2015 3:51 AM, time-nuts-requ...@febo.com
Years ago I ran across a project in which the WWVB signal, after being
siphoned from a cheap TRF clock module with a Hi-Z follower, IIRC, was
shoved directly into the A/D input (10 bits) of a rather low-end PIC
running at a fairly low sample rate - something in the 4-8 kHz range.
IIRC, from
Hello,
I've mounted both my LPRO-101 and FE-5680 in Hammond 1590-type cast
aluminum boxes, bolting the rubidium unit to the lid of said box, and
found the heat sinking of the entire arrangement to be entirely
adequate. In each case there is a (well filtered!) switching regulator
present
One cheap device that has a fairly predictable tempco over a fairly good
range of temperatures is the lowly ceramic resonator - especially the
low frequency variety (e.g. 400-500 kHz) having a reasonably straight
line temperature versus frequency curve. If one already has a decent
frequency
Hi Paul,
Without digging through the archives, I'll rely on your memory of that
past thread!
The scheme of using the doubler relied on the 100 kHz carrier recovery
relied on the fact that the 200 kHz bandpass filters, being based on
quartz crystals, was extremely narrow - on the order of
Other than WWVB-based frequency references/clocks that lock onto the 60
kHz carrier itself, I'm not aware of any WWVB-based clocks that were the
slightest-bit affected by format change (e.g. the addition of the
low-rate BPSK): Please point me to any references to the contrary if
you find
Several years ago I spotted a clever PIC-based software (DSP-ish)
approach to WWVB modulation - but it has thusfar defied my attempts to
find it via Google. It was from the late 90's, early 2000's - and I may
have it in an archive somewhere.
The exact details escape me, but I believe that it
Sometime in the late 1990s, a friend of mine who works for a local city
government asked me if there was something that I could do about some
WWVB clocks located in a conference room, downtown, on a middle floor of
an office building amongst computers and fluorescent lights that never
managed
When I was messing with my SkyScan WWVB clocks to determine if something
that WWVB's signal had done broke them, preventing them from setting
properly and so-doing, I wanted to see what the receiver module was seeing.
(Spoiler: They didn't - they just break if the date is something later
Having used PICs since 1990, I've designed them into projects rather
than getting a board like a Parallax or Arduino (either of which are far
more expensive than the chip and the few components required to make it
work) and then shoehorning someone else's board into my project.
Since the late
Not to beat the topic to death, I did have an occasion to repeat the
WWVB signal. Although the signals here in Utah are very strong (3-5
millivolts/meter, maybe) they weren't strong enough to find their way
into a noisy office building, so about a decade ago I built a system
for a friend of
I found a note on the SkyScan web site itself that attempts to offer an
explanation/excuse as to why some of their clocks no longer synchronize:
http://skyscanatomicclocks.com/site/help-my-86715-86730-87315-is-not-catching-the-signal/
This, however, is a BIG red herring.
The ONLY change that
A few weeks ago I posted a question/comment about some of my WWVB-based
Atomic clocks no longer setting themselves properly. These two clocks,
SkyScan #86716, would show the symbol indicating that they had set
themselves, but their time was drifting away from UTC. Interestingly,
they *would*
Someone pointed out a typo: I wrote model number 86716 where I meant
to write 86715 for the SkyScan clock in question. In the linked web
pages it is correct, however.
73,
Clint
KA7OEI
Clint Turner wrote:
A few weeks ago I posted a question/comment about some of my
WWVB-based Atomic
At about the time WWVB announced switching the format, two of my clocks
- identical SkyScan units bought at about the same time 10 or so years
ago suddenly stopped synchronizing, too. If just one of these clocks
had a problem, I would chalk it up to a random failure - but two of them?
One of
While there could have been a few things to make the WWVB transmissions
easier to recover with low S/N, keeping them compatible with the
legacy time-only receivers was somewhat of a hindrance.
Unlike the DCF77 signal - which has a digital phase modulation that does
NOT really lend itself to
In reviewing the NIST document, I don't see anything particularly
difficult about the new format - either in terms of extracting the time
or phase/frequency information from the transmissions. With
undersampling, carrier recovery (to determine phase and amplitude
information) should be
Years ago (in the 80's) I needed to lock a homebrew DDS to an accurate,
stable 10 MHz reference (a good TCXO in this case) that was set to
WWV/H. Considering that the DDS was clocked at 2^24 Hz (16.777216 MHz)
this was slightly awkward, but I did it using standard HC and 4000 logic.
The
Hello,
After posting a few days ago about one of my '5680A's having the voltage
converter installed - but not connected - I've done a bit of
reverse-engineering and sleuthing around and (probably) have a fairly
complete picture of what it would take to populate that section of the
board.
Hi,
Are you sure about those resistor values? They look like 5.11K and 5.62K
(standard 1% values) to me.
Whoops - you are right: In squinting at the board I'd thought about turning
the thing 180 degrees since the numbers look believable either way! These two
5k-ish values are more in
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