On 12/5/18 6:32 AM, Bob kb8tq wrote:
Hi
On Dec 5, 2018, at 8:45 AM, jimlux <[email protected]> wrote:
On 12/5/18 5:39 AM, Poul-Henning Kamp wrote:
--------
In message <[email protected]>, jimlux writes:
If I were decoding WWVB to start, I'd break my samples up into 0.1
second or 0.5 second chunks and process them to see what the carrier
phase is.
With stable signals like this, it is a bad idea to chop them up,
in particular if your ADC runs from a good stable frequency.
True enough - this was just to get started.
Instead continuously average the square of the signal into a 1
second long circular buffer.
Then multiply/sum that buffer with a 120kHz sine and cosine to find
the phase angle.
yes.. assuming your ADC is running off a sufficiently stable source. I was
thinking about a very low cost implementation where the ADC is running off a
not very wonderful microcontroller clock.
A stable clock probably is a pretty good bet on a “Time Nut” grade design.
Indeed one objective might be to ultimately
read out the phase directly WRT that reference . Some sort of PPS tick likely
would get into all this as well.
I was thinking more about "can you receive it with a SDR implementation
for <$50 and minimal heating of the soldering iron" without worrying too
much about measuring small phase shifts.
Once you've got to that - then you've got a basis for further improvements.
I'll try the RTL-SDR with a non-active antenna on Friday and see what I
can see here in Southern California. I know my old style "atomic" clock
does see the signal sometimes, so I can grab some sample when the clock
says it's live.
If anyone has a suggestion for an off the shelf active antenna that's
orderable and receivable by Friday, I'd love to hear it. There's 3 or 4
of them I've seen (Clifford labs, DX Engineering has one, I'm sure MFJ
has one)
Why available by Friday? I'm going to be really busy starting next week
for a month commissioning a satellite launching next week, so this
weekend is my last opportunity to fool with actual technology.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
