On 12/4/18 9:00 AM, Tim Shoppa wrote:
Because of the Q of WWVB's transmit antenna (at least 300 by my back of the
envelope estimates), I don't think we could ever claim a WWVB PPS edge
sharper than 5 milliseconds and that might be optimistic.
Sure you can.. you do a matched filter to the waveform, so you're not
just looking at a single zero crossing or cycle. Getting fraction of a
degree phase accuracy from a strong signal is entirely possible.
A Q of 300 implies a bandwidth of 200Hz, which would, if a single
section, be a delay of a few milliseconds. But that delay should be
constant. What might be the limit on precision is whether the delay
through the antenna and the ultimate radiated phase changes with, say,
temperature or soil properties.
Tim N3QE
On Tue, Dec 4, 2018 at 11:49 AM Bob kb8tq <kb...@n1k.org> wrote:
Hi
The I2C clock rate is going to matter a bit in terms of what you can
achieve.
Since the device is targeted at low power, the max practical baud rate may
not be very high. I2C can have a lot of wait in it ... There are a lot of
registers
dumped after each “reception attempt”.
There also is the basic question of how the IRQ flag relates to the time
the
chip “sees”. If it’s actually WWVB time sync’d then that’s a useful thing.
None of this is likely to be an issue in a wall clock. If they can run at
a “tens of ms”
sort of level that’s more than good enough. We really want to get to
microseconds
don’t we :)
Bob
On Dec 4, 2018, at 11:25 AM, Majdi S. Abbas <m...@latt.net> wrote:
$69 CAD is roughly $50 USD.
Expensive for what it is but easier to work with than gutting a working
clock and no more expensive.
I ordered one. Curious to see what sort of precision we can get from an
i2c interface.
If nothing else I suppose I can toss a six digit i2c 7 segment module at
it and roll my own WWVB desk clock.
—msa
On Dec 4, 2018, at 07:50, paul swed <paulsw...@gmail.com> wrote:
I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems a
bit
off.
Regards
Paul
WB8TSL
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