> Is the part number correct? I'm looking at the data sheet and don't see
> any I2C or EEPROM.
> http://www.ti.com/lit/ds/symlink/cdc925.pdf
Oops! CDCE925:
http://www.ti.com/product/cdce925
Apologies.
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T
I've had good luck with TI's CDC913/925/937/949 programmable PLLs.
(The middle digit is the number of PLLs, and the last digit is the
number of outputs.)
I haven't tested them for phase noise, but for an NTP application
all you need is long-term phase lock. They're fractional-N PLLs,
so you can u
I wrote:
> The on-board VCXO range is 80 to 230 MHz, so I'd multiply the 10 MHz
> up to 160 MHz and then divide by 10.
In case it's not obvious, I meant to write "the on-chip VCO".
Obviously it's *not* a crystal oscillator; I just failed to
supervise my typing fingers carefully enough.
__
> What's the simplest way to generate 16 MHz from 10 MHz?
Well, it's a few dollars and *is* a TSSOP, but I've been playing with
TI's CDCE913/925/937/949 series. They're nice little I2C-programmable
fractional-N PLL chips.
You can either program them in software, or save the config to on-board
fl
> It's possible to use Bresenham with two integers 10,000,000 and
> 32,768 but I found no way to perform all the 24-bit calculations
> on an 8-bit PIC quick enough. Removing the GCD often helps
> but in this case the accumulator remains 3-bytes wide.
Huh? Dividing 10,000,000 by 4 (to match the PI
The issue here is one of data compression.
On-line clock sync algorithms (like NTP) typically use a very simple
piecewise linear mapping function, but update it very frequently, up
to once per second. Phase is continuous, and steps in rate are small
enough not to be a problem.
This is great if y
> I disagree - call me an old fart or whatever. Your points are valid
> and proper logic, but every situation is just not the same.
>
> Bonding everything is proper, but without an effective ground, lightning
> will still seek a path to dissipate itself. We are taught if the ground
> is not g
Brooke wrote:
> Note old fashioned "Lightening Rods" do not work as well as the brushes.
Sorry to say, but they're heavily marketed hokum. Nobody who's not selling
something has *ever* been able to measure the slightest difference from
such "Early Streamer Emission" devices.
A variety of designs
Although not exactly trivial, it is actually not only possible but
surprisingly easy to design a setup that can indeed withstand repeated
direct lightning strikes without damage.
Large AM transmitters deal with this all the time. Polyphaser
sells a lightning strike *counter* so you can schedule m
Yeah, it gets a bit heated. Since you have the data sheets and all,
could you spare us a bit of work and summarize, for each OCXO:
- What EFC and power voltages it needs.
(Using an input voltage lower than your own supply rail seems odd.)
- What EFC voltage stability (uV per day or whatever) is
); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY
> Even better use a device with built in trimmed resistors.
But they usually only come in decade gains. 1:2 and 1:4 limit
you to only a few devices which may not be suitable on other
specs.
> Try actually reading the OCXO dat
>> One trick I use to get better tracking is to build ratios out of multiples
>> of a single resistor value.
> Can you guarantee this works every time?
Define "guarantee". For a reasonable risk ratio, yes. Resistor
manufacturers don't go out of their way to package resistors from
different ba
); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY
Vos is 1 uV/C guaranteed, 0.15 V/C typical. (And you can get a
high-spec part with the latter guaranteed.) Can take 24 V supply,
and pull to within 1.5V of the rails over the full temperature range,
so can produce +/-10V.
Als
The receiver's been sitting ignored for most of this year, but I just noticed
that it's locked on to GOES East and showing approximately the right time.
I haven't checked it at the PPS level, though.
Anyway, I just thought that was interesting.
___
tim
tvb wrote:
> Maybe you and I are the only ones with GOES
> receivers still powered on?
One more. It's been running for years, and I haven't got around to
digging through the layers of paint to unbolt the antenna.
It's powered on and the internal lock light is still on.
> After 30 years the GOES
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