On 06/02/2013 10:21 PM, Attila Kinali wrote:
Another stupid idea: You have a 19.5MHz crystal, probably some
odd PLL and a varicap diode lying around: Build a VCXO out of the
crystal and lock it to the 10MHz using the PLL.
It has been done with an xor gate, a couple of passives, and the
Looks like the CDCE913 is the simplest one chip solution. The frequency in
the subject line is in error. What is needed is 19.2MHz.
So inside the CDCE913 we divide by 25 then multiply by 23. Or said
differenty 9.2MHz = (23/25) 10MHz.
The CDCE193 is a 14 pin chip that will do the above. It
From: kevin-use...@horizon.com
To: albertson.ch...@gmail.com
Cc: time-nuts@febo.com, kevin-use...@horizon.com
Subject: Re: [time-nuts] have 10MHz need 19.5Mhz
Message-ID: 20130606162408.10277.qm...@science.horizon.com
Any 2-pin crystal connection to an IC is a simple Pierce oscillator
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
On Mon, Jun 3, 2013 at 4:30 AM, Gerd v. Egidy li...@egidy.de wrote:
Hi Chris,
The question is the best way to get from 10MHz to 19.5MHz.
Must it be the RasPi or can it be another cheap Linux device?
There are some out there which have a frequency which is simpler to reach than
19.5 MHz.
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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Since short-term stability is no problem, and you already have the
right frequency in the 19.5 MHz oscillator, you can try
injection-locking it to the 10 MHz. Just divide the 10 MHz by 20, and
feed the 500 kHz edges into the original oscillator section, and lock
to its 39 th harmonic.
Ed
Recent talk about NTP servers. It seems the limit to their accuracy is the
quality of the crystal that drives the CPU clock. Most of them make really
good thermometers. I'd like to try and replace the crystal on a Raspberry
Pi with a signal derived from a time nut quality 10MHz standard.
The
Am 02.06.2013 20:59, schrieb Chris Albertson:
,
The Pi uses a crystal (not a TTL can, a real two lead crystal and a pair of
47pf caps) Both leads of the crystal attach to a pair of pins on an IC. I
figure I can unsolder the crystal and inject a balanced 19.5MHz signal
directly to the IC's
On 02.06.2013 20:59, Chris Albertson wrote:
I thought of using an AD9850 DDS chip. You can buy these on break out
boards very cheap on eBay but they need a 125MHz clock.I could drive
the 9850 with a 120MHz clock that is multiplied up from 10MHz.what is
the simplest 12x multiplier. I
On Sun, 2 Jun 2013 11:59:09 -0700
Chris Albertson albertson.ch...@gmail.com wrote:
Is there a smarter and more direct way to get 19.5MHz for 10MHz?
Are there any documents on the PLL and clock network of the RPI processor?
If so, i would assume that you should be able to switch the input
On 06/02/2013 08:59 PM, Chris Albertson wrote:
Is there a smarter and more direct way to get 19.5MHz for 10MHz?
Well, you *could* do a double-frequency re-generative divider.
Running it at 9.5 MHz and 19.5 MHz in synchronous mode. Should not be
too hard to achieve.
Cheers,
Magnus
On 6/2/13 11:59 AM, Chris Albertson wrote:
Recent talk about NTP servers. It seems the limit to their accuracy is the
quality of the crystal that drives the CPU clock. Most of them make really
good thermometers. I'd like to try and replace the crystal on a Raspberry
Pi with a signal derived
Hi
The Pi is simply a standard ARM CPU. The clock system in it is well documented.
How you get *at* the clock system may or may not be so well documented. There
are bits you flip to switch it from external crystal to external oscillator.
The gain of the stage and the function of the output pin
On Sun, 2 Jun 2013 11:59:09 -0700
Chris Albertson albertson.ch...@gmail.com wrote:
Is there a smarter and more direct way to get 19.5MHz for 10MHz?
Another stupid idea: You have a 19.5MHz crystal, probably some
odd PLL and a varicap diode lying around: Build a VCXO out of the
crystal and lock
Hi
A SI5335 would appear to be a more straightforward way to get the 19.5 MHz.
There are many other clock multiplier IC's out there. You don't need anything
very fancy, just a divide by two on the input, a multiply by 39, and then a
divide by 10. If the internal VCO will go to 400 MHz, you
Hi Chris,
The question is the best way to get from 10MHz to 19.5MHz.
Must it be the RasPi or can it be another cheap Linux device?
There are some out there which have a frequency which is simpler to reach than
19.5 MHz.
Have a look e.g. at the cheap low-power TL-WR703N, they use 25MHz:
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