On 1/13/12 8:15 AM, Chris Albertson wrote:
On Fri, Jan 13, 2012 at 3:19 AM,<[email protected]> wrote:
What we know is that you can set the Rb in 7 E-13. Dithering would allow
even closer setting, the question is what rate will the Rb accept with out
loosing lock or deterioration of the performance. Some one should explore
that. I am still waiting to se some aging. Taking the 10 MHz output and than
use an analog loop and something like a Morion OCXO and you have the best of
all.
Digitally controlling the Rb will cut the cost of the control loop in half.
For $10 in parts and a PC board for less than $10 using Shera like
controller can be realized. What is needed is some one able to do the PIC.
If some one is interested and able, please contact me off list. A low cost
GPS or a 1 pps output of a Tbolt be perfect source.
Bert Kehren
Don't use a PIC for the prototype. A desktop PC could work as well
and everyone here already has one. Connect the FE5680 to the PC's
serial port and send commands to adjust it. The PC also needs to be
able to read a voltage. Many already have audio input with 24-bit
ADC chips.
But those audio inputs are almost always AC coupled.
Bringing up a question: Does anyone know of a cheap (<$20ish) USB
voltage sensor (16 bits or better, ideally).. I can see one of those
Atmel USB capable micros (like the one on the Arduino Uno) hooked to a
dual slope or successive approximation ADC.
There seem to be an amazing number of times that I want something like
that. The DATAQ $29 widget is only 10 bits, unfortunately. A USB
interface DMM would work nicely, but I haven't found one that's in the
under $50 price range.
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