darcyrandall2004 Post subject: Crystal Reference Oscillator Design.
Posted: Sun Oct 21, 2007 3:25 am Colonel Joined:
Tue Feb 27, 2007 6:16 am Posts: 46 Hello, For the sake
of learning and my own interest, I have been designing a UHF data radio.
Is this correct ? If my carrier freq is 450.325MHz accurate
to +/-200Hz Lets say Im using a 20MHz Crystal reference oscillator
for my PLL. Then a rough calculation tells me that my crystal must
be accurate to within -> 20*PPM*(450.325*10^6)/(20*10^6) < 200
-> 0.44PPM. Where PPM is parts per million. If these
calculations are correct, can anyone recommend where I can find a crystal
reference ocillator with a TTL or CMOS output, accurate to 0.44PPM?
I believe an oscillator from 5MHz to 25MHz would be suitable.
FYI my channel width is 25kHz, Im using National's LMx2346. Thankyou
Regards Darcy Randall, Perth, Western Australia _________________
Regards, Darcy Randall, Perth, Western Australia Top
IR Post subject: Posted: Sun Oct 21, 2007 5:14 am Site
Admin Joined: Mon Jun 27, 2005 2:02 pm Posts: 373 Location:
Germany Hello Darcy, Your calculation is correct.
For such a tough spec as you have a simple Crystal is not good enough.
You should use a TCXO. I found an example for one with 0.28PPM and
a CMOS output: https://www.valpeyfisher.com/openlink.as ... FTX160.pdf
You can also ask for samples and define the frequeny that you
need. Please contact the manufacturer for further help. Top
darcyrandall2004 Post subject: Posted: Sun Oct 21, 2007
9:03 pm Colonel Joined: Tue Feb 27, 2007 6:16 am
Posts: 46 Legend. Thankyou _________________ Regards,
Darcy Randall, Perth, Western Australia
Posted 11/12/2012
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