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Crystal Reference Oscillator Design - RF Cafe Forums
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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
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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:
http://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.
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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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