[time-nuts] TPLL linearity and other questions
David Hooke
dhooke at gmail.com
Mon Jul 22 08:23:14 EDT 2013
Hi All,
I've built a measurement PLL along the lines of W. Riley's and Warrens's
designs. It's working, but I have a hole in my understanding of them.
The transfer function of the OCXO (10811-60159 in my case) is decidedly
non-linear, implying that that the voltage output is also not
proportional to frequency. Where does this non-linearity get corrected
before analysis in either Warren's or Bill's systems?
Also, without access to a 5062C as a noise source as some lucky folk do,
what test modulation patterns could I use to verify and calibrate the
gadget? I have an HP8662A, 3325A, 33120A and 8648C which I can rig
together to generate various phase or frequency modulations. Simple FSK
gives the expected square wave output (which is where I noticed the OCXO
non-linearity). What other tests would you recommend?
Also, I have 24bit, 192k sound cards which work down to around 1Hz. Are
there any analysis packages I should look at to explore PN output, or is
spectrum lab the best best?
Thanks from a beginner.
david
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