[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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