[time-nuts] timing properties of "spectrum spreading" clocks

[jimlux]

Has anyone measured the details of the spread spectrum clocks used to 
help meet emission limits (like FCC Part 15)?

It seems, superficially, that they do this with some sort of 
deterministic process (like a linear feedback shift register), and so, 
one might be able to "back out" the (Pseudo)randomization to get better 
timing performance.


https://www.maximintegrated.com/en/app-notes/index.mvp/id/3503
seems to indicate that they use a up/down sweep approach.

https://www.maximintegrated.com/en/products/all-products/archive/MAX9492.html

https://www.idt.com/products/clocks-timing/application-specific-clocks/spread-spectrum-clocks/180-01-low-emi-clock-generator
"IDT's proprietary blend of analog and digital PLL technology"

https://www.idt.com/document/dst/idt5p50911-2-3-4-datasheet

seems to show a triangle wave frequency modulation