Regarding spread spectrum issues:

You might be lucky to find (or have) SSCG implementation that is reasonably 
stable.  I suspect most are - because it is easy to generate hershey kiss 
spectrum based on SM, LUT or some sort of multi-level LFSRs.  I don't know what 
this means - these are some random Internet acronyms so it must be true.

I have several Linux workstations with system board crystals replaced with GPS 
synchronised synthesiser.  Instead of trying to disable SSCG or spending time 
analysing it I have tweaked system clock frequency until local time drift of 
the freewheeling system (with NTP setup with disabled time adjustment and clock 
correction) was less than 1 microsecond per day.  This took several days and 
needed better than 10^-11 level frequency adjustments and stability.  With GPS 
synchronisation this is easily achievable. If I keep NTP local time corrections 
disabled (basically remove all the servers from ntpd configuration) the local 
time drift is better than 0.01ppb.  Interestingly, to achieve that what used to 
be 26.000M crystal has ended up being a system clock that looks more like 
26,000,001.7193Hz 

Leo
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