[time-nuts] gpsdo 10MHz steering resolution

[ed breya]

 From the picture, I'd guess the spurs are due to excessive line 
frequency ripple from your 50 Hz mains (full-wave rectified = 100 Hz 
spurs) - it could be internal to the reference source or other gear in 
the system, or ground loops. Check the specs for residual line noise on 
the various equipment (including the SA itself) - it seems it should be 
much better than what's showing. If the overall setup specs should show 
much better, then look for internal problems like bad filter capacitors 
etc in power supplies, or external ground loops and cable shielding 
failures. If your 1.5 GHz PLL mentioned is home-made, you may want to 
look at that too, and ensure that its power supply is clean enough. If 
you find and fix such failures, you may not need to change to a new 
reference. Good luck.

Ed