Hi > The CNT-91 has a very high noise floor if you are trying to âseeâ phase noise. May be but with this Pendulum CNT-91 I can fix PN degradation in the range -130 ... -150 dBc/Hz where R&S FSQ8 can do nothing... FYI: FSQ8 is not the worst SA: PN floor -130 dBc/Hz @10 kHz on 1 GHz. Karen, ra3apw