Dear experts

First of all, this is more a theoretical question than a simulator question, so please excuse me if it ends up under wrong section.  I have been looking into the slides of cyclostationary noise by Joel Phillips and Ken (available at http://www.designers-guide.org/Theory/). Slide 13 of the same shows noise being modulated with a 1 0 sequence. Now I consider the case where the noise is modulated using 1 -1 sequence instead (as in the case of chopper modulation/demodulation). At a first glance it appears to me as if the statistics of the noise are unchanged irrespective of whether the phase is 1 or -1. Yet in reality the noise is being modulated and should therefore be cyclostationary. Could you please clarify what might be going wrong in this thought process.

Thanks and regards