Zurich Instruments Blogs

In this post, I demonstrate the capabilities of the HF2LI-MOD upgrade by demodulating 4 FM sidebands simultaneously. With the help of a basic sweep routine programmed in LabVIEW, I measure 5 Bessel functions by direct sideband demodulation of an FM signal. This post might give you an inspiration on how to improve your measurement sensitivity by introducing an advanced demodulation scheme of multiple sidebands.

I always had difficulties in understanding frequency modulation (FM) and its frequency spectrum. Even for the pure tone modulation, the FM spectrum consists of an infinite number of sidebands whose signs change from one sideband to the next one and whose amplitudes are given by the horrible Bessel functions. I have a pictorial representation of AM/FM that helped me understand the sidebands.