The HP 3566A and 3567A have the same measurement feature set but differ in maximum frequency span and hardware configuration. Each analyzer includes a source for stimulating circuits or systems. An optional programmable DAC module adds arbitrary waveform and chirp capability. For fast measurement processing, a powerful hardware signal processor module converts time data to frequency domain data using FFT (Fast Fourier Transform) technology. If portability is important, the 4-slot HP 35650B mainframe and a portable PC make a very cost-effective multichannel system.