Cost Effective, Versatile, High Performance, Spectral Analysis in a Synthetic Instrument

This paper described a versatile block of signal conditioning options that process raw data samples from the A/D converter and deliver a filtered and resampled version of those data samples to a conventional FFT based spectrum analyzer. The conditioning performs a number of important processing functions. These include spectral translation to baseband, noise bandwidth reduction to signal bandwidth, and arbitrary resampling to obtain specified spectral spacing with available sized FFTs. The versatility of an FPGA based processor and signal conditioning block enables the use of the signal conditioner blocks to align sample rate with transform sizes without the need to vary input sample clock rate or the cut off bandwidth of analog anti-alias filters in the signal path. A straw man set of specifications for the spectrum analyzer was proposed and used as the basis of the simulations presented in this paper. The processing described here reflects the great versatility and flexibility available to the system designer. Broader bandwidths and greater dynamic range options can be quickly accommodated in the architecture presented here.