Real-time phase noise meter based on a digital signal processor

A digital signal-processing meter for phase noise measurement on sinusoidal signals is dealt with. It enlists special hardware architecture, made up of a core digital signal processor connected to a data acquisition board, and takes advantage of a quadrature demodulation-based measurement scheme, already proposed by the authors. Thanks to an efficient measurement process and an optimised implementation of its fundamental stages, the proposed meter succeeds in exploiting all hardware resources in such an effective way as to gain high performance and real-time operation. For input frequencies up to some hundreds of kilohertz the meter is capable both of updating phase noise power spectrum while seamlessly capturing the analyzed signal into its memory, and granting as good frequency resolution as few units of hertz. After a brief outline of the aforementioned measurement scheme, key features of the adopted digital signal processor are highlighted. Hardware architecture, measurement process, and software strategies peculiar to the proposed meter are then described in detail. At the end, some results of experimental tests, carried out on sinusoidal signals provided by function generators and arbitrary waveform generators, give evidence of the meters reliability and efficacy