Prototype of an Automatic Digital Modulation Classifier Embedded in a Real-Time Spectrum Analyzer

This paper presents a prototype of an automatic digital modulation classifier based on a real-time spectrum analyzer (RTSA) architecture. The modulation classifier is suitable for efficient spectrum monitoring to identify the signals present in a certain frequency band, without the need of knowing any parameter about them. The realized prototype is able to recognize classical single-carrier modulations such as M-ary phase-shift keying (PSK), M-ary frequency-shift keying (FSK), M-ary amplitude-shift keying (ASK), and M-ary quadrature amplitude modulation (QAM), as well as orthogonal frequency-division multiplexing (OFDM) modulations such as the discrete multitone (DMT). To evaluate the performance of the prototype, several experiments with actual signals have been carried out in different operating conditions by varying the values of both the main modulation parameters and the signal-to-noise ratio.