Automatic Modulation Recognition for Aeronautical Telemetry

Abstract

This paper applies the Bianchi-Loubaton-Sirven technique to classification algorithm capable of distinguishing between PCM/FM and SOQPSK-TG. A happy byproduct of the classification algorithm is a reasonably accurate estimate of the bit rate. The classifier is based on the observation that CPM with an integer modulation index contains harmonics at multiples of the symbol rate. The algorithm is based on the CPM representations of PCM/FM and SOQPSK-TG and leverages the property that applying a g-order nonlinearity to any CPM creates a new CPM with modulation index g times the original modulation index. No prior knowledge of the data is assumed. The technique is applied to distinguish between PCM/FM and SOQPSK-TG. Simulation results show that the classifier works essentially error-free for signal-to-noise ratios above 20 dB and for sufficiently high resolution in the search algorithms required by the maximizations.