High-fidelity modulation parameter estimation of non-cooperative transmitters: Carrier frequency

Formulae are derived concerned with the accurate estimation of parameters of modulated transmissions from emitters which need not be cooperative. Thus, the modulation scheme and encryption methods need not be known. Our specific objective is to estimate the carrier frequency of the modulated transmission with high accuracy from large but not quasi-infinite data records oversampled when compared with the (unknown) baud rate. The approach taken is to develop exact descriptions of the second-order statistics of the sampled signal and, from this, to generate carrier frequency estimates together with a characterization of their accuracy, so that successive blocks of data might be analyzed for characteristics such as jitter of this value over time as a means to identify or classify emitters. The technical content of the paper is the derivation of exact formulae for second-order statistics of modulated signal transmissions, their specialization for asymptotic behavior as the number of data increase and for the case where the oversampling is at an integer multiple of the baud rate. (C) 2011 Elsevier Inc. All rights reserved.