Browsing by Subject "Variational mode decomposition"

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Open Access
A new method for specific emitter identification with results on real radar measurements
(IEEE, 2020) Gök, Gökhan; Alp, Y. K.; Arıkan, Orhan
Specific Emitter Identification (SEI) is the process of specifically identifying mobile transmitters by extracting unique features from the precise measurements of their emitted signals. A novel signal processing scheme with two stages is proposed for the identification of specific radar emitters. In the first stage, the received radar pulses are accurately time aligned and coherently integrated in order to increase the Signal-to-Noise (SNR) ratio. Using this technique, measurements with SNR improvements of more than 25 dB are obtained, enabling detection of subtle differences between different emitters. In the second step, Variational Mode Decomposition (VMD) is used to decompose both the envelope and the instantaneous frequency of the received signal into a set of modes. Then, these mode signals are characterized by using a group of features for identification. We demonstrate highly successful identification performance with the proposed method on real radar datasets.
Open Access
Novel signal processing techniques for remote sensing applications
(2021-06) Gök, Gökhan
Remote sensing is the acquisition of information about an object or phenomenon without a direct contact. In this thesis, novel signal processing techniques are pro-posed for two diﬀerent remote sensing applications. First, for the reconstruction of electron density proﬁle in the ionosphere using the ionosonde measurements, a new technique, ISED, is proposed. By using a hidden Markov model, ISED technique ﬁrst identiﬁes actual ionosonde echoes reﬂected from the ionosphere. Then, vertical electron density proﬁle is estimated as the solution to a model based convex optimization problem. Conducted experiments on real ionosonde data show that ISED overperforms the state of the art ionogram inversion tools. Second part, for Speciﬁc Emitter Identiﬁcation (SEI) of radar transmitters, a new SEI technique is proposed. SEI is an important Electronic Warfare (EW) activ-ity that aims to identify unique transmitters, even the emitters of same kind, by using the subtle diﬀerences on the transmitted signals. Proposed SEI consist of two main stages. In the ﬁrst stage, received radar pulses are time aligned and co-herently integrated to reveal subtle diﬀerences which could be used to distinguish diﬀerent radar transmitters. In the second step, Variational Mode Decomposition (VMD) is used to decompose both the envelope and the instantaneous frequency of the received radar signal into a set of modes. Then, these mod signals are characterized by using a group of features for identiﬁcation. Highly successful identiﬁcation performance with the proposed method on real radar datasets is demonstrated.