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This paper investigates a dual satellite transmission scheme with coherent reception. The receiver has a single synchronization circuit and is locked to only one of the satellites. Beam-centric pre-compensation techniques are considered in the paper. The cooperation area in which coherent reception is feasible is characterized analytically. The application of precoding to the orthogonal time and frequency space (OTFS) waveform is considered to counteract the residual offsets, which result from the displacement of the receiver from the selected reference point. Numerical evaluations show that the dual satellite scheme improves the system spectral efficiency as well the link reliability in comparison with the single satellite transmission scheme. This paper is part of the R+D+i project (PID2020-115323RB-C31) funded by MCIN/AEI/ 10.13039/501100011033.

This work presents a novel technique for joint secured and robust transmission of orthogonal frequency division multiplexing (OFDM) based communication systems. The proposed system is implemented by developing a new OFDM symbol structure based on symmetric key cryptography. At the receiver side, data detection becomes infeasible without the knowledge of the secret key. For an intruder who tries to detect the data without the knowledge of the key, the signal will be a noise-like signal. In addition to the system security, theoretical and simulation results demonstrated that the proposed system provides time and frequency diversity, which makes the system highly robust against severe frequency-selective fading as well as other impairments such as impulsive noise and multiple access interference. For particular frequency-selective fading channels, the bit error rate (BER) improvements was about 15 dB at BER of 10E-4., Comment: This article has been submitted for possible publication at the IEEE ICC 2013

In this paper we propose a method of audio chord estimation. It does not rely on any machine learning technique, but shows good recognition quality compared to other known algorithms. We calculate a beat-synchronized spectrogram with high time and frequency resolution. It is then processed with an analogue of Prewitt filter used for edge detection in image processing to suppress nonharmonic spectral components. The sequence of chroma vectors obtained from spectrogram is smoothed using selfsimilarity matrix before the actual chord recognition. Chord templates used for recognition are binary-like, but have the tonic and the 5th note accented. The method is evaluated on the 13 Beatles albums. © 2012 Nikolay Glazyrin et al.