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The objective of this project is to maximise the power and bandwidth efficiency of small satellite earth communication terminals whose main limitation to satellite capacity is a non linear transmitting power amplifier. A form of envelope equalisation is presented in which regular QPSK modulation is used together with instantaneous data magnitude modulation(More)
The objective of the paper is to analyse the advantages and disadvantages of spatial, DFT, DCT and DWT domains and highlight the advantages offered by watermarking wavelet coefficients rather than the DCT or FFT coefficients. The reasons for the DWT advantage are analysed and the choice of a particular wavelet basis is explained. As an illustration of these(More)
This paper investigates the design and application of data magnitude modulation to reduce power amplifier back-off for QPSK and OQPSK modulations for small satellite Earth stations. The coefficients for data magnitude modulation are obtained by using an iterative design loop. The parameters of this loop are tuned to obtain maximum gain. Roll-off factors(More)
This paper describes a high capacity blind video watermarking system invariant to geometrical attacks such as shift, rotation, scaling and cropping. A spatial domain reference watermark is used to obtain invariance to geometric attacks by employing image registration techniques to determine and invert the attacks. A second, high capacity watermark, which(More)
This paper describes a high capacity blind video watermarking system invariant to geometrical attacks such as shift, rotation, scaling and cropping. A spatial domain reference watermark is used to obtain invariance to geometric attacks by employing image registration techniques to determine and invert the attacks. A second, high capacity watermark, which(More)
The purpose of Distributed Speech Recognition (DSR) is to improve the performance of speech recognition services across communication networks. The DSR method is to extract feature vectors at a front-end terminal and transmit them as data with error protection to a back-end server. The ETSI STQ-AURORA DSR working group has standardised such a method. In(More)
The paper discusses the limits of error correction coding for spread spectrum-based video watermarking. The error correction code has as input the watermark data bits and as output the values which will be scaled and used to modify the video pixels (transform coefficients). The data rate of the watermark can increase only at the expense of increasing code(More)