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| 1 | An Approach of Steganography in G.729 Bitstream Based on Matrix Coding and Interleaving显示文摘This paper proposes an approach of secure communication through the Internet based on the technology of speech information hiding. In this approach,the algorithm of embedding a 2.4Kbps low-bit-rate Mixexcitation linear prediction(MELP) speech into G.729 coding speech is presented by adapting the techniques of covering code and the interleaving. The parameters in G.729 source codec are analyzed in the Capability of noise tolerance(CNT) and selected to carry secret speech data because these parameters have less impact on the quality of being reconstructed speech. Experiment results show that the proposed steganography algorithm not only gained a high data embedding rate up to 2.4Kbps but also achieved better imperceptibility, which indicates that the algorithm can be used for high data embedding capacity hiding and can achieve good effect. | WU Zhijun CAO Haijuan LI Douzhe | 2015 | Chinese Journal of Electronics2015，24，1： | 9 |
| 2 | DME Interference mitigation for L-DACS1 based on system identification and sparse representation显示文摘L-band digital aeronautical communication system 1(L-DACS1) is a promising candidate data-link for future air-ground communication, but it is severely interfered by the pulse pairs(PPs) generated by distance measure equipment. A novel PP mitigation approach is proposed in this paper. Firstly, a deformed PP detection(DPPD) method that combines a filter bank, correlation detection, and rescanning is proposed to detect the deformed PPs(DPPs) which are caused by multiple filters in the receiver. Secondly, a finite impulse response(FIR) model is used to approximate the overall characteristic of filters, and then the waveform of DPP can be acquired by the original waveform of PP and the FIR model. Finally, sparse representation is used to estimate the position and amplitude of each DPP, and then reconstruct each DPP. The reconstructed DPPs will be subtracted from the contaminated signal to mitigate interference. Numerical experiments show that the bit error rate performance of our approach is about 5 dB better than that of recent works and is closer to interference-free environment. | Li Douzhe Wu Zhijun | 2016 | Chinese Journal of Aeronautics2016，29，6： | 6 |
| 3 | EffectivefractionscreenofYinchenhaoDecoctiononliverprotectionandjaundiceretreat显示文摘 | DOUZH LUOL HOUJY etal | 2014 | 时珍国医国药2014，25，10： | 1 |
| 4 | Pulse-Pair Interference Automatic Detection and Mitigation for L-Band Aeronautical Communication System显示文摘Pulse-pairs(PP) generated by distance measuring equipment(DME) cause severe interference to the L-band digital aeronautical communication systems.Unlike previous works that mainly improved receiver structure for mitigating the DME interference, this paper proposes a novel and practical time domain PP mitigation method without changing the existing receiver structure.Our method is composed of three parts and utilizes a specific property, i.e., a relatively fixed waveform of DME PP. First, the complex-valued waveform of PP is automatically detected through an iterative weighted average method. Then, on the basis of the detected PP waveform,each PP is reconstructed according to its amplitude, position, and initial phase, which are estimated through a sparse representation algorithm. Finally, the reconstructed PPs are subtracted from the contaminated signal. Numerical experiments show that compared with recently published methods the bit error rate obtained by our method is approximately 5 dB better, while the complexity is maintained at the same level. | Douzhe Li Zhijun Wu | 2017 | Transactions of Tianjin University2017，23，6： | 0 |
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