Radio Frequency Watermarking System Design And Implementation

With the progress of computing performance and decipher technology, the hiding of information requirements is increasing. Represent by the watermarking technology of information hiding technique has been very mature. Existing digital watermarking techniques, the difference is mainly reflected on watermarking embedding and extracting algorithm. In addition to continuously improvement and optimization of the algorithm performance, new information hiding scheme can increase the diversity of choice, further enhancing information security. Existing communication scheme focuses on watermarking signal processing itself, without considering the watermark itself can be superimposed on the carrier directly to the transmission signal. RF watermark is extended exploration of this idea. However, existing research is still lacking experimental data; therefore, the design and implementation of RF watermarking system is of great significance.Based on USRP and RTL-SDR hardware platform, we build a complete radio communication system. By carefully designing watermark embedding and extracting algorithm, the effectiveness of radio frequency watermarking is verified. This paper mainly use digital signal, different modulation methods of digital carrier signal lead to different watermark embedding and extracting algorithm. This article first introduces the basic theory of RF watermarking and basic development environment. Development environment includes USRP, RTL-SDR hardware platform and MATLAB, Simulink software simulation platform. According to the characteristics of the hardware environment, some quantitative tests have been done. Then, for digital RF carrier signal, we proposed two demodulation algorithms, Timing pulse synchronization algorithm and the starting and ending time synchronization algorithm. By carefully design watermark adding and extracting methods, we ensure that the demodulation of original carrier signal and watermark signal is simultaneous and accurate. This paper also put forward some specific technical solutions, such as the caching algorithm according to which we build RF watermarking system. Next, we specifically describe the embedding and extracting algorithm RF watermark signal. We introduce two watermarking embedding algorithms, the one-dimension and two-dimension watermarking algorithm, as well as two watermarking extraction algorithms. For the two-dimension watermarking algorithm, we have also given error rate formulas of RF carrier signal and the watermarking signal, and its correction is verified by simulation.Finally, we introduce the main parameters of the system test results. These parameters include the frequency offset, the amplitude of the watermark, carrier symbol rate, the symbol rate ratio and other parameters. Experimental results show that when the watermark amplitude is-26 dB, carrier symbol rate is 1000 Bd, symbol rate ratio is 50, the carrier and symbol watermark symbols can be correct demodulated.