SISTEM KEAMANAN DATA MENGGUNAKAN SPREAD SPECTRUM IMAGE STEGANOGRAPHY (SSIS) DAN ALGORITMA KRIPTOGRAFI DES ( DATA SECURITY SYSTEM USING SPREAD SPECTRUM IMAGE STEGANOGRAPHY (SSIS) AND DES CRYPTOGRPHY ALGORITHM )

ABSTRAKSI: Steganography merupakan suatu teknik berkomunikasi dimana informasi disembunyikan pada media pembawa seperti citra, suara atau video tanpa memberikan perubahan yang berarti pada media tersebut. Berbeda dengan steganography yang menyembunyikan keberadaan informasi, kriptografi hanya menyembunyikan arti atau isi dari sebuah informasi. Kedua teknik ini dapat digabungkan sehingga menghasilkan informasi yang semakin sulit dilacak. Sistem yang akan dirancang ini meggunakan teknik image steganography dengan data digital yang disisipkan pada citra cover berupa teks (.txt) yang telah dienkripsi terlebih dahulu menggunakan algoritma kriptografi DES. SSIS menggunakan metode spread spectrum, dimana informasi yang akan disisipkan ke citra cover disebar ke dalam noise yang memiliki band frekuensi yang lebar. Noise inilah yang ditambahkan ke dalam citra cover. Sebagai antisipasi terjadi error selama proses transmisi, digunakan teknik Error Control Coding (ECC) yang terdiri dari enkoder konvolusi di transmitter dan dekoder yang menggunakan algoritma viterbi di receiver. Dari simulasi yang dilakukan, diketahui bahwa tingkat imperceptibility citra stego yang dihasilkan pada simulasi I (hanya untuk disimpan) tidak dipengaruhi oleh kriteria citra cover (low detail, medium detail, high detail) tapi dipengaruhi oleh jumlah bit yang disisipkan per tiap píksel citra cover. Kapasitas maksimum citra cover pada simulasi II, selain dibatasi oleh ukuran citra cover itu sendiri, juga dibatasi oleh jumlah code rate dari kode konvolusi yang digunakan dan level kuantisasi. Tingkat imperceptibility citra stego pada simulasi II dipengaruhi oleh kriteria citra cover (low detail, médium detail, high detail), ukuran file teks, dan jumlah bit yang disisipkan pada tiap piksel citra cover. Rata-rata penilai MOS dari sampel 30 orang didapatkan bahwa citra stego memiliki penilaian fine pada kanal dengan SNR diatas 22 dB.Kata Kunci : ABSTRACT: Steganography is a technique in communication system, where information is concealed into a carrier media, such us image, voice and video, without make significant changes to the cover media. Different from steganography which hiding information in plain sight, cryptography applications are used to encrypt information so that only the sender and recipient can understand it. Both of this techniques can be combined so that the information can be more difficult to breaked. This system is designed using image steganography with text file (.txt) as hiding information that was encrypted before using DES algorithm. SSIS is using spread spectrum method, where information that will be embedded into cover image is spreaded whitin noise that has wide band frequency. This noise is added then to the cover image. To anticipate an error along transmittion proccess, SSIS using Error Control Coding (ECC) with convolutional encoder in transmitter and decoder using viterbi algorithm in receiver. From this simulation I (for storage), imperceptibility level of stego image is confined by the number of embedded bit in every pixel of cover image. The image criteria is not determining imperceptibility level. In simulation II, maximum capacity determined by the size of cover image it self, code rate of convolutional encoder and level of quantization. Image criteria (low detail, medium detail, high detail), the size of text file, and the number of embedded bit in every pixel of cover image are the parameter that determine imperceptibility level of stego image in simulation II. MOS subjective values with 30 samples show that received image has high quality ( fine category ) in multipath fading+AWGN channel with SNR upper than 22 dB.Keyword

Binary Template Matching for Morphological Dilation Enhancement in Navigation Radar Imaging

Radar imaging system is strongly influenced by other supporting systems. There is a motor system that provides angular information to the display system, and Digital Signal Processing (DSP) system that provides the main information for radar imaging. The new approach, we substitute a DC servo motor with a DC stepper motor as radar antenna rotator in our navigation radar system development. Different from the use of servo motors that can provide angle movements smoothly, the new motor system provides angle information of 0.56 degrees in every step, results in empty pixel gaps in every 0.56 degrees in radar Plan Position Indicator (PPI) image. The width of the empty pixel gaps becomes wider when the cell array of raw data is increasing regarding the image plotting process. In this paper, we proposed a new morphological dilation method to the radar raw data based on binary template matching to accommodate the various width of empty pixel gaps before the radar raw data are plotted into the radar PPI image. By this method, the morphological dilation will only be applied to the raw data that meet the same criteria as the binary template. Otherwise, the raw data will be left as they are. The result shows that there is 150.52% pixel data addition in the empty pixel gaps from the original image, and 48.44% increase of the morphological dilation without binary template matching method

Robust automotive radar interference mitigation using multiplicative-adaptive filtering and Hilbert transform

Radar is one of the sensors that have significant attention to be implemented in an autonomous vehicle since its robustness under many possible environmental conditions such as fog, rain, and poor light. However, the implementation risks interference because of transmitting and/or receiving radar signals from/to other vehicles. This interference will increase the floor noise that can mask the target signal. This paper proposes multiplicative-adaptive filtering and Hilbert transform to mitigate the interference effect and maintain the target signal detectability. The method exploited the trade-off between the step-size and sidelobe effect on the least mean square-based adaptive filtering to improve the target detection accuracy, especially in the long-range case. The numerical analysis on the millimeter-wave frequency modulated continuous wave radar with multiple interferers concluded that the proposed method could maintain and enhance the target signal even if the target range is relatively far from the victim radar