Vol. 1 No. 2 (2007)

In this paper, we identify some impairments in the Voice over Internet Protocol (VoIP) networks and quantify the levels of voice quality. We propose an optimization model to maximize number of calls in low speed network for Rural Next Generation Network (R-NGN) while maintaining a minimum level of voice quality. The model is based-on Extended E-model to select parameters like voice coder, packet loss level, jitter buffer size, and network utilization. The optimum VoIP access network is achieved by applying G.723.1 5.3 kbps voice coder, packet loss level less than 1%, jitter buffer 50 ms, and…

This paper presents an asymmetric watermarking method in the DCT domain for still images based on permutation and chaos. This method uses secret watermark as private key and public watermark as public key. The public watermark has a normal distribution with mean = 0 and variance = 1. The secret watermark is obtained by permutating the public watermark according to combination of a part of RC4 algorithm and a logistic map. The watermark is embedded into mid-frequency components of the DCT block for better robustness. The detection process is implemented by correlation test between the public…

This Paper addresses Differential Quadriphase Shift Keying (DQPSK) modulation implemented on SDR platform for the development of digital data communications based on Software-Defined Radio (SDR). DQPSK modulation performance perceived at Packet Error Rate (PER) is evaluated in terms of Eb/No or S/N ratio, carrier frequency, bit rate, gain, roll-off factor of root Nyquist filter or root raised cosine filter, and payload size from delivered data. Based on these results, the smallest PER could be obtained by setting Eb/No value greater than 20 dB, carrier frequency of at least 0,3 MHz, optimum…

Computer vision systems have found wide application in foods processing industry to perform quality evaluation. The systems enable to replace human inspectors for the evaluation of a variety of quality attributes. This paper describes the implementation of the Fast Fourier Transform and Kalman filtering algorithms to detect the glutinous rice flour slurry (GRFS) gelatinization in an enzymatic „dodol. processing. The onset of the GRFS gelatinization is critical in determining the quality of an enzymatic „dodol.. Combinations of these two algorithms were able to detect the gelatinization of…