The turn of the century has seen a tremendous rise in technological advances in the field of auto... more The turn of the century has seen a tremendous rise in technological advances in the field of automobiles. With 5G technology on its way and the development in the IoT sector, cars will start interacting with each other using V2V communications and become much more autonomous. In this project, an effort is made to move in the same direction by proposing a model for an automatic car wiper system that operates on sensing rain and snow on the windshield of a car. We develop a prototype for our idea by integrating a servo motor and raindrop sensor with an AT89C51 Microcontroller.
Speech compression is required for storing and transmission of speech signals at low bit rates wh... more Speech compression is required for storing and transmission of speech signals at low bit rates which is needed for wireless communication. In this paper, ten speech signals of female voice are recorded with sampling frequency of 8 kHz and using monochannel in Praat software. In the first part of the paper, wavelet transform is performed on these signals using MATLAB software. It is found that the percentage of zero coefficients after six levels of wavelet decomposition in the speech signal is very high and those can be discarded without much loss of information. The decomposed signal is again reconstructed in MATLAB, and compared with the original signal, the distortion is found to be very less (≈10−5). In the second part of the paper, these same signals are quantized by uniform quantization and also compressed by µ-law companding. After compression, these coefficients are quantized. The q-levels with and without companding are compared. The signals are reconstructed by µ-law expand...
Text Dependent Speaker Recognition Using Linear Prediction Coefficients-Dynamic Time Warping
This project proposes a text-dependent speaker identification system. Isolated digits 0-9 and the... more This project proposes a text-dependent speaker identification system. Isolated digits 0-9 and their concatenations are used for speaking text. For each speech signal Linear Prediction Coefficients (LPC) are extracted and formed as feature vectors. Dynamic Time Warping (DTW) is used to measure distances between referenced and evaluated vectors. These distances, indicating nearness of unknown vectors to references, incorporated with K-Nearest Neighbor (K") decision technique are used for the identification process. In the verification test of the experiment. Consequently, we have experimented on the use of LPC with both DTW (using KNN as a decision rule) and ANN (a well-known Multilayer Perception (MLP) with back propagation learning algorithm). The systems were tested with 0-9 isolated digits. It has been shown that DTW with KNN gives better performance. It is affected by an attempt of ANN to recognize all of training patterns including any low quality voice. In this paper, furt...
Comparison of Different Spectrum Sensing Techniques for Cognitive Radio Systems
In Cognitive radio networks, the optimum utilisation of the spectrum can be ensured by detecting ... more In Cognitive radio networks, the optimum utilisation of the spectrum can be ensured by detecting the unused spectrum by spectrum sensing techniques and sharing it without harmful interference to other users. One important requirement in a cognitive radio network is sensing spectrum holes reliably and efficiently. This paper outlines the different spectrum sensing techniques like matched filter detection, energy detection and cyclostationary feature detection and compares the performance in presence of additive white Gaussian noise. The results are summarized in the concluding section.
Effect of Windowing in the Performance of OFDM Systems
Lecture Notes on Data Engineering and Communications Technologies
Orthogonal Frequency-Division Multiplexing is the key broadband technology, which is the basis fo... more Orthogonal Frequency-Division Multiplexing is the key broadband technology, which is the basis for 4G (Fourth Generation) wireless communication systems. Undistorted OFDM carries many un-filtered Quadrature Amplitude-Modulated (QAM) subcarriers. Thus, the out-of-band spectrum decreases very slowly. This out-of-band spectral characteristic of each symbol interferes with the next OFDM symbol. In this paper, several windowing techniques are used to reduce the out-of-band spectrum of each OFDM symbol. The effects of different windows in Peak to Average Power Ratio (PAPR) and Bit Error Rate (BER) of OFDM signals are also observed. The results are summarized in the concluding section.
Speech Compression with Wavelet Transform and Huffman Coding
The speech signals as it is generated carry lot of information which is redundant and has to be d... more The speech signals as it is generated carry lot of information which is redundant and has to be discarded before efficient storage and transmission. Thus, an efficient technique of speech compression without loss of much information giving less distortion in the reconstructed waveform and also retaining the perceptual qualities of speech is very much needed. This paper deals with the recording of female speech signals in Praat software. Wavelet Transform is carried out on these signals which removes lot of redundant information followed by Huffman coding which compresses the signals further. The average compression ratio obtained is three times higher than that obtained with only Wavelet Transform. The reconstructed signals have very less distortion (10-4) while retaining the maximum percentage of signal energy and perceptual qualities of speech. The detailed results are summarized in the concluding section.
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Papers by Ranjushree Pal