1,720,972 research outputs found
Data-Aided Carrier Recovery with QPSK Modulation
No full textDigital communication has proven to be the most efficient method of data transmission especially where long distances are involved. This led to the invention of more sophisticated methods of communication ranging from mobile handset communication to more advanced satellite communication. The speeds of passing information have been improving over the years and real time video communication has been made possible with digital devices. Various methods of digital data transmission are employed based on the information to be transmitted. This paper focuses on carrier recovery in digital communication systems, especially those based on Quadrature Phase Shift Keying (QPSK) modulation and demodulation scheme. The design being implemented is that of coherent demodulation for QPSK scheme using SIMULINK design tool. Performance of QPSK is also investigated to make a comparison and the suitability of the scheme to use in digital data transmission applications
Performance of 32kb/s ADPCM for data transmission
Full text linkThis study introduces a brand-new modified QAM modem that transmits data at a rate of 14.4 kbps over a 32 kbps Adaptive Differential Pulse Code Modulation (ADPCM) channel. This modified QAM modem’s goal is to lessen the nonlinear distortion that ADPCM introduces. The effectiveness of ADPCM is investigated using modified and regular QAM modems with various constellations. The simulation findings demonstrate that ADPCM performs better when using a customized QAM modem than when using a normal QAM modem. Additionally, a circular constellation performs better than a rectangular one
ПАТЕНТИ США НА СИСТЕМУ ADPCM ТА ЇЇ ЗАСТОСУВАННЯ
No full textThe Adaptive Differential Pulse Code Modulation (ADPCM) has been standardized by the International Telecommunication Union (ITU) due to its significance and extensive applications within telecommunication networks. This paper provides a concise overview of the recent US patents related to ADPCM and its applications, covering the years 2017 to 2025. Additionally, the general architecture of ADPCM is discussed. The findings presented herein aim to inspire researchers and motivate further explorations in this domain. Адаптивна диференціальна імпульсно-кодова модуляція (ADPCM) була стандартизована Міжнародним союзом електрозв’язку (ITU) завдяки її важливості та широкому застосуванню в телекомунікаційних мережах. У статті представлено стислий огляд новітніх патентів США, пов’язаних з ADPCM та її застосуваннями, за період з 2017 по 2025 роки. Також розглянуто загальну архітектуру ADPCM. Отримані результати покликані надихнути дослідників і сприяти подальшим дослідженням у цій сфері
Merni most za određivanje sadržaja vlage za velike količine zrna
No full textThis paper describes the development of a moisture-measuring instrument suitable for large grains. The paper seeks to do the measurement based on the propagation of microwaves through materials of different moisture levels. The principle of operation here is sending an equally divided signal through both arms of the bridge and comparing the output signals’ properties to determine the moisture content of the grains. The design of the bridge using waveguide and coax technology is presented.Ovaj rad opisuje razvoj pogodnog instrumenta za merenje sadržaja vlage u velikim količinama zrna (npr. skladišta, silosi). U radu se prikazuje merenje na osnovu prostiranja mikrotalasa kroz zrnaste ili slične materijale u masi različitih sadržaja vlage.
Princip rada instrumenta je slanje podjednakih signala kroz oba kraka mernog mosta i upoređivanje osobina izlaznih signala radi određivanja sadržaja vlage u masi zrna. Predstavljen je dizajn mernog mosta sa korišćenjem prostiranja talasa kroz cevi i tehnologija koaksijalnih (optičkih) kablova
Biometric Feature Extraction for Iris Scans
Full text linkThis paper generally seeks to demonstrate understanding and use of iris scans for biometric identification. Salient
features of iris are identified, their extracts analyzed critically by use of a software. The software for extraction of the
features is developed on MATLAB platform. Already prepared iris scans are used due to lack of scanners and/or very
high resolution cameras that would have otherwise assisted to obtain the required distinct features for comparison. The
program developed would compare two iris images a time and determine if they came from same individual; what we
are referring to as matching. A computer vision algorithm based on The Hough Transform is made use of in determining
circles present in the image which are essentially the iris and pupil. The region of interest from which the unique features
are obtained would be located between papillary and limbic boundaries. Papillary (between iris and pupil) while limbic
boundary is the one demarcating the iris and sclera. The comparison entails first determining codes of the two iris images
through generation of separate biometric template for them then using encoding procedure. Hamming distance calculation between the iris codes determines if they match
Modified algorithm of 16 kb/s ADPCM
No full textAbstractThis paper presents a new modified algorithm of 16 kb/s ADPCM. The modification is related to the adaptive predictor rather than the adaptive quantiser. The purpose of this modification is to reduce the nonlinear distortion introduced by ADPCM when a high data rate signal passes through it. The performances of standard and modified algorithms are studied using a QAM signal at a data rate of 9.6 kb/s. The simulation results show that the performance of modified ADPCM is better than the standard ADPCM
Comparison between Two Algorithms of 32kb/s ADPCM using QAM Signal at 16.8kb/s
Full text linkThis paper studies the comparison between two algorithms of 32kb/s ADPCM systems. The first algorithm uses 4-bit quantizer with sampling rate of 8000 sample/sec, and the second algorithm uses 5-bit quantizer with sampling rate of 6400 sample/sec. The comparison is done using QAM signal at data rate of 16.8kb/s. Two models of QAM signals are used, the first model operates at symbol rate of 2400 baud with each symbol is represented by 7-bit, while, the second model operates at symbol rate of 2800 baud with each symbol is represented by 6-bit. The contribution of this paper is that sending the second model of QAM signal over ADPCM with 5-bit quantizer. Simulation results show that the performance of ADPCM with 5-bit quantizer is better than 4-bit quantizer for both models of QAM signals. Also, the performance of ADPCM using second model is better than the first model. Furthermore, the performance with circular constellation is better than rectangular on
Study of the tracking of FHSS signal over AWGN channel
No full textFrequency Hopping Spread Spectrum (FHSS) communications utilizes a pseudo random code to spread the bandwidth of the data being transmitted over a much wider range than is required by the data. Due to the pseudo random nature of the carriers selected for transmission, the spreading and dispreading process must occur simultaneously to recover the transmitted data signal. This requires the receiver have knowledge about the instant the transmitter began transmitting and the propagation delay between the two. However, in real world systems, this information is unavailable to the receiver. The paper utilizes MATLAB Simulink to demonstrate a method of synchronizing the code clock at the receiver with the code clock at the transmitter. This fine alignment process is known as code tracking
Pseudohexadecimal near maximum likelihood detector
No full textAbstractThis paper introduces two newly developed near-maximum likelihood detectors, named pseudohexadecimal and modified pseudohexadecimal near-maximum likelihood detectors. These two detectors are tested against a pseudoquaternary near-maximum likelihood detector using data transmission at 9.6 kb/s over a telephone channel. Simulation results demonstrate that the performance of the pseudohexadecimal detector is better than the performance of the modified pseudohexadecimal detector, and the latter is better than the pseudoquaternary detector
On the Design of Smart Home System
Full text linkSmart Home (SH) technology, comprising smart devices in the home context. SH technology has demonstrated new and good contribution to increase safety and reliability, at the same time; it might have its own influence to change our living habit. Use of mobile phones is changing with the development of technology; it can be used for different purposes. With the help of a network, mobile phone can be used to implement the smart home by controlling the devices. The objectives of this paper are to implement a smart home by controlling electronic devices at home remotely and to get an alert on intrusion or movement around the restricted premises. The mobile phone is using the short message service (SMS) service available and the alerts are also received as an SMS mentioning the activity occurring around the premises
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