1,720,955 research outputs found
IMPLEMENTASI DAN SINTESIS SISTEM KOMUNIKASI CAHAYA TAMPAK MENGGUNAKAN I/FFT 64-TITIK PADA FPGA
Full text linkVisible Light Communication (VLC), atau komunikasi cahaya tampak, dapat menjadi alternatif yang baik dalam komunikasi data. LED semakin terang dan murah sehingga penggunaannya mulai menggusur bola lampu biasa sebagai alternatif penerangan. Hal ini memungkinkan integrasi VLC terhadap sistem penerangan yang sudah ada, baik dirumah, dikantor, maupun tempat lain. Sementara itu Fast Fourier Transform merupakan algoritma yang sangat luas digunakan dalam sistem telekomunikasi, terutama transmisi multicarrier.
Dalam tugas akhir ini diimplementasikan sebuah sistem komunikasi cahaya tampak dengan Inverse/Fast Fourier Transform (I/FFT) sebagai metode multiplexing frekuensi. Pada data yang hendak dikirim, dilakukan pemetaan konstelasi menggunakan 4 QAM. Setelah itu, dilakukan multiplexing frekuensi dengan IFFT dan konversi sinyal digital menjadi analog sebelum kemudian ditransmisikan melalui rangkaian penguat LED dan lampu LED Cree XML2, dan diterima oleh photodiode BPV10 pada modul penerima dan penguat transimpedansi. Setelah diproses oleh penerima VLC, dilakukan konversi sinyal analog menjadi digital sebelum dilakukan dilakukan demultiplexing frekuensi menggunakan Fast Fourier Transform (FFT). Setelah itu dilakukan pemetaan balik dari konstelasi menjadi data dengan 4QAM demapper. Sistem komunikasi diimplementasikan dengan papan Altera De-0 Nano dan FPGA Altera Cyclone 4E. Modul pemancar VLC, penerima VLC, dan ADC/DAC diimplementasikan dengan papan bolong.
Sistem komunikasi diimplementasikan denganbitrate 302 kbps. Subsistem analog dan digital pada sistem ini mampu mendukung bitrate tersebut, dan menyuplai lampu LED dengan daya 0.10125 W. Sistem kemudian diujikan pada jarak yang berbeda - beda dari 25 cm hingga 60 cm. Pada 25 dan 30 cm, tidak ada kesalahan pada karakter yang diterima. Akan tetapi pada 35 cm mulai muncul tingkat kesalahan karakter sebesar 0.042 %. Tingkat kesalahan ini terus bertambah ketika jarak ditambah sehingga mencapai 7.42 % pada jarak 60 cm. Hal ini lumrah karena pada jarak 25 dan 30 cm, sinyal yang diterima masih besar sehingga SNR masih baik. Akan tetapi pada 35 cm seterusnya, sinyal yang diterima mulai menurun dan SNR mulai memburuk.
Kata kunci : visible light communication, inverse/fast fourier transform, optical communications
Design and Synthesis of Visible Light Communication Transceiver on FPGA
No full textPre-print :
In this paper, we designed and synthesized a Visible Light Communication (VLC) system with Inverse / Fast Fourier Transform (I/FFT) as a frequency multiplexing method using an FPGA. The system will map the data sent using a constellation mapper, which uses 4-Quadrature Amplitude Modulation. After mapped, the data is frequency multiplexed using an IFFT block and converted into its analog form before being transmitted through an LED amplifier circuit and a Cree XML2 LED. Next, the signal is received by Ba PV10 photodiode on the receiver module and a transimpedance amplifier. Once processed by the VLC receiver, the conversion of analog signals to digital is done before demultiplex the signal using FFT. Then we demapped the signal from back to the original data using a 4QAM demapper. The transceiver system was implemented on Altera De-0 Nano board with an Altera Cyclone 4E FPGA. The VLC transmitter module, VLC receiver, and ADC / DAC were implemented on a breadboard. The communication system works with a bit rate of 302 kbps. The Analog and digital subsystems are capable of supporting the bitrate, and supplying the LED lamp with a power of 0.10125 W. The system was then tested at different distances from 25 cm to 60 cm. At 25 and 30 cm, there is no error on the characters received. But at 35 cm there was a character error rate of 0.042%. This error continued to increase as the distance was added so that it reached 7.42% at a distance of 60 cm. This is normal since, at a distance of 25 and 30 cm, the signal received was still large so that the SNR was still good. But at 35 cm onwards, the received signal started to distort and the SNR started to decrease
Design and Synthesis of Visible Light Communication Transceiver on FPGA
No full textPre-print :
In this paper, we designed and synthesized a Visible Light Communication (VLC) system with Inverse / Fast Fourier Transform (I/FFT) as a frequency multiplexing method using an FPGA. The system will map the data sent using a constellation mapper, which uses 4-Quadrature Amplitude Modulation. After mapped, the data is frequency multiplexed using an IFFT block and converted into its analog form before being transmitted through an LED amplifier circuit and a Cree XML2 LED. Next, the signal is received by Ba PV10 photodiode on the receiver module and a transimpedance amplifier. Once processed by the VLC receiver, the conversion of analog signals to digital is done before demultiplex the signal using FFT. Then we demapped the signal from back to the original data using a 4QAM demapper. The transceiver system was implemented on Altera De-0 Nano board with an Altera Cyclone 4E FPGA. The VLC transmitter module, VLC receiver, and ADC / DAC were implemented on a breadboard. The communication system works with a bit rate of 302 kbps. The Analog and digital subsystems are capable of supporting the bitrate, and supplying the LED lamp with a power of 0.10125 W. The system was then tested at different distances from 25 cm to 60 cm. At 25 and 30 cm, there is no error on the characters received. But at 35 cm there was a character error rate of 0.042%. This error continued to increase as the distance was added so that it reached 7.42% at a distance of 60 cm. This is normal since, at a distance of 25 and 30 cm, the signal received was still large so that the SNR was still good. But at 35 cm onwards, the received signal started to distort and the SNR started to decrease
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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