Purwarupa Modem Audio Berbasis Mikrokontroler dengan Teknik Direct Digital Synthesizer dan Zero Crossing Detector

A microcontroller based audio modem system by means of Digital Direct Synthesizer (DDS) and Zero Crossing Detector (ZCD) technique is proposed in this paper. The modem operates in audible frequency range. The function of this modem is to transmit digital data through analog audio channel. In the modulator, DDS is used to generate sinusoidal audio signal. The modulation technique is 16-tones M-Ary Frequency Shift Keying (M-FSK) or MFSK16. In the demodulator, ZCD technique is used to measure the  sinusoidal signal periods. The experiments were done in the physical layer, to analyze the optimal channel bandwidth, transfer rate, and Bit Error Rate (BER). It was found that the optimal channel bandwidth for each tone is proportional to the frequency, due to fixed error DDS calculation. The performances of the modem are capable to modulatedata in transfer rate 200 bps and BER 2x10−3 without channel coding improvement.keywords: Audio modem, DDS, M-FSK, Zero Crossing Detector, GSMSistem modem audio berbasis mikrokontroler dengan teknik Direct Digital Synthesizer (DDS) dan Zero Crossing Detector (ZCD) diusulkan pada tulisan ini. Modem ini beroperasi pada frekuensi suara audible. Modem ini berfungsi untuk melewatkan data digital melalui kanal audio analog. Pada sisi modulator, digunakan teknik DDS untuk menghasilkan gelombang sinus audio. Teknik modulasi yang digunakan adalah 16 tone M-Ary Frequency Shift Keying (M-FSK) atau MFSK16. Pada sisi demodulator, teknik ZCD digunakan untuk mengukur perioda gelombang sinus. Pengujian dilakukan pada layer fisik modem dengan mencari lebar kanal yang optimal untuk masing-masing tone, nilai transfer rate, dan nilai Bit Error Rate (BER). Hasil pengujian menunjukkan lebar kanal optimal untuk masing-masing tone berbanding lurus dengan besar frekuensi, karena errorperhitungan frekuensi oleh DDS bersifat tetap. Performansi modem mencapai nilai transfer rate 200 bps dengan BER 2x10−3, tanpa penambahan pengkodean kanal.kata kunci: Modem audio, DDS, M-FSK, Zero Crossing Detector, GS

Metode Pemantau Posisi dan Arah Gerak Helikopter Tanpa Awak dengan Google Maps API

Makalah ini membahas metode pemantau posisi dan arah gerak helikopter tanpa awak dengan bantuan layanan Google Maps API dan sensor GPS. Sinyal yang dihasilkan oleh GPS berupa data posisi dalam koordinat lintang dan bujur. Arah gerak helikopter diperoleh dari modul GPS dengan mengkalkulasi data riwayat posisi. Sinyal dari GPS selanjutnya dipancarkan oleh modem radio di helikopter dan diterima oleh modem radio di komputer. Data kemudian diolah oleh program aplikasi yang dibuat dengan Visual Basic 6. Data hasil olahan digunakan oleh program javascript untuk menampilkan posisi dan arah gerak helikopter ke dalam peta yang diperoleh dari layanan Google Maps API. Sebagai hasil akhir, pengguna dapat melihat posisi dan arah gerak helikopter pada browser seperti Mozilla Firefox, Google Chrome maupun browser lain yang mendukung HTML5. Kecepatan pembaharuan data posisi pada jaringan lokal dapat mencapai duapuluh data perdetik atau 20 Hz. Kemampuan ini sangat lebih dari cukup mengingat kemampuan akusisi sensor GPS komersial yang paling mutakhir hanya  berkisar  antara 5-10 Hz. Dengan menggunakan metode ini data GPS dapat diproses tanpa ada data yang terlewat.Makalah ini membahas metode pemantau posisi dan arah gerak helikopter tanpa awak dengan bantuan layanan Google Maps API dan sensor GPS. Sinyal yang dihasilkan oleh GPS berupa data posisi dalam koordinat lintang dan bujur. Arah gerak helikopter diperoleh dari modul GPS dengan mengkalkulasi data riwayat posisi. Sinyal dari GPS selanjutnya dipancarkan oleh modem radio di helikopter dan diterima oleh modem radio di komputer. Data kemudian diolah oleh program aplikasi yang dibuat dengan Visual Basic 6. Data hasil olahan digunakan oleh program javascript untuk menampilkan posisi dan arah gerak helikopter ke dalam peta yang diperoleh dari layanan Google Maps API. Sebagai hasil akhir, pengguna dapat melihat posisi dan arah gerak helikopter pada browser seperti Mozilla Firefox, Google Chrome maupun browser lain yang mendukung HTML5. Kecepatan pembaharuan data posisi pada jaringan lokal dapat mencapai duapuluh data perdetik atau 20 Hz. Kemampuan ini sangat lebih dari cukup mengingat kemampuan akusisi sensor GPS komersial yang paling mutakhir hanya  berkisar  antara 5-10 Hz. Dengan menggunakan metode ini data GPS dapat diproses tanpa ada data yang terlewat

Design and Analysis of Hybrid Vessel Monitoring System based on DTN and Internet Collaboration

In this paper, we propose hybrid Vessel Monitoring System (VMS) design as alternative for current VMS scheme by collaborating internet connection and Disruption-Tolerant-Networks (DTN). The hybrid solution combines offline VMS that use radio networks and online VMS that utilizing satellite-based internet. Hybrid VMS aims to provide a more flexible VMS design and able to speed up delivery process of offline vessel’s data. The concept is both type of vessels must install a standard radio networks for data forwarding. The proposed method to speed up data delivery is by forwarding VMS data from one vessel to another using DTN forwarding scheme. Data can be forwarded to another offline vessel that will return to harbor earlier or to online vessels which have internet connection. Performance measurement is done through simulation analysis using ONE simulator. It aims to measure the speed up data delivery using hybrid VMS implementation compare to a pure offline VMS implementation. Simulation result show that hybrid VMS able to speed up data delivery for offline vessel data in 1.5 up to 2 times faster compare to a pure offline VMS implementation. Hybrid VMS also has advantages in flexible implementation by easily switching between online and offline VMS scheme, according to fisherman financial situation. Spray-and-Wait routing is the most suitable routing algorithm for hybrid VMS according to the efficiency ratio

Approximation-based homomorphic encryption for secure and efficient blockchain-driven watermarking service

Homomorphic encryption has been widely used to preserve the privacy of watermarking process on blockchain-driven watermarking services. It offers transparent and traceable encrypted watermarking without revealing sensitive data such as original images or watermark data to the public. Nevertheless, the existing works suffer from enormous memory storage and extensive computing power. This study proposed an approximation-based homomorphic encryption for resource-efficient encrypted watermarking without sacrificing watermarking quality. We demonstrated the efficiency of the Cheon-Kim-Kim-Son (CKKS) encrypted watermarking process using discrete cosine transform-singular value decomposition (DCT-SVD) embedding. The evaluation results showed that it could preserve the watermarking quality similar to non-encrypted watermark embedding, even after geometrical and filtering attacks. Compared to existing homomorphic encryption, such as Brakerski-Gentry-Vaikuntanathan (BFV) encryption, it has superior performance regarding resource utilization and watermarking quality preservation

Secure protection for covid-19 infographic using blockchain and discrete cosine transform-singular value decomposition (DCT-SVD) watermarking

Covid-19 infographics have a crucial role in mitigating the covid-19 pandemic by conveying the complex Covid19 information in a form of a simple yet understandable image. However, keenly to contribute to mitigating Covid-19, numerous parties and agencies had released Covid-19 infographics that might contain incorrect or inaccurate information. To prevent such recurrent, this paper proposed an authentication system by using a blockchain-based authorization service that lets the authority guarantee the correctness and validity of the infographics in a transparent manner. We proposed smart contract-based watermarking requests and approval management that let anyone track the watermarking process. To prevent unauthorized infographic fabrications, we use the DCT-SVD method considering its robustness against various attacks. We deployed and evaluated the smart contract on Ethereum test networks (Ropsten, Rinkeby, Goerli, and Kovan) to compare the efficiency and the ease of use. The result showed that the test networks have similar efficiency while the Ropsten and Goerli have better ease of use. The watermark validation service is accessible via a web-based interface for anyone to check the validity of the infographic’s watermark

Sentralisasi Pengawasan Informasi Jaringan Menggunakan Blockchain Ethereum

Pengawasan jaringan pada beberapa kantor yang berlokasi berjauhan sangat sulit dilakukan kerana keterbatasan tenaga ahli, biaya, dan teknologi pendukung. Penelitian yang sudah ada tidak dapat menyediakan sistem pengawasan jaringan yang mampu menjamin tiga aspek keamanan sekaligus, yaitu: availability, integrity, dan confidentiality. Teknologi blockchain mampu menyediakan sistem pengawasan jaringan secara terpusat dan aman dengan menjamin keamanan sistem komunikasi pelaporan dan sistem basis data pelaporan. Penelitian ini bertujuan untuk menyajikan purwarupa sistem pengawasan konfigurasi dan statistik jaringan menggunakan jejaring blockchain Ethereum. Metode pengawasan mengharuskan program controller pada setiap jaringan kantor untuk secara berkala menarik informasi flow-rules dari setiap perangkat jaringan dan melaporkan data tersebut dalam sebuah transaksi ke jejaring blockchain. Pada penelitian ini dianalisa dua jenis skema pengiriman transaksi: transaksi berbasis smart contract dan transaksi berbasis zero-payment. Berdasarkan hasil pengujian, transaksi berbasis zero-payment secara rerata hanya membutuhkan sekitar 6 % dari biaya transaksi smart contract. Perkiraan biaya bulanan untuk pensamplingan informasi setiap 10 menit adalah sekitar 1,19 ether per-perangkat jaringan. Meskipun demikian, metode pada penelitian ini lebih sesuai untuk diterapkan pada jejaring Ethereum jenis Proof-of-Authority (PoA) dibandingkan jenis Proof-of-Work (PoW) karena harga Ether yang mahal. AbstractCentralized monitoring of remote networks is hard to implement due to the high cost, lack of experts, and the missing key technologies. The existing researches are unable to provide a secure, centralized monitoring system that satisfies three security aspects, namely: availability, integrity, and confidentiality. Blockchain technology meets those three requirements by providing a reliable reporting and immutable database system. In this paper, we proposed a prototype of a centralized monitoring system that records network statistics and configurations into the blockchain ledger. The method requires the network controller to periodically fetch network information from every network device and submit it as a single blockchain transaction. We compare two kinds of transaction schema, smart-contract based and zero-payment based reporting schemes. The evaluations show that zero-payment transactions only cost 6 % of the smart-contract transactions. The estimation of the monthly cost is 1.19 ether per-device for 10-minutes data sampling. Nevertheless, the proposed method is applicable only for the Proof-of-Authority (PoA) Ethereum networks. It is not feasible for the Ethereum main network that uses Proof-of-Work (PoW) due to the high cost of Ether.

Localizing link failures in legacy and SDN networks

Localizing network link failures is crucial to guarantee sufficient network capacity and to efficiently manage network resources. However, since most of today's networks use link aggregation to increase bandwidth, localizing a single physical link failure within such aggregated links is challenging. In this paper, we propose and evaluate methods, for both legacy networks as well as SDN networks, to localize link failures in the presence of aggregated links.For legacy networks, we propose STreLo for localizing single link failures. We compare STreLo to a state-of-the-art solution, called SCMon, and show that, at the expense of using more probe packets, it is faster and uses less MPLS labels. Since probe packets are small, we deem the trade-off beneficial.For SDN networks, we propose StaF, which works in a decentralized way, requires no controller interaction, and can adapt to topological changes. Moreover, StaF can localize multi-link failures. Both approaches have been tested via Mininet implementations and experiments.</p

Localizing link failures in legacy and SDN networks

Localizing network link failures is crucial to guarantee sufficient network capacity and to efficiently manage network resources. However, since most of today's networks use link aggregation to increase bandwidth, localizing a single physical link failure within such aggregated links is challenging. In this paper, we propose and evaluate methods, for both legacy networks as well as SDN networks, to localize link failures in the presence of aggregated links.For legacy networks, we propose STreLo for localizing single link failures. We compare STreLo to a state-of-the-art solution, called SCMon, and show that, at the expense of using more probe packets, it is faster and uses less MPLS labels. Since probe packets are small, we deem the trade-off beneficial.For SDN networks, we propose StaF, which works in a decentralized way, requires no controller interaction, and can adapt to topological changes. Moreover, StaF can localize multi-link failures. Both approaches have been tested via Mininet implementations and experiments.Embedded and Networked System

DDoS Protection System for SDN Network Based on Multi Controller and Load Balancer

DDoS attacks on SDN networks can create a single point of failure that has the potential to disrupt the overall network performance. In a single controller scheme, there is a potential risk of experiencing buffer overload, leading to traffic congestion as switches must wait for responses from the controller before forwarding network packets. To address this challenge, this research implements security measures using a multi-controller and load balancer approach, aiming to enhance SDN network resilience against DDoS attacks. The system operates by distributing the workload from the main controller to a backup controller through a load balancer when indications of a DDoS attack are detected. These attack indications are determined based on the miss rate value of unique forwarding requests exceeding a specific threshold. The results of this approach have proven effective in improving the reliability, responsiveness, and quality of SDN network traffic during DDoS attacks. The testing parameters involved in this research include controller response time and network traffic quality, comprising latency, bandwidth, throughput, and jitter. Based on the test results, the multi-controller and load balancer-based approach successfully enhanced network quality and controller responsiveness by 66.51% compared to the longer single controller scenario, specifically 202.49% during DDoS attacks. In terms of controller responsiveness, there is a very slight increase of around 0.01% in latency between the two. While Multi Controller demonstrated a remarkable 43.21% increase in throughput compared to Single Controller, this improvement in throughput is accompanied by a significant 204% increase in jitter