Angga Pratama Putra

A low-cost Analog Front-End (AFE) transmitter designs for OFDM visible light communications

One of major challenges in optical communications based visible light is nonlinearity effects which comes from LEDs as light sources. These challenges are exist when VLC systems use analog modulation such as OFDM. Therefore it needs special requirements to design Analog Front-End (AFE), especially at transmitter side. LED driver must be operated at linear mode. In this paper we propose a low cost and simple linear analog AFE transmitter for VLC. According to these problem, the main topic in this paper is to describe a low complexity of AFE transmitter circuit design based OFDM signal. Describing contents consist of: 1) channels model with 3×3×3 of room sizes and single LED, 2) non-linearity LED model transfer function which cover I–V, P-V, and P-I characteristics, 3) proposed AFE transmitter which cover variable non-inverting amplifier, offset adjuster and current-sink LED driver topology.

System-on-Chip architecture for high-speed data acquisition in visible light communication system

On this paper, we present results of our research in system-on-chip architecture for digital data acquisition in visible light communication. The objective of this research is to design data acquisition architecture for signal with high speed frequency using system-on-chip based design. The designed system is divided into two subsystems, hardware layer and software layer. All of the hardware resources are implemented on ZYNQ-7000 System-on-Chip, whereas the software is implemented using Xilinx API to establish connection to PC through UDP-based Ethernet connection. The implemented design has been proven to be able to perform high speed data acquisition for certain frequency sampling and able to transmit data to PC for data processing and displaying.

Analysis of Received Power Characteristics of Commercial Photodiodes in Indoor Los Channel Visible Light Communication

To date, the photodiode still the first choice component is used in optical communication, especially for visible light communication (VLC) system. It has advantages of speed, energy consumption, and sensitivity, compared to other devices (e.g. image sensor). There are many practical implementations of high-speed VLC which uses photodiode. Commercially available photodiode typically have specific characteristics, so that it needs some consideration to be used as optimal receiver devices in VLC system. In this paper, analysis of received power characteristics of the photodiode in indoor line-of-sight (LoS) channel of VLC system is discussed. MATLAB® simulation is used as approach model (student version). The experiments are done by changing several parameters such as the semi-angle half power of the transmitter, distance from the transmitter to receiver, room size, field-of-view (FOV), lens index and optical filter gain. From the results, it can be known that distance, room size, FOV and LED power factor to have linear characteristic against the received power of commercial photodiode. Also in LoS channel model, the gain of optical filter and lens index plays an important role in defining the characteristics of received power.

Trans-impedance amplifier (HA) design for Visible Light Communication (VLC) using commercially available OP-AMP

Trans-impedance amplifier (TIA) are widely used for optical sensing applications (precision instrumentation) and optical communication, such as: fiber optic, IR communication and also Visible Light Communication (VLC). TIA convert the current (I) into voltage (V). Application TIA design depend of objectives requirement system, for high speed as well as high-band, low noise, low power and others. This paper explains the empirical experiment of TIA for high-band VLC with over 1-MHz Gain Bandwidth Product (GPWP) estimated. We implement general topology mode: as photovoltaic. The selection of the best resistor feedback (Rf) and compensator (Cf) are presented, we compare simulation approach against real implementation. The OP-AMP chosen from Texas Instruments® product, OPA 656. The TINA™ SPICE® simulator used as simulations tool. This research contribution lies in applied of engineering design methodology with detailed step to develop major VLC system, we focus on photodiode amplifier only. By depth analysis, can be known next research addresses and obtain the best results without trial and error methods.

Linux based redundant system for satellite on-board computer

In this paper, we present results of our research on designing and implementing a prototype of a redundant system for satellite on-board computer using Intel Galileo. The system is designed to simulate fault tolerant system on satellite on-board computer. The triple modular redundant system implemented on a Linux-based operating system that installed on the on-board computer. Simulation is carried out by testing various possible scenarios. By using this redundant system, the system reliability level is improved in terms of fault tolerance of on-board computer hardware. The testing results show that the system will keep carrying out its mission as long as the fault does not occur on all three on-board computers at the same time.

Design of IP based on-board computer for small satellite

The reliability of satellite data communication is enhanced by designing two subsystem, data communication among OBCs and data communication in Telemetry-Telecommand Management (TMTC). Error Control Coding (ECC) is applied in satellite data communication with Automatic Repeat Request (ARQ) method. Bit error checking use the calculation of 15 bit Cyclic Redundancy Check (CRC) Controller Area Network (CAN) standard. The calculation of CRC is attached in CAN frame over IP communication protocol between primary OBC and secondary OBC. The triple modular redundant system implemented on a Linux-based operating system that installed on the on-board computer. The CAN frame over IP simulation with manual input corrects all corrupt data. When the simulation use the network emulator, the system corrects 100 % data in 0-10 % value of corrupt with maximum time transfer 84.472 seconds. ION DTN corrects all corrupt data with the value from 0 to 2 % and maximum delay at altitude 50,000 kms orbit of data using network emulator for TMTC mission. The testing results shows that the system will keep carrying out its mission as long as the fault does not occur on all three on-board computer at the same time.