Abstract
In this study, we implemented a high-performance multichannel repeater, both for FM and T-Digital Multimedia Broadcasting (DMB) signals using a Field Programmable Gate Array (FPGA). In a system for providing services using wireless communication, a radio-shaded area is inevitably generated due to various obstacles. Thus, an electronic device that receives weak or low-level signals and retransmits them at a higher level is crucial. In addition, parallel implementation of digital filters and gain controllers is necessary for a multichannel repeater. When power level is too low or too high, the repeater is required to compensate the power level and ensure a stable signal. However, analog- and software-based repeaters are expensive and they are difficult to install. They also cannot effectively process multichannel in parallel. The proposed system exploits various digital signal-processing algorithms, which include modulation, demodulation, Cascaded Integrator Comb (CIC) filters, Finite Impulse Response (FIR) filters, Interpolated Second Ordered Polynomials (ISOP) filters, and Automatic Gain Controllers (AGCs). The newly proposed AGC is more efficient than others in terms of computation amount and throughput. The designed digital circuit was implemented by using Verilog HDL, and tested using a Xilinx Kintex 7 device. As a result, the proposed repeater can simultaneously handle 40 FM channels and 6 DMB channels in parallel. Output power level is also always maintained by the AGC.
Highlights
Since recently, natural disasters such as tsunamis, earthquakes, heavy rains, and strong winds caused by climate change, and the collapse of buildings and massive power outages can be accurately predicted and situations can be minimized by promptly communicating them to the public, and many countries have a variety of disaster networks.For example, the United States created the Emergency Alert System (EAS) in 1994 to inform the public of the dangers of natural disasters such as typhoons, hurricanes, floods, tsunamis, earthquakes, and heavy snow, as well as emergencies such as fire, poisonous gas, power outages, and industrial accidents
Since the digital repeater operates in an Intermediate Filtering (IF) band, the signal passes through a Digital Down Converter (DDC) and Digital Up Converter (DUC) [8], passes through a filter section and Automatic Gain Controllers (AGCs)
Though the Terrestrial Trunked Radio (TETRA) repeater is different than the repeater we propose in this paper in frequency bands, they are same in basic structure and format
Summary
Natural disasters such as tsunamis, earthquakes, heavy rains, and strong winds caused by climate change, and the collapse of buildings and massive power outages can be accurately predicted and situations can be minimized by promptly communicating them to the public, and many countries have a variety of disaster networks. In a system for providing such services using wireless, a radio-shaded area occurs due to special topography and property between base stations constituting a wireless-communication service network. These spaces are very wide-ranging, from shopping malls, airports, and parking lots, which are fully open spaces, to fully enclosed mines, trains, or automobile tunnels. A repeater device capable of improving signal quality in such a radio-shaded area at low cost was researched and developed. We designed and implemented a repeater system with digital-signal-processing (DSP) algorithms using FPGA, which can reduce the radio-shaded area and increase reliability of the signal. We designed digital circuits for a multichannel repeater for both FM and DMB signals by employing DSP algorithms and implementing them in FPGA.
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