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Antenna systems
Published in L. Tetley, D. Calcutt, Understanding GMDSS, 2012
An active antenna, such as the type used for GMDSS NAVTEX reception, is one which has an in-built signal amplifier at the base of the physical antenna. This amplifier provides a high degree, typically 10 dB, of signal gain before the signal passes down the coaxial feeder wire where losses will occur. It is essential that the amplifier is fitted directly at the base of the antenna in order to amplify the signal before external noise degrades the signal/noise ratio further. The coaxial feeder will therefore carry a d.c. power supply up the mast to supply the amplifier whilst coupling the signal down to the receiver input.
Electronic Equipment for a GPS System
Published in Franjieh El Khoury, Antoine Zgheib, Building a Dedicated GSM GPS Module Tracking System for Fleet Management, 2018
Franjieh El Khoury, Antoine Zgheib
The GPS antenna requirements for an optimal GPS performance are the following (Motschenbacher and Connelly 1993; U-blox 2009): An active antenna, which contains active built-in electronic components (e.g., transistors) in order to have a wider frequency range (i.e., bandwidth) and helps to keep the receiver noise figure low.A low level of directivity, that measures the degree to which the radiation emitted is concentrated in a single direction.Good antenna visibility for the sky.Good matching between antenna and cable impedance. This represents the ratio of the amplitudes of voltage and current of a single wave propagating along the line and travelling in one direction when there is an absence of reflections in the other direction.High gain (e.g., >4 dBi), which represents the ratio of the power produced by the antenna to the power produced by a hypothetical lossless isotropic antenna. It increases with the level of directivity. The gain unit is represented in decibel isotropics (dBi).A low-noise amplifier (LNA) (e.g., <2 decibels [dB] noise figure), which amplifies a very low-power signal and minimizes additional noise.A filter, to perform signal processing function by removing the unwanted frequency components from the signal and enhancing the wanted ones.
Network polar coded cooperative GSM scheme based on Plotkin’s construction
Published in International Journal of Electronics, 2023
Chunli Zhao, Fengfan Yang, Daniel Kariuki Waweru, Rahim Umar
Multiple-input multiple-output (MIMO) systems have been recognised as a core technique for improving spectral efficiency and reliability compared with single antenna systems. A well-known MIMO technique is vertical-Bell Labs layered space–time architecture. However, at the receiver, inter-channel interference (ICI) will be caused since multiple independent data streams are simultaneously transmitted from multiple antennas on the same frequency. A recently developed technique called spatial modulation (SM) (Mesleh et al., 2008) can effectively alleviate the ICI. This is because only one active transmit antenna is used by SM to convey a constellation symbol at each time instant. By exploiting active antenna index to transmit information, spectral efficiency is boosted. However, the number of transmit antennas required must be a power of 2 in SM.
Power allocation for AF relaying aided spatial modulation in the presence of imperfect channel state information
Published in International Journal of Electronics, 2019
Qing Pan, Xiangbin Yu, Yaping Hu, Tao Liu
where is an -dimensional column vector, and the unique nonzero element is in the row. It means that the constellation point is transmitted by the antenna of the source. Based on the AF protocol, the transmission process is divided into two stages. At the first stage, the active antenna transmits the signal to the relay and the destination with the transmission power of . The respective received signals at the relay and the destination are expressed as
Design and Development of FPGA-Based Spectrum Analyzer
Published in IETE Journal of Education, 2018
Rupali Borade, Akash Dimber, Damayanti Gharpure, Subramaniam Ananthakrishnan
A 1-meter long monopole active antenna, designed for low-frequency radio astronomy observation was used for testing as shown in Figure 14. Signals picked up by the antenna are filtered out with band pass filter of 0.2–20 MHz to select the desired range of frequencies. To validate the output of the FPGA-based spectrum analyzer, the results are compared with the Agilent N1996A spectrum analyzer. For this purpose, the output of the filter was split using a Mini Circuits ZX10R-14-S+ splitter, and one output is fed to the Agilent spectrum analyzer and the other to the FPGA-based spectrum analyzer.