L band

About: L band is a research topic. Over the lifetime, 674 publications have been published within this topic receiving 4570 citations.

Digital Interference Mitigation Technique for the Interoperability of two Airborne two SatCom Systems for Small Aircraft

Abstract: The Inmarsat and Iridium systems and signals share the same upper and lower frequency limit on the 1626.5 MHz frequency, affecting its interoperability and simultaneous full dual usage. For this reason, the two systems cannot be used simultaneously, especially in small/medium aircraft, since the Inmarsat transmitter power density affects the Iridium receiver in certain circumstances and configurations. This paper proposes the modeling and development, based on Software Defined Radio, of a digital interference mitigation technique in order to make possible the integration and deployment of the two systems in a reduced space without degrading the global performance of both systems under their operation. For this, we use a digital notch filter in order to reject the Inmarsat interference signal in the reception RF path of the Iridium system. Results in laboratory show the feasibility of the technique as a possible solution for Inmarsat/Iridium interoperability for dual onboard SatCom in small aircrafts opening the door for its usage on drones, in the near future.

Modernized Solar Radio Spectrograph in the L Band Based on Software Defined Radio

Abstract: The paper presents the concept, implementation, and test operation of a modernized solar radio spectrograph for an investigation of the solar emission and solar bursts in radio frequency bands. Besides having a strong diagnostic significance for studying the flare energy release, the solar radio bursts can also cause strong interference for radio communication and navigation systems. The current spectrograph for the Ondrejov observatory (Astronomical Institute of Czech Academy of Sciences) was modernized by using a direct-conversion receiver connected to a field-programmable gate array (FPGA) for the fast Fourier transform (FFT) spectrum estimation and put into the test operation. The higher time and frequency resolution and lower noise in comparison with the existing analog instrument were reached by the implementation of the latest optimal signal processing methods. To reduce the costs for such modernization, the operating frequency range was divided into four sub-bands of bandwidth 250 MHz, which brings another benefit of greater scalability. The first observations obtained by the new spectrograph and their comparison with the analog device are presented in the paper with future steps to put the spectrograph into the regular operation.

Forest vegetation Interaction with L-band Satellite Signals

Abstract: A method for calculating the electro-physical parameters of forest vegetation cover interacting with the signals of navigation satellites in the frequency bands 1.2-1.6 GHz is proposed. A technique for the experimental measurement of linear attenuation coefficient of satellite signals on test areas of canopies was developed, taking into account their calibration at the input. The proposed forest vegetation model describes the group of crowns as a system of quasi spherical "capsules", located chaotically in the air matrix. The scattering and penetration cross sections and the coefficient of linear attenuation of radio waves were calculated using the approximation of anomalous diffraction for crowns and the results of solving the diffraction problem for trunks. The effects of multiple scattering were taken into account.