Wyniki wyszukiwania - BazTech

1

Wykorzystanie rekonfigurowalnych matryc antenowych wraz z informacją kontekstową

Kułacz Łukasz, Kliks Adrian

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

|

2023

|

nr 4

281--284

PL

Rekonfigurowale matryce antenowe mogą zostać użyte z powodzeniem do sterowania środowiskiem radiowym. Proste sterowanie kątem odbicia sygnału od powierzchni pozwala na maksymalizację lub minimalizację odbieranej mocy w określonych miejscach. W artykule przedstawiono symulacje, gdzie możliwy jest odbiór sygnału w miejscu, w którym nie było to możliwe, wykrycie zajętości widma w miejscu, w którym detektor nie był w stanie dokonać prawidłowej detekcji, czy zminimalizowanie zakłóceń w konkretnym odbiorniku.

EN

Reconfigurable intelligent surfaces can be successfully used to control the radio environment. Simple control of the reflection angle of the signal from the surface allows maximization or minimization of the received power in specific places. The paper presents simulations where it is possible to receive a signal in a place where it was not possible, to detect the occupancy of the spectrum in a place where the sensor was unable to make correct detection or to minimize interference in a specific receiver.

2

Analiza przykładowych odpowiedzi impulsowych kanału hydroakustycznego pomierzonych w ruchu

Czapiewska Agnieszka, Łuksza Andrzej, Studański Ryszard, Wojewódka Łukasz, Żak Andrzej

Przegląd Elektrotechniczny

|

2023

|

R. 99, nr 9

234--237

PL

W artykule przedstawiono przykładowe wyniki i analizę pomiarów odpowiedzi impulsowej kanału hydroakustycznego zrealizowanych w ruchu na basenie modelowym Politechniki Gdańskiej.

EN

The article presents exemplary results and analysis of impulse responses of an underwater acoustic channel measured in motion in a towing tank of the Gdańsk University of Technology.

3

Site diversity performance in Ka band using a 7.3 m antenna diameter at tropical climate: a comparison of prediction models

Samat Fazdliana, Singh Mandeep Jit

Acta Geophysica

|

2020

|

Vol. 68, no. 4

1213--1221

EN

Site diversity gain prediction models were created to estimate mathematically the acquired benefts from the implementation of site diversity at place of choice. This work contributes to the comparison of existing gain prediction model to the gain of measured attenuation at Cyberjaya and Rawang, Malaysia. The experiment has been conducted for 4 years from 2014 to 2017, in Ka band using a large 7.3-m diameter antenna and a high elevation angle of 68.8°, together with the rain analysis at both places for the same duration. The average monthly rainfall and attenuation for 4 years were presented. The results revealed that prediction model Hodge performs better than other models, while X. Yeo and Panagopoulos models appear to exhibit very similar graph shape to the measured gain data. More research on gain development in tropical region should be conducted, as the existing prediction model appears to be less consistent with the current data.

4

Study of the GNSS Jamming in Real Environment

Morong Tomáš, Puričer Pavel, Kovář Pavel

International Journal of Electronics and Telecommunications

|

2019

|

Vol. 65, No. 1

65--70

EN

GNSS systems are susceptible to radio interference despite then operating in a spread spectrum. The commerce jammers power up to 2 watts that can block the receiver function at a distance of up to 15 kilometers in free space. Two original methods for GNSS receiver testing were developed. The first method is based on the usage of a GNSS simulator for generation of the satellite signals and a vector signal RF generator for generating different types of interference signals. The second software radio method is based on a software GNSS simulator and a signal processing in Matlab. The receivers were tested for narrowband CW interference, FM modulated signal and chirp jamming signals, and scenarios. The signal to noise ratio usually drops down to 27 dBc-Hz while the jamming to signal ratio is different for different types of interference. The chirp signal is very effective. The jammer signal is well propagated in free space while in the real mobile urban and suburban environment it is usually strongly attenuated.

5

Maximum Rain-Rate Evaluations in Aegean Archipelagos Hellas for Rain Attenuation Modeling at Microwave Frequencies

Karagianni E.Α., Vazouras C.N., Papageorgiou E.H., Sarantopoulos A.D., Nistazakis H.E.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2016

|

Vol. 10, no. 1

117--123

EN

By utilizing meteorological data such as relative humidity, temperature, pressure, rain rate and precipitation duration at eight (8) stations in Aegean Archipelagos from six recent years (2007 – 2012), the effect of the weather on Electromagnetic wave propagation is studied. The EM wave propagation characteristics depend on atmospheric refractivity and consequently on Rain-Rate which vary in time and space randomly. Therefore the statistics of radio refractivity, Rain-Rate and related propagation effects are of main interest. This work investigates the maximum value of rain rate in monthly rainfall records, for a 5 min interval comparing it with different values of integration time as well as different percentages of time. The main goal is to determine the attenuation level for microwave links based on local rainfall data for various sites in Greece (L-zone), namely Aegean Archipelagos, with a view on improved accuracy as compared with more generic zone data available. A measurement of rain attenuation for a link in the S-band has been carried out and the data compared with prediction based on the standard ITU-R method.

6

Signal propagation in multi-wire cables

Tarczyński W., Kopka R.

Zeszyty Naukowe Akademii Marynarki Wojennej

|

2015

|

R. 56 nr 4 (203)

51--63

EN

The article presents the analysis of the influence of the pulses propagating in the wires of a multi-wire cables. Special attention was drawn to the process of pulses inducing in the wires to which no pulse signal was provided. The pulses interaction occur in those sections of a cable where a change of wave impedance causing a change in the reflectance is present. The pulse interaction changes its shape and amplitude. This pulse interaction can be used to diagnose the technical condition of the electric power and telecommunication cables.

PL

W artykule przedstawiona jest analiza oddziaływania impulsów przemieszczających się w przewodach linii wieloprzewodowych. Zwrócono uwagę na powstawanie impulsów w przewodach, do których nie jest podawany sygnał impulsowy. Oddziaływanie impulsów występuje w miejscach linii, w których jest zmiana impedancji falowej powodująca zmianę współczynników odbicia. Oddziaływanie impulsów powoduje zmianę ich kształtu oraz amplitudy. Zjawisko oddziaływania impulsów można wykorzystać do diagnostyki stanu technicznego linii elektroenergetycznych i telekomunikacyjnych.