scholarly journals Effects of Rainfall Attenuation on Frequencies 1 and 3 GHZ in Nigeria

2016 ◽  
Vol 15 (5) ◽  
pp. 6711-6723
Author(s):  
Ogherohwo, E. P ◽  
Bukar, B ◽  
Baba, D. D.
Keyword(s):  
Frequency Dependence ◽  
Everyday Life ◽  
Frequency Spectrum ◽  
Spectral Range ◽  
Mobile Communications ◽  
Electromagnetic Waves ◽  
Rain Rate ◽  
Rainfall Data ◽  
Radio Communication ◽  
Rainfall Attenuation

Mobile communications are part of our everyday life. The non-ideal environment which is filled with many attenuation factors affects the electromagnetic waves, which radio communication depends. This study considers the spectral range of 1 and 3GHz. At these frequencies, interesting phenomena due to rain are supposed to happen. The study of this frequency spectrum has been undertaken in an attempt to evaluate the frequency dependence of rain effects on electromagnetic waves. The study of rain effects on communication presented in this study relied solely on rainfall data collected from Nigeria Metrological Agency (NiMet) station in Lagos, Nigeria. The months for January to December for 1981-2011 were summed together and the averages were determined. The average is then used to calculate the rain rate and rainfall attenuation using the extracted results for all the locations (Bauchi, Ikeja, Jos, Kebbi, Maiduguri and Warri). The results show that Warri has the highest rainfall rate followed by Lagos. Kebbi and Maiduguri has the least while Jos and Bauchi demonstrated moderate rainfall rates. This also deduced that attenuation has less impact on lower frequencies but increase with higher frequencies. The study reveals that at higher frequencies, the rainfall attenuation is observed to be greater.

scholarly journals Rain event properties at the source of the Blue Nile River

2011 ◽  
Vol 15 (3) ◽  
pp. 1023-1034 ◽  
Author(s):  
A. T. Haile ◽  
T. H. M. Rientjes ◽  
E. Habib ◽  
V. Jetten ◽  
M. Gebremichael
Keyword(s):  
Rain Rate ◽  
Rainfall Data ◽  
Nile River ◽  
Rain Event ◽  
Spatial And Temporal Patterns ◽  
Mountain Area ◽  
Event Duration ◽  
Blue Nile ◽  
Event Time ◽  
Rain Events

Abstract. In the present study, spatial and temporal patterns of rain event properties are analysed. These event properties are rain event depth, event duration, mean event rain rate, peak rain rate and the time span between two consecutive rain events which is referred to as inter-event time (IET). In addition, we assessed how rain event properties change when the period over which rainfall data is aggregated changes from 1 to 6 min and when the minimum inter-event time (MIT) changes from 30 min to 8 h. Rainfall data is obtained from a field campaign in two wet seasons of June–August (JJA) of 2007 and 2008 in Gilgel Abbay watershed that is situated at the source basin of the Upper Blue Nile River in Ethiopia. The rainfall data was automatically recorded at eight stations. The results revealed that rain event depth is more related to peak rain rate than to event duration. At the start and towards the end of the wet season, the rain events have larger depth with longer duration and longer IET than those in mid-season. Event rain rate and IET are strongly related to terrain elevation. Sekela which is on a mountain area has the shortest IET while Bahir Dar which is at the south shore of Lake Tana has the longest IET. The period over which rainfall data is aggregated significantly affected the values of rain event properties that are estimated using relatively small value (30 min) of MIT but its effect diminished when the MIT is increased to 8 h. It is shown that increasing the value of MIT has the largest effect on rain event properties of mountain stations that are characterised by high rainfall intermittency.

scholarly journals The texture of our business

2013 ◽  
Vol 1 (1) ◽  
pp. 141-146 ◽  
Author(s):  
Richard Harper
Keyword(s):  
Mobile Phone ◽  
Everyday Life ◽  
Mobile Communications ◽  
Research Topic

A key theme in mobile communications research is the idea that people are suffering from communications overload. This essay remarks on what that term might mean and how it ought to be addressed when viewed from the perspective of mobile phone research. It will argue that its use in everyday life is rich and complex, and that this use ought to be a research topic in its own right. Some of the difficulties that will need to be addressed when this occurs are noted.

ORIGINATIONS AND EXTINCTIONS: ANALYSES OF FOSSIL DATA AND SIMULATIONS

2000 ◽  
Vol 11 (02) ◽  
pp. 277-285 ◽  
Author(s):  
TANE RAY ◽  
LEO MOSELEY ◽  
NAEEM JAN
Keyword(s):  
Fourier Transform ◽  
Frequency Dependence ◽  
Frequency Spectrum ◽  
Fossil Record ◽  
Trophic Levels ◽  
The Other ◽  
Simulation Data ◽  
The Past ◽  
Other Hand ◽  
Fossil Data

We analyse the fossil data of Benton1 with and without interpolation schemes. By Fourier transform analysis, we find a frequency dependence of the amplitude of 1/f for the various interpolation schemes used in the past. We illustrate that shuffling the interpolated data changes the spectra only slightly. On the other hand, an identical analysis performed on the raw (uninterpolated) fossil data gives a flat frequency spectrum. We conclude that the 1/f behavior is an artifact of the interpolation schemes. We next introduce a simulation of extinctions driven only by interactions between two trophic levels. Fourier transform analysis of the simulation data shows a frequency dependence of 1/f. When the data are grouped into a form resembling the fossil record the frequency dependence vanishes, giving a flat spectrum. Our simulation produces a frequency spectrum that agrees with the observed fossil record.

Comparison of measured rain attenuation and ITU-R predictions on experimental microwave links in Malaysia

2011 ◽  
Vol 3 (4) ◽  
pp. 477-483 ◽  
Author(s):  
Amuda Yusuf Abdulrahman ◽  
Tharek bin Abdulrahman ◽  
Sharul Kamal bin Abdulrahim ◽  
Ulaganathen Kesavan
Keyword(s):  
Cumulative Distribution Function ◽  
Rain Rate ◽  
Rain Attenuation ◽  
Rain Gauge ◽  
Cumulative Distribution ◽  
Rain Gauge Data ◽  
Tropical Regions ◽  
International Telecommunication ◽  
Rain Rates ◽  
Rainfall Attenuation

This paper presents the results of direct rain attenuation measurements carried out on four experimental microwave links, installed at UTM, Malaysia. The links operate at frequencies of 15, 22, 26, and 38 GHz and the cumulative distribution function for different rain rates have been generated from the measured 4-year rain gauge data. The experimentally measured attenuation data have been compared with International Telecommunication Unior-R rain attenuation predictions; and it has been found that the latter have underestimated the measured values, especially at higher rain rates. The deviations have been modeled as a function of rain rate exceedances R%p. It is hoped that the study will provide useful information for estimation of rainfall attenuation on microwave links in tropical regions that have similar situation to Malaysia.

scholarly journals A Comparison of Gamma and Lognormal Distributions for Characterizing Satellite Rain Rates from the Tropical Rainfall Measuring Mission

2004 ◽  
Vol 43 (11) ◽  
pp. 1586-1597 ◽  
Author(s):  
Hye-Kyung Cho ◽  
Kenneth P. Bowman ◽  
Gerald R. North
Keyword(s):  
Gamma Distribution ◽  
Lognormal Distribution ◽  
Rain Rate ◽  
Tropical Rainfall Measuring Mission ◽  
Rainfall Data ◽  
Retrieval Algorithm ◽  
Sample Mean ◽  
Tropical Rainfall ◽  
Lognormal Distributions ◽  
Rain Rates

Abstract This study investigates the spatial characteristics of nonzero rain rates to develop a probability density function (PDF) model of precipitation using rainfall data from the Tropical Rainfall Measuring Mission (TRMM) satellite. The minimum χ2 method is used to find a good estimator for the rain-rate distribution between the gamma and lognormal distributions, which are popularly used in the simulation of the rain-rate PDF. Results are sensitive to the choice of dynamic range, but both the gamma and lognormal distributions match well with the PDF of rainfall data. Comparison with sample means shows that the parametric mean from the lognormal distribution overestimates the sample mean, whereas the gamma distribution underestimates it. These differences are caused by the inflated tail in the lognormal distribution and the small shape parameter in the gamma distribution. If shape constraint is given, the difference between the sample mean and the parametric mean from the fitted gamma distribution decreases significantly, although the resulting χ2 values slightly increase. Of interest is that a consistent regional preference between two test functions is found. The gamma fits outperform the lognormal fits in wet regions, whereas the lognormal fits are better than the gamma fits for dry regions. Results can be improved with a specific model assumption depending on mean rain rates, but the results presented in this study can be easily applied to develop the rainfall retrieval algorithm and to find the proper statistics in the rainfall data.

Discovery and Integration of Mobile Communications in Everyday Life

2001 ◽  
Vol 5 (2) ◽  
pp. 109-122 ◽  
Author(s):  
Leysia Palen ◽  
Marilyn Salzman ◽  
Ed Youngs
Keyword(s):  
Everyday Life ◽  
Mobile Communications ◽  
Discovery And Integration
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