The Effect Of Humidity And Temperature On The Receiving Of Satellite Broadcast

ABSTRACT

Meteorological data from the Department of Satellite Application Facility on Climate Monitoring (CM- SAF), DWD Germany have been used to study and investigate the effect of relative humidity and temperature on reflectivity in twenty six locations grouped into for climatic regions aloft Nigeria (Coastal, Guinea savanna, Midland and sub Hegelian regions). The four years data collected ranged from 2004 to 2007 and was evaluated on their linear variation of reflectivity on both temperature and relative humidity at different atmospheric level. The coefficient of determination (CD) was also determined for each relation. The results obtained establish the seasonal variation of temperature and relative humidity to reflectivity across the region especially at low and mid-level. The coefficient of determination at both region is high for the variations measured against relative humidity and reflectivity, while that of temperature and refractivity is low. This affirms that changes in relative humidity influence reflectivity more than temperature at lower and middle level.

 WORDS AND MEANING

Signal strength (SS)

Quality of signal (QOS)

Short message services (SMS)

Code Division Multiple Access (CDMA)

TT&C =tracking telemetry and control

Geo-Synchronous Earth Orbit

RSSI =Received  Signal Strength Indicator

LQI =Link Quality Indicator

RSS =Received satellite signal

PRR =Packet Reception Ratio

SNR  = Signal to  Noise  Ratio

AH =Absolute humidity

Relative humidity (RH)

 CHAPTER ONE

1.0                                          INTRODUCTION

1.1                                           BACKGROUND

Many wireless sensor networks (WSNs) and their applications are in use outdoors exposed to changing environmental conditions. Weather conditions particularly can have a significant impact on the performance of WSNs and therefore cannot be ignored [1], [2], [3]. While the location of nodes may be fixed and their surroundings might remain almost static, the weather will not remain stable. The ambient temperature and humidity will change and fluctuate temporally, having both diurnal and seasonal variation. In addition, there can be spatial variation in weather, which affects WSN due to microclimates. While changes in weather conditions are inevitable and may have significant effects, they are usually measurable and could be mitigated based on experimental measurements. Hence, it is essential to explore weather-related factors affecting radio link quality in order to mitigate their impact and to adapt to varying conditions.

The effects of weather conditions on link quality (e.g., signal strength) in WSNs have been explored in quite a few studies (e.g., [2], [4], [3], [1], [5], [6], [7], [8], [9]). However, no  clear consensus has been achieved so far. Some studies report that temperature is the dominating factor affecting signal strength while others claim that humidity is the main reason. Some suggest also other reasons. Furthermore, research methods, radios and platforms employed and a number of explored weather variables vary between studies, occasionally resulting in contradictory results and conclusions. Hence, there definitively seems to be a need for further studies.

This paper sets out to find out the effects of temperature  and humidity on radio signal strength in outdoor WSNs. Experimental measurements were carried out using Atmel ZigBit 2.4GHz wireless modules [10] with AT86RF230 radios in a university campus area during December 2013 and July 2014. Unlike most previous studies, we employed all the 16 radio channels specified by IEEE 802.15.4 for 2.4GHz ISM frequency band (channels 11−26) using two different transmit power levels. For the purpose of measuring local weather conditions, each node was integrated with a sensor (SHT75) to measure the ambient temperature and relative humidity. To begin with, we show the temporal variation of signal strength. To find out the role of temperature and humidity    on this variation, we study how signal strength correlates with temperature, relative humidity, and absolute humidity. Further- more, we apply linear regression to explore the magnitude     of these effects. We also highlight the differences between channels, the utility of frequency diversity, and the difference between the transmit power levels used. Our findings may     be useful for designing algorithms and protocols which are adaptive and robust against the effects of weather. In particular, RSSI-based ranging and localization could benefit from these results.

In summary, our study has the following main contributions:

1. We show that changes in weather conditions affect radio signal strength. Temperature seems to be the best explanatory variable for signal strength variation and has a negative, linear effect on signal strength in general, while high relative humidity may have some effect, particularly when temperature is below 0^◦C.
2. We show that correlation between signal strength and the studied weather variables vary depending on radio channel and link. Applying frequency diversity will alleviate these effects.
3. We show that smaller transmit power results in smaller unexplained variation in received signal strength (in most cases) and thus stronger correlation with the studied weather

1.2                                 THESIS MOTIVATION

The rate of which satellite technology swept the world in recent time, has been so swift, and has been a major advancement in technology. But Nigeria being the giant of Africa in terms of market size of 200 million still does not get the best benefit out of this technology advancement which is also slowly evolving but not still able to spread its coverage to many parts of the country.

With the establishment of big time satellite providers in Africa like DSTV, GOtv etc. One would be tempted to think that the best services should be rendered, but we seem to be far from there.

The need then arouses to check what would have been the problem of these providers. Visualizing that subscribers face more problems when watching from different location, thus, a reason for that should be found there has always existed claims of effect of the many satellite broadcasting system existing on humans, yet Nigeria in particular and African in general get even crazier about the signal strength variation of the satellite broadcast.

The existence of signal strength variation of satellite broadcasting system has been a challenge in the telecommunication sector. Maiduguri city witness signal strength variation when watching from different location in the city according to the temperature and humidity of such location. Being one of the indigent of this city it has been a motivation to me to undertake my final year project. To make sure the signal strength is fixed all over the city not only the city but all over Nigeria and the rest of the countries.

1.3                                 PROBLEM STATEMENT

The satellite broadcast system been the best communication device nationwide. A study on causes of signal strength variation is mostly caused by atmospheric temperature and relative humidity of the receiving environment.

1.4                                 AIM OF THE STUDY

The aim of this project is to study and investigate the effect of relative humidity and temperature on refractivity of satellite broadcast

1.5                              OBJECTIVES OF THE STUDY

At the end of this study students involved will be able:

1. Outline the causes of signal strength variation of satellite broadcast cause by temperature and humidity.
2. Outline Proper solution to the problem in the first stage

1.6                                           METHODOLOGY

1. First stage of research involve going to satellite network provider to inquire about the interconnection (coverage) signal strength, and number of mast of both operators,
2. Second stage of this research is collection of some data from Nigerian Communication Commissions (NCC) to compare with the one collected from the first stage.

• Third stage of the research work is by downloading journals and browsing for necessary information.

1.7                                 SCOPE OF STUDY

Many wireless sensor networks operating outdoors are exposed to changing weather conditions, which may cause severe degradation in system performance. Therefore, it is essential to explore the factors affecting radio link quality in order to mitigate their impact and to adapt to varying conditions. In   this paper, we study the effects of temperature  and  humidity  on radio signal strength in outdoor wireless sensor networks. Experimental measurements were performed using Atmel ZigBit 2.4GHz wireless modules, both in summer and wintertime. The results show that changes in weather conditions affect received signal strength. Of the studied weather variables, variation in signal strength can be best explained by the variation in temperature.

1.8                             SIGNIFICANCE OF THE STUDY

People want to communicate with their family and friends and to be communicated with. This desire makes it all the more frustrating when the network is poor or doesn‟t go through at all. There have been serious complains raised by satellite  subscribers regarding poor quality of services (QoS) rendered by the satellite operators in this study area especially during cloudy wheather and low temperature hour. The most annoying aspect of this is the fact that all the satellite  subscribers irrespective of the operator are being affected. [1] Based on these customer complains, this study was embarked upon to examine the causes of this problem and find ways of proffering solutions. This paper therefore measures signal strength of satellite broadcast at the receiving end. This study would help operators to enhance coverage, improve quality and increase capacity in the days to come.

1.9                            APPLICATIONS OF THE STUDY

Apart from Satellite communication, this work also finds its applications in the following areas −

• In Radio broadcasting.
• In TV broadcasting such as DTH.
• In Internet applications such as providing Internet connection for data transfer, GPS applications, Internet surfing, etc.
• For voice communications.
• For research and development sector, in many areas.
• In military applications and navigation.

1.10                                  RESEARCH QUESTION

1. What is a satellite signal?
2. What causes weak signal?

• What are the measures of solving weak satellite signal?

1. Does Humidity Affect Radio Waves?
2. Does Temperature Affect Radio Waves?
3. How does humidity and temperature affect signal strength?