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INVESTIGATION AND EVALUATION OF SCINTILLATION PREDICTION MODELS AT OTA

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International Journal of Mechanical Engineering and Technology (IJMET)
Volume 10, Issue 03, March 2019, pp. 127-132. Article ID: IJMET_10_03_012
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=3
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication
Scopus Indexed
INVESTIGATION AND EVALUATION OF
SCINTILLATION PREDICTION MODELS AT
OTA
S. A. Akinwumi, T. V. Omotosho, M. R. Usikalu, M. E. Emetere, O. O. Adewoyin and T.
A. Adagunodo
Department of Physics, College of Science and Technology Covenant University PMB 1023,
Ota, Ogun state, Nigeria
O. O. Ometan and O. M. Adewusi
Department of Physics, Lagos State University, Ojo, Lagos State, Nigeria
ABSTRACT
Understanding of scintillation is a significant occurrence in the design of
communication satellite system. In this research, two years (January 2015-December
o
2016) tropospheric scintillation records dig out from Astra 2E/2F/2G at 28.2 E
o
o
Satellite path link observation at (Lat: 6.7 N, Long: 3.23 E) at Ota, southwest
o
Nigeria, at 12.245 GHz and an elevation angle 59.9 . The result and analysis were
likened with some reliable tropospheric scintillation estimate models in order to
acquire best model for Ota environment. The result findings revealed that the
Karasawa model provides the minimum percentage error for scintillation fades and
enhancements of approximately 0.57 % at 0.1 unavailability of time and 6.93 % at
0.01 unavailability of time respectively. Hence, Karasawa model is the most found
suitable for the estimation of transmission loss in this region. Also, scintillation
intensity is noticed to be high throughout the non-rainy season likened to rainy season
months. Conversely, the model must be verified more by means of higher frequency
band like Ka and V bands to affirm the accurateness of the model. The statistics
provided in this work will assistance in fade margin for performance and antenna
sizing required for communication satellite link.
Keywords: Attenuation prediction, electromagnetic wave, Ku band, Satellite
communication Tropospheric scintillation
Cite this Article: S. A. Akinwumi, T. V. Omotosho, M. R. Usikalu, M. E. Emetere,
O. O. Adewoyin, T. A. Adagunodo, O. O. Ometan and O. M. Adewusi, Investigation
and Evaluation of Scintillation Prediction Models at Ota, International Journal of
Mechanical Engineering and Technology, 10(3), 2019, pp. 127-132.
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=3
http://www.iaeme.com/IJMET/index.asp
127
[email protected]
S. A. Akinwumi, T. V. Omotosho, M. R. Usikalu, M. E. Emetere, O. O. Adewoyin, T. A.
Adagunodo, O. O. Ometan and O. M. Adewusi
1. INTRODUCTION
Scintillation manifestations emerges to be unique of the major signal losses that effect
satellite to earth path link in recent communication systems, particularly at Ku-band
frequency and above [1, 2, 3, 4]. The impact of tropospheric scintillation on communication
signal cannot be over emphasised owing to its continuous deviation in amplitude and phase
that interrupt signal strength [5, 6]. At little millimeter-wave or microwave bands tropospheric
scintillation intensity rise with fall in size of the antenna, angle of elevation and with surge in
frequencies [7]. Nevertheless, scintillation is significant in event of satellite-ground
communication pathway, that consist of the occurrence of atmospheric gasses, and boundary
close to height above sea level around 20 km contained by the humid atmosphere [8].
The received electric field of the amplitude and phase from the scintillation discrepancies
were transformed. In genuine detail, tropospheric scintillation power is a phenomenon which
can be affected by tropospheric environments, while resulting variability in scintillation
intensity takes an important influence on the information of the scintillation development [9].
Similarly, scintillation is known to demonstrate strong relationship with major meteorology
factors like pressure, temperature and relative humidity. Scintillation intensity link budget
design normally increase under frequency above 10 GHz, reduced elevation angle and low
receiving antenna which are important for low fade margin systems [5]. Although,
tropospheric scintillation occurs under during rainy and non-rainy conditions, however, signal
fade cause by rain is of less interest to signal fade cause by clear-sky for purpose of little
availability of satellite system design.
Nigeria been a tropical climate is close to the equator and therefore has high temperature
and an increase in relative humidity, whereas, most equipment shipped into the country from
European countries that are temperate climate. Also, most tropospheric scintillation models
are developed from Europe except Karasawa model that is developed from Japan (Asia)
which is also a tropical climate like Nigeria (Africa). Therefore, because of the huge disparity
in climate of Nigeria and Europe it is necessary to analyse and compare the scintillation
intensity measures in Ota, Southwest, Nigeria, and already established prediction models.
2. METHODS AND DATA ANALYSIS
The scintillation data is collected from Astra 2E/2F/2G satellite of 12.245 GHz on Latitude,
Longitude and Elevation angle Lat: 6.7 oN, Long: 3.23 oE, Elev. Angle: 59.9o respectively at a
sample proportion of 1 second at the Covenant University, Ota. The two year observed data
for this research is between January 2015 and December 2016. The rainy days were parted
from non-rainy days for this study by means of spectrum analyser and Davis automatic
weather stations at rain rate 0 mm/h measured for non-rainy events, however, rain rate
directly above 0 mm/h were deducted from the equivalent days and time data within the
period of surveillance. A periodic average data were utilised as position data signal level and
were minus from everyday observed established data signal level in way to acquire the
tropospheric scintillation on every single one minutes for each non-rainy day. Subsequently,
pass through a filter process result in data comprises of fade (negative) and enhancement
(positive) tropospheric scintillation intensity that is below or above the average level.
Furthermore, the measured tropospheric scintillation data at Ota were associated with more or
less present scintillation calculation models that predict the variance of signal log-amplitude
are: [10, 11, 12, 13] models. Hence, the performance assessment of individual scintillation
model were verified founded on the significant percentage error (%) as:
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128
[email protected]
Investigation and Evaluation of Scintillation Prediction Models at Ota
(1)
Error ( ) =
Table 1: Percentage Error of the Models
% OF
TIME
0.01
0.1
1
10
ITU-R
FADE
KASARAWA
OTUNG
55.78
22.37
-2.98
-33.29
28.03
0.57
-20.26
-51.33
190.93
45.80
-25.89
-56.62
VAN DE
KAMP
-39.13
-54.71
-66.61
-78.53
ENHANCEMENT
KASARAWA OTUNG
6.93
-10.21
-24.19
-44.93
71.49
1.61
-51.41
-98.28
VAN DE
KAMP
-31.75
-50.26
-64.61
-77.54
3. RESULT AND DISCUSSION
Statistical comparison between enhancement (positive) and fade (negative) of tropospheric
scintillation prediction models is shown in Table 1. It can be detected that Karasawa model
provided the least error for fade around 0.57 % at 0.1 % and 28.03 % at 0.01 % percentage of
time followed by ITU-R model around 22.37 % at 0.1 % percentage of time respectively.
Similar was witnessed for enhancement at 0.01 % percentage of time trailed by Van de kamp
model. Still, on fade scintillation at 1 % and 10 % of time ITU-R is noticed to have lowest
percentage error. Figure 1 revealed the calculation of the measured data in Ota and numerous
models estimation for both fade and enhancement, in order to comprehend the limits of
individually predicted model and the progression of validity in Ota region.
For negative tropospheric scintillation amplitude, Karasawa model (0.1 %) and ITU-R
model (1 %) shows a precise near agreement by means of the observed measured data values
in Ota practically for entire percentage of time predicted. Otung model followed marginally
and deviate from other models at 0.01 % while Van de Kamp model differ from the rest
model could be credited to the tropospheric scintillation observation occurrence of rainfall
and heavy clouds. Though, scintillation enhancement signal amplitude likewise demonstrates
close link amid observed data and predicted Karasawa model at entire level of proportion of
time (most particularly at 0.1 %). This nearness could be for the reason that the model been
established for the period of non-rainy by means of robust impact of water vapour acquire
from surface humidity and temperature. No account for ITU-R model in positive scintillation
(signal enhancement) due to the model been designed only to produce result for negative
scintillation (signal fade).
Figure 2 and 3 shows monthly variation of standard deviation of the tropospheric
scintillation intensity of ground measurement and that of the existing prediction models. High
scintillation intensity was observed February and March for both Ota (0.081 dB, 0.085 dB)
and ITU-R (0.087 dB, 0.088 dB) respectively in figure 2, while others models show a weak
intensity during the same period of the months. Increase in temperature and humidity may be
attributed for this high scintillation for the period of the month. Actually, the measured
temperature of Ota is at 28 oC and that of humidity is at 85.8 % which is the highest that year.
Also in figure 3, Ota follows ITU-R closely with high scintillation intensity between April
and May of about 0.086 dB. This is closely followed by Karasawa model while Otung and
Van de Kamp models are weak and are therefore distance from other models because this
models are generated from temperate region. ITU-R indicate high scintillation during rainy
season because of its dependence on refractivity (Nwet) which normally occur between
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129
[email protected]
S. A. Akinwumi, T. V. Omotosho, M. R. Usikalu, M. E. Emetere, O. O. Adewoyin, T. A.
Adagunodo, O. O. Ometan and O. M. Adewusi
March to October every year. However, scintillation intensity is expected to be stronger
during dry term period compare to wet term period of the year as revealed in the figures.
FADE
1
0.7
ITU-R
KASARAWA
OTUNG
VAN DE KAMP
OTA
0.8
0.6
0.4
scintillation amplitude (dB)
scintillation amplitude (dB)
1.2
ENHANCEMENT
KASARAWA
OTUNG
VAN DE KAMP
0.6
0.5
0.4
0.3
0.2
0.2
0.1
0
0.01
0.1
1
10
0
Percentage of time (%)
0.01
0.1
1
10
Percentage of time (%)
Figure. 1: Comparison of Ota data with Four existing models for fade and enhancement
Scintillation Intensity (dB)
2015
0.13
0.11
0.09
0.07
0.05
0.03
0.01
JAN
FEB
MAR APR MAY JUN
JUL
AUG
SEP
OCT NOV DEC
Months
ITU-R
KASARAWA
OTUNG
VAN DE KAMP
OTA
Figure.2: Comparison of monthly variability of Standard Deviation of Scintillation Intensity between
Ota and prediction models in 2015
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130
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Investigation and Evaluation of Scintillation Prediction Models at Ota
2016
Scintillation Intensity (dB)
0.12
0.1
0.08
0.06
0.04
0.02
JAN
FEB
MAR APR MAY JUN
JUL
AUG
SEP
OCT NOV DEC
Months
ITU-R
KASARAWA
OTUNG
VAN DE KAMP
OTA
Figure. 3: Comparison of monthly variability of Standard Deviation of Scintillation Intensity between
Ota and prediction models in 2016.
4. CONCLUSION
Assessment of four (4) predicted non-rainy scintillation models that is: Karasawa, ITU-R,
Van de kamp and Otung models have been offered in this work. This predicted models were
likened with the measured data acquired at 12.245 GHz from Astra 2E/2F/2G satellite beacon
positioned at Covenant University in Ota. The measurement from Ota established that
Karasawa model provided the top prediction for scintillation intensity for Ota and its
environs. Also, scintillation intensity is noticed to be high during non-rainy season in
comparison to rainy season months.
ACKNOWLEDGEMENT
The authors would like to appreciate Covenant University for full sponsorship of this
research.
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