journal of engineering precipitation effect on the...

International Journal of Engineering and Technology Volume 4 No. 9, September, 2014

Precipitation Effect on the Coverage Areas of Terrestrial UHF Television Stations in Ondo State, Nigeria

Ajewole1 M. O, Akinbolati2 A, Adediji3 A. T and Ojo4 J.S

Department of Physics, Federal University of Technology, Akure, Ondo State, Nigeria.

ABSTRACT

The quality of terrestrial television signal received by viewers is of keen interest to stakeholders in the broadcast world. This research investigates the coverage areas of UHF television signals in Ondo State, Nigeria, andthe effect of precipitation on signal strength through quantitative measurement of the electric field strength of these signals. The signal strength of the transmitters of the Ondo State Radiovision Corporation (OSRC), Akure, (CH 23, transmitting frequency of 487.25 MHz); OSRC, Oka Akoko, (CH 25, of transmitting frequency 503.25 MHz); and OSRC, Okitipupa, (CH 27, of transmitting frequency 519.25 MHz); were taken radially along several routes with the transmitting stations as reference. These measurements were taken using Digital Signal Level Meter, Dagatron TM 10 type and a GPS MAP 76– personal navigator for determining the geographical coordinates as well as the line of sight distances of the various data points from the base stations. Data were taken during the onset of raining season, period of intense rains and the early part of dry season around the towns and villages in all the Local Government Areas of the State as far as road accessibility permits until the signal faded away completely. For channels 23, 25 and 27,the study revealed that coverage areas of 53.5%, 10.0% and 9.0% respectively were possible with the present configuration of the transmitters over the OndoState land mass during the onset of the raining season. During the peak of the raining season,the study revealed that coverage areas of 50.5%, 9.0% and 8.0% were possiblefor Channels 23, 25 and 27 respectively.The study further revealed that coverage areas of 55.5%, 10.5% and 9.5% were possible during the dry season with the present configuration of the transmitters over the Ondo State land mass for Channels 23, 25 and 27 respectively.The combined coverage areas of the three transmitting stations as a percentage of the State land mass was 72.5% for the onset of raining season, 67.5% during the peak of raining season and 75.5% during the early part of dry season. The overall result reveals the significant effect of precipitation on the coverage areas of UHF television signal over Ondo State land mass. Keywords: Signal Strength, Line of Sight(LOS), Contour Map and Coverage Area.

1. INTRODUCTION

Television broadcasting is an important aspect of human development. The yearnings of people for information via the television have continued to be on the increase for entertainment, education, information and enlightenment. To these extents, both the Federal and State Governments in Nigeria have continued to establish television stations to meet the yearnings of the people and also for political reasons. The first television station in Nigeria, the western Nigeria Broadcasting Services (WNBS) Ibadan, was established in October 31, 1959 (Ajewole, 2011) by the then Premier of Western Nigeria-Late Chief ObafemiAwolowo. Since then, the business of television broadcasting has been the exclusive rights of both the State and Federal Governments in Nigeria. However, in the last two decades the Federal Government opened the business to private investors and individuals (www.nbc.ng.org). Consequently, there are now about 250 terrestrial television stations in Nigeria, both private and government owned, with about 50% of them on the UHF band (BON, 2010 directory).In view of the importance of television broadcasting to the socio-economic development of

the populace and the competition in business, viewer’s interest has grown from just watching anything on screen to qualitative, clean and sharp signals on television screen (Akinbolati, 2012).To this extent, researchers have continued to carryout work to determine the actual coverage areas of some broadcasting stations(Ajayi and Owolabi, 1979), their optimum signal level (Ajewole e tal, 2013) and the deterioration of signal strength with distance from the transmitter which is useful for the design and transmission of radio signals. Furthermore, much work had been done on the A.M radio signals in this regard (Ajayi and Owolabi, 1979), being the first generation radio stations in Nigeria. (Ajewole, 2011). Few works had been done on the F.M Signal (Eiche, 2012, and Ajewole et al, 2012a) and little work had been done on the television signals in Nigeria, (Moses, 2012,and Ajewole et al, 2012b) thus the motivation for this work. The field strength of an antenna’s radiation at a given point in space, is equal to the amount of voltage induced in a wire antenna 1m long, located at that given point (Kennedy and Bernard, 1992). This field strength is affected by a number of conditions such as the time of day, atmospheric conditions, the transmitter-receiver distance, transmitter power (Kennedy and Bernard, 1992). Others are, terrain effect, transmitting and

ISSN: 2049-3444 © 2014 – IJET Publications UK. All rights reserved. 524

International Journal of Engineering and Technology (IJET) – Volume 4 No. 9, September, 2014 receiving antenna height, and the gain of the transmitting antenna (Bothias, 1987).

1.1 Study Area

OndoState is one of the thirty six States in Nigeria located in the South West geo-political zone of the Country, with Akure as the State Capital. It was carved out of the old Western Nigeria on February 3, 1976. Though, the present Ekiti State, Nigeria, was

carved out of the State on October 1st, 1996. The State haseighteen local government areas and lies between latitude 7010'north and longitude 50,05' east with a landmass of 15,300km2. It has a population of 3,440,000 (2006 Nigerian Census) and a population density of 220/km2. The State is the largest producer of cocoa, and the fifth producer of crude oilin Nigeria. It has three major divisions- Ondo North,Ondo Central and Ondo South. Fig. 1 presents the location of Ondo State on the map of Nigeria.

Fig.1: Location of Ondo State on the map of Nigeria

2. MATERIALS AND METHOD Detailed characteristics of the experimental stations are presented in Table 1, while Figure 2 presents the digitized map of Ondo State showing the Local Government Areas where the measurements were carried out.

Table 1: Characteristics of the Experimental Stations

S/N PARAMETER OSRC, AKURE. OSRC, OKA

AKOKO.

OSRC, OKITIPUPA.

1 Base Station’s Geographical Coordinate Lat. 7.300N, Long.

5.160E

Lat. 7.450N, Long.

5.800E

Lat.6.550N, Long. 4.750E

2 Base Station Carrier Frequency /Channel 487.25 MHz/UHF 23 503.25MHz/UHF25 519.25 MHz /UHF 27

3 Base Station Transmitting Power (W) 16,000 200 450

4 Transmitter Harris 40kW UHF

Sigma Diamond Drive

EMCEE TV 1000

FA

EMCEE TV 1000 FA

5 Height of Transmitting Mast(m) 333.00 121.90 134.10

6 Transmitting Antenna Gain(dB) 31.70 1.00 1.00

7 Height of Receiving Antenna(m) 1.83 1.83 1.83


International Journal of Engineering and Technology (IJET) – Volume 4 No. 9, September, 2014

2.1 Instrumentation

Figures 3 and 4 present the picture of the field strength meter and the GPS used. The field strength meter is the Dagatron TM 10 type with signal level range of 15-120 dBµV and frequency range of 5-852 MHz. The GPS is the GARMIN Map-76 personal navigator type. Other instruments used are field car, connector, coaxial cables, dual dipole receiving antenna and the digitized map (fig. 2) of Ondo State

Fig.2: Digitized map of Ondo State showing thedemarcation of the Local Government Areas

Fig.3: The Dagatron TM10 Field Strength Meter Fig. 4: Global Positioning System (GPS) Receiver; GARMIN MAP 76 personal

navigator

DELTA STATE

EKITI STATE

ATLANTICOCEAN

EDO STATE

OSUN STATE

OGUNSTATE

AKOKO NORTHWEST

AKOKO NORTHEAST

AKOKO SOUTHWEST

AKOKO SOUTHEAST

OSE

OWO

AKURENORTHAKURE

SOUTH

IDANRE

IFEDORE

ILE-OLUJIOKEIGBO

ONDOEAST

ONDO WEST

ODIGBO

OKITIPUPA IRELE

ESE ODO

ILAJE

4 4.5 5 5.5 6LONGITUDE (E)

6

6.5

7

7.5

LATI

TUDE

(N)

KOGISTATE



2.2 Field Strength Measurement and Analysis

Measurement of electric field strength ofOndo State Terrestrial TV Stations onChannels 23, 25 and 27 and transmitting at the Ultra High Frequencies (UHF) of 487.25 MHz, 503.25MHz, and 519.25MHz respectively was carried out radially from the base Stations along different routes in the State. Measurement and data collection were made at an interval of 10km from the main

station in Akure and 1km interval from the booster stations in Oka Akoko in the northern part and Okitipupa in the southern part of the State. The State was divided into three major routesclassified as A, B and C and eight sub routes for easy data collation, observation and analysis for the main station, while two routes were considered for each of the booster stations. The details of the categorization of the routes and the local government areascovered are presented in Table 2.

Table 2: Categorization of experimental routes

Route Local Govt. Areas

A: Ondo North Owo, Akoko South West, Akoko South East, Akoko North East, Akoko North

West and Ose.

B: Ondo Central Akure South, Akure North, Ifedore and Idanre

C: Ondo South Ondo East, Ondo West, Odigbo, Okitipupa, Ile Oluji/Okeigbo, Irele, EseOdo

and Ilaje

The base station transmitting antenna located at OritaObele, Akure, was marked and used as the reference point using the GPS receiver (GARMIN MAP- 76, figure 3)for all the routes. Its coordinates are; latitude 7.3040N, and longitude 5.1610E. The GPS receiver cursor was placed on the base station’s location already marked as OSRC on the GPS waypoint memory. The line of sight from the base station was monitored during the drive. The GPS measured the location’s Longitude, Latitude, and the elevation above sea level. The Dagatron TM10 field strength meter (Fig.2) with the receiving antenna connected to it via the coaxial cable using an I-connector was powered for the field strength to be measured. Meanwhile, the base station’s frequency of 487.25MHz which had been stored in the field strength meter’s memory was recalled and the multiple values of the electric field signal strength recorded. This procedure was repeated for subsequent measurements. Electric field strength values were equally taken in all the towns on each of the routes and recorded. This method was used while taking the quantitative measurements of the electric field strength of the remaining channels 25 (503.25 MHz) station, Oka Akoko and 27 station (519.25 MHz), Okitipupa. This procedure was also repeated for subsequent measurements during the onset of raining season (April- June), the peak of raining season (July-August) and the early part of dry season (September-December) covering a period of nine months. Subsequently, the electric field strength of the transmitted television signal for different locations with their corresponding line-of-sight distances(LOS) from the base stations were determined, measured and recorded. Generally, about 350 data sets were obtained along three major and twelve sub- major routes across the state. The data collected were used to determine and classify the coverage areas of the stations for

each of the seasons. Contour maps were generated,the electric field strength were over laid on the digitized map of Ondo State for the early part of the raining season, the peak of raining season and the early part of dry season. Usingthese maps, the percentage of coverage as a function of the state land mass was determined for each of the seasons.

2.3 Determination of Percentage of Coverage as a

function of the State Landmass in this work This was calculated by inserting equal number of square boxes on the contour over laid digitized map of Ondo State. The corresponding number of boxes within the primary, secondary, and fringe contours and as well as the areas not covered were now calculated as a percentage of the total number of boxes in the overlaid map to arrive at the respective percentage of coverage for each of the season and the grades of coverage.

3. RESULTS AND DISCUSSIONS Figures 5, 6 and 7 show the contour maps of the electric field strength produced for channel 23 television signal for the three seasons under survey while figures 8, 9 and 10 present the combined electric field strength contour maps for the three stations at the onset of the raining season, the peak of raining season and the early part of dry season respectively. Table 3 presents the average percentage area covered by the signal as a percentage of the state’s landmass for the three stations investigated. The coverage areas for the combined stations for the three seasons under consideration are as depicted in Table 4.



Fig. 6: Contour map of the electric field strength of CH. 23 UHF, (OSRC Akure) during the peak of raining season over Ondo State land mass.

DELTA STATE

EKITI STATE

ATLANTICOCEAN

EDO STATE

OSUN STATE

OGUNSTATE

AKOKO NORTHWEST

AKOKO NORTHEAST

AKOKO SOUTHWEST

AKOKO SOUTHEAST

OSE

OWO

AKURENORTHAKURE

SOUTH

IDANRE

IFEDORE

ILE-OLUJIOKEIGBO

ONDOEAST

ONDO WEST

ODIGBO

OKITIPUPA IRELE

ESE ODO

ILAJE

4 4.5 5 5.5 6LONGITUDE (E)

6

6.5

7

7.5

LA

TIT

UD

E (

N)

KOGISTATE

Transmission Base Primary coverage Area (Signal Level ≥ 40dBµV) Secondary coverage Area Signal Level (20dBµV - 39dBµV) Fringe coverage Area Signal Level < 20dBµV



Transmission Base, Ch. 23

Booster Station, Ch. 25

Booster Station, Ch. 27

Primary coverage Area (Signal Level ≥ 40dBµV)

Secondary coverage Area (Signal Level (20dBµV - 39dBµV)

Fringe coverage Area (Signal Level < 20dBµV)

Fig. Total Contours for the Coverage Areas of the three UHF Channels

Fig. 9: Combined contours of the electric field strength of OSRC Channels 23, 25 and 27 UHF during the peak of raining season over Ondo State land mass.



Table 3: Coverage Areas as a Percentage of the Ondo State landmass for each of the three stations under consideration.

UHF Station % of coverage during the onset of

raining season % of coverage during the peak of raining season

% of coverage during the early part of dry season

CH.23, OSRC, Akure

53.50 50.45 55.00

CH.25, OSRC, Oka Akoko. 10.00 9.00 10.50

CH.27, OSRC, Okitipupa. 9.00 8.00 9.50

Table 4: Combined Coverage Areas as a Percentage of the state’s land mass for the three stations

Results from Tables 3 and 4 show that there is reduction in the signal coverage of the study area during the raining season compared to the dry season by the three stations under study. Also, the sub-stations recorded lower coverage areas apparently due to the low output power of their transmitters. The signal loss in the first case is as a result of the presence of hydrometeors especially rain as well as some other factors such as wetness of the vegetation which was not part of this study. The total coverage areas by the three UHF, television signals in the state was averagely 71.65% of the landmass of Ondo State, while an average of 28.35% of the state’s land mass was not serviced by any of the stations. From the combined contour map (Fig.10) of the electric field signal strength, and as shown in Table 4, the early part of the dry season recorded the highest signal strength of 75.0% coverage followed by the onset of raining season (Fig.8) which marked the cessation of the dry season with a combined coverage of 72.5%. The peak of the raining season (Fig.9) recorded the lowest signal strength and coverage of 67.45%. This is a further confirmation of the effect of rain on the signal transmitted at Ultra High Frequencies in the locations studied. 4. CONCLUSION This work presents the effects of rain on the coverage areas of Ondo State Radiovision Corporation (OSRC) UHF Television signals transmitted on Channel 23(487.25MHz), Channel

25(503.25MHz), and Channel 27(519.25MHz) in Ondo State. However, the main findings are as follows: From the combined contour maps of the signal strength, the early part of the dry season recorded the highest signal strength of 75.0% coverage followed by the onset of raining season at a value of 72.5%. The peak of the raining season recorded the lowest electric field signal strength and coverage of 67.45%. There is the need for the stations to upgrade their facilities to enhance the signal strength across the state and as well increase their transmitter power especially during the raining seasons. In view of the socio-economic importance of television news and programming to the populace, at least two or more booster stations are recommended for the Ondo State Government, for all the local government areas in the State to be well serviced. REFERENCES

[1] Ajayi G. O. And Owolabi I. E. (1979):“Coverage Area of the 10kW, 702kHz Medium Wave Transmitter at Minna and Feasibility Studies for full Radio Coverage of Niger State”. Technical Report of the Electrical Communication Consultancy Unit (ECCU), Department of Electrical and Electronics Engineering, University of Ife, Nigeria.

UHF Station % of coverage during the

onset of raining season

% of coverage during the

peak of raining season

% of coverage during the

early part of dry season

CH23, CH 25 andCH 27

OSRC television

Stations

72.50 67.45 75.00



[2] Ajewole, M.O (2011): ” Radio and Rain: Friends and Foes” An inaugural lecture delievered at the Federal University of Technology, Akure, Nigeria, pp 23-25

[3] Ajewole, M.O, Oyedun, O. D, Adediji, A. T, Eichie, J. O and Moses, A. S (2012): Spatial Coverage of FM Radio Transmitters in Niger State, Nigeria:IUP Journal of Telecommunications, Vol. iv, No. 4, 2012, Pp7-19. #70j-2012-11-01-01.

[4] Ajewole, M.O, Oyedun, O. D, Adediji, A. T, Moses, A. S, and Eichie, J. O (2013): Spatial Variability of VHF/UHF Electric Field Strength in Niger State, Nigeria, International Journal of Digital Information and Wireless Communications Vol. 3(3), pp26-34.

[5] Akinbolati, A (2012): “Survey of Electric Field Strength and Path Loss Prediction of UHF Television Signals in Ondo State, Nigeria”.

[6] Bothias,L. (1987): “Radio Wave Propagation”

McGraw-Hill Inc. New York St. Louis San Francisca Montreal Toronto. Pp. 144-175.

[7] Broadcasting Organization of Nigeria (BON) 2010 Directory. Pp 10-70.

[8] Collin, R. E. (1985): “Antennas and Radiowave Propagation”. McGraw Hill Inc. New Delhi, Pp (401-409).

[9] Kenedy, G. And Bernard, D. (1992): “Electronic Communication System, McGraw Hill/Macmillian, Singapore. Pp (80-150)”

[10] www.nbc.ng.org


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