The African Review of Physics (2018) 13: 0014

Proceedings of the first African Conference on Fundamental Physics and Applications 2018, Namibia. Guest Editors: K. A. Assamagan, M. Backes, D. Charlton, S. Muanza , D. Sahu, and D. Singh

Effective Coverage Area Enhancement of a Solar Powered Ultrasound Pest Control Device through Ultrasound Booster System Design

Ibrahim A.G and Oyedum O.DDepartment of Physics, Federal University of Technology, Minna, Nigeria.

A solar powered ultrasound pest control system comprising of the standalone device and a booster unit was designed, implemented and their performance evaluated both in laboratories and in farms. The concern of this work is to further enhance the coverage area of the device through an effective booster system design, explore better configuration options which can be applied in large farm type, formulate the mathematical expressions relating the area of ultrasound coverage on a farm to the number of booster units required and the associated power analysis indicating the solar panel and battery requirement when such configurations are implemented. Result and analysis of the designed and constructed booster system reveals that it enhanced the effective coverage area of the standalone device by a factor of five and nine when in isolated and contact placement methods of booster configuration respectively.

1. Introduction

An ultrasound pest control booster is a device that is used to improve the signal strength of an electronically generated ultrasound for the purpose of pest control [1]. Ultrasound refers to high intensity sound beyond 20 kHz [2] and [3]. At determined frequencies (25 and 35 kHz), though being inaudible to humans [4], has a scary effect on weaver birds. In a previous work [5], an ultrasound booster, simply referred to as the booster box was designed, implemented and tested. In the design concept, raw ultrasonic signal was transferred from an ultrasound generator to a remote station, here referred to as booster location where it is processed and transmitted within the locations with a 360o horizontal spread and a bottom boost. The five-segment concept and the nature of transducer orientation used keeps the entire booster location and the standalone location saturated with ultrasound while in operation. Furthermore, the design economics of having an ultrasound booster rather than replication of standalone device gives credence to the low-cost design concept. The focus of this research is on further enhancing the ultrasound

coverage area by increasing the number of booster units, improve on the gains of the ultrasound booster so designed by expanding its design concept and to make appropriate modification on the standalone device to accommodate the expansion made.

The significance of this study is that by this work, more area of land will be covered and the pest deterrent property of ultrasound shall be extended to more crops as they are brought under its protective cover.

2. Review of previous efforts

2.1 Design description In this work, the entire ultrasound pest control system consists of two sub devices namely: the standalone unit and the booster unit. Each unit is made up of the device itself and other supporting parts working together to achieve same objective. The schematic diagram adopted to depict the design connection between the standalone unit and its booster unit is shown in Figure 1.

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(b) Booster Unit

Figure 1: Schematics of the Ultrasound Booster System [6]

BoosterCord

SolarPanel

StandaloneDevice

AdjustableStand

AdjustableStand

Booster Box

(a) Standalone Unit

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The standalone device is capable of independently generating its power and ultrasound requirements, selects a portion of the ultrasound signal for amplification and transmission in order to deter weaver bids away from the area of coverage. The booster device functions along with the standalone device from where it derives its electric power and ultrasound signal. It receives raw ultrasound signal from the standalone device, amplifies and transmits it in their booster location. The idea behind the booster device is to increase the area of coverage of the standalone device. Rather than duplicating the standalone device, which is a more expensive venture, the idea of low cost booster unit having similar reach as the standalone device was considered. The concern then was not on the standalone, but on booster unit. However, due to the interdependence between both devices, a few sections being shared by both devices shall be discussed.

2.1.1 Power Supply

The source of power for the booster system was conveniently derived from the standalone unit’s 18 V solar panel a 12 V rechargeable battery. The power requirement was tapped from the output of the tripping circuit to the booster outlets from where it is conveyed via booster cables to a booster location and from where it is regulated to meet the needs of various sections inherent in the booster circuit. Connecting from the output of the standalone tripping circuit which is a photo sensitive circuit [7], ensures that both device shares the benefit of tripping ON and OFF at sunrise and sunset coinciding with the period of weaver bird pests activities. 2.1.2 Ultrasound Generator

The 25 and 35 kHz ultrasound to be boosted is generated by the 25 kHz and 35 kHz oscillators of the standalone device. The IC, 555 Timer was used in the implementation of the oscillator circuits [8].

2.1.3 Frequency Selection Section

The frequency selection section of the standalone system does the job of selecting between the 25 kHz and 35 kHz ultrasound frequency output of their respective oscillators in fifteen seconds interval. The circuit comprises of a 555 timer in a monostable mode and a microcontroller (AT89C52) as the excitation agent sending pulses to the timers input every fifteen seconds causing it to change state simultaneously. This operation causes a relay at the timers output to toggle, thereby connecting the 25 kHz oscillator and disconnecting the 35 kHz on one hand and disconnecting 25 kHz and reconnecting the 35 kHz oscillators on the other hand [1]. The output of the frequency selection circuit was tapped to the booster outlet from where the ultrasound signal was tapped to each of the booster locations via the booster cables for further processing. This connection means that the

signal to be boosted is also an intermittent selection of 25 kHz and 35 kHz every fifteen seconds [9].

Other successive sections of the device discussed below (2.1.4 – 2.1.6) are located away from the standalone device and cased separately at a location (booster location) where it is expected to play its role of saturating the locations with ultrasound to deter the weaver birds.

2.1.4 Booster Preamplifier Section

The preamplifier of the booster circuit is designed after that of the standalone circuit. The UR741 Integrated Circuit was used to raise the strength of the ultrasonic signal by 500 [10]. The circuit design and analysis is same as that of the preamplifier of the standalone device. The booster cable evacuating ultrasound signal from the standalone system terminates at the input of the UR741 of the preamplifier. The preamplifier and its ajoining sections constitute the booster circuit at a particular location. A similar voltage gain of 500 was designed for the preamplifier as that of the standalone device.

2.1.5 Booster Power Amplifier

The power amplifier circuit of the standalone system was replicated for the booster system. Same gain design of 200 was accomplished using the LM 386 Integrated Circuit. The power amplifier’s input signal is the pre-amplifiers output signal. In order to obtain a higher gain from the IC, the circuit is modified between pin 1 and pin 8. According to National Semiconductor data sheet [11], to obtain the maximum gain of 200. With this level of amplification, the ultrasound will propelled to penetrate deeper into the air and saturate the vicinity of broadcast to a reasonable distance. The total gain of the amplification section is given by the product of the preamplifier gain and the power amplifier gain. That is,

Total Gain = (Preamplifier Gain) × (Power Amplifier Gain) = 100,000

Therefore, an overall amplification (preamplifier and power amplifier) gain of 100,000 in five segments for each of the five booster locations was maintained.

2.1.6 Booster Ultrasonic Transducer

For the ultrasonic transducers which will serve as the load in each direction, same dual diaphragm, dual outlet twitters (twin twitters) as used for the standalone was also used. Among the specifications of the ultrasonic twitters are that their frequency response must be beyond 35 kHz [9]. Coupling to the ultrasonic transducer was with a 220 µF capacitor, C4. The circuit diagram of the booster circuit in one of the five directions/segments at a booster location is shown in Figures 2.

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With the booster switch located on the standalone device activated, the booster mode is enabled and the preamplifier, power amplifier and ultrasonic transducers of the booster systems will automatically start operating in addition to those of the standalone device. In this mode, the standalone device will functions as the ultrasound generator and power house of the entire system. The booster circuit was physically implemented using electronic construction technology [10].

2.2 Casing Design

For the booster system’s casing design, a dimension of 33 cm x 29 cm x 16 cm was chosen to adequately house the electronic panel and ultrasonic twitters. Features on the casing include: Five broadcasting outlet (one on each side and one at the bottom); booster inlet and four clips at the base for fastening to the stand. The casing, together with its circuitry, is also referred to as the booster box. The sides, top and bottom of the casings were also sprayed with black paint from within, to absorb the heat generated by the components away from the circuitry. The design

concept is such that the booster box will sit on a four-legged adjustable stand. It can be adjusted from a height of 1.2 meters to 5.5 meters. A detachable horizontal platform of dimensions 35 cm x 35 cm was mounted on the stand on top of which the booster devices will sit. A little portion of the platform having dimension 13 cm x 6 cm was opened to provide space for the bottom broadcasting outlet. These stand help to raise the device to the same height with the crops. Millet, sorghum and rice, for example, have their pest target points located at their topmost part. Therefore, the adjustable stands will help in achieving this leveling which allows for better interaction between the signal and the pest in different farm types [10].

3. Methodology

The fresh design concept in this work entails the duplication of existing booster box into three equivalent booster boxes having similar specification and dimension. This is followed by modifications in the standalone unit in order to accommodate the expansion. Systems of arrangement that best enhances ultrasound coverage using the standalone device in collaboration with the four booster boxes constructed were proposed. Mathematical argument was used to arrive at a conclusion over the degree of coverage area enhancement attained.

3.1 Design Concept

The block schematic showing the ultrasound signal flow through major sections of the design concept is shown in Figure 3. Same design equations, parameters, specifications and dimension as discussed in section 2.1.4

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Ultrasonic Transducer

C4

.

.

Figure 2. Booster Preamplifier, Amplifier and Ultrasonic Transducer Circuit Design in One of the five Directions [9]

Preamplifier Design

Power Amplifier Circuit Design

R1

>>>>>> Rf 1

4

4

22 IC2 5

1VINIC6

C1 7

63 6

C3

Vcc

3 18

C2

78107805

Vcc

^̂^̂^̂

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- section 2.1.6 was utilized in the duplication of additional three booster boxes.

B1, B2, B3 and B4 refers to booster box 1, 2, 3 and 4 respectively. B1 has previously been constructed as discussed in section 2. The inner block numbering 1, 2 and 3 refers to the booster preamplifier, booster power amplifier and the booster ultrasound transducer replicated in five segments as discussed in section 2.1.4 – 2.1.6. Same was replication for the three new booster boxes. Therefore, a total of twenty segments were obtained for a 360o coverage and a bottom boost at all the four booster locations (five for each booster location). A maximum of four booster boxes were conceived for two reasons, firstly, additional units will place an overwhelming electric power

demand on the standalone device which will warrant a major modification of the power supply section. From power analysis, four units can be conveniently powered with slight modification. Secondly, four booster boxes can be used to express various interesting formations that will enhance better ultrasound coverage.

The physical realization was done using electronic construction technology and fabrication processes [12]. The conceived idea and the implementation of the design concept give rise to the ultrasound pest control booster system comprising of the standalone device and four booster boxes shown in Plate I.

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Standalone Device

Figure 3: Schematics for the Ultrasound Booster System

B4B3B2B1

3

1 2

1 3 2

3

1 2

3

1 2

3 1 2

Standalone Unit

Booster Unit

Solar Panel

Booster Signal Inlet

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To operate the device in booster mode, the following steps are followed while on the farm:

i. The stand of the standalone system and the four booster stands are coupled by adjusting the supports and attaching the horizontal platforms;

ii. The standalone device and the booster boxes are placed on their respective platforms and fastened; iii. The solar panel is placed above the standalone device by screwing the front to the platforms support and the rear is hooked to the stopper as shown in Plate I. In this position the panel is at the required angle of 10o to the horizontal; iv. The standalone system is rotated such that the solar panel faces south. This provides the required direction for a direct exposure to the sun’s rays;v. The solar panel’s cable is plugged into the standalone device’s power socket and the charging bottom is pressed to commence charging the battery; vi. The booster cords are plugged into the booster outlet on the standalone device and into the booster intlet of the booster box(es). This will make available to each booster location the needed power supply to boost the ultrasonic frequency signal to be supplied along the same cord when booster mode is enabled; vii. The booster box(es) and stand(s) are taken to desired booster location(s); viii. The stands are adjusted to about the same height as the crop. This levelling is necessary for better interaction with target part of the crops;ix. Pressing the power button and activating the booster switch on the standalone device makes the supply voltage (VCC) available to the tripping section. If it is daytime, the section automatically clicks and feeds the supply line to power the other sections. But at evenings, this section trips OFF, disconnecting the other sections. When tripped ON, the timing section sets the frequency with which each of the oscillators will operate. The 25 and 35 kHz frequency signals generated by the oscillators are intermittently selected

at 15 seconds interval by the frequency selection section and passed to the booster outlet and from where the signal is transmitted through the booster cords to booster locations for amplification and broadcasting.

3.2 Modification of Standalone Device

To be able to accommodate the design expansion, the following modifications were made on the power supply section of the standalone device.

1. Capacity of solar panel: The expansion will require more electric power supply than the previous design. From the power analysis carried out, each of the booster boxes will require 10 W to effectively power the unit. In addition, the requirement for the standalone device is 25 W. Therefore, a minimum power of 65 W is required. This value is above the rating of the previous design for which a 50W solar panel was used to take care of the 35 W required for the standalone device and a booster box. To effectively power the current 65 W system, a 100 W solar panel was used. Table 1 shows the specification of the solar panel used for the previous and current design respectively.

Table 1. Electrical Rating of Solar Panel at standard test condition

(STC): E = 1000Wm-2, AM = 1.5, Tc = 25oC

Electrical Rating Previous Values

Current Values

Open circuit voltage (Voc)

50 W 100 W

Open circuit voltage (Voc)

21.5 V 28 V

Short circuit current (Isc)

18 V 25 V

Maximum power current (Im

2.77 A 4.5 A

Output tolerance (%) +3 +3Operating temperature (oC)

-40 - +80

-40 - +80

Length (mm) 670 750Width (mm) 300 370Height (mm) 4.35 4.35

1. Number of batteries: A 12 V, 1.2 A rechargeable battery provided the power bank for the previous design. In order to boost this current, two 12 V, 1.2 A batteries were connected in parallel. The 2.4 A effective current will sufficiently drive the system requiring an overall current of 1.97 A.

2. Booster outlet: The booster outlet on the standalone device was increased to a four outlet plug and the internal connection was made. Each of the booster boxes will respective receive ultrasound signal from these outlets for processing and transmission at their booster locations.

3.3 Booster Configuration

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Booster configuration refers to various practicable placement methods for which the booster boxes can be arranged into to allow for wider reach. To formulate these orientations, an idea of the distance and area of coverage for each booster box and standalone device is required. In this work, two booster configurations were formulated: the placement in isolation and contact placement methods of booster configuration.Placement in Isolation: In this placement method, each booster units is positioned well apart from the effective distances of the other. This placement method in which no definite angle of orientation or distance between booster stands is maintained was introduced in order to prevent wastage incurred by saturating unnecessary areas with ultrasound. Figure 5 illustrates one out of several formations of such booster configuration.Contact Placement: In this placement method, the booster units are kept close such that their distance of coverage overlaps with themselves and with that of the standalone unit. A definite orientation is maintained by the booster units around the central standalone unit. Figure 6 illustrates one out of several formations of such booster configuration.

4. Results and discussion

Test results using an ultrasound detector and field evaluation in weaver birds infested farms show that the vicinity of broadcast was kept saturated with ultrasound as all the twenty transmission directions of the booster units and five directions of the standalone device were respectively transmitting high intensity ultrasound as designed. The five-segment concept and the nature of transducer orientation used keeps the entire booster location and the standalone location saturated with ultrasound while in operation. By this, more area of land is covered and the pest deterrent property of ultrasound is extended to more crops as they are brought under its protective cover.

For any booster configuration to be implemented, the effective distance of coverage of both devices need to be ascertained. To do this, the devices were evaluated in terms of ultrasound reach. An ultrasound detector [13] was used to probe in all direction. The result shows that ultrasound from the device was sensed up to a distance of 35 meters, became faint on further probing and faded away beyond forty meters. This gave the result that the effective distance of coverage for the booster unit as 35 meters. Figure 4 can be used to depict the observation.

For the effective area of coverage, the formula for the area of a circle was used [14]. That is:

where A is the effective area of coverage, π is 22⁄7 and de is the radius, that is the effective distance of 35 m. Substituting into (1) yields:

Thus, a booster unit provides an effective weaver

bird pest cover to an area of about three thousand eight hundred and fifty square meters. This result is similar to that obtained when the performance of the standalone device was evaluated in which same effective distance holds [15]. This is because, same ultrasound twitters, preamplifier and amplifier design with uniform gain was implemented for both devices. This gave the idea of the configuration to adopt using four booster boxes for both the placement in isolation and contact placement discussed earlier.

Placement in isolation: In this configuration in which each of the four booster units was positioned well apart from the effective distances of each other, no definite angle of orientation or distance between booster stands is maintained as only favorite feeding spots of the weaver birds will be covered. This placement method was informed by factors such as mixed cropping (where the pest selects preferred crops), different planting times leading to certain crops approaching the critical stage of vulnerability to pest attack differently and selective harvesting. Figure 5 illustrates one of such placements in isolation on a hypothetical farm. The booster cables connecting the standalone unit to the booster units are laid underground.

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A=π de2 (1)

A=π x (35)2 (2)A¿3,850 m2 (3)

35m

35m

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35m

35m

35m3

35m3

Figure 5: Placements in Isolation on a Farm

335m

35m3

35m

35m

3

3

35m

35m

35m3

35m33

35m

35m3

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It can be observed that same effective distance of about 35 meters and effective area of 3,850 m2 was maintained for this placement method around each stand. Therefore, the total area of coverage achievable for this method was computed by summing over all the units. The result is nineteen thousand, two hundred and fifty square meters. This is five times the coverage area of the initial standalone device.

Contact Placement: In this placement method, the four booster units were kept close such that their effective distance of coverage overlaps with themselves and with that of the standalone unit. A definite orientation of 90o was each maintained by the booster units around the central standalone unit resulting to a 360o spread. In this placement method, the standalone unit is centralized while the booster units were positioned seventy meters away from the centralized standalone unit. That is, thirty five meters effective distance for the standalone device and another for the booster box will sum up to seventy meters. In addition to this distance is the other end (35 meter) of the booster transmission. It can be seen from figure 6 that the effective distance from the central ultrasound generator sum up to one hundred and five meters. From equation (1), the effective area of coverage of the device in contact placement type of booster was worked out as:

Thus, a total area of thirty four thousand six

hundred and fifty square meters of effective weaver bird pest deterrent is guaranteed using four booster boxes. This value to nine times the coverage area of

the standalone device.

5. Conclusion

The booster system designed and placement method used in this work has enhanced the effective coverage area of the ultrasound pest control device by a factor of five and nine in the case of isolated and contact placement respectively. The maximum area of coverage of thirty four thousand six hundred and fifty square meters using contact placement amount to an effective weaver bird pest cover on 3.465 hectares of farm land obtained using only four booster units. The design economics of duplicating the ultrasound booster rather than the standalone device gives credence to the low-cost design concept. The focus of future research is about designing a software capable of running simulation on the ultrasound booster system involving more booster boxes and their configuration and the corresponding area of coverage, power requirements, cost implication and likely positions of neutral points. The acceptance and deployment of the ultrasound pest control booster system which has been attested to as being cheap, ecosystem friendly, environmentally friendly and with no risk to humans [16] will make a considerable impact towards the attainment of food sufficiency.

References

[1] Ibrahim, A.G. Development and Performance Evaluation of a Solar Powered Ultrasonic Device for the Control of Weaver Birds in Farms. Ph.D Thesis, Department of Physics, Federal University of Technology, Minna, Nigeria (2015).

[2] Novelline, R. Squire's Fundamentals of Radiology (5th ed.). U.S.A: Harvard University Press (1997).

[3] Ainslie, M. A. A (2015). Century of Sonar: Planetary Oceanography, Underwater Noise Monitoring, and the Terminology of Underwater Sound. Acoustics Today.

[4] Berke, M. Introduction to ultrasonic testing, Germany: Hurtu Press, (2002). pp. 3.

[5] Ibrahim A.G., Oyedum O.D., Awojoyogbe. Ultrasound Booster Design and Implementation for Electronic Pest Control. Journal of Science, Technology, Mathematics and Education. (2018) 14 (1):1-12.

[6] Ibrahim A.G. Booster Mode Analysis for a Designed Ultrasound Pest Control Booster System. A proceeding of the International Engineering Conference (IEC). Federal University of Technology, Minna, Nigeria. (2017). 2:116-120.

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A=π x (105)2 (4)A ¿34,650m2 (5)

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[7] Ibrahim, A.G., Oyedum, O.D., Awojoyogbe, O.B., Okeke, S.S.N. Electronic Pest Control Devices: Their Necessity, Controversies and Design Considerations. The International Journal of Engineering and Sciences (2013). 2(9) 26-30.

[8] Tony, V. LM 555 AND LM 556 Timer Circuits, DoctronicsWilliams Lab Retrieved on August 15, 2010 from http://www.matni.com/Arabic/Elec.../NE555%20DETAILS/555.html

[9] Ibrahim A.G., Oyedum O.D., Awooyogbe O.B. Design Description of a Standalone, Auto-Frequency Ultrasonic Brand of Weaver Bird Pest Control Device for Field Applications, International Journal of Engineering and Manufacturing (IJEM), (2017). 7(5): 1-15.

[10] Ryan,V. The 741 Operational Amplifier. Retrieved f on September 17, 2011 from http://www.technologystudent.com .

[11] National Semi-conductor Data sheet LM 386. www.alldatasheet.com/datasheet-pdf/pdf/9027/NSC/LM741.html

[12] Usifo, O. Research Project Implementation Made Ease (1st Edition). ECAS Ltd, Nigeria, (2004). pp. 121.

[13] Seriki, D. (2015). Design and construction of an Ultrasound Detector. B. Tech. Thesis, Department of Physics, Federal University of Technology, Minna. Nigeria (2015).

[14] Stewart, J. Single variable calculus early transcendentals. (5th. ed.). Toronto ON: Brook/Cole. (2003). p3.

[15] Ibrahim, A.G., Oyedum, O.D., Awojoyogbe, O.B., Aje, J.D. and Gimba M. Performance Evaluation of a Designed Stand-alone Solar Powered Ultrasound Weaver Bird Pest Control Device. Advances in Multidisciplinary and Scientific Research, (2017), 3(3) 51 – 64.

[16] Liroff, R.A. Balancing risks of DDT and Malaria in the global POPs treaty. Pesticide Safety News. (2000), p3.

Received: 11 October, 2018

Accepted: 20 October, 2018

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