Runway Lighting

Team Members:

Matt Anker

Jeff Endicott

Clint Heiney

Foreword: In Greek mythology, Icarus had to escape danger by flying with wings made of wax and feathers engineered by his Father. Although pre-warned to stay far away from the sun, young naive Icarus could not avoid temptation which resulted in the failing of his wings and his demise. The Goal of TEAM GOLDEN ICARUS is to harness the power of the sun and allow for the Safe landing of aircraft.

Runway Lighting – Team Golden Icarus

TI Design Contest

Final Report

ECE682

i

Executive Summary

1. Introduction

The project’s wireless system will provide a low cost effective lighting solution to nocturnal take-off and landing of aircraft. This system will be portable and easily implemented to new or existing areas, therefore covering a vast market.

2. Background

Design influences came from personal desires and hope to develop an easy implementation of a complete system. At present time, there are very few other systems on the market similar to the one that is designed in this report. The major benefit will provide an inexpensive alternative to current runway lighting solutions

3. Requirement Analysis and Specifications

The requirements for this system are based on current “wired” runway lighting of active airfields. It should be able to be implemented quickly and with little effort to any plausible area. Design specifications can be found in section 3, and Operational specifications our shown below.

• Pilot Controlled activation • Runtime of 5 minutes per cycle, with warning flash at 4.5 minutes • 1 hour cumulative runtime operation • Dual intensity setting • 3 mile visibility

4. Project Design

To design and build at least two demonstrator samples for an innovative wireless runway lighting system. The lights will exist as a system of 24 units for a 2,000ft runway, scalable to 5,000ft runways or large helicopter landing zones. The constraints and requirements will be evaluated to complete the design and construction. Once a solution has been solidified a working model will be built. Then the units will field tested and analyzed to further study any needed modifications.

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5. Statement of Work

Four Texas Instruments integrated circuits were chosen to be implemented into the circuit design. The lighting unit circuit was completed with fabricated printed circuit boards. Microcontroller code was developed to control the main lighting units through an MSP430 coupled with a CC2500 RFIC for radio control. Three proof-of-concept demonstrator units using TI EZ430-RF2500 evaluation boards, two TPS6205x DC/DC converters, and a TPS2052B power distribution switch have been constructed and are awaiting refinements in the coding. Additionally, a light-controlled unit using two Texas Instruments TPS6205x DC/DC converters, a TLV3492 nano-power comparator, and a TPS2090D power distribution switch was built and tested.

6. Resources

The team consists of three well qualified individuals. The work will sectioned off toward individual strengths. These team members all have skill to complete the given tasks, but a collective force will be used in many areas of the design. Equipment for the project will be obtained through TI and other resources will be utilized at The Ohio State University.

7. Schedule and Costs

The design was broken into specific steps toward project completion. Development hardware and software will be provided by TI so costs will only involve the construction of the individual lighting units, which should approximately be $50/unit. Initial circuit component costs are tabulated.

8. Design Review Strategy

The design review will consist of in lab testing and review as well as field testing and review. In the in lab testing each component was tested separately for functionality, and then combined for a system level test. Tested components were then assembled on printed circuit boards for field testing. Pending completion of field testing of a small batch of units, the design will be scaled for small-scale production and tested on an airfield.

iii

Table of Contents

List of Tables and Figures ............................................................................................................. iv 1. Introduction............................................................................................................................. 1

1-1. Purpose............................................................................................................................ 1 1-2. Problem Statement .......................................................................................................... 1 1-3. Scope............................................................................................................................... 1

2. Background............................................................................................................................. 1 3. Requirement Analysis and Specifications .............................................................................. 2 4. Project Design......................................................................................................................... 2

4-1. System Design Overview................................................................................................ 2 4-2. Control unit ..................................................................................................................... 4 4-3. Lighting Unit................................................................................................................... 5

TI- TPS6205x.......................................................................................................................... 5 TI- TPS2052B......................................................................................................................... 6 TI- MSP430F2274 .................................................................................................................. 6 TI- CC2500 ............................................................................................................................. 6

4-4. Power Analysis, Lighting units....................................................................................... 7 4-5. Circuit operation and Coding.......................................................................................... 8 4-6. Physical Design............................................................................................................... 9

5. Statement of Work ................................................................................................................ 13 6. Resources .............................................................................................................................. 15

6-1. Personnel....................................................................................................................... 15 6-2. Facilities and Equipment............................................................................................... 15

7. Schedule and Costs ............................................................................................................... 16 7-1. Schedule History........................................................................................................... 16 7-2. Cost ............................................................................................................................... 17

8. Design Review Discussion ................................................................................................... 19 Appendix A:................................................................................................................................ A-1

Code ........................................................................................................................................ A-5 Master control unit.............................................................................................................. A-5 Lighting unit........................................................................................................................ A-6

Appendix B:................................................................................................................................ B-1 Light Level Controlled Runway Lighting Unit ...................................................................... B-1

System Design .................................................................................................................... B-1 TI- TPS6205x.................................................................................................................. B-1 TI- TPS2090D................................................................................................................. B-1 TI- TLV3492................................................................................................................... B-1

Power Analysis ................................................................................................................... B-2 Cost Analysis ...................................................................................................................... B-2 Performance Analysis ......................................................................................................... B-3

iv

List of Tables and Figures

Figures

Figure 4.1.1: Control unit System Diagram……………………………………………………………………….3

Figure 4.1.2: Light Unit System Diagram………………………………………………………………………….4

Figure 4.2.1: Control Unit Schematic……………………………………………………………………………....5

Figure 4.3.1: Light Unit Schematic………………………………………………………………………………….7

Figure 4.6.1: Housing design of lighting units……………………………………………………………………10

Figure 4.6.2: Lighting Unit PCB Layout [RED-top layer, BLUE-bottom layer, GREEN-via]………..…...11

Figure 4.6.3: Completed Lighting Unit PCB…………………………………………………………………….12

Figure 4.6.4: Completed Lighting Unit, Side View………………………………………………………………12

Figure 4.6.5: Completed Lighting Unit with Solar Disc……………………………….………….…….………13

Figure A-1: Detailed Control unit schematic…………………………………………………………..………….A-1

Figure A-2: Detailed Lighting unit schematic………………………………………………………….………….A-2

Figure A-3: Flow chart for lighting unit code…………………………………………………………….……….A-3

Figure A-4: Detailed Physical dimensions and layout of housing………………………………….…………..A-4

Figure B-1: Light-Controlled Runway Light--System Schematic……………………………………………… .B-2

Figure B-2: Light-Controlled Lighting Unit Prototype…………………………………………………………..B-4

Figure B-3: Light-Controlled System Schematic (Full Size)……………………………………………………..B-5

Tables

Table 7.1.1: Labor Schedule………………………………………………………………….…………………….17

Table 7.2.1: Main circuit component costs…………………………………………….…………………………18 Table B-1: Light-Controlled Lighting Unit Bill of Materials B-3

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1. Introduction

1-1. Purpose At the end of the project period the team will have a complete design and documentation along with a working prototype of a wireless runway lighting system.

1-2. Problem Statement Most private general aviation airports do not have runway lighting. Therefore night operations are nonexistent. The project’s wireless system will provide a low cost effective lighting solution to nocturnal take-off and landing of aircrafts. This system will be portable and easily implemented to new or existing areas, therefore covering a vast market.

1-3. Scope The project will develop working units to be integrated into a wireless runway lighting system. Final circuit analysis and troubleshooting should result in these units. Upon completion of the TI contest, units will be able to be streamlined and assembled with the given board design, and complete systems can then be marketed.

2. Background

At present time, there are very few other systems on the market similar to the one that is designed in this report. One known existing system, Model A704-5 by Flight Light Inc1, is much more robust and expensive. The lighting system in this report is designed to be much cheaper and used for smaller applications. The Model A704-5 has many more features to make it applicable for military applications as well as larger scale air landing strips. The one being proposed is meant for smaller applications where basic lighting is needed. Design influences came from personal desires and hope to develop an easy implementation of a complete system. The major benefit will provide an inexpensive alternative to current runway lighting solutions. Further more the units will be capable of remote location due to the wireless and use of alternative energy source.

1 Model A704-5 by Flight Light Inc.: http://www.flightlight.com/airportlighting/6.5.1/6.5.1.html

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3. Requirement Analysis and Specifications

The wireless lighting system has to meet selected parameters to be practical. It should function in the same way as current “wired” systems used in the active airfields today. A list of operational and design specifications are shown below. Operational

• Pilot Controlled activation • Runtime of 5 minutes per cycle, with warning flash at 4.5 minutes • 1 hour cumulative runtime operation • Dual intensity setting • 3 mile visibility

Design

• Alternative power source • Low Cost materials • Minimal maintenance • System must be portable • Wireless unit control • Weather-resistant • Operational temperature -20 to 50 degree Celsius

4. Project Design

The following sections will explain the complete project design. Starting with an overview and then detailed sections of the function and workings of individual components.

4-1. System Design Overview

The runway lighting system hardware is comprised of two different components; the lighting units and a master control unit. In a typical installation, the lighting units will be distributed at intervals of 200 feet along the edges of an airport runway. The number of lighting units will vary with the length of the airfield to be lit and/or the desired coverage. The system will require a single control unit typically located inside or mounted externally on a structure such as a hangar where AC power is available. Antennas will be mounted externally from the control unit to ensure optimal radio operation. The purpose of the master control unit is to receive signals in the form of noise pulses from the radio transmitter of the aircraft controlling the runway lighting system and translate those into commands usable by the 2.4 GHz command network. The Hamtronics R122 air band receiver will receive the command signal from the aircraft

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and pass that to a MSP430 microcontroller for interpretation. The MSP430 will then instruct the CC2500 2.4GHz radio frequency transceiver to transmit a digital signal indicating a desired level of illumination. The block diagram for the conceptual MCU design is shown in Figure 4.1.1 below.

Figure 4.1.1: Control unit System Diagram

The purpose of the lighting unit is primarily to illuminate the outline of a runway in order to aid a pilot in aligning the aircraft for takeoff or landing. The lighting units will accomplish this by gathering sunlight through a photovoltaic array during the day and storing that energy for use at night. Energy is to be stored in a single Lithium-Ion cell with a nominal voltage of 3.7V, and requiring a charge voltage of 4.2V. The lighting unit is to receive a 2.4 GHz digital command signal through a CC2500 RF transceiver which is then passed to the MSP430 microcontroller. The MSP430 is then to activate a MOSFET switch IC which will power the LED array. The MSP430 will then command the CC2500 to retransmit the command signal to nearby lighting units as a daisy chain network. The microcontroller must then start a timer to shut down the LED array after a fixed amount of time expires. Finally, the microcontroller must strobe the LED array as a pre-shutdown warning just prior to runtime expiration. The conceptual block diagram of the lighting unit is shown in Figure 4.1.2 below.

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Figure 4.1.2: Light Unit System Diagram

4-2. Control unit

The control unit is comprised of two primary components, a MSP430F2274 microcontroller coupled with a CC2500. Ancillary components include a UA78M33C 3.3V linear voltage regulator and two opto-isolators. The control unit is to interface with a Hamtronics R122 air band receiver via a four pin header on the control unit printed circuit board. The R122 uses current sinking bipolar transistor outputs and it is powered by a 12V power supply. Therefore a pair of opto-isolators will be used to interface the R122 to the MSP430 microcontroller’s 3.3V logic levels. A logic low input on the MSP430 will cause the control unit to execute its program code and transmit control signals. The MSP430 writes to the CC2500 RF transceiver, whose RF output is matched to an externally mounted 50 Ohm antenna through a lumped element balun. The CC2500 will transmit blindly for a preprogrammed duration of 5 seconds on the 2.4 GHz unlicensed band and is expected to have a range of 400 feet with a standard omni-directional antenna. The control unit schematic is shown in Figure 4.2.1 below and is reprinted in Appendix.

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UA78M33C

IN

COM

OUT

GROUND

L11.2 nH

L2 1.2 nHL3 1.2 nH

C810 uF

Vcc

C933 uF

SMA

1

2

ANTENNA 2.4GHz 50 Ohm

+12V

R7150

R8150

HAMTRONICS R122 VHF AIR BAND RECEIVER

PROGRAMMING HEADER

C16

C17

C18220 pF

1234

J3SMA

1

2

MSP430F2274IDA

P3.5/UCA0RXD/UCA0SOMI26

P4.1/TB118

DVCC2

P3.2/UCB01SOMI/UCB0SCL13

RST*/NMI/SBWTDIO7

P1.3/TA234

DVSS4

P1.6/TA1/TDI/TCLK 37

P4.4/TB1A1321

XIN/P2.66

P3.6/A627

P4.6/TBOUTHA1523

P2.3/TA1/A3/VREF-/VeREF-/OA1I1/OA1O29

P3.0/UCB0STE/UCA0CLK/A511

P3.7/A728

P4.3/TB0/A1220

P1.7/TA2/TDO/TDI38

P3.3/UCB0CLK/UCA0STE14

P4.0/TB017

P3.4/UCA0TXD/UCA0SIMO25

XOUT/P2.75

P2.4/TA2/A4/VREF+/VeREF+/OA1I030

P1.2/TA133

P2.1/TAINCLK/SMCLK/A1/OA0O9

AVCC16

P2.0/ACLK/A0/OA0I08

P4.7/TBCLK24

P4.2/TB219

P3.1/UCB0SIMO/UCB0SDA12

AVSS15

TEST/SBWTCK1

P4.5/TB2A1422

P1.0/TACLK/ADC10CLK31

P2.2/TA0/A2/OA0I110

P1.4/SMCLK/TCK 35

P1.1/TA032

P1.5/TA0/TMS 36

P2.5/ROSC3

CC2500

GDO23

R_BIAS 17

XOSC_Q210 XOSC_Q1

8

GDO0(ATEST)6

SO(GDO1)2

DVDD4

DCOUPL5

AVDD9

GND19

DGUARD18

GND16

RF_P12RF_N13

AVDD15CSn

7AVDD

14

SI20

SCLK1

AVDD11

R356 K

C710 nF

R447 K

J1

CONN PCB 6-R

123456

26.0 MHz

C527 pF

C627 pF

C10100 pF

C11 100 pF

C121.0 pF

C131.0 pF

C141.8 pF

C151.5 pF

ISO1

12

54

ISO2

12

54

1234

R547 K

R647 K

+12VDC Supply

R122 E4

R122 E5

R122 E6

Figure 4.2.1: Control Unit Schematic

4-3. Lighting Unit

The lighting unit is required to capture solar energy, store that energy for later use, receive a RF signal to activate its lighting array, and transmit a signal to other lighting units to activate their lighting arrays and retransmit the control signal. With all these requirements, the lighting units are significantly more complex than the master control unit. The lighting unit gathers solar energy using a series pair of PowerFilm MP3-37 thin film photovoltaic cells, each rated at 3V nominal at a maximum current of 50mA. The photovoltaic cells are connected in series and their 6 Volts are applied to the input of a TPS62050DGS adjustable output synchronous step-down converter. TI- TPS6205x

The TPS62050 is a high-efficiency inductive buck converter using PWM control and integrated N- and P-channel power MOSFET switches all in one small package. The adjustable TPS62050 requires an external feedback loop using a voltage divider circuit, an external power inductor, and two ripple-rejection capacitors.

The converter is set to 4.5V and is connected to the lithium-ion cell through an external Schottky diode having a voltage drop of 0.3V. This results in a regulated charge voltage of 4.2V to the Tenergy T18650 lithium-ion cell having a nominal voltage of 3.7V and capacity of 2200mAh. The lithium-ion cell supplies a TPS62056DGS fixed output synchronous step-down converter set at 3.3V. The TPS62056 has identical specifications to the TPS62050, and requires only an external feedback loop, a power inductor, and two

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ripple-rejection capacitors. The filtering capacitor on the output side of the 3.3V regulator requires a value of 100μF to ensure ripple-free power to the logic circuitry. The lighting array uses twelve white light emitting diodes mounted in two groups of 4 and 8 LEDs to enable various lighting levels. The LED array is controlled by a TPS2052B current limited power distribution switch drawing unregulated power directly from the Li-Ion cell.

TI- TPS2052B The TPS2052B is a dual channel switch using a pair of 70 mΩ N-channel

MOSFET power switches whose gates are driven by an internal charge pump resulting in complete isolation between the control side and the power side of the IC. The TPS2052B is current limited to 500mA and has an undervoltage lockout at 2.7V which will prevent damage to the Li-Ion cell from excessive discharge.

TI- MSP430F2274 A MSP430F2274 microcontroller is used to control the lighting unit. The

MSP430 is a low power device with a 16-bit RISC CPU, 32KB of non-volatile flash memory, and 1KB of RAM. The microcontroller is powered from the Vcc bus off of the TPS62056 3.3V power converter. The MSP430 is interfaced with the TPS2052B power distribution switch and the CC2500 RF transceiver.

TI- CC2500 The CC2500 is a 2.4 GHz radio frequency transceiver integrated with a

configurable baseband modem. The CC2500 is a low-power device that can polled at low duty cycles to save power due to its fast startup time. The CC2500 uses a 26 MHz crystal oscillator for a frequency reference. A simple microstrip folded dipole antenna with 7.4 dB of gain is used with the CC2500 transceiver.

The complete light unit schematic is shown in Figure 4.3.1 below and in

Appendix A.

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MSP430F2274IDA

U1

P3.5/UCA0RXD/UCA0SOMI26

P4.1/TB118

DVCC2

P3.2/UCB01SOMI/UCB0SCL 13

RST*/NMI/SBWTDIO7

P1.3/TA2 34

DVSS4

P1.6/TA1/TDI/TCLK 37

P4.4/TB1A1321

XIN/P2.6 6

P3.6/A6 27

P4.6/TBOUTHA1523

P2.3/TA1/A3/VREF-/VeREF-/OA1I1/OA1O 29

P3.0/UCB0STE/UCA0CLK/A5 11

P3.7/A728

P4.3/TB0/A1220

P1.7/TA2/TDO/TDI 38P3.3/UCB0CLK/UCA0STE

14

P4.0/TB017

P3.4/UCA0TXD/UCA0SIMO25

XOUT/P2.75

P2.4/TA2/A4/VREF+/VeREF+/OA1I0 30

P1.2/TA1 33

P2.1/TAINCLK/SMCLK/A1/OA0O9

AVCC16

P2.0/ACLK/A0/OA0I08

P4.7/TBCLK 24

P4.2/TB219

P3.1/UCB0SIMO/UCB0SDA 12

AVSS15

TEST/SBWTCK1

P4.5/TB2A1422

P1.0/TACLK/ADC10CLK 31

P2.2/TA0/A2/OA0I110

P1.4/SMCLK/TCK 35

P1.1/TA032

P1.5/TA0/TMS36

P2.5/ROSC3

CC2500

U2

GDO23

R_BIAS17

XOSC_Q210 XOSC_Q18

GDO0(ATEST)6

SO(GDO1)2

DVDD 4

DCOUPL5

AVDD 9

GND 19

DGUARD 18

GND 16

RF_P 12RF_N 13

AVDD 15CSn7 AVDD 14

SI20

SCLK1

AVDD11

TPS62050DGSU3

PG 4

LBO 2

3

GND

SW 9

LBI6

10

PGND

EN8

SYNC7

FB 5VIN1

TPS62056DGSU4

PG 4

LBO 2

3

GND

SW 9

LBI6

10

PGND

EN8

SYNC7

FB 5VIN1 Vcc

R356 K

D1

1PS76SB10

TPS2052BDRU5

EN24IN2

GND1 OUT2 6OUT17

EN13

OC2 5

OC1 8

PROGRAMMINGHEADER

3.7VT18650 Li-Ion

C710 nF

SLX-LX5093UWC/C

L1 10 uH

R447.5 K

R1768 K

R293.1 K

LED1H1

123456

LED2

C8 220 pF

C9C10

C27.0 pF

C322 uF

C110 uF C11

10 uF

LED1LED2

MP3-373V / 50mA

MP3-373V / 50mA

26.0 MHzX1

L2 10 uH

C527 pF

C627 pF

C4100 uF

Vcc

Figure 4.3.1: Light Unit Schematic

4-4. Power Analysis, Lighting units

The lighting units must be built to operate independently of external power sources, and will be deployed on an airfield with varying solar exposure and weather conditions. With this requirement in mind, the lighting unit must be able to collect more energy than would be needed for operation according to the requirements analysis such that energy could be stored for future use. Solar energy is captured with the PowerFilm Solar MP3-37 thin film photovoltaic cells wired in a series configuration that will provide 6V and 50mA with direct solar exposure. Assuming 12 hours of daylight with 4 hours of direct exposure and 8 hours of indirect exposure, the amount of energy captured can be calculated as follows:

mAhmAmAEEE INDIRECTDIRECTtotal 400)25(8)50(4 =+=+= ∑ Using a TPS62050 inductive buck-converter and assuming an efficiency of 92% as predicted by the converter’s datasheet, the amount of energy delivered to the battery is approximately 368mAh. A potential concern with using a Lithium-Ion cell is to protect the cell from both over- and under-charging. The manufacturer’s datasheet on the Tenergy T18650 3.7V 2,200mAh lithium-ion cell instruct that charging should be done under a constant voltage of 4.2V and current limited. The TPS62050 delivers 4.2V to the battery after subtracting the forward voltage of the Schottky diode used for reverse current flow protection. Under testing with a bench power supply, the current delivered to the cell would decrease to micro-amp levels as the cell voltage reached 4.2V. With photovoltaic cells supplying the power converter, the maximum current that could be delivered to the cells is only 50mA. Overcharging is therefore not considered an issue. Undercharge protection is contained within the TPS62056 power converter supplying

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power to the logic circuitry. When the battery voltage drops below 2.7V, this exceeds the dropout voltage of the logic power converter and load is removed from the cell. The LED array requires 120mA of current with all the lights on as measured. If the runway lights were required to be lit for a total of one hour, then only 120mAh of the Li-Ion battery’s 2,200mAh capacity is to be used for lighting. The control circuitry including the MSP430 microcontroller and the CC2500 radio transceiver will be operated such that the CC2500 polls once every second then shuts down if no packet is received. The CC2500 requires 8.1μA in this configuration, and the MSP430 requires 270μA in active mode. Assuming that the pair use an average of 280μA when in standby (defined as polling the radio every second waiting for a command signal), the energy required is only approximately 7mAh per day. The energy requirements of the control circuitry are insignificant compared to the amount of energy captured. The lighting unit can therefore remain in standby for weeks without significant sunlight before the battery is depleted.

4-5.Circuit operation and Coding As mentioned earlier control of each lighting unit will be accomplished by integrating a Texas Instruments MSP430 microcontroller and a Texas Instruments-Chipcon CC2500 RF transceiver into each unit. The lighting units will be pilot activated using a Hamtronics R122 Aircraft Band Receiver2 interfaced with another MSP430 and CC2500 in a master control cabinet. The R122 will receive the aircraft’s signal as a series of microphone clicks over a given period of time and activate one of three outputs to set intensity levels. These outputs will be connected to input ports on the MSP430 microcontroller which will then interpret the selected lighting intensity and send that code to the RF transceiver which will repeat the transmission for a set period of time expected to be 1 to 3 seconds. The nearest lighting units will receive the transmission from the master controller and will then pull their microcontrollers out of low power mode by means of an interrupt. The microcontroller will read the intensity code, activate the appropriate LED array, and start its internal clock for 5 minute activation (with shutdown warning flashes to begin at 4 minutes 30 seconds elapsed time). The microcontroller then sends a command to the RF transceiver chip to transmit the activation code for 1 second. At this point, the microcontroller will be set to ignore further signals from the RF transceiver for a period of 30 seconds as the control signals propagate down the length of the runway. As the maximum range of an individual transmission will only need to be 250 ft, RF power levels and consequently power consumption will be kept at a minimum. The short range of transmission will also allow the requisite RF antenna(s) to be fabricated using inexpensive microstrip techniques built onto the main printed circuit board rather than requiring an external whip antenna. The actual code of this operation is attached in Appendix A along with a flow chart in Figure A-3.

2 Hamtronics R122 Airband Receiver: http://www.hamtronics.com/r122.htm

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4-6. Physical Design The lighting unit is intended to be housed inside inexpensive materials such as PVC pipe, and as such is a circular design of 3.25” diameter. The LED lighting array is to be mounted on a set of four riser boards pointed outward at a slight upward angle.

The housing for these units is designed using existing off-the-shelf materials that will be both inexpensive and simple to fabricate. Durability is also an important consideration because the housings will be left in the elements for their entire design lifespan; therefore, the materials chosen must operate under a wide temperature range. The housing will be fabricated out of polyvinyl chloride (PVC) and the lamp lens will be fabricated from cast acrylic. The PVC housing consists of three components, a ground stake made of 3/4” (nominal) schedule-40 water pipe, a body consisting of a 3” (nominal) drain pipe cap, and a solar disc made of 1/16” PVC sheet stock. The ground stake and body are to be bonded with PVC cement, as are the body and solar disc. The lamp lens assembly is to be fabricated from 3” ID cast acrylic tubing with a wall thickness of 1/8” bonded with IPS Weld-On #4 acrylic cement to a top cap of 1/8” cast acrylic sheet stock. The lens assembly is then bonded to the solar disc/body tube assembly, and upward facing joints will be caulked with silicone adhesive. After the solar cells are bonded to the solar disc and electrical connections established, the cells will be laminated with sheet of 0.060” cast acrylic to protect them from weather effects. Finally, the lens and solar cells are to be masked off, and the entire assembly painted with industrial grade fluorescent marking enamel, standard orange hazard color. The design utilizes inexpensive existing materials which can be easily hand assembled on a small scale, but could also be scaled-up to mass production using purpose-built molds.

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Figure 4.6.1: Housing design of lighting units.

The printed circuit board was designed in EAGLE 4.13 as a two layer all-surface-

mount PCB. All traces were hand routed with 10 mil widths for data traces and 24-32 mil widths for power traces. All vias used a 20 mil diameter. The entire bottom layer, except for several interconnect traces, is ground plane. IC pads used include a DA38 TSSOP SMT package used for the MSP430F2274IDA, a QLP20 quad leadless package used for the CC2500, MSOP10 SMT package used for the TPS6205x power converters, and the SOIC8 used with the TPS2052 power switch. With the exception of the MSOP10, the packages were available in the EAGLE libraries. The RF transceiver uses a folded dipole antenna fabricated from microstrip traces according to Texas Instruments design note DN004 on the CC25xx family of RF transceivers. The bottom ground plane is absent below the microstrip antenna. Silkscreen component labeling was added to the top layer of the board for ease of assembly. The single lighting unit PCB was then copied and tiled in the EAGLE editor to fill a 12x12” PCB blank for most economical production. The PCB layout is shown in Figure 4.6.2 below.

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Figure 4.6.2: Lighting Unit PCB Layout [RED-top layer, BLUE-bottom layer, GREEN-via]

The PCBs were fabricated using the Quick-turn Q2 service from Sunstone Circuits. This process creates a .062” 1-oz copper FR4 printed circuit board in a photolithography process. The board may be up to two layers, has tinned pads, plated through-holes/vias, soldermask layer on both sides, and silkscreen on the top layer. The individual lighting units are then separated from the 12x12” production board with a scroll saw. Assembly of the prototype lighting units is performed by hand using a hot air process for all surface mount ICs and discrete components smaller than 0603 packages. Solder paste was applied to the pads on the PCB for the device to be mounted, and then the larger packages were held in place with Kapton tape or smaller components with fine tweezers. Hot air was applied from a Xytronic HAP-60 hot air pencil to reflow the solder paste, and then bond the components once reflow was complete and the air

12

temperature ramped up. Visual and electrical inspection of all solder joints is performed after the component is in place. Components such as power supply capacitors and inductors were soldered in place with a temperature regulated pencil tip iron from a Xytonic 988-D rework station. A completed lighting unit PCB is shown in Figures 4.6.3 and 4.6.4 below. The semi-completed lighting unit is shown with the solar disc attached for charging tests in Figure 4.6.5.

Figure 4.6.3: Completed Lighting Unit PCB

Figure 4.6.4: Completed Lighting Unit, Side View

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Figure 4.6.5: Completed Lighting Unit with Solar Disc

5. Statement of Work

Initial power supply testing was conducted using a pair of Texas Instruments TPS62050EVM power converter evaluation modules, neither of which was functional upon arrival. All extraneous passive components were removed from the EVM boards such that the design matched the published TI reference circuit. Both power converter ICs were replaced using a hot air rework process, with one of the converters changed to a TPS62056 fixed voltage power converter. The TPS62050 was set to output a voltage of 4.2V, and a series pair of MP3-37 photovoltaic cells connected to the input terminals. With direct sunlight, the charging system was capable of delivering 4.2V at 50mA as rated. Connecting the output of the power converter EVM to the Li-Ion battery, the charging system was capable of delivering 50mA to the battery when the cell voltage was 3.6V. When the solar lighting levels dropped to twilight levels, a reverse flow of just less than 5mA was observed. In order to prevent power losses from reverse flow and to protect the power converter and photovoltaic cells from damage, a Schottky diode with a forward voltage of 0.35V was installed on the output of the power converter. Increasing the output voltage of the converter to 4.5V rendered the same performance as before. With the power converter circuitry installed on the prototype circuit boards, the battery charging converter performed just as did the evaluation module. The 3.3V logic circuitry regulator, the TPS62056 showed a measured output voltage of 1.56V and the output waveform showed a significant amount of ripple with the average level at 1.56 as measured. A 10μF capacitor was applied across the power input rail and output levels

14

were then 3.3V as rated. A significant amount of power supply noise and ripple could be observed on an oscilloscope, and this noise was overwhelming the signal from the crystal oscillator on the CC2500 transceiver. The anti-ripple capacitor size was increased from the 22μF value suggested in the TI reference design to a 100μF electrolytic. This removed all remaining ripple and a clean clock waveform could be observed from the crystal oscillator. Once the power supply noise had been remedied and a clean clock signal appearing on the oscillator terminals, it was expected that the CC2500 would then be able to transmit and receive using the TI distributed temperature sensor sample code. When the CC2500 is transmitting, a slight spike can be observed on the otherwise DC waveform seen on the antenna terminals. The CC2500 is not functioning because of either of the following: incorrectly sized power supply decoupling capacitors or thermal damage to the IC during installation. The device datasheet mentions IPC/JEDEC J-STD-020D soldering standard, which must be purchased. Excerpts of the standard mention a maximum reflow temperature of 235°C which is lower than the minimum available temperature on the hot air pencil. Attempting to solder the devices using minimum temperature settings on the hot air pencil failed to melt the solder paste as the circuit traces were acting as a heat sink. In order to successfully solder the CC2500 RF IC to the fabricated circuit boards a reflow oven will be necessary. Otherwise the fabrication will have to be contracted out to a prototyping facility with the proper equipment. The MSP430 is fully functional as the microcontroller can be programmed by a computer, and its outputs can be controlled from the debug interface. Activating the lighting arrays through ports P3.3 and P3.4 on the MSP430, the logic high output levels do turn on the LED array through the TPS2052 NMOS power switch. In order to complete testing of the proof of concept units, three circuit boards were assembled with power converters and the TPS2052 power control IC installed. An EZ430-RF2500 evaluation module was then wired to the completed power supplies. The boards were installed in a completed housing. With this configuration, the lights can be controlled through the debug interface of the MSP430, and the microcontroller/RF combination runs the TI distributed temperature sensor code and communicates with an access point. However, completion of a purpose specific code based on peer-to-peer signaling has been significantly delayed by the lack of documentation on coding using the SIMPLICI-TI networking protocol, particularly in a p2p configuration. Further testing of the radio controlled system will be completed if better code documentation becomes available. An analog version of the runway lighting unit that senses light levels and battery voltages to control light activation requiring only minor modifications to the lighting unit PCBs was constructed and is fully described in Appendix B.

15

6. Resources

6-1. Personnel This project involves three Electrical Engineering students; Matthew Anker, Clint Heiney, and Jeffery Endicott. Each has 4 years in the Ohio State University Engineering program. They are all preparing to graduate with degrees in electrical engineering.

Matthew Anker has an extensive background in general aviation as an instrument rated private pilot flying Cherokee's off of a private grass airfield. Electrical engineering experience includes coursework in electromagnetics, microwave circuits, and analog/mixed signal circuitry. Matt has run an audio electronics modification firm, SACDmods.com, for 6 years and has experience and equipment for fabrication of the design.

Clint Heiney’s background is imbedded in power system analysis and electric machines. Other skills that will benefit this project are experience with lab work on microprocessor and digital logic. Project history includes a Microwave circuit where he gained extensive knowledge on the benefits of utilizing Matlab for design purposes.

Jeff Endicott has taken the Resolve class series, ECE 561, and ECE 662. The resolve series studies good programming practices. ECE 561 is a class in the use and design of basic computer chips. ECE 662 studies the design and operation of microprocessors. Also taken an internship with JDSU where he studied VoIP and IMS.

6-2. Facilities and Equipment

The University will provide meeting area as well as resources to buy most of the parts to make a prototype of the system. Labs with ample computers and internet access will be utilized in any/some testing. The following items will be needed to construct and test the working prototypes. Further details on testing equipment and facilities are listed here.

1. Matt Anker’s SACDmods mobile shop:

• Test Equipment: a) Tektronix 7904 500MHz analog oscilloscope b) Fluke 73-III auto-ranging digital multimeter c) BK Precision 875B LCR meter

• Fabrication Equipment: a) Xytronic 988D digital soldering station HAP-60 hot air pencil b) Delta SM600 scroll saw

• Programmer:

16

a) TI EZ430-RF2500 Development Tool modified with .100” plug b) Dell Inspiron 1000 with Windows XP Pro

2. Caldwell Laboratory, Room 239 • Used primarily as a meeting room, and design discussion with the

professor and assistant.

7. Schedule and Costs

7-1. Schedule History The division of labor over the 9 week design is shown in Table 7.1.1 on the following page.

17

7-2. Cost Preliminary costs of the main circuit components are shown below in Table 7.2.1. Housing and final costs will be calculated upon completion.

18

Table 7.2.1: Main circuit component costs. Part Ref. Mfg. Part # Description DK P/N Unit Price

U1 MSP430F2274IDAR IC MCU 16BIT 32K FLASH 38-TSSOP 296-21439-1-ND $5.3600

U2 CC2500RTKR IC RF TXRX SNGL-CHIP LP 20-QFN 296-19586-1-ND $2.7000

U3 TPS62050DGSR IC STEP-DOWN CONV HI-EFF 10-MSOP 296-14392-1-ND $3.3300


U5 TPS2052BDR IC POWER DIST SWITCH DUAL 8-SOIC 296-17451-1-ND $1.1000

L1 SLF7032T-100M1R4-2-PF INDUCTOR SHIELD PWR 10UH 7032 445-1998-1-ND $0.9650


X1 NX3225SA-26.000000MHZ CRYSTAL 26.000000 MHZ SMD 8PF 644-1054-1-ND $0.6130

H1 22-28-4060 CONN HEADER 6POS .100 VERT TIN WM6406-ND $0.4040

C1 ECE-V1CS100SR CAP 10UF 16V VS ELECT SMD PCE3061CT-ND $0.1960

C2 ECJ-0EC1H070D CAP 7.0PF 50V CERAMIC 0402 SMD PCC070CQCT-ND $0.0141

C3 ECE-V0JS220WR CAP 22UF 6.3V ELECT VS SMD PCE3308CT-ND $0.1820

C4 ECE-V0JA101SP CAP 100UF 6.3V ELECT VS SMD PCE3058CT-ND $0.2400

C5 ECJ-0EC1H270J CAP 27PF 50V CERAMIC 0402 SMD PCC270CQCT-ND $0.0141


C7 ECJ-0EB1C103K CAP 10000PF 16V CERAMIC 0402 SMD PCC103BQCT-ND $0.0141





D1 1PS76SB10 T/R DIODE SCHOTTKY 30V 200MA SOD323 568-3406-1-ND $0.0875

D2-13 SLX-LX5093UWC/C LED 5MM WHITE WATER CLEAR LENS 67-1691-ND $0.6628

R1 ERJ-3EKF7153V RES 768K OHM 1/10W 1% 0603 SMD P768KHCT-ND $0.0279

R2 ERJ-3EKF9532V RES 93.1K OHM 1/10W 1% 0603 SMD P93.1KHCT-ND $0.0279

R3 ERJ-2RKF5622X RES 56.2K OHM 1/16W 1% 0402 SMD P56.2KLCT-ND $0.0304

R4 ERJ-2RKF4752X RES 47.5K OHM 1/16W 1% 0402 SMD P47.5KLCT-ND $0.0304

S1 MP3-37 PowerFilm MP3-37 3 Volt 50 mA Thin Flexible Solar Module $5.9500


B1 18650 Tenergy Li-Ion 18650 3.7V 2200mAh Battery $4.8900

Printed Circuit Board $3.0000

Housing $7.0000

TOTAL $47.3365

19

8. Design Review Discussion

The design of the runway lighting units has been subject to delays since the very beginning of the project and related design competition. Parts were difficult to obtain, often did not work on arrival, and manufacturer technical/engineering support was not readily available. Development of this design began in Autumn quarter of 2007 with conceptual design completed at that time, and components tentatively chosen. Design and testing began Winter quarter of 2008. During this time the evaluation modules for the charging system were tested, the power distribution switch was tested, and the LED lighting array’s power consumption measured. Some evaluation of the EZ430-RF2500 EVM was completed using an evaluation board that a team member personally purchased. A circuit board based on the reference designs for the various TI components was laid out in EAGLE printed circuit board CAD and fabricated. Sample components were soldered to the PCBs using a hot air rework process previously described. Charging, power distribution, and microcontroller systems on the PCBs functioned properly, but the RF integrated circuits had unpredictable failures. Problems with the RF system can be attributed to soldering problems because none of the equipment available to the team is capable of properly heating the CC2500 RFIC. In order to test these designs an IR reflow oven will have to be purchased or the assembly contracted out to a prototype facility.

Using the EZ430-RF2500 evaluation modules in place of the MSP430/CC2500 pair on the circuit boards, RF link can be demonstrated using TI sample code, and as before the lights can be controlled by accessing the registers of the microcontroller through the debug interface. However, the lack of documentation on peer to peer networking using the SIMPLICI-TI networking protocol has further delayed the coding. The code included in this report is only partially functional, and operates the microcontroller and RF circuitry in fully active mode such that the system uses too much power to be useful. The pilot-controlled version will be completed at some time in the future. Finally an all-analog version of the runway lighting system was constructed due to the problems with the development of the pilot-controlled version. As described in Appendix B, the light controlled version uses many of the same parts as the more complex pilot-controlled version, but uses a comparator to determine the appropriate solar light level for activation. This version has been tested for 2 weeks during the Spring and is capable of collecting enough solar energy to operate for an entire night. As this system is built from simple and proven technology, commercial development may follow a series of full scale field tests to commence Fall of 2008.

A-1

Appendix A:

Figure A-1: Detailed Control unit schematic

A-2

Figure A-2: Detailed Lighting unit schematic

A-3

Figure A-3: Flow chart for lighting unit..

A-4

Figure A-4: Detailed Physical dimensions and layout of housing.

A-5

Code

Master control unit #include "bsp.h" #include "mrfi.h" #include "nwk_types.h" #include "nwk_api.h" #include "bsp_leds.h" #include "bsp_buttons.h" #include "vlo_rand.h" #include "nwk.h" void linkTo(void); void MCU_Init(void); void main (void) WDTCTL = WDTPW + WDTHOLD; // Stop WDT // delay loop to ensure proper startup before SimpliciTI increases DCO // This is typically tailored to the power supply used, and in this case // is overkill for safety due to wide distribution. volatile int i; for(i = 0; i < 0xFFFF; i++) // SimpliciTI will change port pin settings as well P1DIR = 0xFF; P1OUT = 0x00; P2DIR = 0x00; // P2 will be an input from the hamtronics P3DIR = 0xC0; P3OUT = 0x00; P4DIR = 0xFF; P4OUT = 0x00; P1OUT = 0x00; BSP_Init(); SMPL_Init(0); linkTo(); void linkTo() BSP_TOGGLE_LED1(); //red BSP_TOGGLE_LED2(); //green NWK_DELAY(0xFFFF); NWK_DELAY(0xFFFF); NWK_DELAY(0xFFFF); NWK_DELAY(0xFFFF); NWK_DELAY(0xFFFF); if (BSP_LED1_IS_ON())

A-6

BSP_TOGGLE_LED1(); if (BSP_LED2_IS_ON()) BSP_TOGGLE_LED2(); uint8_t msg[1]; int high = 1, low = 2; while (1) if (P2OUT == 0x01 || P2OUT == 0x11) if(P2OUT == 0x01) msg[0] = high; else msg[0] = low; //wait "a while" NWK_DELAY(0xFFFF); NWK_DELAY(0xFFFF); // send. doesnt need to be link to anyone they just have to listen int i = 20; //try for 20 secs while (SMPL_SUCCESS != SMPL_Send(SMPL_LINKID_USER_UUD, msg, sizeof(msg)&& i >0)) int j = 12000; // Delay 1 sec do (j--); while (j > 0); //keep trying /*------------------------------------------------------------------------------ * ADC10 interrupt service routine ------------------------------------------------------------------------------*/ #pragma vector=ADC10_VECTOR __interrupt void ADC10_ISR(void) __bic_SR_register_on_exit(CPUOFF); // Clear CPUOFF bit from 0(SR)

Lighting unit #include "bsp.h" #include "mrfi.h" #include "nwk_types.h" #include "nwk_api.h" #include "bsp_leds.h"

A-7

#include "bsp_buttons.h" #include "vlo_rand.h" #include "nwk.h" void linkTo(void); void MCU_Init(void); void main (void) WDTCTL = WDTPW + WDTHOLD; // Stop WDT // delay loop to ensure proper startup before SimpliciTI increases DCO // This is typically tailored to the power supply used, and in this case // is overkill for safety due to wide distribution. volatile int i; for(i = 0; i < 0xFFFF; i++) // SimpliciTI will change port pin settings as well P1DIR = 0xFF; P1OUT = 0x00; P2DIR = 0x3F; // set P2.3,4 to output direction to control lights P2OUT = 0x00; P3DIR = 0xC0; P3OUT = 0x00; P4DIR = 0xFF; P4OUT = 0x00; P1OUT = 0x00; //initiate chip BSP_Init(); TACCR0 = 12000; // ~ 1 sec //initiate the SympliciTI network SMPL_Init(0); linkTo(); //start main program void linkTo() uint8_t msg[1], len; //define the recieving class //signal the start main fuction BSP_TOGGLE_LED1(); //red BSP_TOGGLE_LED2(); //green NWK_DELAY(0xFFFF); //delay the lights so they can be seen easley NWK_DELAY(0xFFFF); //turn off the LEDs if (BSP_LED1_IS_ON()) BSP_TOGGLE_LED1(); if (BSP_LED2_IS_ON()) BSP_TOGGLE_LED2();

A-8

int ONLOW = 1, ONHIGH = 2; // set the light conditions while(1) //main loop BSP_TOGGLE_LED2(); //green -signal in main loop waiting for a recieved transmission NWK_DELAY(0xFFFF); NWK_DELAY(0xFFFF); //delay the lights so they can be seen easley NWK_DELAY(0xFFFF); if (BSP_LED2_IS_ON()) BSP_TOGGLE_LED2(); NWK_DELAY(0xFFFF); NWK_DELAY(0xFFFF);//delay the lights so they can be seen easley NWK_DELAY(0xFFFF); //this will accept a message from any device they do not have to be link if (SMPL_SUCCESS == SMPL_Receive(SMPL_LINKID_USER_UUD, msg, &len)) //did we recieve a message? if (len && (msg[0] == ONHIGH || msg[0] == ONLOW)) //is it valide if(msg[0] == ONHIGH)//need lights on high? P2OUT |= 0x18; //turn lights on high else //else they go on low P2OUT |= 0x08; //turn lights on low int i = 30, sent = 0; //for at least 30 sec try to send to next device for 30 secs while(i > 0 && sent == 0) BSP_TOGGLE_LED2(); //green- try to send the received message int j = 12000; // Delay 1 sec do j--; //this will try to send a message to any device without being link //the recieving device only has to be listening if(SMPL_SUCCESS == SMPL_Send(SMPL_LINKID_USER_UUD, msg, sizeof(msg))) //was the sending a success? //if yes then stop trying //wait "a while" NWK_DELAY(0xFFFF); NWK_DELAY(0xFFFF);//delay the lights so they can be seen easley NWK_DELAY(0xFFFF); BSP_TOGGLE_LED1(); //red -recieved message sent NWK_DELAY(0xFFFF); NWK_DELAY(0xFFFF);//delay the lights so they can be seen easley NWK_DELAY(0xFFFF); if (BSP_LED1_IS_ON()) BSP_TOGGLE_LED1(); sent = 1;

A-9

while (j != 0 && sent == 0); i--; i = 270; // Delay 4min 30 secs //keep lights in for another 4 min 30 sec do i--; int j = 12000; // Delay 1 sec do (j--); while (j != 0); while (i != 0); //after 4 min 30 sec start too flash lights if(msg[1] == ONHIGH)//if lights on high flash high // toggle turn-on high for(i = 30;i > 0; i--) // Delay 30 sec P2OUT ^= 0x18; int j = 12000; // Delay 1 sec do (j--); while (j != 0); P2OUT &= ~0x18; // Clear P2.0 LED off - lighst off else//else flash lighst low // toggle turn-on low for(i = 30;i > 0; i--) // Delay 30 sec P2OUT ^= 0x08; int j = 12000; // Delay 1 sec do (j--); while (j != 0); P2OUT &= ~0x08; // Clear P2.0 LED off- lights off //if no message recieved or a message was just handled then sleep for 1 sec SMPL_Ioctl( IOCTL_OBJ_RADIO, IOCTL_ACT_RADIO_SLEEP, "" ); __bis_SR_register(LPM3_bits+GIE); // LPM3 with interrupts enabled SMPL_Ioctl( IOCTL_OBJ_RADIO, IOCTL_ACT_RADIO_AWAKE, "" ); /*------------------------------------------------------------------------------ * ADC10 interrupt service routine ------------------------------------------------------------------------------*/ #pragma vector=ADC10_VECTOR __interrupt void ADC10_ISR(void) __bic_SR_register_on_exit(CPUOFF); // Clear CPUOFF bit from 0(SR)

A-10

/*------------------------------------------------------------------------------ * Timer A0 interrupt service routine ------------------------------------------------------------------------------*/ #pragma vector=TIMERA0_VECTOR __interrupt void Timer_A (void) __bic_SR_register_on_exit(LPM3_bits); // Clear LPM3 bit from 0(SR)

B-1

Appendix B: Light Level Controlled Runway Lighting Unit System Design A “pure hardware” design was desired due to delays in the coding for the radio controlled lighting system, resulting in the light controlled variant of the previously described system. This design can be built using modified printed circuit boards designed for the radio controlled system, and also required four integrated circuits. Components Used TI- TPS6205x The TPS6205x is a 95% efficient synchronous step-down converter. The device pulses

current through an external inductor based on an internal frequency reference that is typically 850kHz. The compact MSOP-10 package is capable of handling 800mA output current, and is available in fixed-voltage and adjustable-voltage versions.

TI- TPS2090D The TPS2090D is a dual channel switch using a pair of 70 mΩ N-channel MOSFET

power switches whose gates are driven by an internal charge pump resulting in complete isolation between the control side and the power side of the IC. The TPS2090D is current limited to 500mA and has an undervoltage lockout at 2.7V which would theoretically prevent damage to the Li-Ion cell from excessive discharge.

TI- TLV3492 The TLV3492 is a dual channel, push-pull output, comparator. The device operates on

supply voltages as low as 1.8V using CMOS technology, and has an extremely low supply current of 0.8μV, and is referred to as a nanopower device.

Solar energy is collected by four PowerFilm MP3-37 thin film photovoltaic cells configured as 6V pairs. This configuration yields 6V at 100mA into the TPS62050 DC/DC buck converter under full direct sunlight. The DC/DC converter is set to 4.5V and charges a Tenergy 18650 Li-Ion cell through a Schottky diode for isolation. The battery provides power to a TLV3492 dual channel low power comparator which compares the voltage output from the solar cells to a 0.3V reference set by a Schottky diode. If the solar cell voltage drops below 0.3V, then output one goes high. Using the photovoltaic cell as a light reference allows the standard resistive photocell to be omitted. The other channel compares the battery voltage to a 2.7V Zener diode voltage reference, and output two goes low when required to protect the lithium cell. The TLV3492 comparator drives a TPS2090D dual channel power distribution switch. Channel one of the chip closes when the comparator detects that the ambient light is low enough

B-2

to turn on the LED array. The output of channel one is looped back to the power input of channel two, which is closed when the comparator determines that the lithium cell has sufficient voltage. The TPS2090D drives the input of a TPS62056 fixed voltage DC/DC buck converter. The TPS62056 is set to output 3.3VDC nominal at 95% efficiency, and in this application is delivering 3.1V to the LED array comprised of eight white LEDs. The power converter maintains the LED array at a constant light level for most of the runtime and by reducing voltage drain reduces the current draw.

Figure B-1: Light Controlled Runway Light--System Schematic Power Analysis Unlike the radio controlled version of the lighting system, the light controlled version must capture significantly more solar energy. Four of the MP3-37 photovoltaic cells are used on this design rather than the two cells in the radio controlled version. This configuration yields 6VDC at 100mA in direct sunlight. The more robust four cell design is able to capture still significant energy under obscured sunlight. Power outputs of 50mA can be observed on days when the cloud ceiling can be described as broken, and 25mA under an overcast layer. Usable charging current has been observed under a thick, low altitude overcast. Assuming 100mA for four hours and partial sunlight providing 40mA for eight hours, the power stored in the battery is as follows: mAhmAmAEEE INDIRECTDIRECTtotal 720)40(8)100(4 =+=+= ∑ The power consumption of the control circuitry is 0.24mA in the off-state. Power consumption with the LED array activated is 95mA. Based on the 720mAh delivered to the battery during the charge cycle, the effective runtime of the lighting unit is just under eight hours. As cell voltage decreases so does the current draw from the LED array, and visible light can still be observed after a 10 hour runtime. Cost Analysis The light controlled version of the runway lighting unit uses the same housing as the radio controlled design which is described in Section 4.6. For test and evaluation purposes the same printed circuit board can be used, although this design requires less board area for implementation.

B-3

Table B-1: Light-Controlled Lighting Unit Bill of Materials

Part Ref. Mfg. Part # Description DK P/N Unit Price


U2 TLV3492AID IC COMPARATOR P-P NANOPWR 8-SOIC 296-14054-5-ND $0.8700

U3 TPS2090D IC POWER DIST SWITCH DUAL 8-SOIC 296-3437-5-ND $0.9100





C2 ECJ-0EC1H070D CAP 7.0PF 50V CERAMIC 0402 SMD PCC070CQCT-ND $0.0141




D1 1PS76SB10 T/R DIODE SCHOTTKY 30V 200MA SOD323 568-3406-1-ND $0.0875

D2 MAZ30270HL DIODE ZENER 2.7V 200MW MINI 3P MAZ30270HLCT-ND $0.2050

D3-11 SLX-LX5093UWC/C LED 5MM WHITE WATER CLEAR LENS 67-1691-ND $0.6628

R1 ERJ-3EKF7153V RES 768K OHM 1/10W 1% 0603 SMD P768KHCT-ND $0.0279








B1 18650 Tenergy Li-Ion 18650 3.7V 2200mAh Battery $4.8900

Printed Circuit Board $3.0000

Housing $7.0000

Total Cost $49.1568

Performance Analysis The light controlled version of the runway lighting system has a demonstrated runtime of 10 hours when operated in the summer months when the daylight period is 14 hours and the night 10 hours. This means that the runway lighting system is proven acceptable for use in the tested region of 40° North Latitude during the Spring/Summer months. This system would be effective for VFR (visual flight rules) use when supplemental runway lighting would be a safety benefit to the pilot. Given that most recreational night flights are conducted at twilight or no more than several hours afterward, this would be extremely effective for lighting a grass runway.

B-4

Figure B-2: Light-Controlled Lighting Unit Prototype

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Figure B-3: Light-Controlled System Schematic (Full Size)

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B-5

Documents

Runway Lighting