A Data Network for Emergency Communication Tucker Dunham, KD2JPM Abbie Heim, KD2PUA 1
About Me • Tucker – KD2JPM • Licensed: October 2016 • Warren County, NJ • Eagle Scout • Junior at Warren County Technical School- Electronics • Certified Electronics Technician Associate • Placed 2 nd in NJ SkillsUSA for Electronics Technology. 2
About Abbie 3
Cellphone Service in Puerto Rico after Hurricane Maria Source: FCC Communications Status Report September 28, 2017 4
Communication During Emergencies During Emergencies passing accurate information is key: Location of Shelters Medical Assistance Rescue Operations Food and Water Health and Welfare During Hurricane MARIA in the Puerto Rico, MOST communications systems were OFFLINE 5
Challenges Cannot rely on commercial power at all! Generators become useless when fuel cannot be obtained! 6
Inspiration 7
Requirements • Made with readily available materials • Easily manufactured and reproduced • Self Sustaining • Simple • Effective • Versatile • Portable • Low Cost 8
The Solution Portable Solar Powered Digipeater 9
Field Research When communicating information TEXT wins over VOICE “Text me the movie times ….” “Text me your address …..” “Text me where we should meet …..” As opposed to: “Wait let me find a pencil and paper …...” “How do you spell that?? P-E-R-R-I-E or with a Y ??” 10
Which Digital Mode? MESH networking uses 2.4, 3.4 and 5.8 GHz Bands Very unforgiving to path loss like trees and buildings Alignment is critical Typical Emergency traffic doesn’t require high - speed data or multimedia AX.25 1200 baud packet is sufficient for “text messages” 11
Packet Radio??? But that’s so 80s!! 12
What is Packet Digipeating Connect computers to radios with Terminal Node Controller (TNC) That forms the packets and modulates AND DEMODULATES DATA. Packet Framing and addressing 13
System Overview 14
Antenna Twin-Lead Half-Wave “J pole” inside of 1/2” PVC 15
3D Printed Parts 16
Solar panel holders Radio holders Threaded base Vertical mount for PI 17
Sketchup -Easy to use and free CAD software 18
Printer • Creality CR-10 3D printer 19
Container What shapes you considered What was the goals ….. Fit Good for solar panels Mechanical flow Weatherized Folding solar panel mounts The project was built to fit inside a cylinder because PVC is readily available, cheap and can be cut to size. • Solar panels can moved easily to follow the sun when mounted on a cylinder 20
Solar Panel Mounts Cylinder makes good platform for mounting solar panels 21
Power Supply Solar panels power radio, Raspberry Pi, and charge batteries during the day. Batteries power the system by night. 22
Block diagram of the power 23
Why SLA batteries Shape • SLA was used for their large energy density and how easy it is to charge. • Lithium-ion was considered, but the complexity required to charge them was not practical when using solar panels. • Liquid batteries could leak if the unit was knocked over. • Can survive being undercharged and overcharged more forgivingly than lithium batteries. 24
Voltage converters Describe them What each one does Why their different • The first voltage converter (buck/boost) that is wired directly to the solar panels steps down the voltage from the solar panels to the correct voltage to charge the batteries, keep them on standby during the day, and provide power to the second converter. • The second converter is a buck converter that steps the 13.8 volts from the first to the 7.6 volts required to power the Yaesu radio, • The third and provide power to the raspberry pi 5 volt power supply. 25
Solar panels How many …. Why these Size … voltage … current • The panels we chose claimed to be able to provide 500mA at 5V, but after testing them under load, we learned that was not possible. (what was the actual performance) • The size of the panels was small enough that it could be mounted to almost any surface, such as an ammo box, PVC pipe, or a custom 3d printed enclosure. • There were also solder pads on the back to allow us to arrange the panels in any configuration, high current at low voltage or high voltage at low current. • Originally, we purchased twelve believing that we only need six to power the project, leaving us enough to build two units. All twelve eventually ended on the final design to compensate for the lack of performance and to provide power to charge the batteries more to make up for cloudy days • 26
Why a raspberrypi Computer platform • The raspberry pi was chosen because it ease of use • It is a full single board computer running the popular linux operating system • The raspberry pi was also the most economic solution, price-wise and in terms of power consumption. • The raspberry pi also has many GPIO pins on it to allow the user to connect a multitude of sensors that can provide data that can be transmitted as its own message or along with the intended data. 27
Tncpi What is it How does Read the docs 28
Local networking RaspberryPi acts as a wifi access point for easy local access with a computer or smartphone Could be used as a communication end point in addition to a repeater 29
Radio Why this radio It worked better than the baofengs Talk about the problems 3d printed radio holder • Originally, we had chosen to use Chinese made Baofeng radios with the intent to keep each unit as cost effective as possible. • After hours of testing and troubleshooting, it was determined that the poorly designed receiver of the Baofeng was distorting the incoming data signal and not allowing the data to be recognized by the receiving unit. • After finding an economical, better engineered radio, we built a new interface cable and tested the new radio’s capabilities. • With a new receiver that was designed under higher quality control, the data was transmitted and received perfectly clear. 30
Diagram How it works Interface cable 31
Final Overview Portable Solar Powered Digipeater RaspberryPi with TNC-PI 2 Meter Handi-Talkie Voltage Regulators Charge Control Batteries Solar Panels Antenna Portable / Transportable Enclosure 3D Printed Parts 32
Compact 2M Handie Talkie Raspberry Pi Power Management Circuits 6V SLA Batteries 33
Final Product 34
Video Demonstration Note: unfortunately the size of the video precluded it from being loaded onto the RCA site. 35
Expandability - Enhancements APRS Repeater Weather station Message Post Office Alternate Antenna Configuration RaspberryPi Base allows for almost infinite software or sensor expansion 36
APRS repeater Add GPS module for self position reporting Change repeater soft 37
Weather Station 38
Post office 39
Thanks to all that helped ….. Carole Perry, WB2MGP, for the opportunity to present Abbie Heim, KD2PUA, enclosure top & bottom and antenna Caleb Lee, KD2NUC, RaspberryPi research, held SD cards John Metroke, WA2SME, Electronics Instructor at WCTS Bob Oppen, NE2C, Antenna materials and guidance st The 721 Mechanized Contest Battalion, for what they do best 40
The End! Thank you for your time. If any one has any questions feel free to ask. WC2FD.COM 41
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