For my 8th grade science project in 2015, I created the world's first Digitally Controlled Heliograph.  A Heliograph is a sun telegraph.  I learned a lot (how to research, design, build, solve problems, test, evaluate data, and present my results) and the project won "best in category" and "best overall" for middle school science fair projects in the State of Hawaii.  The project also advanced to the semi-finals of the Broadcom Masters competition.  People still ask me about the project, so I created this site for others to see.  If you have read this far, you probably find this interesting too.

the world's first digitally controlled heliograph

Digital Inter-Island Solar Communication

My project is to modernize the Heliograph technology that was used successfully over 120 years ago to communicate over long distances, using only reflected sunlight that is encoded into dots and dashes.

My hypothesis is that a digitally controlled Heliograph (or sun telegraph) is more accurate and consistent than the manually operated ones that were once used.

A Heliograph sends encoded pulses of reflected sunlight to a distant observer by periodically tilting a mirror, or by using a shutter to interrupt the reflected sunlight. The original Heliographs were operated by a human entering Morse code by tapping a key. My improvement is to use a micro-controller to energize a solenoid to tilt a mirror to send coded messages over long distances, such as between islands. A Heliograph has several advantages for communication. It is very energy-efficient. Sunlight is used directly, without conversion to electricity. The only electricity that my digitally-controlled Heliograph uses is a very small amount (from a battery) to power the micro-controller, and another batter to power the solenoid. Unlike radio waves, it is almost impossible to intercept a signal from a Heliograph. The signal is only visible where it is aimed. The range of a Heliograph matches our inter-island distances very well.

After researching the design and construction of Heliographs from approximately 1890, I designed a modern version that uses a micro-controller and a solenoid to control the tilting of the signal mirror. I built my Heliograph using sheet acrylic (or plexiglass) because we had some scraps of it in our garage. The micro-controller, relay, and solenoid were ordered from China. For the software, I downloaded and studied many different programs that convert text into Morse code. All those programs either sounded a buzzer, or flashed an LED. None of them were designed to control a solenoid. I then found one program to control a relay (but it had nothing to do with Morse code). I was able to combine features of two programs to convert text into Morse code, and then control the tilting of a mirror. You are looking at the world's first, and only, digitally-controlled Heliograph.

Before building, I made a design drawing in AutoDesk based on my research and what I thought I could build. I then measured and cut pieces of plexiglass, and then glued or bolted them together. When I finished building it, I made an updated drawing that incorporated the improvements that I made.

The greatest range that I have sent signals has been from my house to the summit of Diamond Head crater, 19.1 miles away. To test and evaluate the accuracy of the digital Heliograph compared to the original, manually-controlled Heliograph, I sent identical messages by manual and automatic control. Even when I prepared detailed and precise scripts of how to send manual messages, the digitally-controlled messages were more accurate.

The world record for a Heliograph transmission distance was 183 miles in 1894. This indicates that inter-island use of a Heliograph is definitely possible. In fact, my Heliograph is capable of communicating between many of the islands. The range can be increased by just using a larger mirror, or by locating it on mountains (where there is less atmospheric interference).

The technology has some potential for emergency communications, and might someday be used for sending data in space, such as between Mars and Earth orbit. The lack of atmospheric interference, and the very small requirements for electrical power would give it some advantages over radio communications.

Further improvements to this project would be using a larger mirror, having an automatic solar tracker to eliminate manual aiming, having several units operating as an array, and incorporating error checking similar to what is used in verifying packets of internet data.

Island Pacific Academy
Kapolei, Hawaii
September 2015