Internet of LightOver the power line
PLC adapters use the mains wiring as a communication path. Interference can make delivery uneven.
ELEN4012A · FINAL-YEAR CAPSTONE
One connection.
Two ways to
carry a message.
Sending data through power lines and light. We’re exploring the bridge between the wiring in a room and a beam from an LED.
POWER LINE COMMUNICATION × VISIBLE LIGHT COMMUNICATION
THE SIGNAL JOURNEYProject illustration
Carried by copperDelivered by light
01 / THE PROJECT
Existing wires. A small buffer. A different last hop.
FROM WALL TO LIGHT
How a message finds its way.
PLC brings the data in. A buffer helps manage the handoff. VLC carries it across the optical link.
Through a buffer
Queued messages wait at the gateway until the optical transmitter is ready to carry them.
Out through light
An LED carries the encoded message. A photodiode and receiver electronics turn it back into data.
A CLOSER LOOK
Inside the receiver.
Actual circuit drawings from the project workspace. Bench photographs will be added when supplied.
Turning light into a signal
The photodiode input stage.
Preparing the signal for the ESP32
The receiver amplifier stage.
The bench, in pictures
PLC equipment, gateway, LED transmitter, and complete setup photographs are awaiting team contributions.
02 / TRY THE IDEA
A little memory makes a difference.
Explore the tradeoff between buffer size and burst losses before trying the message studio.
Buffer simulator
Illustrative modelThe power line stalls, then releases a burst. Find the smallest buffer that keeps simulated losses under 1%.
Power line downBuffer fillBuffer sizeData lost
–Data lost
–Peak buffer fill
–Worst added delay
–Longest dropout
Illustrative data, not bench measurements. Each interference level uses the same trace for a fair comparison. This simulator never controls the rig.
03 / FROM THE BENCH
What we’ve verified so far.
Local optical image tests recorded on 12 October 2026. These results describe the USB → light test route.
32 × 16 PIXELS
0.797s64 packed image bytes
64 × 32 PIXELS
2.547s256 packed image bytes
128 × 64 PIXELS
8.110s1,024 packed image bytes
Source: the project’s high-resolution image acceptance report. Source and received pixels matched exactly. Times include host pacing and receiver feedback; they are not optical flight times. The PLC → VLC route and this web portal still require end-to-end verification.
04 / MAKE IT YOURS
Words. Pixels. A sketch.
Start with a message.
Prepare something on your phone, preview what the receiver will see, and explore the transmission journey.
THE PEOPLE BEHIND THE LINK
A final-year engineering project.
School of Electrical and Information Engineering
University of the Witwatersrand
ELEN4012A
Team names, supervisor details, and contact information will be published once supplied.
View the project on GitHub ↗