Opcio Data is an independent editorial reference covering the disciplines where electrical engineering meets computing. It exists for a specific reader: someone who has met a term like state estimation, wide-bandgap semiconductor or partial discharge in a datasheet, a lecture or a news article, and wants an honest explanation of what it means and why practitioners care — without a paywall, a sales pitch, or three thousand words of preamble.
The field is enormous, and most of the accessible writing about it sits at one of two unhelpful extremes. At one end are marketing pages that explain nothing. At the other are peer-reviewed papers that assume a decade of background. This reference aims squarely at the middle: enough rigour that a practising engineer would not wince, enough plain language that a second-year student or a technically curious reader can follow it.
The Ten Areas Covered Here
The site is organised around ten established subfields. They are not arbitrary — they map closely onto how university departments, standards bodies and professional societies actually divide the discipline.
- Power systems — generation, transmission, distribution, and the control problem of keeping supply and demand matched second by second.
- Power electronics — the switching converters that move and reshape electrical energy between sources and loads.
- High voltage engineering — insulation, breakdown, and the physics of moving energy at hundreds of kilovolts.
- Communication, control and robotics — feedback, autonomy, and how machines are told what to do.
- Systems science and signal processing — extracting meaning from measurements, and the mathematics that makes it possible.
- Image processing and biomedical imaging — turning raw sensor data into pictures a human or an algorithm can interpret.
- Electromagnetics and photonics — fields, waves, antennas and light as an engineering medium.
- VLSI and integrated circuits — how billions of transistors are designed, verified and manufactured on a single die.
- Nano devices and integrated systems — engineering at scales where classical assumptions start to fail.
- Measurements and instrumentation — the unglamorous discipline that decides whether any of the above can be trusted.
Why These Areas Belong Together
Read in isolation, the ten look like separate specialisms. In practice they are a single chain, and the joins are where the interesting engineering happens. A modern grid-connected solar installation touches every one of them: photovoltaic physics is a semiconductor problem, the inverter is power electronics, the grid connection is a power systems stability question, the anti-islanding protection is a signal processing problem, the remote monitoring is a communications problem, and the revenue metering is a measurement problem with legal consequences.
That interconnection is the reason a reference organised by discipline still needs to be read across disciplines, and why nearly every page here ends by pointing at its neighbours rather than pretending its subject is self-contained.
A Practical Route Through the Subjects
When a technical claim crosses several subjects, begin with the quantity that was observed. Ask which sensor produced it, what bandwidth and range applied, and how uncertainty was carried into later calculations. The measurements and instrumentation guide sets out that chain; from there, follow the page links toward the system that generated the signal and the processing that turned it into a reported value.
Then separate the physical layer from the interpretation. A converter may switch correctly while its controller uses a poor estimate; a sensor may be accurate while the sampling system aliases its output. Moving through the subjects in this sequence keeps cause and evidence distinct, which is often the shortest route from an impressive claim to the engineering question that can verify it.
Where the Ground Truth Comes From
Explanatory writing is only as good as what it is anchored to. Where this reference states a physical constant, a standard, or a piece of measured data, it points at a primary source rather than paraphrasing another explainer. In practice that means a small number of institutions do most of the load-bearing work: the National Institute of Standards and Technology for measurement and units, the IEEE Standards Association for the interface and test standards engineers actually build against, and national statistical agencies for anything about how much energy is generated and where it goes.
For the wider view — what is being built now, what failed last year, what the arguments in the field currently are — general engineering journalism such as IEEE Spectrum covers ground no reference page can keep up with. This site deliberately does not try to be a news source.
How to Use This Site
There is no required order. Each topic page stands alone, opens with the shortest honest definition of its subject, and then works outward: the core physical or mathematical idea, how it shows up in real equipment, the failure modes that make it a discipline rather than a formula, and where to read further. If a page uses a term it has not defined, that is a defect — the aim is that each page can be handed to a capable non-specialist without a glossary.
Two pages sit outside the ten topics. Finding and judging technical literature is a practical guide to locating credible engineering sources and, just as importantly, recognising venues that are not what they claim to be. About this reference sets out what the site is, what it is not, and the editorial rules it holds itself to.