OOK Remote Transmitter
How simple OOK remotes work
What it does
SimpleLots of simple remotes — like some old gates, fans, or cheap toys — work by sending a short pattern of 'on' and 'off' blips. This app shows how that kind of signal is put together, which is a great way to understand why very simple remotes aren't secure and why modern ones use clever changing codes instead.
The important idea to learn here is the difference between a 'fixed code' (the same every time, easy to copy) and a 'rolling code' (different every press, much safer).
How it works
SimpleThink of Morse code but for machines: the remote turns its radio on and off in a set rhythm, and the receiver recognises that exact rhythm as 'open'. If the rhythm is always the same, anyone who writes it down can repeat it — which is why good remotes change the rhythm every single time.
How to use it, step by step
Simple- Open the 'OOK TX' app to see how a pattern is defined.
- Look at how the on/off timing spells out 1s and 0s.
- Compare a 'fixed code' (always the same) with the idea of a 'rolling code' (always changing).
- Understand why the changing one is much safer.
Examples
Learn why a fixed-code remote can be copied from a single capture while a rolling-code one cannot.
Break down how on/off durations encode bits, sync, and repetition in a classic sub-GHz remote.
Reason through what you'd add (a counter, encryption) to turn an insecure fixed code into a secure one.
Tips & things to try
- The security lesson is the point: fixed codes are a cautionary tale, not a good design.
- Rolling codes and challenge-response are the modern defences — OOK replay can't beat them.
- Only ever experiment with hardware you personally own, and check what's permitted where you live.