Machines · Study 066
Harbour Radar
A plan position radar scope: the beam sweeps the harbour every six seconds and each vessel flashes, then fades until the next pass.
What you're looking at
The bright line is the antenna's current bearing. A contact is only painted when the sweep crosses it, then its glow decays, which is why you see where a ship was a few seconds ago and not where it is now. The contacts drift slowly on their own headings between passes.
The idea behind it
The fading is how real scopes worked. The cathode ray tube was coated with a long persistence phosphor so that echoes stayed visible for a full rotation. Operators learned to read course and speed from the short trail a moving target left across successive sweeps.
Try this
Click or tap inside the scope to add a contact at that range and bearing.
