1904

Telemobiloscope

• Heinrich Hertz had discovered that electromagnetic waves
• bounced off metallic objects.
• Christian Hülsmeyer used that idea
• to invent the telemobiloscope.
• A spark-gap transmitter and a rotating parabolic antenna
• detected the presence and the direction of a ship in the fog.
• Additional measurements and basic trigonometry
• determined an object’s distance.
• However, lacking tuning circuits, the telemobiloscope
• was confused by wireless devices on other ships.

Radar

• Add control for the signal frequency.
• Add tuning for the receiver.
• Add amplification.
• Add slotted waveguide.
• Add parabolic dish for broadcasting and receiving.
• Add control of the signal polarization.
• Add Doppler analysis to detect movement.
• Add digital signal processing.
• Add chain of coastal stations.
• Add phased array radars.

Signals

• I send out signals all the time,
• see if any bounce back,
• tell me what’s out there
• and how far away,
• whether it’s moving in my direction
• or farther away,
• whether to dodge or chase it.
• I send signals out in all directions,
• see if anyone responds.
• I gradually improve the signal
• and the signal processing.
• Yes, this has been a metaphor
• from the beginning.
• I’m just trying to see
• if you’re paying attention.