Deadlands: The Way of the Brave
Astral Echo Resonance Sensor
A radar system for detecting magical creatures, effects, or items
The Astral Echo Resonance Sensor (AERS) was developed by William Keller Burton. The basic idea came to him in a feverish dream after he had examined the devices of Sterling Simms for the St. Louis authorities.
The AERS was essentially a magical radar. It sent out a wave of magical energy that was bounced back to the device if a source of similar magical energy was encountered. Unfortunately, it was a bit bulky. It had a hand-sensor connected to a large apparatus that was worn on a person’s back. A hand crank provided power to the device. (William generally required two assistants when using the AERS.)