Graphic demonstrating Radio Acoustic Ranging (RAR).Developed in 1923, RAR was the first non-visual navigation system.Combined velocity of sound in water with radio to obtain fix.
3/20/2019 12:32:33 PM
Date: 1931
Credit: NOAA Central Library
Location: Georges Bank
Subject: Charting
Subject: Navigation
Subject: Electronic
Subject: Radio-Acoustic Ranging