Download or read book GEMA written by Harry von Kroge and published by CRC Press. This book was released on 2000-01-01 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Germany, the development of the first technologies of sonar and radar were interrelated. Following Christian Hulsmeyer's forgotten invention of the "Telemobiloskop" in 1904, two Berlin engineers, Paul Gunther Erbsloh and Hans-Karl von Willisen, developed and built devices to locate targets accurately by reflections with underwater sound and radi