The presentation was given in one of the IEICE meetings on Space, Aeronautical and Navigational Electronics on on May 22, 2017 in Tokyo, Japan. The official website of the presentation is as follows.
http://www.ieice.org/ken/paper/20170522Lbth/eng/
The silent radar refers to a radar emitting a radiofrequency with spectrum spreading, especially, direct-sequence spread spectrum. This presentation suggests that the silent radar with the application of microwave auditory effect has been used for clandestine operations against personnels since its development during the WWII.
34. スペクトル拡散SSコンセプト
means for producing a controlled signal
energy spread over a wide bandwidth to
thereby establish a low value of energy at
any specific single frequency in said
bandwidth,
Claim1, US Patent 6420995
36. DSSS文献
Raymond Pickholtz, Donald Schilling, and
Laurence Milstein, "Theory of spread-
spectrum communications--a tutorial." IEEE
Trans. Com. vol. 30, no. 5, pp. 855-884, 1982.