strategic deployment commenced with the installation in Hawaii in January 1958, and was followed by installations in Germany (Pirmasens/Kaiserslautern, February 1958), Japan, and the Philippines. With the threat of a blockade of Berlin, the equipment assigned to Clark Field in the Philippines was moved in crates of Phillipine mahogany to Berlin in the spring of 1959. Rake appliques for the F9C-A receivers were fabricated later by the National Company of Malden, MA. These were produced with an improved, yet simplified, circuit configuration, invented at General Atronics [160], which employed tap units having a full 10 kHz of internal bandwidth instead of being structured as in Figure 2.24(b). Additionally, the F9C-A/Rake The Historical Origins of Spread-Spectrum Communications appliques introduced a novel method of ionospheric multipath display, in which the multipath-matched tap-combining weights were successively sensed by a short pulse traveling along the magnetostrictive delay line, the pulse duty cycle being low enough to have negligible effect on the Rake sig- nal processing. Bernie Goldberg was the Project Director for this effort and Robert L. Heyd served as the Project Engineer. Together they also devel- oped Goldberg's innovative "stored ionosphere" concept [161] in which the F9C-A/Rake's multipath measurement function was used to record ionos- pheric channel fluctuations for their later re-creation in testing short-wave apparatus. This measurement capability was also employed to assess multi- path effects, between Hawaii and Tokyo, of a high altitude nuclear detona- tion in the Pacific in July 1962. The F9C-A/Rake is no longer on-site, operational or supported by the Army. 2.2.9 A Note on PPM As the Hartwell report indicated, J. R. Pierce of BTL had suggested that covertness be achieved by using extremely narrow pulses for communica- tion, thereby spreading the transmission spectrum. This idea was undoubt- edly based on BTL's postwar work on pulse position modulation (PPM) [96]. After discussing the CDM