 session" initi- ated by Chereau who had put forth the idea of echo cancellation. The mem- orandum was written shortly before Deloraine and Busignies, along with Emile Labin and Georges Chevigny and their families, escaped via Marseilles, Algiers, Casablanca, and Lisbon to New York, arriving on New The Historical Origins of Spread-Spectrum Communications Year's Eve, the last day of 1940. Busignies filed his application in the United States on March 5, 1941, and was granted U.S. Patent 2 570 203. Busignies, a remarkably prolific inventor who over his lifetime was granted about 140 patents, soon collaborated with Edmond Deloraine and Louis deRosa in applying for a patent [68] on a facsimile communication system with intriguing anti-jam possibilities here set forth: [The system uses a transmitter which sends each character] a plurality of times in succession, [and a receiver in which the character signals are visually repro- duced,] one on top another to provide a cumulative effect. [If] the interfer- ence signals are not transmitted to provide such a cumulative effect, the interference will form only a bright background but will not prevent the signals from being read. RADIO RECEIVER TO RADIO TRANSMITTER WOBBLE SPEED DRIVE PHASER POWER SUPPLY VERTICAL REFLECTORS TO HORIZONTAL REFLECTORS Figure 2.5. The core of Deloraine, Busignies, and deRosa's time-wobbling system consisted of a drum containing a slot track for each transmittable character. When the drum is turned at a constant speed, the signal produced by reading a track with a light beam was that required to create a character on a CRT screen. For security, the drum's rotation rate was "wobbled" and compensating variations in the CRT beam deflection voltages were inserted, SO that interference, being wobbled on receive only, could not easily produce a bright screen signal. (Redrawn from [68], [69].) Emerging Concepts From a jamming viewpoint, the real novelty in the disclosure is in the fact that the mechanisms which read the characters at the transmitter and w