1896 __ Transmission and reception of information by wireless telegraphy
‣ Comment : Beginning in the early 1890s he continued the experiments of other radio pioneers, such as Heinrich Hertz. In 1894 he built his first radio receiver, a version of the coherer. Further refined as a lightning detector, it was presented to the Russian Physical and Chemical Society on May 7, 1895. — the day has been celebrated in the Russian Federation as "Radio Day". The paper on his findings was published the same year. In March 1896, he effected transmission of radio waves between different campus buildings in St Petersburg. Upon learning about Guglielmo Marconi's system, he effected ship-to-shore communication over a distance of 6 miles in 1898 and 30 miles in 1899. — Popov found that he could detect distant atmospheric lightning discharges by connecting one end of the coherer to a wire antenna and the other end to a good earth ground. The coherer and the relay also were used to activate a pen mechanism recording device. The pen made a mark on a slowly rotating cylinder when a lightning discharge occurred. It was this lightning detection apparatus that Popov demonstrated to the members of the Russian Physical and Chemical Society on May 7, 1895. On this day, Alexander Popov presented a demonstration which would become recognized as an historic achievement. This demonstration, together with another by Popov which reportedly took place the following year, eventually would produce controversy among historians concerning whether the credit for "inventing" radio should be given to Marconi or to Popov. Those in attendance for Popov's May 7 presentation were very much impressed when he demonstrated a receiver which could detect the electromagnetic waves produced by lightning discharges in the atmosphere many miles away. The value this instrument could have in weather forecasting was obvious. While this demonstration by Popov did not involve the transmission and reception of a message, it nonetheless was a significant scientific achievement for that time. Clear written records of the event were made and preserved. Later that same summer, he set up his thunderstorm detecting and recording instrument at the Institute of Forestry in St. Petersburg. With Popov's equipment, lightning discharges occurring as far away as 20 miles were detected. Each year on May 7, the Soviet Union and now Russia still celebrates "Radio Day" to commemorate the achievements of Alexander Popov. During 1896, teaching responsibilities and the desire to conduct experiments with the recently discovered Roentgen rays (X-rays) kept Popov busy. He had little time to devote to new electromagnetic wave experiments. On 12th of March 1896 Popov together with Ribkin demonstrated wireless transmission of Morse signals from one university building to another that was 200 meters far from the first one. It was the first sensible transmission of text in the world. Reports also exist that some ten months later on March 24, 1896 Alexander Popov demonstrated the transmission and reception of information by wireless telegraphy. The occasion was another meeting of the Russian Physical and Chemical Society and the location was the St. Petersburg University. Wireless telegraph signals, transmitted a distance of over 800 feet from another building on the campus, were audible to all in the meeting room. The President of the Society, F. F. Petrushevsky, stood at a blackboard holding a paper on which a listing of the letters of the alphabet and their equivalents in Morse Code were written. As the signals were received, Petrushevsky referred to the paper and wrote the appropriate letter on the blackboard. The letters spelled out the name "HEINRICH HERTZ" – the name of a great German physicist who first convincingly demonstrated the existence of the electromagnetic waves predicted in 1864 by James Clerk Maxwell. Unfortunately, no written record was made at the time of this wireless telegraphy demonstration to provide documentation for historical purposes. The reports of the event which do exist are based on the recollections of several persons present at the time, but were not recorded until almost thirty years later. In spring of 1897 Popov conducted some experiments on the ships and was able to transmit information to a ship that was as far as 640 meters from Popov. He was increasing the distance of transmission day by day. (. (Compiled from various sources)
‣ French comment : Décembre: Popov décrit dans le "Journal de la Société Russe de physique chimie " (vol. 28, pp. 1-14, 1896) un : "Appareil pour la détection ("recording") et la réception des oscillations électriques". Conclusion de la communication : « J'exprime l'espoir que mon appareil, quand il aura été perfectionné, pourra être utilisé pour transmettre des signaux à distance au moyen d'oscillations électriques rapides, dès qu'une telle source d'oscillations disposant d'une énergie suffisante aura été mise au point ? ». (Ch. Süsskind: "Popov and the Beginnings of Radiotelegraphy" in "Proceedings of the IRE", p. 2039 - 1962, Oct.) — Voir aussi la recopie manuscrite par E. Ducretet d'une longue lettre de Popov qui traduit lui-même en français le texte du "Journ. de la Soc. de Phys.-Chimie" de Saint Petersbourg - (Janv. 1896) - (Photocopies communiquées par M. B. Ducretet) : « Pour conclusion, je peux exprimé l'espérance, que mon appareil dans son perfectionnement peut être appliqué pour la transmission des signaux à distance à l'aide des vibrations électriques rapides ? ». (Traduction, orthographe et ponctuation de Popov respectées.)
‣ Source : Ledos, J-J. (1996), "1996 CENTENAIRE DE LA RADIO ?", Article publié in "CAHIERS D'HISTOIRE DE LA RADIODIFFUSION", n° 49, Juin-Août 1996.
‣ Urls : http://web.chr.free.fr/info/detail.php?SID=955866757&ID=60 (last visited ) http://chem.ch.huji.ac.il/history/popov.html (last visited )
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