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A memorial tribute to Isao Someya, 1915-2007.

Dr. Isao Someya, one of the inventors of the sampling theorem, died of an acute respiratory failure on 31 December 2007 in Tokyo at the age of 92 years and 9 months.

Isao Someya was born in Saitama Prefecture outside Tokyo on March 23, 1915. He received a B.E. degree in Electrical Engineering from the University of Tokyo in 1938. In the same year, his research career began at the Electrotechnical Laboratory (ETL) of the Ministry of Communications. Since the Olympic Games were scheduled to be held in Tokyo in 1940, experimental television broadcast trials were being conducted in Tokyo by the Japan Broadcasting Corporation (NHK) at that time. There was also a plan to send TV images to Osaka, which is the second largest city in Japan, some 600 km away from Tokyo. Someya was involved in the research on transmitting TV signals from Tokyo to Osaka using coaxial cables. During this research, he frequently encountered the issue of band-limited signals, and it was quite natural for him to propose a fundamental question, namely, 'what properties do band-limited signals possess?'

During World War II, he was involved in research on various subjects. At the conclusion of the war, he came back to Tokyo from a rural region where he had been evacuated. However, his laboratory had no equipment at that time. Besides plowing the vegetable field in the courtyard of the laboratory, a task assigned to each employee in order to address the serious shortage of food, he did theoretical research on waveform transmission, since it did not require any laboratory equipment. Clearly, during this time, the underlying issue that motivated his research was the nature of band-limited signals. Unfortunately, given the economic situation at the time, access to even domestic research articles was difficult, let alone international articles. He independently thought over this problem and finally arrived at his discovery of the sampling theorem.

In a state of confusion after the war, scientific societies could not publish their journals, and researchers had no chance to present their new results. In order to overcome these problems, plans were made to publish a book series named the Library of High Frequency Science in order for new scientific results to be immediately disseminated. Someya was selected as an author and his contribution to this series was the historic book Wave form Transmission, published in 1949 [1]. The book contains the sampling theorem with its various extensions, such as sampling theorems for an over-complete system and sampling theorems in the frequency domain. In the book, these theorems are used to solve many practical problems, for example, the impulse response of a transmission system, aliasing error, waveform distortion, and designing a frequency analyzer. On the basis of the contributions of this book, he received the Ph.D. degree in Electrical Engineering from the University of Tokyo in 1950.

In 1952, the communication division was separated from the Electrotechnical Laboratory, and the Electrical Communication Laboratories of the Nippon Telegraph & Telephone Public Corporation (NTT) were created. At the new laboratories, Someya was engaged in many large-scale R&D projects such as 200MHz Range Super Multichannel Telephony, the Microwave Radio Relay System for Television, and the Microwave Radio Relay System for Super Multichannel Telephony. Finally, his research contributed to the implementation of a commercial microwave radio relay system. For these contributions, he received the Distinguished Services Award from the Institute of Television Engineers in 1960, the Minister's Prize from the Ministry of Posts and Telecommunications in 1961, the Minister's Prize from the Science and Technology Agency in 1961, and the Purple Ribbon Medal from the Prime Minister of Japan in 1967.

He became Deputy General Manager of Electrical Communication Laboratories in 1959. In 1966, he left NTT and joined NEC Corporation as General Manager of Central Research Laboratories. In 1972, he was promoted to Senior Vice President and Member of the Board.

Continuing his academic activities, Someya joined the Institute of Television Engineers and became Vice President in 1962. He was also a member of the Institute of Electronics, Information and Communication Engineers, Japan (IEICE), where he served as Vice President from 1967 to 1969 and held many other managerial positions. He received the Distinguished Achievement and Contributions Award form the IEICE in 1976, and became a Fellow and Honorary Member in 1980.

Furthermore, Someya served on many government committees. For example, he was a member of the Science Council of Japan, the Radio Technical Council of the Ministry of Posts and Telecommunications, and the Electrotechnical Council of the Science and Technology Agency, and served as Vice President of the Japan Patent Association.

Isao Someya was graceful of bearing. He enjoyed playing golf, the game of go, and various mathematical games. For more detail on Dr. Someya and his contributions, readers can refer to [2].

Pray for his soul to rest in peace.


[1] I. Someya, Wave form Transmission, Shyukyo Ltd., Tokyo, 1949.

[2] H. Ogawa, Sampling theory and Isao Someya: A historical noteC Sampl. Theory Signal Image Process., 5(3), 247-256, 2006.

--This memorial was written by Hidemitsu Ogawa.
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Publication:Sampling Theory in Signal and Image Processing
Article Type:In memoriam
Geographic Code:9JAPA
Date:Sep 1, 2008
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