David G. Messerschmitt

Roger A. Strauch Professor Emeritus

Dept. of Electrical Engineering and Computer Sciences

University of California at Berkeley

Contact information and supporting staff

Interstellar communication

Modern communications systems have a very different character than the popular perception of AM or FM modulation of analog signals such as broadcast radio or television. They employ exclusively digital signals, and employ sophisticated coding algorithms mapping information bits into modulation codes. Combined with similar approaches to the compression of sources, orders-of-magnitude improvements in power- and/or bandwidth-efficiency have been obtained. I have been applying modern communications theory and technology to the challenge of digital communication at interstellar distances. There are three primary applications of this that I have been addressing:

· Interstellar spacecraft. There is increasing attention being paid to the possibility of exploration by robotic space probes within our region of the Galaxy, beyond the reaches of the Solar System. The two most significant challenges are propulsion (not my department) and communication with the spacecraft. A specific concrete project is Breakthrough Starshot, which is seeking microscale spacecraft at the distance of Alpha Centari (see Z Merali, Shooting for a star. Science, 2016.) I am interested in the communication downlink for transferring scientific data in the mission such as Starshot using the most advanced available communication techniques.

Messaging of extraterrestrial intelligence (METI). There is increasing debate about transmitting toward the stars. These discussions focus primarily on what information we should communicate with extraterrestrials, and how we should encode this information in ways that an extraterrestrial without any shared context can interpret this information. My work focuses on the complementary problem of how to encode this information as an actual transmitted electromagnetic signal. The primary goals that I see as important are (a) obtaining the lowest radiated power of transmission (these powers are intrinsically very large due to the great distances), (b) enabling the receiving civilization to identify and decode this signal without any explicit coordination, and (c) making the signal intrinsically immune to the radio-frequency interference (RFI) that is likely to be encountered at the receiving site. Encouragingly, I have proposed a specific approach that achieves all three goals (see Design for minimum energy in interstellar communication. Acta Astronautica, 2015.)
Searth for extraterrestrial intelligence (SETI). The searches to date have focused on information-free beacons. In particular, at radio frequencies they have looked for continuous-wave (CW) single-frequency signals. My approach is to inform the strategies of a SETI program by what we learn from METI. In particular, current searches can be supplemented by looking explicitly for information-bearing signals, and my work on METI informs the nature of signals we have been looking for. They are very different from CW, and the inherent immunity to RFI is a major advantage. Mitigation of RFI is necessary in radio astronomy, but it is not necessary in SETI.

Please also see my recent paper on relativistic timekeeping, which argues that relativity theory (especially the special variety) needs to be integrated into our engineering education. It develops a new formulation of special relativity that is more appropriate for that purpose.

Recent papers and reports:

Messerschmitt, D.G. Relativistic timekeeping, motion, and gravity in distributed systems. IEEE Proceedings, August 2017. [link]

Lubin, P., Messerschmitt, D.G., Morrison, I. Interstellar mission communications low background regime. [link]

Messerschmitt, D.G. Design for minimum energy in interstellar communication. Acta Astronautica, 2015. [link]

Messerschmitt, David G. (2012). Interstellar communication: The case for spread spectrum. Acta Astronautica, 81(1). [link]

Messerschmitt, David G; & Morrison, Ian S. (2011). Design of Interstellar Digital Communication Links: Some Insights from Communication Engineering. Acta Astronautica, 78(1), 80 - 89. [link]

Messerschmitt, David G. (2013). End-to-end interstellar communication system design for power efficiency. Draft technical report available on arXiv.org. [link]

S. K. Blair, D. G. Messerschmitt, J. Tarter, and G. R. Harp, "The Effects of the Ionized Interstellar Medium on Broadband Signals of Extraterrestrial Origin". D. Vakoch, editor, Communication with Extraterrestrial Intelligence, State University of New York Press, 2011.

Other current activities

I possess an FCC Amateur Radio License. My call sign is KK6KFQ. I find this excellent exposure to the practical side of radio communications, and some cutting-edge experimentation within this community turn out to be directly applicable to interstellar communications as well.

I am a volunteer at the Chabot Space and Science Center, where I introduce the public and school classes to astronomy and space.

Brief biography

David G. Messerschmitt is the Roger A. Strauch Professor Emeritus of Electrical Engineering and Computer Sciences (EECS) at the University of California at Berkeley. The first ten years of his career was spent at Bell Laboratories, where he participated in the exploratory development of digital communications. At Berkeley he has done research in digital communications and audio and video encoding, and has served as the Chair of EECS and the Interim Dean of the School of Information. He is the co- author of five books, including Digital Communication (Kluwer Academic Publishers, Third Edition, 2004). His doctorate in Computer, Information, and Control Engineering is from the University of Michigan, and he is a Life Fellow of the IEEE, a Member of the National Academy of Engineering, and a recipient of the IEEE Alexander Graham Bell Medal recognizing "exceptional contributions to the advancement of communication sciences and engineering".