Phil Karn

Lore & Background

Phil Karn began his career at Bell Labs in 1979, working in Naperville, Illinois, and Murray Hill, New Jersey, before moving to Bell Communications Research in Morristown, New Jersey, from 1984 to 1991. He then joined Qualcomm in San Diego, where he specialized in wireless data networking protocols, security, and cryptography until his retirement. In the amateur radio community, he is best known for developing the KA9Q Network Operating System, which was judged more suitable for deployment than an Air Force Institute of Technology packet radio system in a 1991 master's thesis. He also created early 9600 bit/s FSK radio modems and, in the early 2000s, worked to introduce forward error correction into amateur radio satellites, applying it to the 400 bit/s PSK telemetry from the AO-40 satellite.

Karn has been an active contributor to the Internet Engineering Task Force, particularly in security and Internet architecture, authoring or co-authoring at least six RFCs. In 1990, he predicted that wired links for the Internet's 'capillaries' would become 'history' as most users would access it via wireless radio links. He is currently a board member and President Emeritus of Amateur Radio Digital Communications (ARDC), a non-profit foundation funded by the sale of part of its IP address space (44/8), which manages the remaining space by providing financial grants to amateur radio, digital communications, and related groups.

Reader's Guide

Phil Karn's significance lies in his dual impact on Internet engineering and amateur radio. His invention of Karn's Algorithm remains a fundamental method for calculating round-trip time in IP packet retransmission, directly influencing the reliability of TCP/IP networks. The KA9Q NOS software, named after his amateur callsign, became a widely used platform for packet radio, enabling digital communication over amateur radio frequencies. His early work on 9600 bit/s FSK modems and forward error correction for the AO-40 satellite advanced the capabilities of amateur satellite telemetry. Karn's 1990 prediction that wireless radio links would replace wired connections for Internet access anticipated the rise of mobile and wireless networking. His involvement in the crypto export lawsuit, where he challenged the U.S. State Department's ruling that source code on floppy disks was subject to munitions export controls, contributed to the eventual relaxation of restrictions on freely available crypto source code in 2000. As a board member and President Emeritus of ARDC, he continues to support amateur radio and digital communications through grants funded by the organization's IP address space.

Did You Know?

• Karn invented Karn's Algorithm, a method for calculating round-trip time for IP packet retransmission.
• He created the KA9Q Network Operating System, named after his amateur radio callsign.
• In 1990, he predicted that most Internet users would access it via wireless radio links, making wired 'capillaries' history.
• He was interviewed on Internet Talk Radio's 'Geek of the Week' podcast in 1994.