Pioneer of the acoustically coupled modem, van Geen made advances that led to the release of the first public modem. A researcher at the Stanford Research Institute, he was known for his advances in the acoustically coupled modem. His enhancements allowed the designed receiver to detect data (in the form of bits) and distinguish it from background noise more reliably than any previous models.
Phone companies at this time did not allow unapproved devices to be attached to phone lines, but van Geen won approval for the modem by making it mimic the characteristics of an ordinary telephone handset. He also greatly improved the ability of the modem to extract data bits from the background hiss of standard telephone connections.
Until the 1980s, acoustic modems operated by inserting a standard phone handset into the two soundproofed depressions on the modem chassis.
