Product: System for Increasing Analog Telephone Line Capacity Developers: Joshua Piasetzky, Itzik Dana, Shraga Eliav, Aharon Segev Company: ECI Year of Patent: 1977
We all remember the old films in which a telephone operator connects people by inserting a pair of phone plugs into the appropriate jacks in a large telephone switchboard. The exploding global communications revolution of the 1970s and the need to connect ever-widening circles of people around the world, required a new technology - one that would enable a more efficient use of telephone lines that until then enabled only a single conversation over each line. The development of the Telephone Line Doubler (TLD) by the Israeli Corporation ECI provided the answer.
Based on an idea explored in the United States during the 1960s, the R&D team at ECI headed by Joshua Piasetzky built a prototype, originally developed for the army’s signal corps to scramble telephone calls, that enabled the number of calls on analog lines to be doubled. The underlying concept was that since average utilization of voice capacity on a telephone channel is only 37 percent , the “quiet” times during calls (“ quiet” spaces of the channel) could be identified and used for additional calls.
Following registration of patent in 1978, the line doubler’s first international commercial breakthrough came with the signing of a contract with Deutsche Bundespost (German Post Office) in 1983. At the same time, TLD and its developers at ECI were forced to contend with the ever-increasing pace of the digitalization process of both transmission equipment and the switching exchanges. In response, ECI decided to change the product’s name to Digital Trunk Expander (DTX) and adapted it to the changing face of communications. DTX technology constituted the base of the TAT-8 Project – an underwater transatlantic fiber optic communication cable.
Having paved the way on land and under the sea, the next generation of line doubler technology was also extended to space. Digital Circuit Multiplication Equipment, or DCME, was a type of voice compression equipment that is installed at either end of a long-distance link (typically communications satellite or submarine communications cable). DCME enabled five simultaneous conversations on each line and was instrumental in enabling the construction of a highly cost-effective satellitebased telecommunications system that was used by public telecommunications service providers to transmit both voice and data calls worldwide.
The TLD Project has been recognized as an innovative and very important breakthrough in the world of telecommunications. Marking 60 years of Israeli independence, the Office of the Chief Scientist granted Outstanding Achievement Awards to prominent R&D projects that led to technological breakthroughs with an important impact on our lives. ECI’s Telephone Line Doubler System was selected as one of nine projects (out of forty thousand nominated projects) to win this prestigious award.
