In 1880, the Russian military communications engineer G.G. Ignatiev designed the world's first system of simultaneous telegraphy and telephony on the same wire.
G.G. Ignatiev was born on September 11, 1846 in the province of Poltava. Upon completing Moscow Military Engineering School, he was appointed lieutenant to serve in the 7th Military Telegraph Park where he trained soldiers in alarm installation, building telegraph lines and work on the telegraph apparatuses generally.
In 1878, on the initiative of the St. Petersburg Engineers Corps in the Telegraph Parks, telephones were sent for testing to pave the way for their use in the army's telecommunications facilities.
Heading the 7th Military Telegraph Park, Captain Ignatiev oversaw experiments which were conducted with existing telegraph wire and special telephone lines. During testing, when telephones were connected through the telegraph wire, Ignatiev found that normal conversation was only possible when the telegraph apparatus was switched off. Interference from the telegraph was so strong that the telephone conversation was quite impossible. So G.G. Ignatiev set himself the task of eliminating this interference, for which he proposed the use of a condenser as a variable frequency current divider (between the telegraph and the telephone). Incidentally, P.M. Golubitsky, completely independently of Ignatiev, also introduced the use of a condenser for the same purpose.
To compensate for the inductance of electromagnets in the telegraph design, Ignatiev applied special coils with two windings, one of which was included in the curcuit, while the other remained with ends disengaged. As a result, the telegraph pulses were sharper. Thus the clarity of the devices' performance increased without any perceptible increase in interference.
In 1880, Ignatiev demonstrated his system in action at the Physics Department in Kiev University and, in early 1881, it was successfully tested near Kiev between mine technicians and infantry camps over 14.5 km apart. This system was later used in the Russian army. (It should be noted that Ignatiev produced his first devices using personal funds and, only in 1888, did he manage to obtain 500 rubles from the War Department to construct more advanced devices).
The Ignatiev system didn't receive large notoriety as his achievements remained in the domain of the military. It was only in 1892 that he was allowed to exhibit his devices at the 4th St. Petersburg Electrotechnical Exhibition, where he was awarded a golden medal.