Transmission Lines

loading coils, history of transmission lines

Telephone Lines Connect the Coasts

Telephone line audio interface circuits
Telephone to studio mixer interface
(caution! pop-ups)

Telephone Timeline

George A. Campbell and the Electric Wave Filter

...  a chronology of Telegraph, Telephone and   Radiotelephone, the three services reaching across the Atlantic before the 1960 Echo satellite.
(1880 - Oliver Heaviside's analysis shows that a uniform addition of inductance into a cable would produce distortionless transmission.
(It would be 40 more years before Bell Labs devised a practical method
of producing uniform inductance -- "permalloy" magnetic ribbon spiral
winding around a conductor. This would permit 400 WPM on the
New York-Azores Western Union cable in 1925.)

***** The Telegrapher's Equation *****


pulse reflection

Transmission lines
If you look at the direction of displacement in the pulse, it reverses on reflection.
Thus, a wave of displacement to the right is returned as a wave of ...