Telephone cable

Blimey! 186 dB of attenuation!!!!!!!

You would have had to stick a kilowatt of power into one end to get a barely measureable signal out the other!!!

Imagine the speed of transmission, it would have to be so slow in the 1930s. No wonder they gave up on it!!!

John.

As far as I can gather the scheme was abandoned on economic grounds not technical as the cost was estimated at $15m in 1929 just as the great depression started ( rather a lot for one speech channel although many simutaneous telegraph channels could have used it when it was not needed for speech).

I think 186 db loss was my misprint It should have been 168 db assuming the insulation was good for 1400v peak 10KW could be inputed ( well within the capacity of audio amplifiers in 1929 ) giving 1.6 *10^-13 Watts at the other end an adequate level.

"

1928 - Design of a continuously-loaded Newfoundland-Ireland cable begins, as a joint AT&T-British Post Office project. The planned loss was 165 dB over 1800 miles. It used 4 layers of Perminvar tape for loading. Manufacturing in Germany began in 1930. The Depression caused all work to be abandoned. By the late 1930s, submerged repeaters and multiplexing promised more circuits at the same cost. "

What I would really like to know what was the frequency a phase charictaristics, it would be a trivial matter to correct these today but what did they plan to do in 1930 ?.

Was there some scheme for two way transmission or was it this over and out business ?