Delaying The Broadcast

[xoxoxoBruce]

From a 1939 Mechanix Illustrated article;

There was a problem where two radio stations were broadcasting the same syndicated content on the same frequency. Listeners near either station had no problem. However there were locations where both signals could be recieved. This would be fine, except for the fact that the cable running to one of the stations was longer than the other, so the signal was delayed by 1/23000 of a second. Enough to cause destructive interference. So the engineers solution was to create an acoustic delay line out of 23 feet of lead pipe stuffed with cloth and gauze with a speaker on one side and a microphone on the other. The slower speed of light delayed the signal long enough for the two stations to be in sync.

The article goes into how they had to set up filters, amplifiers and all the other equipment involved to solve this problem. It was soooo much harder then.

[SteveDallas]

Fascinating but . . .

. . . an acoustic delay line out of 23 feet of lead pipe stuffed with cloth and gauze with a speaker on one side and a microphone on the other. The slower speed of light delayed the signal . . .

They mean the speed of sound, don't they?

[wolf]

Gauze slows down light too, doesn't it?

[xoxoxoBruce]

Yeah, speed of sound for 23 feet to make up for the 500 miles of cable and 250 miles through the air at the speed of light.
Hey, whadda ya want from a 10 cent magazine.