Synchronised AM networks.

[Colly0410]

In 1967 a new AM national British radio station called BBC Radio1 started broadcasting using a 'single frequency synchronised network.' It used about 14 transmitters dotted all over the Country using one frequency 1214 Khz (247 metres) the powers went from 140 KW's down to 500 watts. It covered most of the Country, but some areas picked up a signal from from more than one transmitter, these were known as mush zones, the signal faded & speech & music was distorted in these areas. Of course I had the bad luck to live in a mush zone..

In 1978 Radio1 changed over to a duel frequency AM network, 1053 Khz & 1089 Khz, it still had a bit of a mush zone problem but nowhere near as bad as before the change, vast majority of listeners could get at least fair reception from one of the transmitters..

Were single frequency networks ever used in USA?