The daily frequency test on the line to the
transmitter in Berlin - this was at the height of the Cold War and
Berlin was still an isolated city. The jackfields were for setting up
special situations; most switching was done by a roomful of
uniselectors (like a telephone exchange) adjacent to the Control Room.
Taken in 1965.
to see details of the Automatic Switching Unit from the 1968 edition of the operating manual ('BU1').
The Automatic Switching Unit - ASU - was programmable with the changing networks which were sent to each line to transmitters. Previously done manually, this was a remarkable piece of engineering for the period.
First picture below, one of the two
columns of uniselectors. Every 15 minutes they all stepped on one
position: at midnight they all returned to the first position with an
Then a close-up of one uniselectors, clearly showing the 'combs'
inserted to cause the switching, and a typical 'comb': the
arrangement of the teeth specified the network required.
© Roger Wilmut. This
site is not associated with the BBC