From DANNY BURNSTEIN
Re the problem of television ‘ghosts’ caused by reflected signals from
Canary Wharf tower (Technology, 18 July). Until recently, most local television
programmes in New York City were transmitted from the Empire State Building,
and aside from problems caused by an overenthusiastic simian visitor (King
Kong), this system generally worked.
However, in the late 1960s construction began on the World Trade Center
towers, a twin set of 110-storey buildings, rectangularly shaped, and clad
in highly reflective metal. As they are located approximately 3 miles south
of the Empire State Building, a great deal of multi-path ghosting was expected,
and, in fact, occurred.
To ameliorate the problem, ‘translators’, or ‘repeaters’, were placed
in service to rebroadcast the affected signals on a different frequency,
and in a directional beam facing northwards. The people affected by ghosting
then had the option of switching to a second frequency, on a different channel,
which, being directional, did not bounce off the towers
Danny Burstein New York City, US
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