A TDD signal booster includes first and second bidirectional terminals and an amplifier circuit arranged in a signal path between said first and second terminals. The amplifier circuit is to amplify TDD signals received at one of said first and second terminals for transmission from the other of said first and second terminals. The amplifier circuit is operable in a first configuration for amplifying TDD signals in one direction along the signal path and a second configuration for amplifying TDD signals in the opposite direction along the signal path. A control circuit is arranged to detect a silent period in said TDD signals, e.g. the guard period, and, in response to detecting the silent period, control said amplifier circuit to change configuration.