Switching device for changing television programme to alternative programme, e.g. for determining effectiveness of advertisements

摘要

A receiver (16) receives an alternative programme, such as a test commercial. A control device (18) contains control information for the switching device (10). An output (14) is connected to an antenna input to a television receiver or video recorder. A cross-fading device (20) is coupled to the control device for supplying the alternative programme or the television programme to the output, based on the control information. The cross-fading device includes a tunable modulator for shifting the channel frequency of the alternative programme to the channel frequency of the television programme. An Independent claim is included for a method of switching from a television programme to an alternative programme.