A television system comprising a television set with at least one television tuner, and a broadcast data receiver for selective operation to receive data for the generation of one of a number of selectable television channels, and a detector to detect spectral emissions from the television tuner. The spectral emissions are a value from the local oscillator to allow identification of an analogue channel selected for display by the user. The broadcast data receiver is controlled to decode and process digital data relating to the identified analogue channel and display the processed digital data to produce the selected channel via the television system.