A digital television receiver and antenna control method in the digital television receiver are disclosed. Methods and apparatus are disclosed for building ontologies and dynamically expanding ontologies. The removed conversations may be moved to an archive which may be automatically maintained in response to size constraints. The spectral channels are selectively optically coupled to the selected beam deflector array, which selectively optically couples the spectral channels between one or more input ports and one or more output ports. The whole of the first current mirror circuit and the second current mirror circuit is divided into an input circuit and an output circuit; and the divided position is provided on a voltage route of the first current mirror circuit or a voltage route of the second current mirror circuit.