The present invention is directed to a display for easily understanding time changes of communication conditions of channels using a plurality of sub-carriers. Layers corresponding to the plurality of channels are displayed along the time base in such a manner that width of each layer is determined in accordance with the number of sub-carriers used for each channel at any given time. Additionally, colors or patterns of each layer may be modified in accordance with modulation types or power levels of the corresponding layer. The relationship between colors or patterns of the layer and modulation types or power levels is displayed.