Dynamic Range Target Simulator.

A station judges, when a request to transmit information to the other stations is generated, that the station subsequent thereto does not send out a transmission request packet at the time point where a gap of time delta (i.e., a non-signal period of time delta ) is confirmed from the receiving of a token immediately after the generation, to send out the transmission request packet onto a control channel of an outbound bus transmission line. The station sends out an information packet onto a data channel of the outbound bus transmission line when time Tf, i.e., time required to prepare receiving in the other station (time required to tune the wavelength of a variable wavelength filter) has elapsed since a token was received immediately after sending out the transmission request packet. The other station recognizes by a token that it has a transmission request to itself, and prepares the receiving of the information packet in response to the subsequent token, and receives the information packet from the data channel at the same time when the preparation of the receiving is terminated.