Abstract: An optical transmission system including an optical transmission device and an optical reception device that receives, via an optical transmission line, a signal transmitted from the optical transmission device, the optical transmission system including a transmission-mode selection unit that selects transmission mode information in descending order of priority out of transmission mode information, which is combinations of a plurality of parameters concerning transmission performance, the transmission mode information being a plurality of kinds of the transmission mode information common to the transmission performance of the optical transmission device and the optical reception device, a signal transmission unit that transmits, to the optical reception device, a signal modulated based on the selected transmission mode information, and a signal reception unit that receives the signal and modulates the received signal based on the transmission mode information selected by the transmission-mode selection unit.

Abstract: A top launching device for launching a top includes a device body and an operating belt. The device body includes first and second input rotors to rotate, an output rotor configured to hold the top in a state with a central axis of the output rotor aligned with a central axis of the top and configured to rotate and impart the rotational force to the top, and a coupling rotor configured to transmit the rotational force from the input rotor to the output rotor. The operating belt is configured to be inserted in the device body, and to be engaged with either the first or the second input rotor. The output rotor is configured to rotate the top, impart the rotational force to the top, and release the top. The operating belt is configured to be selectively engaged with one of the first and second input rotors.