Abstract: An air conditioner duct being suitable for connection with an air conditioner arranged in a cab. The air conditioner duct is provided with an air outlet member, which includes an air release portion for releasing air into the cab and plural fins for guiding air to the air release portion. The air outlet member comprises a turnable air outlet member shaped to enclose a duct portion, to which the turnable air outlet member is connected, and is turnable relative to the duct portion.

Abstract: A digital signal transmitting system includes a digital signal generator, such as, an A/D (analog-to-digital) converter, for producing digital information signals representing music or data, and a control signal generator for producing a frame synchronizing signal and service bit signals which are time division-multiplied with the digital information signals for producing a composite digital signal. Further, a terminal number and a scramble key code are time division-multiplexed on the service bits within each different frame of the composite digital signal so as to make available the scramble key code at a terminal unit or receiving side of the system.

Abstract: A digital signal transmitting system includes a signal generator for producing time division-multiplexed digital audio signals and service bit signals, a modulator for modulating a carrier in accordance with the time division-multiplexed signals and a transmitter to transmit the modulated carrier through a CATV (cable television) transmission line. In a receiver, the service bit signals are decoded so as to control the channel changeover of a television receiver when an emergency broadcast signal is transmitted. A muting control circuit is also provided so as to mute an audio signal from a D/A (digital-to-analog) converter.