Abstract: A cradle comprises a first connecting unit to which a portable content playback apparatus is connectable; a second connecting unit to which a computer is connectable; an output unit that outputs content data; a controller that controls the portable content playback apparatus; a hub that is connected to the second connecting unit, a first switch, and a second switch; the first switch that switches between connection of the first connecting unit to the controller and connection of the first connecting unit to the hub; the second switch that switches between connection of the output unit to the controller and connection of the output unit to the hub; and a switch control unit that controls switching of the first switch and the second switch.

Abstract: A cradle comprises a first connecting unit to which a portable content playback apparatus is connectable; a second connecting unit to which a computer is connectable; an output unit that outputs content data; a controller that controls the portable content playback apparatus; a hub that is connected to the second connecting unit, a first switch, and a second switch; the first switch that switches between connection of the first connecting unit to the controller and connection of the first connecting unit to the hub; the second switch that switches between connection of the output unit to the controller and connection of the output unit to the hub; and a switch control unit that controls switching of the first switch and the second switch.

Abstract: A low-pass filter with a high signal-to-noise ratio is provided. A low-pass filter includes a first RC filter circuit, a differential operation circuit subtracting an output signal from a low frequency component of an input signal and outputting a differential signal, a second RC filter circuit, a voltage-current conversion circuit, and a capacitor. The voltage-current conversion circuit includes an operational amplifier, a first resistor, and a feedback circuit generating a feedback voltage in accordance with a voltage applied to the first resistor. If resistance values of first to fourth resistors are R1, R2, R3, R4, a relational expression of R1*R3=R2*R4 is satisfied, and output current i becomes constant regardless of a resistance value of a load resistance. Since only a first resistor is connected between the input and the output of the voltage-current conversion circuit, thermal noise decreases, and a signal-to-noise ratio becomes high.

Abstract: A low-pass filter with a high signal-to-noise ratio is provided. A low-pass filter includes a first RC filter circuit, a differential operation circuit subtracting an output signal from a low frequency component of an input signal and outputting a differential signal, a second RC filter circuit, a voltage-current conversion circuit, and a capacitor. The voltage-current conversion circuit includes an operational amplifier, a first resistor, and a feedback circuit generating a feedback voltage in accordance with a voltage applied to the first resistor. If resistance values of first to fourth resistors are R1, R2, R3, R4, a relational expression of R1*R3=R2*R4 is satisfied, and output current i becomes constant regardless of a resistance value of a load resistance. Since only a first resistor is connected between the input and the output of the voltage-current conversion circuit, thermal noise decreases, and a signal-to-noise ratio becomes high.

Abstract: An automatic music selecting system is provided which can select a piece of music more suitable for an occupant of a mobile unit. It includes a music data storing section that stores music data corresponding to a plurality of pieces of music; a navigation system for detecting the current position of the mobile unit; a first keyword generating section for generating a first keyword in response to current position information indicating the current position detected by the navigation system; sensors for detecting environment of the mobile unit; a second keyword generating section for generating a second keyword in response to the environment information indicating the environment detected by the sensors, a music selecting section for selecting a piece of music in response to the first keyword and second keyword; and a reproducing section for reading the selected music data from the music data storing section to reproduce.

Abstract: An automatic music selecting system is provided which can select a piece of music more suitable for an occupant of a mobile unit. It includes a music data storing section that stores music data corresponding to a plurality of pieces of music; a navigation system for detecting the current position of the mobile unit; a first keyword generating section for generating a first keyword in response to current position information indicating the current position detected by the navigation system; sensors for detecting environment of the mobile unit; a second keyword generating section for generating a second keyword in response to the environment information indicating the environment detected by the sensors, a music selecting section for selecting a piece of music in response to the first keyword and second keyword; and a reproducing section for reading the selected music data from the music data storing section to reproduce.