Systems and methods for providing network access to mobile devices that travel with a vehicle, such as a train, a bus, a boat, etc. The first compressor has a first closed casing, a first compression mechanism, an expansion mechanism, and a shaft. The detection portion is located such that the media sensor faces the detection portion. A current-to-voltage converting section converts an analog output current flowing through the analog output current terminal into an analog output voltage in response to the analog output current and supplies the analog output voltage to an analog output voltage terminal. And it carries out all of these legitimate interests in a way that is fast, simple to use and easy to audit.