Abstract: A signal level switching circuit is provided with input resistors 2a and 2b connected between input terminals 1a and 1b of a signal and output terminals 5a and 5b used to be connected to a reception circuit 6; a switch circuit 3 which has been constituted by a plurality of switching elements and has been connected to the output terminals 5a and 5b; and a voltage dividing resistor 4 for selectively switching/connecting with respect to the input resistors 2a and 2b by this switch circuit 3.

Abstract: A bandpass filter 51 extracts a Nyquist tone signal from an input signal, and a power calculation unit 52 checks the level of the extracted tone signal. A line equalizer control unit 53 controls a line equalizer 42 based on the level of the calculated tone signal. If the level of the tone signal fluctuates beyond a prescribed range, a level adjustment circuit compulsory activation control unit 54 compulsorily activates the line equalizer control unit 53, and if it is judged from the level of the tone signal that the apparatus is in a normal communication state, the level adjustment circuit compulsory activation control unit 54 nullifies the compulsory activation of the line equalizer control unit 53.

Abstract: In a motorcar having a compressed fuel cylinder charged with a compressed fuel disposed in a compartment, pipes connected to the fuel cylinder within the compartment are connected to a joint unit penetrating a partition wall partitioning the compartment from an outside and the joint unit is connected to pipes connected to an internal combustion engine and the like out of the compartment. A fuel charge passage, a fuel supply passage and a relief passage in a cylinder cap of the fuel cylinder and a fuel charge passage, a fuel supply passage and a relief passage in an interior side of the joint unit are connected with each other through an interior charge pipe, and interior supply pipe and an interior fuel relief pipe, respectively. A fuel charge pipe, a fuel supply pipe and a relief pipe out of the compartment are connected to a fuel charge passage, a fuel supply passage and a relief passage in an exterior side of the joint unit.