COMMUNICATION DEVICE, COMMUNICATION SYSTEM, AND VEHICLE

A communication device includes: an oscillating circuit (602) for generating a single including a signal potential that is based on a reference potential; a first terminal (TS1) for communicating with a vehicle (10); and a first resistance circuit (RB) connected between an output of the oscillating circuit (602) and the first terminal (TS1) and having a resistance value variable according to a first input signal (SB). Preferably, the vehicle (10) includes: a second terminal (TS2) connected to the first terminal (TS1); and a second resistance circuit (RA) connected between a ground node (512) fed with the reference potential and the second terminal (TS2). The vehicle (10) is provided with a first signal extraction node (N1) on a path connecting the second terminal (TS2) and the second resistance circuit (RA) to each other.