Car access control system antenna circuit diagnosis unit switches antenna to static diagnosis unit with exact resistors in supply path

摘要

A car access control system antenna (2) circuit (1) diagnosis unit switches (21, 22) the antenna from the signal to a static diagnosis unit (20) applying the supply potentials (VCC, GND) to exact resistors (29, 30) and a dynamic diagnosis unit (10) applying the alternating current (13) through a transformer (6). Independent claims are included for the procedures used by the unit and for a third diagnosis unit measuring phase differences.