Transmitter unit with antenna for motor vehicle antitheft system, has switch operated at carrier frequency of transmission signal, and connected in parallel with capacitor

摘要

The output stage (AS) of a series oscillator circuit, comprising a coil (Ls), capacitor (Cs) and a switch (SW) in parallel with the capacitor, is driven by a voltage (Us) containing the amplitude information of the transmission signal (S). The switch is operated at a predetermined carrier frequency of the transmission signal. The antenna (Ant) is connected to a terminal (A10) between the coil and the capacitor. An Independent claim is included for the use of the transmitter unit for transmitting amplitude-shift keying signals.