Mehrfachfrequenzsender

摘要

A vehicle transmitter for transmitting a coded RF signal to a receiver for remote activation of a device, such as a garage door opener, includes an actuation switch e.g. 44 provided for actuation by a vehicle occupant, and a signal generator actuated by it for sequentially generating and transmitting at least two control signals having the same code and different RF carrier frequencies. By sequentially transmitting the control signals at slightly different carrier frequencies falling within the bandwidth of the receiver of the remote device, the present invention minimizes frequency-dependent nulls in the transmission pattern and thereby reduces RF fading resulting from reflections from the vehicle. The transmitter may be a multi-channel trainable transmitter.