Remote convenience method and apparatus with reduced signal nulls

摘要

A vehicle control system is described including radio-frequency receiver. The receiver includes an antenna input adapted for connection to an antenna for receiving radio frequency signals, a source of at least a first local oscillator frequency and a second local oscillator frequency, a demodulator for demodulating the signal received via the antenna input with the first local oscillator frequency to generate a first demodulated signal and, separately, for demodulating the signal received via the antenna input with the second local oscillator frequency to generate a second demodulated signal, and a control circuit that evaluates the first and second demodulated signals according to at least one criterion and utilizes for control purposes whichever of the demodulated signals is better, according to that criterion.

主权项

1. Apparatus for use in a vehicle convenience system comprising:
a receiver adapted for mounting on a vehicle, said receiver including an antenna input adapted for connection to an antenna for receiving radio frequency signals, a source of at least a first local oscillator frequency and a second local oscillator frequency separated by a difference large enough that nulls associated with the first and second frequencies are found at different angular locations around the vehicle, a demodulator for demodulating the signal received via said antenna input with said first local oscillator frequency to generate a first demodulated signal and, separately, for demodulating the signal received via said antenna input with said second local oscillator frequency to generate a second demodulated signal, and a control circuit for controlling at least one vehicle system, said control circuit evaluating the first and second demodulated signals according to at least one criterion and, responsive to said evaluation, utilizing for control purposes one of said first and second demodulated signals.