| 摘要 |
A low powered RF receiver for receiving a modulated carrier having a coded transmission so as to remotely control a number of vehicular devices includes an antenna, a preamp stage, mixer, local oscillator, first and second IF bandpass filters, first and second IF amplifiers, a received signal strength indicator/detector circuit, and an adaptive threshold/filter circuitry. The signal strength indicator/detector circuit is interconnected between the first and second IF amplifiers and generates a strength indicator signal which is proportional to the strength of the modulated carrier signal received. The adaptive threshold/filter circuitry is responsive to the strength indicator signal and has a varied threshold reference level for eliminating noise and for converting the strength indicator signal to a logical level. A microcontroller is provided for further signal processing, decoding, and executing the function corresponding to the vehicular device to be controlled.
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