| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the power consumption of power supply of a car battery etc., by receiving an ASK modulated high frequency signal, converting the frequency of the received high frequency signal to output an intermediate frequency signal, demodulating the intermediate frequency signal and detecting the high frequency signal to obtain a carrier detection signal. SOLUTION: The ASK modulated wave is received by the antenna of a receiver which is mounted on a car, amplified by a low noise amplifier 1a of a high frequency party 1 of the receiving circuit and inputted to a carrier detection circuit part 2 and a frequency conversion circuit part 3 respectively. The part 3 includes a mixer 3a, a local oscillator 3b, a BPF 3c, etc. The oscillator 3b outputs a local oscillation signal and inputs it to the mixer 3a. The ASK modulated wave is inputted to the mixer 3a, mixed with the local oscillation signal and converted into an intermediate frequency signal. The intermediate frequency signal is transmitted through the BPF 3c and inputted to a 2nd detection diode 5a of a demodulation part 5.</p> |
