| 摘要 |
<p>PURPOSE: To avoid interference from surrounding to each transmission and reception signal, in relation to a system which detects an object by transmitting a signal of specified frequency from a travelling car and then receiving a reflected signal from surroundings. CONSTITUTION: A microwave transceiver part 102 transmits a time multiplexing microwave signal having at least two channels (frequencies) with an interval about 250kHz, and receives it. The time multiplexing signal hits an object after transmission, and a part of the transmission signal is reflected, and then returns to an antenna 108. A frequency difference signal which is equal to that between transmission signal and reception signal is generated, and digitized, and further, FFT(fast Fourier conversion) is performed. The energy spectrum is analyzed with digital signal processing and a micro controller in a control circuit 106, for detecting interference. When, an interference is detected, the micro controller changes a transmission frequency till a frequency with relatively less interference is found.</p> |
