| 摘要 |
<p>The same information (51, 52) is transmitted to two distinct carrier waves of frequencies, F1, F2. The receiver has two independent receivers which are able to receive respective two carrier frequencies and are sensitive to a frequency band (3) including the carrier and a number of accessory frequencies (8-12) outside the reception band and above a certain signal level (N). The bands (3a, 8a-12a) of one receiver and those (3b, 8b-12b) of the other are separated so that all signals below the given level (N1, N2) are received by one receiver and undetectable by the other. The ratio of carrier wave frequencies is at least (-) and they lie either side of 300 MHz. The certain signal level is at least 20 dB above the smallest detectable signal.</p> |
