| 摘要 |
<p>1,164,684. Radio receiving systems. RAYTHEON CO. 3 May, 1967 [1 July, 1966], No. 20627/67. Heading H4L. In an arrangement for bringing a plurality of received signals into a predetermined phase relationship, e.g. in a diversity system, signals received via spaced aerials 90, 92, 94, 96, Fig. 1, are supplied to mixers 100, 102, 104, 106 respectively and heterodyned with a common signal supplied via line 108 from the output circuit. Considering mixer 100, the difference frequency is selected by filter 110, limited at 120 and fed to a mixer 130 which has as its other input the received signal applied to mixer 100, the outputs of mixers 102, 104, 106 being similarly treated and fed to mixers 132, 134, 136 respectively. The limiters may be omitted to provide "ratio squared" combining. The outputs of mixers 130, 132, 134, 136 are added at 140 and the sum frequency is selected by a filter 142, amplified at 144 and fed to the output stage and also fed back via lead 108 as the common heterodyning signal. The arrangement is applicable to frequency-modulated signals. The received signals may be in frequency-diversity form if the filters 110, 112, 114, 116 are tuned appropriately.</p> |
