| 摘要 |
An FDM communication system is disclosed wherein two separate intermediate frequencies are utilized in such manner that the difference between transmitting and receiving frequencies thus generated is the difference between the two separate intermediate frequencies, thereby providing the capability of using independent sideband transmission instead of single sideband transmission, thus providing additional channel capacity. A single synthesizer is utilized and a single bandpass filter selects the appropriate upper or lower sidebands of transmission for full duplex operation. One of the two available sidebands is then used for communication, with the other sideband available for signalling, monitoring, break-in or other telecommunication functions.
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