| 摘要 |
The hub station of a network receives a multiplicity of signals in different frequency channels and possibly on different antennas. The individual signals to be demodulated may coexist in a radio frequency channel using FDMA, TDMA, or CDMA or other signal types or combinations thereof. The received frequency band is divided into subbands which are all translated to baseband and distributed to the backplane of one or more demodulator chassis (each of which contains many demodulators). In this way, any demodulator may be connected to any signal. Relatively large segments of the input bandwidth are translated to baseband. These segments are then digitized and further band segmentation is performed digitally. In this way, the digitation and switching functions are almost all done with digital hardware. This affords considerable advantage in hardware cost, size, and reliability. The sharing of common equipment for translation to baseband affords major reductions in quantity of such translation equipment compared to conventional systems where each demodulator has its own associated translation equipment. This provides great advantages in cost, size and reliability. The demodulator outputs are decoded using bulk processing. This leads to considerable hardware savings with no reduction in demodulator allocation flexibility. The use of bulk processing allows the memory 31 associated with the decoder 30 to be located in a separate low-cost standards memory rather than in the more expensive special integrated circuit memory and this leads to further cost savings. |
