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Digital synthesis technique for pulses having predetermined time and frequency domain characteristics
Digital synthesis technique for pulses having predetermined time and frequency domain characteristics
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机译:具有预定时域和频域特性的脉冲的数字合成技术
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摘要
A digital synthesis technique provides pulse shaping in accordance with predetermined time domain and frequency domain constraints. In the technique, the informational content of a binary bit stream is used by an access circuit (12) to form address words for accessing a read-only- memory (13). The digital representations stored in the ROM (13) represent a superposition of temporally-displaced truncated impulse time functions, each weighted by the discrete transmission symbol levels of the analog output signal. The digital representations from two ROMs (13-1 and 13-2) are toggled by a sequencng circuit. In other embodiments of the invention, different memory arrangements ranging from a signal ROM (142) to an array of ROMS (163-1 through 163-3 and 164-1 through 164-3) are respectively used to decrease circuit complexity. In a digital radio transmission application of the technique, this arrangement is economical, readily reproducible and stable since it obviates the need for conventional complex analog filters.
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