| 摘要 |
A signal shaping circuit for shaping amplitude shift keyed digital pulses of a digital data stream is set forth. The digital data stream is comprised of a plurality of symbols from which the signal shaping circuit generates an output signal having sinusoidally shaped transition regions between logic level transitions of the digital data stream. The signal shaping circuit comprises an input lead receiving each of the digital pulses of the digital data stream. A delay circuit receives each of the digital pulses of the digital data stream at the input lead and, after a predefined time delay, outputs delayed digital pulses corresponding to each of the digital pulses received at the input lead. A ringing filter circuit having a linear response receives each of the digital pulses of the digital data stream provided from the input lead and each of the digital pulses provided at the output of the delay circuit. The ringing filter circuit has a ringing period about equal to or less than twice the symbol period of the digital data stream which, in turn, sets the value of the predefined delay. More particularly, the predefined delay of the delay circuit is about equal to half of the ringing period. As a result, the ringing filter circuit generates an output amplitude shift keyed digital data stream directly corresponding to the digital data stream provided at the input lead which has sinusoidally shaped transition regions between its logic level transitions. The resulting waveform has a lower bandwidth than the corresponding input signal and, further, has no intersymbol interference associated with it. |
