| Popis: |
In this paper, we conduct a detail analysis of a kind of base-band symbol distortion and spectrum-spreading caused by the limiter in the quadrature modulation system. The selected symbol is sin2(πt/4T). In order to improve the system bandwidth efficiency, we introduce the inter symbol interference, giving a method to analyze the base-band symbol distortion after adding the limiter, and got 64 kinds of distorted symbol waveform and expressions as well as the cross-correlation properties of the adjacent symbol. We also compared the modulated signal's frequency spectrum characteristics before and after adding the limiter. Using the obtained distorted symbol waveform and adjacent code properties, we achieved the modulation process, verifying the correctness of the very method. The very method also provide a useful reference on analyzing other quadrature modulation system, whose base-band symbol distortion and spectrum spreading caused by the limiter. |
