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声表面波(SAW)卷积器能进行可编程匹配滤波,具有大的处理增益、良好的动态范围、宽的带宽、小的尺寸和重量以及低的功率需求等所希望的特性。而基于SAW的调制器也同样有用,它在扩频系统中产生可靠传输所需的伪随机码序列。SAW滤波器提供可精确重现编码波形的脉冲成形,具有与卷积器同样的优点。在频谱空间变得较为拥挤的情况下,传输信息的频谱效率最佳化是十分重要的。正交相移键控(QPSK)和最小相移键控(MSK)是两种最流行的正交调制方式。本文介绍一种由几个幅度加权的QPSK信号组成的新调制技术(AWQPSK),这种调制方法的带宽效率优于QPSK和MSK。给出了系统的分析和特性参数以供评价。讨论和提出了一种SAW调制器的实现方法。
Surface acoustic wave (SAW) convolvers enable programmable matched filtering with the desired characteristics of large processing gain, good dynamic range, wide bandwidth, small size and weight, and low power requirements. SAW-based modulators are equally useful, generating pseudo-random code sequences for reliable transmission in spread spectrum systems. The SAW filter provides pulse shaping that accurately reproduces the encoded waveform with the same advantages as the convolver. In the case of a more congested spectrum space, it is important to optimize the spectral efficiency of the transmitted information. Quadrature phase shift keying (QPSK) and Minimum phase shift keying (MSK) are the two most popular types of quadrature modulation. This paper presents a new modulation technique (AWQPSK) consisting of several amplitude-weighted QPSK signals, which has better bandwidth efficiency than QPSK and MSK. The system analysis and characteristic parameters are given for evaluation. Discuss and propose a realization method of SAW modulator.