| 题名 | 低频发射换能器瞬态抑制技术研究 |
| 作者 | 张建兰 |
| 学位类别 | 博士 |
| 答辩日期 | 2007-07-13 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 声学研究所 |
| 关键词 | 换能器 瞬态响应 瞬态抑制 |
| 其他题名 | Study on transient suppression of low-frequency emission transducers |
| 学位专业 | 声学 |
| 中文摘要 | 低频声波在海水中的衰减系数小于高频声波，其传播距离更远，因而为了加大主动声纳的探测范围、提高水下通信的距离，水声设备需要更低的工作频率并在更宽的频带内处理信号，这就要求水声换能器向低频、宽带的方向发展。 而小尺寸的低频换能器为了保证有足够的声辐射效率，其机械品质因数Q会很高，其带宽必然很窄。而就目前的技术水平来说，很难从制作商处获得小尺寸、低频和宽带兼得的理想换能器。研究如何使用窄带换能器发射象编码调相信号这样的宽带信号成为有突出现实意义的课题。 针对窄带换能器的宽带发射问题，文章讨论了一种基于一个自由度线性振子模型的瞬态抑制技术—在发射信号的同时发射消影脉冲，用消影脉冲的响应抵消信号响应中的瞬态项，获得理想的信号输出，实现窄带换能器的宽带发射。在换能器等效电路参数已知的条件下，推导出换能器输出响应的解析表达式，分离出瞬态响应项，得到瞬态抑制脉冲的解析表达式，并分析了五种形式的消影脉冲的瞬态抑制性能。当换能器等效电路参数未知时，文章讨论了一种自适应方案，即应用自适应控制理论，通过最小二乘法数值地求解消影脉冲。 计算机模拟计算和水库实验证明了我们所讨论的瞬态抑制方案的有效性和可行性。 |
| 英文摘要 | Abstract: Sound with low frequency has smaller attenuation than high frequency, resulting a greater propagation distance. In order to increase the detection ranges of active sonars and propagation distances of underwater acoustic communications and the accuracies of underwater measurements, the underwater instruments need to operate on lower frequencies and processing signals in broader bandwidths, thus leading to the development trend of low frequency and broadband. According to the conventional design theories on transducers, the lower the resonant frequency of the transducer, the greater the size and the weight. While to guarantee the efficiency of sound radiation, the designed mechanical quality factor Q of a small transducer is high, resulting a narrow bandwidth. How to transmit broadband signal using a narrowband transducer becomes a significant task. A method on transient suppression is discussed in the paper, based on a model of a single-degree-of-freedom linear vibrator. With this method, a pedestal pulse is to be transmitted simultaneously with the driving signal. The output response of the pedestal pulse is used to eliminate the transient response of the driving signal, therefore, a desired output is obtained, achieving the broadband transmission using a narrowband transducer. When the parameters of the equivalent circuit of a transducer are known, the analytic expressions of the output response are derived. Then the analytic representations of the pedestal pulses are obtained by separating the transient components from the complete response. The features on transient suppression of 5 different pedestal pulses are discussed in the paper. When the parameters of the equivalent circuit of a transducer are unknown, the analytic expressions for the output responses cannot be written explicitly. An adaptive scheme is considered to solve the pedestal pulse numerically by using the least-square algorithm. Simulations and experiment results show the effectiveness and feasibility of the transient suppression schemes. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 99 |
| 内容类型 | 学位论文 |
| 源URL | [http://159.226.59.140/handle/311008/8]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 张建兰. 低频发射换能器瞬态抑制技术研究[D]. 声学研究所. 中国科学院声学研究所. 2007. |
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