共查询到17条相似文献，搜索用时 929 毫秒
1.
在复杂的水声信道中 ,实现高速率的数据传输 ,水声换能器的带宽是一个重要的技术问题。实验中 ,为了拓宽换能器的带宽 ,我们利用圆柱形压电换能器的径向振动与液腔振动相耦合原理研制自由溢流式换能器和利用纵向振动与前盖板弯曲振动相耦合原理研制纵向振动复合棒换能器。本文介绍适应于复杂的水声信道中 ,进行高速率数据传输的两种宽频带换能器的研制 相似文献
2.
本文介绍在设计夹心换能器纵振动的谐振频率计算中，由振子的厚度等效于基波的半波长出发，导出纵向振动换能器的频率方程。使谐振频率计算更加简便。实验表明，该方法计算方便，精确，适用于设计夹心换能器纵向振动的谐振频率计算。 相似文献
3.
本文介绍利用圆柱形换能器水平无方向性和换能器的近场波束特性，采用压电陶瓷圆柱的径向振动和壁厚振动不同振动模式，设计适宜于声波对海洋生物影响实验使用的换能器。 相似文献
4.
利用纵振换能器的纵向振动与换能器前盖板的弯曲振动相耦合原理，采用纵振换能器与声反射器配合，研制出一种适应在复杂海洋声信道进行高速率传输，具有低频，宽带，大功率等优点的水声换能器。 相似文献
5.
路德明 《山东海洋学院学报》1983,13(2):30-34,i001
前言 由压电陶瓷作为驱动元件的复合式纵向振动换能器，具有结构简单，加工容易，机械强度高，效率高等优点，是目前国内外比较广泛使用的一种换能器。 相似文献
6.
对于组合式纵振压电水声换能器，当采取增加它的辐射面积、减小辐射盖板的厚度和降低机械Q值等方法来提高它的辐射功率并展宽其工作频带时，实验观测到换能器的辐射面不再作纯等幅纵振动，而耦合有弯曲振动。因此存在节线区域，它们一般呈圆线状， 相似文献
7.
运用表观弹性法,采用二次径向谐振频率计算表观弹模量,设计高度与直径可比拟,谐振频率不满足压电晶片和金属圆片最低径向谐振频率方程的多维耦合振动复合电振子。用本方法设计垂直探鱼仪的换能器和提高优质单胞藻饲料多不饱和脂肪酸含量的超声辐射仪换能器。计算结果表明,理论与值与实验值相符合。这种方法简单,方地压电晶片的径向谐振频率低于换能器揩能器谐振频率的多维耦合振动复合压电振的设计。 相似文献
8.
本文介绍根据压电效应原理，对纵向压电换能器进行预应力控制。在纵向压电换能器的制作中，通过调整预应力的大小以保证换能器性能的一致性。 相似文献
9.
本文介绍利用表观弹性法,设计纵向振动与径向振动相耦合的朗芝万型换能器,该换能器用于大深度声遥测触底指示仪上,实验表明,理论计算值与实验值相符合,计算方法简单、方便。 相似文献
10.
在水声领域中 ,宽频带换能器是一个极其重要的研究方向。许多学者利用压电陶瓷圆柱各种振动模式的耦合 ,研究设计出各种类型的宽带换能器。Ｍｃｍａｈｏｎ１９６４年采用开口式压电陶瓷圆管 ,利用液柱共振频率与圆管径向共振频率相耦合设计宽带自由溢流式换能器。袁易全１９８３年 ,利用有限长压电薄圆管的径、长耦合设计宽频带发射换能器。上述学者均是对低频宽带换能器进行研究。在作者承担的利用超声波辐射提高海水鱼类精子受精能力的研究课题中 ,需要应用水平方向性均匀、高频宽频带发射器。为此 ,通过合理地设计换能器的结构尺寸 ,采用… 相似文献
12.
Parametric transduction offers valuable advantages for underwater acoustic communications. Perhaps the most significant benefit is the fact that high directivity is achieved by means of a physically small transmit transducer. This feature may, ultimately, be employed to permit long-range, low-frequency communication using a compact source. The high directivity is desirable to combat multipath propagation and to achieve data communications in water which is shallow by comparison with range. A real-time, high data-rate “model” differential phase shift keying (DPSK) communication system has been constructed and demonstrated. This system uses parametric transduction, with a 300-kHz primary frequency and a 50-kHz secondary frequency. Experimental results show that the system can be employed to combat multipath propagation in shallow water and can achieve high data-rate text and color image transmission at 10 and 20 kb s-1 for 2-DPSK and 4-DPSK, respectively, through a transmission bandwidth of 10 kHz. The “model” system was developed to confirm performance predictions for a future, operational long-range link employing a 50-kHz primary frequency and a 5-kHz secondary frequency 相似文献
13.
Bjerrum-Niese C. Bjorno L. Pinto M.A. Quellec B. 《Oceanic Engineering, IEEE Journal of》1996,21(2):143-149
The paper discusses the development of a simulation tool to model high data-rate acoustic communication in shallow water. The simulation tool is able to generate synthetic time series of signals received at a transducer array after transmission across a shallow-water communication channel. The simulation tool is suitable for testing advanced signal processing techniques for message recovery. A channel model has been developed based on the physical aspects of the acoustic channel. Special emphasis has been given to fluctuations of the signal transmission caused by time-varying multipath effects. At shorter ranges, the temporal variations are dominated by acoustic scattering from the moving sea surface. Therefore, the channel model produces a coherence function which may be interpreted as a time-varying reflection coefficient for the surface scattered acoustical path. A static, range-independent ray model identifies the significant multipaths, and the surface path is modulated with the time-varying reflection coefficient. The advantages and limitations of the channel model are discussed and assumptions necessary to overcome the limitations are emphasised. Based on the assumptions, an algorithm has been developed and implemented to model how a binary message will be modulated when transmitted by a transducer, is distorted in the channel and finally is received by a transducer array 相似文献
14.
P. Cobo C. Ranz A. Fernández M. Cuesta D.K. Anthony M. Siguero 《Marine Geophysical Researches》2005,26(2-4):87-95
Vertical resolution is of fundamental importance in sonar exploration and is directly related to the duration of the acoustic
pulse generated by the transducer. The shorter the radiated pulse, the higher the vertical resolution. Many sub-bottom profiling
sonar systems use piezoelectric transducers because they are reversible and well understood. Piezoelectric projectors are
normally resonant transducers, which are intrinsically narrowband. A piezoelectric transducer is usually driven by a tone-burst.
However, it is possible to use Fourier techniques to find a pre-compensated electrical driving function so that the transducer
radiates a prescribed wider band acoustic waveform. This technique can be applied to synthesize zero-phase cosine-magnitude,
Gaussian, and bionic pulses, with a conventional sandwich transducer. Zero-phase cosine-magnitude waveforms provide minimum
length pulses (and therefore maximum resolution) within a prescribed frequency band.The aim of this paper is to illustrate
the synthesis of wideband acoustic pulses using an underwater piezoelectric projector. The conventional acoustic waveform
radiated when a Tonpiltz transducer is transiently excited using a “click” and allows its frequency response function to be
measured. This function is used to design the electrical signal which then drives the transducer so that it radiates the shortest
pulse compatible with its mechanical response. The significant resolution enhancement of the waveform shaping process is illustrated
by its application to a sediment wedge model. 相似文献
15.
16.
Kopp L. Cano D. Dubois E. Wang L. Smith B. Coates R.F.W. 《Oceanic Engineering, IEEE Journal of》2000,25(3):282-295
From a designer viewpoint, a parametric array should not appear different from any other type of acoustic transducer and should be described by a limited set of design equations together with their range of validity. In this paper, these design equations are stated and discussed. They are used to optimize the acoustic parameters of an underwater communication system using parametric transduction and to evaluate its performance in terms of signal-to-noise ratio and data-rate limits as a function of transmission range. It turns out that, for a maximum data transmission rate at a given range, there is a set of optimum design parameters which is a function of the array size only. This means that, once given an operational range, the primary frequency, the electrical power, the maximum acoustic source level, and the directionality of the transducer can be deduced directly from the array diameter 相似文献
17.
本文从理论上分析了影响夹心型水声换能器温度稳定性的主要原因。提出了采用温度稳定性较好,谐振频率及温度系数较小的压电陶瓷,并在压电陶瓷圆片和钢片之间设置缓冲层,进一步改变换能器的结构,从而提高了夹心型水声换能器的温度稳定性。 相似文献