Based on the results of the theory analysis and computer simulation of suspended stripline low pass filter , band pass filter , the transition from waveguide to finline and the transition from waveguide to suspended stripline , the structure design and manufacture were made . the measured results match the requirement . different from the traditional mixers used in the domestic communications satellites , the sub - harmonic balance mixer type was used in the ka - band mixer design 在ka频段混频器的研究过程中，通过对卫星和飞船所用到的混频器进行研究，在对ka波段的传统射频前端电路的分析基础上，提出改变以往星上传统的基波混频方案，采取了次谐波混频方案，降低了本振频率，简化了本振链路，使噪声特性、可靠性获得改善。
Using sige bicmos darlington configuration as the input stage , the input resistance is increased by the mos devices while the transconductance of sige hbts is maintained . in the same time , the equivalent input noise is controlled well because of the sige hbts ’ good noise performance in the input stage 输入级的设计采用sigebicmos达林顿结构,在保留sigehbt高跨导优势的基础上充分利用mos器件来提升运放输入电阻,此外,基于输入级中sigehbt良好的噪声特性,运放的输入参考噪声电压可以大大降低。
Traditional spread spectrum communication adopts pseudo - noise ( pn ) codes as spreading codes . however , pn sequence is fixed and periodic , which threatens the transmission security . self - encoded spread spectrum ( sess ) employs random spreading sequences that are extracted from the random information data , abandoning the fixed sequence 传统的扩频通信广泛采用伪噪声( pseudo - noise , pn )序列作为扩频序列, pn序列具有类噪声特性,但它实际上是确定的周期序列,容易被复制。
On the basis of analysis of vibration and noise characteristics , measures for controlling noise and vibration in high - speed ship were described in this paper . frequency storage of different precision calculated by different method was also put forward . in dealing with the fluid in the tank , which affects the vibration of bottom plates in the ship , new regulations given in the paper are in better accordance with practical circumstance 在分析了高速船振动、噪声特性的基础上，阐述了适合高速船的振动与噪声控制措施，提出了相应不同计算方法精度的不同频率储备量，对处理舱内液体对船底结构振动的响应提出了更符合实际情况的新规定
Frequency response , quantization noise , reconstruction error and its sensitivity to mismatch among adcs are studied at length in prqmf banks adc system , and the theoretic results include : ( 1 ) the distortion / aliasing functions of hybrid filter banks adc system is similar with that of switch capacitor filter banks adc system ; ( 2 ) for wide or narrow band input signal , the effective resolution of the two adc systems is 0 . 51og2m bits higher than their adc ; ( 3 ) reconstruction error ' s sensitivity to mismatch among adcs of the two adc systems is reduced effectively than time interleaved adc system 2对prqmf滤波器组adc系统的频响、量化噪声特性、重建误差特性以及重建误差对adc间的失配敏感性进行了理论分析研究，所得到的理论结果为： ( 1 )混合滤波器组adc系统与开关电容滤波器组adc系统的失真/混迭函数一致； ( 2 )无论输入宽带还是窄带信号，这两种adc系统的有效分辨率均比其adc提高了0 . 5log _ 2m比特； ( 3 )这两种adc系统的重建误差对其adc间的失配敏感性均明显低于时间交织adc系统。
This article firstly deal with the sound source , noise measurement and analysis , noise control principle and some basic noise control technology , then elaborate the current noise detection standard and method for the coach in our country , the noise mechanism . characteristics and the measures of noise - controlling , finally . describe the actions of noise control , noise detection and optimization in our coach detailedly , which have met with the expectation 本文首先叙述了声音的产生原因、噪声的度量和分析方法；介绍了噪声的控制原理和原则以及一些基本的噪声控制方法。然后，介绍了我国目前的客车车内噪声的检测标准和方法；详细阐述了客车主要噪声源的产生机理和噪声特性以及车内噪声控制措施；最后，理论与实际相结合，对我公司的lck6122型大型客车采取了相应的噪声控制措施以及并其进行了测试和优化。
Meanwhile , with the development of wdm / dwdm communication systems , more and more attention is paid on the edfas with broader bandwidth , good gain and noise feature , and gain clamping , etc . according to the tianjin natural science foundation project : intelligent fiber amplifiers and light sources , the tianjin natural science foundation project : ( c + l ) broadband fiber amplifier and the nankai - delta ( tianjin ) project : development of gain flattened erbium - doped fiber amplifiers , this dissertation is mainly focused on the study of novel gain - clamped edfa , light sources , multi - wavelength fiber laser and variable optical attenuator for gain - clamped usage , gain and noise improvement of edfa , and broadband edfa Wdm / dwdm通信系统的发展又需要edfa具有更大的带宽、优良的增益和噪声特性和增益控制等功能。基于上面的情况,并结合天津市重点基金项目? ?智能光纤放大器光源的研究、天津市重点基金项目? ? ( c + l )超宽带掺杂光纤放大器和南开-达尔泰(天津)项目? ?开发增益平坦的掺铒光纤放大器等课题,论文主要围绕新型增益控制edfa 、增益控制用光源、多波长激光器及可调光衰减器、 edfa性能优化和超宽带edfa等方面进行了理论和实验研究。
On the basis of analyzing noise property , this thesis emphasizes on two noise estimation methods : classical method based on voice activity detection ( vad ) and the latest method based on optimal smoothing and minimum statistics . some improvements have been proposed to enhance the vad ’ s performance based on lpc cepstrum coefficients 2 .在分析噪声特性的基础上,重点研究了基于语音活性检测和基于连续更新噪声谱的两种噪声参数估计方法,并提出了将能零积的思想应用到基于lpc倒谱系数的语音活性检测算法中。
System scheme of speech coding plus spread spectrum communication was presented based on a full analysis of noise characteristic , attenuation characteristic and impedance characteristic of low - voltage power line . spread spectrum carrier ( abbreviated as ssc ) technology is adopted to overcome problems existing in signal transmission over power line . high quality , low rate mbe compression algorithm was used to complete speech encoding and decoding 在对低压电力线路的噪声特性、衰减特性和阻抗特性三个方面充分分析的基础上，本文提出一种语音编码+扩频传输的系统总体方案，采用扩频载波( spreadspectrumcarrier ，缩写为ssc )技术克服电力线传输信号存在的问题，采用语音合成质量高并具有较低码率的mbe压缩算法完成语音信号的编解码。
This dissertation is different from traditional speech enhancement methods which are based on noise characteristic such as adaptive noise cancellation or spectral subtraction processing . in this dissertation the speech signal conducted by bone was taken as the object to be studied and the exploitive study on the acoustical characteristic of speech signal conducted by bone was performed by the method of theory combined with experiment . then a proposition about speech reconstruction based on speech signal conducted by bone was presented , and the design of software and hardware was completed 本文与传统的基于噪声特性的自适应噪声抵消法、频谱减法等语音增强降噪技术不同，是以骨导语言为研究对象，采用理论与实验相结合的方法对骨导信号的声学特性进行了探索性研究，进而提出了基于骨导信号的语音重构技术，并完成了相应的软硬件开发。
