To utilize the advantages of dsp chips, the system should be computing sources economical. according to digital signal processing theory, the poly - phase fir can help reduce the workloads of the ddc / duc. therefore, adding the complex carrier mixers, the channelization system ( a method of using a single wideband facility to transmit many relatively narrow - bandwidth signals. by subdividing the frequency spectrum used in the wideband channel ) can be formed utilizing the characters of fft
為了使開發出的軟體可以適用於高速dsp器件開發,節省系統資源,課題首先從數字信號處理的理論進行分析,得出可以利用抽樣率轉換的數字
濾波器的特點,即多相
濾波實現數字上下變頻計算負擔的減小,之後進一步將多相
濾波器與頻譜搬移部分結合,通過公式的推導,得出可利用快速傅立
葉變換的特點實現多路信號的通道化發射和接收的處理模型。
The signal process function of the software include these function : digital filter, windowing, auto - correlation function and cross - correlation function, mean and variance, probability density function and probability distribution function statistic ; auto - power spectrum, cross - power spectrum, frequency response function, coherence function, cepstrum analysis based on fft ( fast fourier transfer ) ; joint time - frequency analysis based on stft ( short - time fourier transfer )
軟體的處理功能包括:數字
濾波、時域加窗、自相關與互相關處理、均值和方差計算、概率密度和概率分佈函數計算;在快速傅立
葉變換( fft )基礎上計算自功率譜、互功率譜、頻率響應函數、相干函數、倒頻譜分析;基於短時傅立
葉變換( stft )的聯合時頻分析等。
The equation including the nonlinear dispersion, i. e. the modified nonlinear schrodinger ( mnls ) equation, is a better model. in this thesis, we take mnls solitons as a model for femtosecond soltions. then based on the recently developed direct perturbation theory for perturbed mnls equation, we study the raman self - frequency shift of femtosecond solitons and its suppression by the means of frequency filters. for this purpose, first, we define the physical parameters of mnls solitons ; next, through the direct perturbation theory for perturbed mnls equation, under adiabatic approximation, we obtain the evolving parameters of mnls soliton on our questions and then choose the parameters of frequency filters based on it ; at last, we directly numerically simulated our questions by split - step fourier ( ssf ) method after improving the arithmetic of the differentiation of the nonlinear item for satisfying mnls equation
本論文以mnls孤子作為光纖飛秒孤子的模型,通過新近建立的mnls孤子直接微擾理論,研究光纖中由拉曼效應引起的飛秒孤子在傳輸中的自頻移,以及通過頻率
濾波對自頻移的抑制。為此,首先給出描述mnls孤子的各物理量,然後用mnls孤子直接微擾理論,解析地得到這些問題絕熱近似下的孤子參數演化,並由此選擇頻率
濾波的參數,最後用分步傅里
葉方法,在對非線性項微商的演算法做出了適合於mnls孤子的改善後,對拉曼效應及頻率
濾波進行了直接數值模擬,其中頻率
濾波參數用微擾理論確定。
Tea bag paper of non heat seal type
非熱封型茶
葉濾紙
Tea bag paper - heat seal
熱封型茶
葉濾紙
The results show that the self - adaptive filter can be used to detect line spectrum, the wavelet transform and the fourier transform can be used to detect the ship noise in modulating the anisotropic noise field
結果表明:自適應
濾波對于各向異性噪聲場中的線譜檢測有良好的效果;而小波變換和短時傅里
葉變換對各向異性噪聲場中的艦船噪聲調制信號檢測有良好的效果。
Eyccl vertical sluicing discharge pressure leaf filters are quite similar to the horizontal plate filters except for the orientation of the filter elements which are vertical rather than horizontal
Eyccl型立式加壓
葉濾機通過在密閉的容器內,垂直放置多片
濾葉作為過
濾元件,進行加壓或真空過
濾。
Afterwards, a relatively brief introduction to spam judge subsystem is given, including mail head analyse, bayes filtering and filtering based on rules
然後相對簡略介紹了垃圾郵件判定子系統的設計實現原理:包括郵件頭分析、貝
葉斯過
濾和基於規則的過
濾。
Through the fundamental research of the blade destruction, the digital filter software, the monolithic integrated circuit system software and hardware, the vibration acceleration sensor realizes the vibration protection together
通過對
葉片破壞形式的理論研究,由數字
濾波軟體、單片機系統軟硬體、振動加速度傳感器共同實現振動保護。
In this paper, the self - adaptive filter, the wavelet transform and the fourier transform are used to detect the stationary and the non - stationary signal of underwater sound in anisotropic noise field
本文以各向異性噪聲場為例,分別對聲矢量信號中的聲壓、振速探討應用自適應
濾波、小波變換、短時傅里
葉變換檢測水聲平穩和非平穩信號的應用效果。
The test instruments based on this method are highly precise, but costly. the author develops a grounding measurement system of substations based on the virtual instruments, which uses labview as the development software and adopts the small electric current method. the fft method is used to process the measurement data, which can decrease the measurement error
本文作者研製了基於虛擬儀器的變電站接地網接地測量系統,該系統以labview為軟體開發平臺,採用小電流測試法,並利用快速傅立
葉變換方法對測試信號進行數字
濾波處理,提高了該系統的信噪比。
The leaves filter medium
濾葉安裝形式
2. a user friendly approach. 3. greatly reduced recurring expenses due to no filter cloth requirement. 4. no spillage rate as a result of closed and compact operation
該葉濾機採用密封加壓多濾葉微孔精密過濾的方法來實現較理想的分離效果。