Design of bessel low pass filter in direct digital synthesizer 直接數字合成器中貝塞爾低通濾波器設計
Through the research of direct digital synthesizer ( dds ) used as a divider in phase lock loop ( pll ) , a frequency synthesizer with small frequency resolution ratio and high purity frequency spectrum can be realized 摘要通過對直接數字合成器在鎖相環路中作為分頻器應用的研究,使頻率合成器可以在實現超細頻率分辨率的同時達到高的頻譜純度。
This paper studies the system and hardware design of the arbitrary waveform generator based direct digital synthesizer in detail . and a theoretical analysis of the system performance is also given 本文主要研究了基于直接數字合成( directdigitalsynthesizer )技術的任意波形發生器( arbitrarywaveformgenerator )的整體方案和核心部分的硬件設計。
The developed module are the arbitrary waveform generator based on dos ( direct digital synthesizer ) technology as a signal source of testing system and the common testing device such as virtual spectrum analyzer - , virtual digital storage oscilloscopes virtual frequency counter etc 所開發的模塊有,采用dds技術實現的任意波形發生器作為測試系統中的信號源,以及常見的信號測量設備,如虛擬頻譜分析儀,虛擬數字存儲示波器,虛擬頻率計數器等虛擬儀器。
This paper deals with fundamental principles and characters of direct digital synthesizer ( dds ) , analyzes the principle of dds in modulation , also presents various basic schemes to implement gmsic 4dqpsk and qam , and makes an initial analysis on their performances 本文介紹了直接數字頻率合成( directdigitalsynthesizer , dds )的基本原理及特性,分析了dds用于調制的原理,并給出了實現gmsk 、 / 4dqpsk和qam等調制的多種方案,同時對其性能進行初步分析。
The modulating signal is generated in the way of direct digital synthesizer technology . the signal has many characteristics such as ultra wide frequency bandwidth , ultra high frequency resolution and ultra good phasic continuity , etc . thus it can be achieved the high frequency and amplitude stability of the modulating signal 本文采用了數字頻率合成技術( dds )來產生調制信號,它具有超寬的頻率帶寬、超高的頻率分辨率和相位連續性等特點,可以實現聲光調制信號的頻率和振幅的高穩定性。
The paper lays a strong emphasis on discussing the realization of the autocontrol of raster scanning of the scanner in x - y dimension , the " tapping " of the cantilever of the tappingmode afm by a direct digital synthesizer . then a method of parallel communication between dsp and pc in epp mode is given . finally , the author discussed the digital pid closed loop control of the scanner in z - direction , the automatic approaching of the tip using step - motor , and also some electro - magnetic interferences 論文首先簡單介紹了掃描探針顯微鏡的發展、分類、工作原理及應用;接著對ti公司的tms320vc5402dsp的特點及外圍擴展作了簡單介紹;然后分章節重點講述了利用vc5402dsp實現掃描探針顯微鏡的核心部件? ?壓電陶瓷管的x向和y向的光柵掃描控制;借助直接數字集成器( dds )實現輕敲式原子力顯微鏡的微懸臂的“輕敲” ; vc5402dsp的主機接口( hpi )與pc機在增強并行口( epp )模式下的通信;論文最后還介紹了掃描管z向的數字pid閉環控制,步進電機的自動進針,并對實際出現的一些電磁干擾問題作了討論。