| 1. | Design of bessel low pass filter in direct digital synthesizer
直接数字合成器中贝塞尔低通滤波器设计 |
| 2. | 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
摘要通过对直接数字合成器在锁相环路中作为分频器应用的研究，使频率合成器可以在实现超细频率分辨率的同时达到高的频谱纯度。 |
| 3. | 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数字合成( directdigitalsynthesizer )技术的任意波形发生器( arbitrarywaveformgenerator )的整体方案和核心部分的硬件设计。 |
| 4. | 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
所开发的模块有，采用dds技术实现的任意波形发生器作为测试系统中的信号源，以及常见的信号测量设备，如虚拟频谱分析仪，虚拟数字存储示波器，虚拟频率计数器等虚拟仪器。 |
| 5. | 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
本文介绍了直接数字频率合成( directdigitalsynthesizer ， dds )的基本原理及特性，分析了dds用于调制的原理，并给出了实现gmsk 、 / 4dqpsk和qam等调制的多种方案，同时对其性能进行初步分析。 |
| 6. | 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
本文采用了数字频率合成技术( dds )来产生调制信号,它具有超宽的频率带宽、超高的频率分辨率和相位连续性等特点,可以实现声光调制信号的频率和振幅的高稳定性。 |
| 7. | 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
论文首先简单介绍了扫描探针显微镜的发展、分类、工作原理及应用；接着对ti公司的tms320vc5402dsp的特点及外围扩展作了简单介绍；然后分章节重点讲述了利用vc5402dsp实现扫描探针显微镜的核心部件? ?压电陶瓷管的x向和y向的光栅扫描控制；借助直接数字集成器( dds )实现轻敲式原子力显微镜的微悬臂的“轻敲” ； vc5402dsp的主机接口( hpi )与pc机在增强并行口( epp )模式下的通信；论文最后还介绍了扫描管z向的数字pid闭环控制，步进电机的自动进针，并对实际出现的一些电磁干扰问题作了讨论。 |
