基于ARM920T嵌入式低频数字扫描仪设计

Design of ARM920T-based embedded low-frequency digital scanner

系统采用ARM920T作为核心处理器,以低频信号作为信号源,采用DDS技术,从而实现相频、幅度、频率特性的分析仪器,能够简单地实现信号源的时域和具体参数的波形。系统主要由ARM920T控制处理器、DDS扫频模块、ADC采样模块、DAC输出模块、检波滤波器模块、扫频信号源幅度模块组成。其中处理器采样ARM920T,扫频信号源采样DDS芯片AD9851,检波模块以AD637JQ芯片构成,相位检测模块由AD8302芯片构成,DAC芯片TLV5618控制扫频信号的幅度。实验结果表明,仪器可以检测20 Hz^1 MHz左右的频率信号源,可以显示在LCD屏幕上,直观地读出频率、幅度和相位。

Direct digital synthesizer （DDS） technology was employed to implement phase frequen- cy, amplitude, frequency characteristics analysis instruments, in which advanced RISC machines （ARM） 920T was adopted as core processor and low frequency signal as the signal source. The sys- tem can simply realize the time domain of signal sources and specific parameters waveforms （simple signal source in the time domain waveform and specific parameters ）, which mainly consists of ARM920T processor, DDS frequency sweeping module, analog to digital converter （ADC） sampling module, digital to analog converter （DAC） output module, waveforms detection filter module and frequency sweeping signal source amplitude module. The processor sampling was controlled by ARM920T, while the frequency sweeping signal source sampling was implemented by DDS chip AD9851. The waveform detection module was controlled by AD637JQ chip. The phase detection module and the frequency sweeping signal amplitude were controlled by AD8302 chip and the DAC chip TLV5618, respectively. The instrument can detect frequency signal source ranged between 20 Hz to 1 MHz and can directly display frequency, amplitude and phase on the liquid crystal display （LCD） screen.