低频力学谱仪信号测量系统的改进设计

Design of Signal Measurement System for Low Frequency Mechanical Spectroscopy Improvement

LMA-1型低频力学谱仪在强迫振动模式下测量固体材料内耗时,存在数据采集卡利用率不高且对其依赖性较大、无法消除信号干扰及小内耗测量时波形失真的缺点。文中设计了基于ARM7的信号测量系统,被测信号整形后由ARM7直接测量出其相位差并通过串行口传送至上位机。该系统提高了信号的抗干扰能力,避免了波形失真,采用信道交换技术消除了由于硬件参数不匹配所产生的误差,从而摆脱了对于数据采集卡的依赖,减少了系统研制成本。通过在Proteus软件下的仿真分析,该系统完全能够满足强迫振动模式下固体材料内耗的测试需要。

Internal friction test of solid materials with LMA-1 low frequency mechanical spectroscopy in force vibration mode relied on the DAQ card with low utilization rate. Interferences in signals could not be removed and waveform distorted when small internal friction materials were tested. A signal measurement system based on ARM7 was designed. The phase difference of the rectified signals was measured by ARM7 directly and sent to PC through COM port. The capacity of anti-interference was improved, waveform distortion was avoided and phase errors caused by the delay of using different signal channels were eliminated with the method of signal channel exchanging. So the DAQ card is not needed and the cost of the system is reduced. The simulation results in Proteus show that it can meet the requirements of internal friction test of solid materials perfectly in force vibration mode.