微波激励热声信号分析及预处理器研制

Analysis of Microwave-induced Thermoacoustic Signals and Research-development Preprocessor

通过对微波激励热声信号的分析,初步估算出热声信号的幅值和频率范围,确定信号预处理器的设计参数。制作了在通带范围为50 KHz^3 MHz、增益可调范围为55~105 dB、零输入增益为105 dB时输出噪声为1.32V的信号预处理器。讨论了信号消噪提取的方法,结合数字式平均处理后系统可以实现幅值为5μV甚至更小的热声信号的放大提取。结果表明,该预处理器在带宽、增益和噪声三个方面的设计都满足了对热声信号采集的要求。

According to the results of analyzing the microwave-induced thermoacoustic signals, the amplitude and frequency were estimated and the designing parameters of preprocessor were decided. Based on the parameters, the signals preprocessor was designed with the band pass frequency ranging from 50 KHz to 3MHz, the gain ranging from 55dB to 105dB and the output noise being 1.32V when the input was zero and the gain was 105dB. The de-noising method of thermoacoustic signals was also discussed. The signals can be picked up by the preprocessor combined with the digital multipoint average method. The amplitude of signals is only 5 μV or even less. The results indicated that the preprocessor can meet the needs of thermoacoustic signals acquisition in bandwidth, gain and noise control.