【摘要】 通过在频域内对流动谷物碰撞噪声信号的分析,建立了10～20 kHz 频率范围内声能与谷物含水率关系的数学模型,采用所设计的带通滤波放大器可有效地获取该频率范围内的声能信号。利用窄带信号采样方法和适合于计算机二进制运算的对数计算方法,在以单片机为核心的测量系统中对声压信号进行处理,实现了流动谷物含水率的在线测量。更多还原

【Abstract】 The frequency characteristics of impacting noise for flowing grain is ana- lyzed.Statistic linear relation between the sound energy and grain moisture content in 10～20 kHz frequencies is established.A three-stage band-pass filter is designed to efficiently take the signals in 10"-20 kHz.A sampling method of narrow-band signal and an approximate logarithmic calculation for computer binary operation are presented.A signal processing method is employed to realize the on-line measure- ment for moisture content of flowing grain.更多还原