华东交通大学-机械工程测试技术课后习题答案-祝海林版

2-10周期三角波的傅里叶级数展开式为2-112-122-132-142-152-16求正弦信号)sin()(taAtx的绝对均值x，均方根值)(rmstx解π2cosπdsin2d)sin(1d)(12/02/02/2/2/2/AatAtatTAtatATttxTTTTTTTx2d22cos1dsin12020222AtatTAtatATTTxAtxx22)(2rms2-172-18求被矩形窗函数截断的余弦函数t0cos(题图1.4)的频谱，并作频谱图。TtTtttx0cos)(0解TTTtttttetX00j0dcoscos2dcos)(tttTd])cos()[cos(0000000])sin[(])sin[(TT])c[(sin])c[(sin00TTTT题图1.4或者，tetXTTtdcos)(j0teeTTttd)(21)j()j(00])c[(sin])c[(sin00TTTT