机械工程测试技术基础第三版课后题答案
y(t)?0.5?0.816cos(10t?26.56?)?0.2?0.408cos(100t?45??78.69?)?0.408cos(10t?26.56?)?0.0816cos(100t?33.69?
)51 t h(t)???e??;(t?0,??0) ?0;(t?0) R)????t??)dt??????t??(t??) x(???h(t)?h(0eedt ???5.2
????0e???e?2?tdt?e2?x(t)?A1sin(?1t??1??2)?A2sin(?2t??2??2)
由同频相关，不同频不相关得：
22Rx(?)?A12cos?1??A22cos?2?
5.3：由图可写出方波的基波为x41(t)?sin(?t???2)
Rxy(?)?2?cos(????2)
5.4: Sxy(f)?H(f)Sx(f)
H(f)?Sxy(f)/Sx(f)
Sxy(f)?F[Rxy(?)]
Sx(f)?F[Rx(?)]?F[Rxy(??T)]?F[Rj?Txy(?)]e
H(f)?e?j?T5.5:见图5-16
5.6:由自相关函数的性质可知:
?2x?Rx(0)?Acos0?A x2rms??x?A
5.7:由对称性性质:
F{sinc2(t)}?1 f??2?f??2
??2?sinc2(t)dt??df??
????2Bbbbbb
11