机械工程测试技术基础第三版课后题答案
110?3
H(?)?j??1
A(?)?11?(??)2?11?(10?3
?)?3
?(?)??arctan(??)??arctan(10Uy?)
0?10A(1000)sin(1000t??(1000))?10?0.707sin(1000t?45)?7.07sin(1000t?45)0
4.11 解：A(?)?11?(??)2 ?(?)??arctan(??)
??10时，A(10)?11?(0.05?10)?0.816
?(10)??arctan(0.05?10)?26.56?
A(100)?11?(0.05?100)?0.408 ??100时，
??(100)??arctan(0.05?100)?78.69
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)?????
5.1
5.2 x(t)?A1sin(?1t??1??2)?A2sin(?2t??2??e??t;(t?0,??0)h(t)???0;(t?0)??????t??(t??)Rx(?)???0??h(t)?h(t??)dt?????0eedt???ee?2?tdt?e???2??2)
Bb 11
机械工程测试技术基础第三版课后题答案
由同频相关，不同频不相关得：
Rx(?)?A122cos?1??A222cos?2?
4sin(?t?5.3：由图可写出方波的基波为x1(t)?Rxy(?)?2cos(????2?)
?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[Rxy(?)]eH(f)?e?j?Tj?T
5.5:见图5-16
5.6:由自相关函数的性质可知: ?x?Rx(0)?Acos0?A xrms?2?x?2A
5.7:由对称性性质:
F{sinc(t)}?1 f???222?2?f??2
?sinc??(t)dt???2?df??
Bb 12