【名词&注释】
应答器(transponder)、机车信号(cab signal)
[单选题]Iff1(t)←→F1(jω),f2(t)←→F2(jω),Then()
A. A、f1(t)*f2(t)←→F1(jω)F2(jω) B. B、f1(t)+f2(t)←→F1(jω)F2(jω) C. C、f1(t)f2(t)←→F1(jω)F2(jω) D. D、f1(t)/f2(t)←→F1(jω)/F2(jω)