\begin{aligned} &\text { 4.4-2 Find } \varphi_{\mathrm{LSB}}(t) \text { and } \varphi_{\mathrm{USB}}(t) \text { for the modulating signal } m(r)=\pi B \operatorname{sinc}^{2}(2 \pi B t) \text { with } B=2000

\mathrm{~Hz}\\ &\text { and carrier frequency } f_{c}=10,000 \mathrm{~Hz} \text { . Follow these steps: } \end{aligned} \text { (a) Sketch spectra of } m(t) \text { and the corresponding DSB-SC signal } 2 m(t) \cos \omega_{c} t \text { . } (b) To find the LSB spectrum, suppress the USB in the DSB-SC spectrum found in part (a). (c) Find the LSB signal LsB (1), which is the inverse Fourier transform of the LSB spectrumfound in part (b). Follow a similar procedure to also find PusB(1).