4.2-6 Amplitude modulators and demodulators can also bebuilt without using multipliers. InFig. P4.2- 6, the input (1) = m(t), and the amplitude A > l(). The two diodes are identical, with a resistance of r ohms in the conducting mode and infinite resistance in the cutoff mode. Show that the output eo(t) is given by 2R eolt): R+p W(1) m(1) where w(t) is the switching periodic signal shown in Fig. 2.20a with period 2.7/Wc seconds. (a) Hence, show that this circuit can be used as a DSB-SC modulator. (b) How would you use this circuit as a synchronous demodulator for DSB-SC signals. Figure P.4.2-6 (1) A cos I R Slope (1) R (a) (b)