7. Consider a voice signal of bandwidth 4 kHz. Determine the minimum bandwidth required for transmission of the voice signal (a): When it is transmitted by an AM modulator with modulated index of 0.5; (b) When it is transmitted by an AM modulator with modulation index of 0.5. 8. Calculate the average/bit-to-noise ratio required to maintain a bit error rate of 0.0002 with BPSK and DPSK demodulators