Frequency inverters have been used for many years for speech scrambling. Indeed, a voice...

Frequency inverters have been used for many years for speech scrambling. Indeed, a voice signal x(n) becomes unintelligible if we invert its spectrum as shown in Fig. P5.58.

(a) Determine how frequency inversion can be performed in the time domain.

(b) Design an unscrambler. (Flint The required operations are very simple and can easily be done in real time.)