Unlike the convolutional codes considered in this chapter, we recall from Chapter 6 that the convolutional code used in the voice band modem V.32 modem is nonlinear. Figure shows the circuit diagram of the convolutional encoder used in this modem; it uses modulo-2 multiplication and gates in addition to modulo-2 additions and delays. Explain the reason for nonlinearity of the encoder in Figure, and use an example to illustrate your explanation.

Yan Mod-2 multiplier Output Input Mod-2 adder Flip-fiop Yon