State two advantages of changing the signal into digital form before transmission.
The change with time of the potential difference (p.d.) of the input signal is shown in Fig. 5.2. The ADC works with a sampling frequency of $250\,\text{Hz}$ and 4-bit sampling, where the least significant bit corresponds to $1\,\text{mV}$. The signal is sampled first at time $0$. State the sampled bits at time $4\,\text{ms}$ and time $8\,\text{ms$.
Part of the signal received by the receiver, after the sampled signal has gone through the DAC, is shown in Fig. 5.3. On Fig. 5.3, finish the line to show the received signal from time $0$ to time $12\,\text{ms}$.
The ADC in (b) is replaced by one with a sampling frequency of $500\,\text{Hz}$ and $3$-bit sampling, where the least significant bit corresponds to $2\,\text{mV}$. On Fig. 5.4, sketch the signal that is now received, after it has passed through the DAC, from time $0$ to time $12\,\text{ms}$.