Physics 9702 · AS & A Level · Characteristics of alternating currents
Characteristics of alternating currents — practice question
The analogue signal from a microphone is to be sent in digital form. Figure 5.1 shows how part of the microphone signal varies with time $t$. The microphone output is sampled by an analogue-to-digital converter (ADC) at a frequency of $5.0\,\text{kHz}$. The ADC output is a sequence of $4$-bit numbers. The least significant bit has a value of $1.0\,\text{mV}$. The first sample is taken at time $t = 0$.
(a)[2]
Complete Fig. 5.2 using Fig. 5.1.
(b)[4]
Once the digital signal has been transmitted, a digital-to-analogue converter (DAC) converts it back into an analogue signal. Using the information in Fig. 5.1, draw the DAC output level on the axes of Fig. 5.3 for the transmitted signal from time $t = 0$ to time $t = 1.2\,\text{ms}$.
(c)[2]
In modern telecommunication systems, it is common for the ADC and the DAC to use more than four bits in each sample. State and explain the effect of this increase on the transmitted analogue signal.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct point: $(0.2\,\text{ms},\; 8.0\,\text{mV},\; 1000)$” …