Physics 9702 · AS & A Level · Characteristics of alternating currents
Characteristics of alternating currents — practice question
The change in the voltage level of part of an analogue signal with respect to time $t$ is illustrated in Fig. 5.1. The signal is sampled every $0.25\,\text{ms}$. Each sample is turned into a four-bit digital number. Fig. 5.2 shows several times $t$ at which the voltage level is sampled. The digital number for $t = 0$ is shown.
(a(i))[1]
In Fig. 5.2, underline the most significant bit (MSB) of the digital number at time $t = 0$.
(a(ii))[2]
Fill in Fig. 5.2 for the times indicated.
(b)[3]
Once the digital numbers have been transmitted, the signal is sent through a digital-to-analogue converter (DAC). On Fig. 5.3, plot the analogue signal produced by the DAC.
(c)[4]
The transmitted signal in (b) has less detail than the original signal in Fig. 5.1. Suggest and explain two ways in which the detail in the transmitted signal could be increased.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “$1011$ as the binary value” …