Eduqas A-Level Electronics Signal conversion and communications overview quiz quiz

$8$

$16$

$255$

$256$

$19.5\ \text{mV}$

$0.5\ \text{V}$

$4.9\ \text{mV}$

$5.0\ \text{mV}$

$30\ \text{kHz}$

$7.5\ \text{kHz}$

$15\ \text{kHz}$

$60\ \text{kHz}$

Sampling far faster than the Nyquist rate set by the highest frequency

Sampling below twice the highest signal frequency

Using too many quantisation bits in the converter

Using a low-pass reconstruction filter at the converter output

It is slower but much cheaper because it needs fewer total components overall

It needs no op-amp at its output to sum the currents

It uses only two resistor values that are easy to match accurately

It automatically provides more bits of resolution than a binary-weighted DAC

To amplify the staircase output so the signal carries over a much longer cable run

To digitise the signal

To add quantisation noise

To smooth the staircase output into a continuous signal

Serial

Parallel

Neither

Both equally

Each gets a different frequency band at the same time

Each gets a brief time slot in turn

They are all sent at once on the same frequency

Only one signal is ever sent

To make it louder so that the listener at the receiver hears a stronger and clearer sound from the connected loudspeaker

To convert the analogue audio waveform into a stream of binary digital samples before any of it can be radiated from the transmitter aerial

Audio radiates inefficiently because the aerial would be impractically large; a high-frequency carrier allows a practical aerial

To remove noise

AM, because its narrower bandwidth means the receiver collects far less added noise power

They are equally noise-immune

Neither is affected by noise

FM, because the information is in the frequency not the amplitude

Total internal reflection at the core-cladding boundary

Refraction that bends each ray back towards the central axis of the core

Diffraction

Absorption by the cladding

It is cheaper and quicker to splice in the field because the joints need no special alignment tools

Much higher bandwidth and immunity to electromagnetic interference

It is more robust mechanically

It radiates a stronger signal