Patterns & Codes for Information

Question 1

Two communication systems are used to send the same text message over a long cable that has background electrical noise. System A encodes each letter as an analog pulse whose voltage height varies to represent the letter. System B encodes the message as a series of digital pulses that are either a high voltage (representing a 1) or a low voltage (representing a 0). At several points along the cable, repeaters amplify the signal so it can continue traveling. Which statement best explains why System B’s digitized signals are more reliable for transmitting the message?

Accepted Answer

The digital pulses can be regenerated at each repeater to restore the original high‑or‑low levels, preventing the small voltage changes caused by noise from accumulating.

Answer

The analog system uses varying pulse heights, which makes it easier to detect the intended signal even if some noise is present.

Answer

The digital pulses travel faster because they are shorter in duration, so they spend less time exposed to noise.

Answer

The analog pulses can be amplified at repeaters without any change in their shape, so they are less likely to be distorted by noise.

Question 2

Which of the following statements best supports the claim that digitized signals (sent as wave pulses) are a more reliable way to encode and transmit information than continuous analog signals?

Accepted Answer

Digitized signals consist of distinct pulses that can be recognized even when noise distorts the signal, so the original information can still be recovered.

Answer

Digitized signals require fewer devices to generate, making the system simpler and therefore more reliable.

Answer

Digitized signals never lose any information, regardless of the conditions of the transmission line.

Answer

Digitized signals travel at a higher speed than analog signals, so they reach the receiver more quickly.

Question 3

A lab compares two ways of sending the same message through a cable that adds random small fluctuations in signal amplitude. Device A uses a continuous sinusoidal wave whose amplitude varies to represent the message. Device B sends short wave pulses where a pulse represents a “1” and no pulse represents a “0.” Which statement best supports the claim that digitized signals (sent as wave pulses) are a more reliable way to encode and transmit information?

Accepted Answer

Because the pulses are either present or absent, small fluctuations in the cable’s amplitude do not change a “1” into a “0,” so the original message can still be recovered.

Answer

The pulse method requires precise timing, and any delay caused by the cable will make the pulses unreadable, reducing reliability.

Answer

Analog signals can be amplified to any level, so they are less likely to be lost in transmission than digital pulses.

Answer

Since the continuous wave can be smoothly adjusted, any slight change in amplitude can be corrected by averaging the signal over time.

Try three questions

Which of the following statements best supports the claim that digitized signals (sent as wave pulses) are a more reliable way to encode and transmit information than continuous analog signals?

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