Practice question · Sort into groups
A digital receiver reads any voltage above 2.5 volts as a 1 and anything below it as a 0. Sort each measured voltage by the bit it is interpreted as.
Groups: Read as 1 · Read as 0
- 3.1 volts
- 2.6 volts
- 2.4 volts
- 4.8 volts
- 0.4 volts
Hints
- Compare each voltage with the single threshold, nothing else.
- Two of these sit very close to the threshold on opposite sides of it.
Show the answer
Read as 1: 3.1 volts, 4.8 volts, 2.6 volts
Read as 0: 0.4 volts, 2.4 volts
Why
Only the side of the threshold matters, so 2.4 and 2.6 volts are read as opposite bits despite differing by a fifth of a volt. Signals near the threshold are exactly where noise causes errors, which is why real designs keep the levels far from it.
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