FREE LESSON · Physics & signals · 2 OF 6
Analog vs Digital Sampling Explained
Sampling a continuous world: What measurement keeps, and loses
A digital measurement makes two approximations.
Sampling chooses when to observe a changing signal; quantization chooses the nearest representable amplitude. Sampling too slowly can make a high-frequency pattern masquerade as a slower one, aliasing. Too few amplitude levels introduce quantization error. More samples and bits improve fidelity but consume bandwidth, storage, and energy.
Every measurement pipeline has a resolution budget in time and amplitude.
Why anti-alias filtering happens before sampling
Frequencies above the representable range can fold into false lower frequencies after sampling. Once folded, the samples no longer reveal which frequency was original. A low-pass filter removes those components before the irreversible sampling step.
Protect information before a lossy boundary; after ambiguity is introduced, later software cannot reliably undo it.
Sources and further reading
- Signals and Systems: MIT OpenCourseWare
- Introduction to EECS I: MIT OpenCourseWare · open text and labs