Introduction / Context:
Real-world phenomena (temperature, pressure, sound, light) are analog and must be translated into digital form for processing by a computer. The claim that no conditioning is needed tests basic knowledge of data acquisition chains: sensors, signal conditioning, sampling, and quantization via an ADC (analog-to-digital converter).
Given Data / Assumptions:
- “Electrical quantities” may be arbitrary voltages/currents from sensors.
- Digital input pins expect logic-level signals in specified ranges (e.g., 0–5 V TTL, 0–3.3 V CMOS).
- Goal is accurate, safe, and standards-compliant acquisition.
Concept / Approach:
Digital computers can only sense defined logic levels or digitized samples. Arbitrary analog signals must be conditioned: scaled, shifted, filtered, protected, and then sampled by an ADC to produce numeric codes. Without conditioning, signals may exceed safe limits, violate common-mode ranges, include noise/aliasing, or fail to meet impedance requirements, leading to damage or erroneous readings.
Step-by-Step Solution:
Acquire sensor output → may require amplification/attenuation and offset adjustment.Apply anti-aliasing filter to limit bandwidth before sampling.Feed conditioned signal into an ADC that meets resolution and sampling rate needs.Deliver digital samples to the computer/MCU for processing and interpretation.
Verification / Alternative check:
Review MCU datasheets: ADC input specs demand certain ranges and impedances; GPIO pins are not general-purpose analog inputs without ADC hardware.
Why Other Options Are Wrong:
Correct: Would ignore essential conditioning/ADC stages for analog quantities.Only true for logic-level DC signals: Even then, level shifting and protection may be required; general analog values still need ADC.Depends solely on clock speed: Sampling theory involves bandwidth and resolution, not just clock speed.
Common Pitfalls:
Feeding sensors directly into GPIO without considering voltage limits or ESD protection.Skipping anti-aliasing, resulting in distorted digital measurements.
Final Answer:
Incorrect
Discussion & Comments