Deep Dive: E8A09
The correct answer is D: 256. An analog-to-digital converter with 8-bit resolution can encode 256 different input levels. The number of levels equals 2 raised to the power of the number of bits. For an 8-bit ADC: 2^8 = 256 levels. This means the ADC can distinguish 256 different voltage levels between its minimum and maximum input range. The resolution determines how finely the ADC can quantize the input signal. More bits mean more levels and finer resolution. An 8-bit ADC divides the input range into 256 steps, while a 10-bit ADC would have 1024 steps (2^10), and a 12-bit ADC would have 4096 steps (2^12).
Why Other Answers Are Wrong
Option A: Incorrect. 8 is the number of bits, not the number of levels. The number of levels is 2^8 = 256. Option B: Incorrect. The number of levels is fixed by the bit resolution (2^8 = 256), not multiplied by amplifier gain. Gain affects the input range, not the number of quantization levels. Option C: Incorrect. The number of levels is 256, not divided by gain. Gain affects what voltage range the 256 levels cover, but doesn't change the number of levels.
Exam Tip
8-bit ADC levels = 2^8 = 256. Remember: An N-bit ADC can encode 2^N different levels. For 8 bits, that's 2^8 = 256 levels.
Memory Aid
**8**-bit **A**DC = **2**^**8** = **256** levels (think '8A = 2^8 = 256')
Real-World Example
You're using an 8-bit ADC in your circuit. The ADC can distinguish 256 different voltage levels. If the input range is 0-5 volts, each level represents about 19.5 millivolts (5V / 256). This resolution determines how accurately the ADC can represent the input signal.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E8A
Reference: FCC Part 97.3
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E8A topic.