FCC Exam Question: 42F2
What is the maximum length of a USB 2.0 cable between two hubs or between a hub and peripheral?
Explanation: The maximum specified length for a passive USB 2.0 cable is 5 meters. This limitation is critical for maintaining signal integrity and ensuring proper power delivery. USB 2.0 operates at a high speed of 480 Mbps. Over longer cable lengths, signal degradation becomes a significant issue due to attenuation and increased capacitance, which can lead to data errors and timing skew. Furthermore, voltage drop over the cable's resistance can reduce the 5-volt power supply available to the connected peripheral, potentially causing it to malfunction or not operate at all. Beyond 5 meters, active extension cables or hubs are required to regenerate the signal and boost power, effectively creating new 5-meter segments. Options B, C, and D are incorrect because passive cables of those lengths would experience excessive signal loss and voltage drop, rendering the connection unreliable or non-functional. Understanding signal loss and impedance over transmission lines is a foundational concept applicable across various electronic communications, including amateur radio.
46F1
48G2
30C6
1A6
40E4
Pass Your FCC Exam!
Study offline, track your progress, and simulate real exams with the GMDSS Trainer app.
Includes Elements 1, 3, 6, 7R, 8, and 9.