Construction Coordinator Practice Exam

Why has the impedance for the broadband cable industry been standardized at 75 ohms (Ω)?

1. To enhance signal reception in urban areas

2. To minimize attenuation while providing adequate breakdown voltage

3. To reduce manufacturing costs

4. To comply with international standards

The correct answer is: To minimize attenuation while providing adequate breakdown voltage

The standardization of impedance for the broadband cable industry at 75 ohms is primarily due to the need to minimize signal attenuation while maintaining adequate breakdown voltage. At this impedance level, coaxial cables are able to transmit high-frequency signals more efficiently, ensuring that the signal remains strong over longer distances without excessive loss. High-frequency electrical signals travel best through cables with an impedance that balances both the inductive and capacitive characteristics. The choice of 75 ohms provides an optimal performance balance for video and broadband applications, where signal integrity is crucial. By minimizing attenuation, the cable can deliver clearer signals and maintain the quality of service expected in communications. Additionally, while other options discuss potential benefits like reducing manufacturing costs or compliance with standards, the technical performance aspect—specifically the balance between attenuation and breakdown voltage—is the primary reason behind the 75-ohm standardization in broadband cable. This ensures that various devices can reliably communicate over coaxial cables without significant signal degradation.