Construction Coordinator Practice Exam

How much intermodulation distortion degradation is added with two identical line extender amplifiers in cascade?

1. 3 decibels (dB)

2. 6 decibels (dB)

3. 12 decibels (dB)

4. 15 decibels (dB)

The correct answer is: 6 decibels (dB)

When two identical line extender amplifiers are cascaded, the intermodulation distortion (IMD) degradation they introduce is cumulative. Each amplifier generates its own intermodulation products, and when these amplifiers are used in succession, the distortion effects combine in a specific way. In the case of identical amplifiers, the increase in intermodulation distortion is typically quantified, and the general rule is that the total distortion introduced by two amplifiers cascaded together is an additional 6 decibels (dB). This is because the intermodulation distortion does not simply double or triple; rather, it increases logarithmically with respect to the number of amplifiers. This 6 dB degradation occurs because each amplifier contributes equally to the overall distortion in a manner that incorporates its gain and the characteristics of the signals passing through it. Thus, this specific increase of 6 dB reflects the reality of how these devices interact in terms of signal degradation, making it the correct answer in this scenario.