Why is it acceptable to use dBmV, a voltage measurement, for power allocation in a channel bandwidth?

Using dBmV as a voltage measurement for power allocation in a channel bandwidth is appropriate primarily because it is tailored for systems operating with a 75-ohm impedance, which is standard in many television and cable distribution networks. dBmV, or decibels relative to 1 millivolt, effectively conveys the level of voltage over this specific impedance, allowing for straightforward comparisons and calculations regarding signal strength within the relevant system.

The choice of a 75-ohm impedance is particularly relevant in the context of broadcast and cable systems, where it balances the transmission line losses and reflections effectively, thus optimizing performance. Therefore, the measurements provided in dBmV can be directly associated with the power levels transmitted, ensuring that technicians can make accurate assessments and adjustments to maintain signal integrity across the system.

Other options do not accurately apply to the context of using dBmV in cable systems: for instance, while fiber optics might use standard measurements, they operate under different principles and do not utilize dBmV for power allocation. Similarly, 50-ohm impedance is more common in RF applications and is not aligned with the traditional practices of cable transmission, which favors the 75-ohm standard. The term "universal standard" also implies a broader application