When should the headend combining network design be reevaluated?

The headend combining network design should be reevaluated primarily when the modulator output level in the network is too low despite high unit output. This situation indicates that the existing combining network may not be effectively managing the signal levels, which can lead to inadequate signal strength for distribution. If the output from the modulators is high yet the signal is still low, it suggests that the combining network's specifications, configuration, or equipment may need adjustment or enhancement to address the attenuation or losses occurring in the system.

Considerations such as the modulation formats, types of channels, and any additional signal processing must be taken into account to ensure optimal performance. Reevaluating the design under these circumstances helps in diagnosing potential issues with equipment or layout that could negatively impact overall network performance.

While adding additional channels is a significant factor and can warrant a reevaluation of the network, it is the low output level issue that directly affects the quality and reliability of broadcasting. Consequently, this makes it crucial to address and rectify any signal-level deficiencies promptly to maintain service integrity.