Which action is not a function that a controller can perform with the Indicator Control C-8625/T (A-Box)?

The action of reducing the maximum range of processing time in the video signal processor is not a function that a controller can perform with the Indicator Control C-8625/T (A-Box). This device primarily focuses on providing controls and functionalities that aid in displaying and managing aircraft identification within specific parameters, such as mode of interrogation, altitude limits, and discrete identity combinations.

The other options reflect the intended capabilities of the A-Box. Requesting a particular mode of interrogation allows the controller to tailor the information gathered from the aircraft. Selecting display parameters for altitude limits helps in filtering the information to only the relevant aircraft within a certain flight level, which enhances situational awareness. Additionally, the option to select up to 10 discrete identity display combinations enables the controller to manage and differentiate multiple aircraft effectively. These functionalities are integral to the operation of the A-Box, whereas managing video signal processing is outside the scope of the controller's responsibilities related to this device.