Which of the following functions is unaffected by the timing circuit?

The resolver output is the correct answer because it refers to the output generated by a resolver, a type of rotary electrical transformer used for measuring degrees of rotation. The key aspect here is that the resolver operates based on mechanical movement and feedback rather than electronic timing circuits. Its output is a continuous function of the angle of rotation, meaning it does not rely on timing signals that could be altered or affected by circuit configurations.

In contrast, other functions listed are more closely linked to timing circuits. For instance, pulse repetition frequency is inherently dependent on timing as it measures how often pulses are repeated within a specified period. Sweep drive refers to the ability to vary the frequency or amplitude of a signal in a controlled manner, which also typically involves timing mechanisms to ensure proper synchronization. Modulation is the process of varying a carrier signal in order to encode information, where the timing of the modulation plays a crucial role in accurately conveying data.

Thus, the resolver output stands apart as it derives directly from physical movements rather than being influenced by electrical timing circuits.