Which spectrum analyzer function is useful for capturing and analyzing ingress and impulse noise?

The Max Hold function on a spectrum analyzer is particularly useful for capturing and analyzing ingress and impulse noise because it continuously updates the display to show the highest amplitude of signals detected over time. This is especially important when dealing with transient signals such as impulse noises, which can appear sporadically and with high amplitudes.

When Max Hold is engaged, the trace on the display will "hold" the maximum level of each frequency component, allowing the technician to see the peaks of intermittent noise that would otherwise be missed by other functions. This feature is essential for diagnosing issues related to ingress noise or other fleeting disturbances in the signal path, as it ensures that even short-lived spikes in noise are recorded for analysis.

Other options, while useful in certain contexts, do not serve this specific purpose as effectively. For instance, the Peak Hold function captures peaks but will reset after a certain period or when a new peak is detected, potentially missing important impulse noise. The Average function smooths out the signal over time, which can obscure brief spikes of noise. The Zero Span function, on the other hand, provides a view of a single frequency over time but is not specifically intended to capture peak noise events effectively.