If the Fmax of the spectrum is increased without changing the lines of resolution, what happens?

When the Fmax (the maximum frequency in the spectrum) is increased while keeping the lines of resolution constant, this typically means that the range of frequencies being analyzed is expanded, but the number of frequency bins (or lines) available remains unchanged.

The lines of resolution refer to the spacing between each frequency bin in the spectrum. If the Fmax increases but the number of lines does not, each line now covers a broader range of frequencies. This effectively means that each line's resolution in distinguishing between closely spaced frequencies is diminished.

As a result, the ability to resolve individual frequency components becomes poorer because they are now spread over a larger frequency range without an increase in the number of lines to effectively capture them. Thus, finer details may blend together, making it harder to interpret the spectrum.

In summary, with an increase in Fmax without a corresponding increase in lines of resolution, the ability to differentiate between frequencies diminishes, leading to a worsening of resolution in the resultant spectrum.