# Zero Relative Frequency

| The relative frequency display mode allows you to plot the data as a frequency shift from a reference point. That is, the frequency is plotted relative to a reference frequency which you set via the Zero Rel F button. Whenever you click this button, the current frequency measurement is then used as the reference frequency against which all other frequencies are plotted.

Another thing the button does is store a tag value in the log file. This value is also plotted on the screen.
Note that the software does not re-calculate the data already plotted relative to a new reference frequency. Only new data is plotted against the new reference frequency.
If you ever become confused as to what the data has actually done while using the relative frequency mode, you can always change the Frequency Display Format Selector to Raw Frequency. The raw frequency display is completely unaffected by changes in the relative frequency plot.