This program produces an animated display which tracks the amplitude and phase
of selected line features in the spectrum. It has a number of user-settable options
which determine how the line is tracked. To run this program, type
`tracker | xmgr -pipe`

and an animated display will start up. In normal use, the parameters should be
set as follows:

`num_points`: a power of two. A single phase/amplitude point is printed for each set of`num_points`samples.`padding_factor`: a power of two. This determines the amount of padding done on the data set, and thus the ultimate frequency resolution of the line discrimination.`fpreset`: your best guess for the frequency that you want to track. If the actual frequency of the spectral line differs from this value, then the phase will slowly drift as a linear function of time. (The`tracker`program does a robust best linear fit to this slope, and uses it to report a best frequency estimate.)`estimate`: if set to zero, then the phase of the line found is always compared with the frequency preset above. If set non-zero, then`tracker`will make a ``best estimate" of the true frequency, and compare the phase of the line found with the phase appropriate to that sinusoid.`nbins`: the number of (padded) frequency bins adjacent to the one of interest in which the line will be searched for. The frequency range covered is thus given by

(16.29.334) `num_display`: the number of points displayed by`tracker`. The total amount of time covered by the output is`num_display``num_points`where is the sample interval.`num_win,nwdt`: these parameters are described in the section on multi-taper methods.`maxpass`: the number of passes to make within`remove_spectral_lines()`. This number should be set as small as possible, provided that you still ``catch" the line of interest.

- Authors: Bruce Allen (ballen@dirac.phys.uwm.edu) and Adrian Ottewill (ottewill@relativity.ucd.ie).
- Comments: None.