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FretFocus home
About FretFocus
Try these sample simulations:
The FretFocus simulator
To make it easier to get experience with how FretFocus behaves depending
on the kind of data coming in, FretFocus has a simulator mode. In this mode,
FretFocus will not allow entries in the Value column.
Instead, as soon as you enter a Low Fret,
High Fret, and inside/outside measurement
type, the simulator supplies the corresponding measurement from a simulated
instrument that can be configured. FretFocus uses the
simulator-supplied entries the same way it uses real entries from you to
fit a solution to the data.
In addition to the scale length, frets per octave, nut compensation, and
fret width, the simulator also lets you configure:
- Number of frets
- The simulator calculates the fret positions for the given number of
frets. Asking for measurements at higher fret numbers won't work.
- Calculation method
- The simulator will lay out fret positions by one of three methods: the
best available (in Java double precision), or one of two
common luthier approximations, 17.817 or
17.835, so you can see how one of these approximations
used in construction would affect FretFocus's analysis of an
instrument. (More about the calculation methods.)
- Standard deviation in construction
- To model the realities of fabricating a real fretboard from wood and
wire, the simulator applies a standard deviation for construction.
The location for each fret is computed precisely and then offset by a
small random amount with a normal distribution and the given standard
deviation to find the ‘actual’ location for the fret.
These locations are all computed once when the simulator starts and then
remain fixed, to model the finished fretboard.
- Standard deviation in measurement
- To model the uncertainty of measurement, each measurement the simulator
supplies is precisely computed from the finished fretboard model and then
offset by another normally-distributed random amount with the given
standard deviation of measurement. Unlike the construction deviation,
applied once at startup, this is applied for every measurement: if you
get a simulated measurement at two frets, drop it, and ‘measure’
the same frets again, the value will be slightly different each time.
Either standard deviation, or both, can be set to zero, to see how FretFocus
would perform on an instrument that could be built or measured perfectly.
With both set to zero, you can also use the FretFocus simulator as a sort
of overkill fretboard calculator, where you set the scale parameters and it
gives you the distance between any pair of frets.
Custom simulations
For the moment, FretFocus does not have an exposed user interface to set
up the simulator with custom values. To set up a new simulation, you can
copy one of the existing simulation HTML files from the sidebar of this
page, and edit it to change the simulator parameters. Comments in the
HTML will show you what to change.
$Id: Simulator.html,v 1.4 2005/07/06 23:01:52 chap Exp $