| File
name
|
AnACF.[ch]
|
| Description
|
This
module generates an auto-correlation function from the connected input signal.
It puts the result in the output signal, overwriting any previous data if the
signal has already been initialised. The function is calculated backwards from
the time, timeOffset (s) for a period of period (s). An
exponential decay function is included with the time constant,
timeConstant (s). The same binning as for the input signal is used.
|
| Example
parameter file format
|
0 Normalisation mode standard or unity (0, or 1). -1.0 Time offset, t0 (if -ve the end of the signal is assumed) (s). 2.5e-3 Time constant, tw (s). 7.5e-3 Maximum autocorrelation period (lag), t (s). |
| Test
program directory
|
Tests/Analysis
|
| Syntax
|
BOOLN Calc_Analysis_ACF(EarObjectPtr data);
|
| Returns
|
TRUE
if the process is successful, otherwise it returns FALSE.
|
| Syntax
|
BOOLN SetNormalisation_Analysis_ACF(int
theNormalisation);
|
| Special
Values
|
Set
the normalisation mode to "0" or "1"
|
| Returns
|
TRUE
if the function is successful, otherwise it returns FALSE.
|
| Syntax
|
BOOLN
SetPars_Analysis_ACF(int normalisationMode, double timeOffset,
double timeConstant, double
period);
|
| Returns
|
TRUE
if the function is successful, otherwise it returns FALSE.
|
| Syntax
|
BOOLN SetPeriod_Analysis_ACF(double
thePeriod);
|
| Returns
|
TRUE
if the function is successful, otherwise it returns FALSE.
|
| Syntax
|
BOOLN SetTimeConstant_Analysis_ACF(double
theTimeConstant);
|
| Returns
|
TRUE
if the function is successful, otherwise it returns FALSE.
|
| Syntax
|
BOOLN SetTimeOffset_Analysis_ACF(double
theTimeOffset);
|
| Special
Values
|
If
negative it is assumed that the autocorrelation will start (backwards) from the
end of the signal.
|
| Returns
|
TRUE
if the function is successful, otherwise it returns FALSE.
|
# # Main Parameter file # output.dat Name of output file. # # Module specifications. # #Par. file Name Description #--------- ----- ------------- PTone1.par PureTone Stimulus generation paradigm. AutoCor1.par Analysis_ACF Analysis module.
Figure [32] Output for ACF test.
The autocorrelation function is used to investigate periodicity in signal processing. A pure tone stimulus is generated in this test, and the last specified section of the signal is autocorrelated. The autocorrelation function for a pure tone should also be a sinusoid. The data is output to file with each line in the format:-
time delay, ACF
- where the time delay is in seconds and the autocorrelation functions is the square of the amplitude (micro Pascals squared).