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GetUniPolar.m
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GetUniPolar.m
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function UniPolarSignal = GetUniPolar(Parameters, ActionPotentialVelocity, Time)
% Create a Unipolar action potential
%
% C T Clarke
% Edited by L F Tiong 06/05/2016
%
% Use a parameter structure like this:
% Parameters = struct ( ...
% 'Electrodes', 11 , ...
% 'ElectrodeSpacing', 0.003, ...
% 'SamplingFrequency', 100000 , ...
% 'ActionPotentialType', 'long' , ...
% 'StartTestVelocity', 1 , ...
% 'StepTestVelocity', 1 , ...
% 'EndTestVelocity', 100 , ...
% 'NoiseLevel', 0.01 );
% Other parameters may be included but will be ignored
% Establish implied cuff parameters
if (Parameters.Electrodes > 1)
ElectrodeDelay = Parameters.ElectrodeSpacing ./ ActionPotentialVelocity;
else
ElectrodeDelay = 0;
end
% Get the length of sequence to produce
SequenceLength = max(size(Time));
A = [2.2e7,0.47e9,2.6e1,4.08e-3,7.44e-11];
B = [3.6e3, 1e4, 1.5e4, 1.5e4, 1e4];
n = [3, 3, 1, 1, 3];
%Use 1 for long, 2 for short, 3 for new
% Use on of the standard formulae for the action potential
switch lower(Parameters.ActionPotentialType)
case 'long'
TMAP = 1;
case 'short'
TMAP = 2;
case 'new'
TMAP = 3;
case 'tmap1'
TMAP = 4;
case 'tmap2'
TMAP = 5;
otherwise
disp('Unknown Action potential type.')
end;
% Standard Unipolar signal (ActionPotentialVelocity^2 * )
UniPolarSignal = zeros(Parameters.Electrodes,SequenceLength);
for i = 1 : Parameters.Electrodes
UniPolarSignal(i,:) = ActionPotentialVelocity^2 * max(0,A(TMAP)*((Time - (i-1) * ElectrodeDelay).^n(TMAP)).*(exp((-B(TMAP))*(Time - (i-1) * ElectrodeDelay))));
end;
% Work out the approximate RMS value of the signal
% max/root(2) is used as this negates the effect of an overly long sequence
% with a short AP.
%SignalRMS = max(max(UniPolarSignal)) / sqrt(2);
% Constant noise level for all AP amplitudes (SignalRMS * )
% Add normally distributed noise
UniPolarSignal = UniPolarSignal + Parameters.NoiseLevel * randn(Parameters.Electrodes,SequenceLength);