function [indexes,RM,segind]=signaltest(x,step,mode,th1)
%
% detecting severe quality loss in ECG
% In:
% x = evaluation signal (square of the WT in scale 1)
% step = samples to consider in each subinterval for local evaluation (use samplig frequency, by default 1000)
% mode = signaltest mode 1:RMS max test (default)
%
% Out:
% indexes - samples with possible quality loss
%
% RM - root of the mean of signal x values
% segind - samples corresponding to the RM evaluation (beginning and end of each segment, beginning of each subsegment)
%
% The root of the mean of signal x (RM) in each 2^16 maximum length segment
% is compared with the global segment threshould th1=2*step
% If RM>th1 the RM in each subsegment of length step is compared with
% the the local threshould th2=step and indexes for which RM>th2 are retrieved
%
% Created by Rute Almeida (rbalmeid@unizar.es) on May 14, 2009.
% Revision 10MAR2009
if nargin<4
%th1=2*step*10;
%th1=1.75*step*10;
%th2=step*10;
th1=sqrt(mean(x.^2));
if nargin<3
mode=1;
if nargin<2
step=1000;
end
end
end
if isempty(mode)
end
seglength=length(x);
segment=[-seglength+1 0];
RM=[];detector=[];
X=zeros(size(x));
segind=0;
lead=1; %#ok<NASGU>
flag=0;
n=length(x);
while segment(end)<n
segment=[(segment(1)+seglength) (min(segment(end)+seglength,length(x)))];
X((segment(1)):(segment(end)))=x;
count=ceil(length(x)/step);
intervals=[1 fix(n/4); fix(n/4) fix(n/2); fix(n/2) fix(n*3/4); fix(n*3/4) length(x)];
RM_seg=[sqrt(mean(x(intervals(1,1):intervals(1,2)).^2)) sqrt(mean(x(intervals(2,1):intervals(2,2)).^2)) sqrt(mean(x(intervals(3,1):intervals(3,2)).^2)) sqrt(mean(x(intervals(4,1):intervals(4,2)).^2))];
RM_ind=RM_seg>(th1*1.2);
th2=mean(RM_seg(~RM_ind));
if sum(RM_ind)>0
flag=1;
for j=1:count
segind=[segind segment(1)+(j-1)*step]; %#ok<AGROW>
RM=[RM sqrt(mean(x((segind(end)-segment(1)+1):min(segind(end)-segment(1)+1+step,length(x))).^2))]; %#ok<AGROW>
end
segind(1)=[];
else
segind= intervals;
RM=[RM RM_seg]; %#ok<AGROW>
end
end
if flag==1;
detector=segind(find(RM>(2*th2))); %#ok<FNDSB>
end
if ~isempty(detector)
indexes=ones(step,1)*detector+(ones(length(detector),1)*(1:step))';
%indexes=(ones(step,1)*detector*(step-1)+(ones(length(detector),1)*(1:step))');
indexes=indexes(:);
else
indexes=[];
end
if length(indexes)>0.9*length(x(:,1))
indexes=[];
end