% pltimp(x,Fa,Nw,NP)
function y = pltimp(x,Fa,Nw,NP)

xn = x(1:NP)/max(x(1:NP));
Px = sm2(xn(1:NP).^2,Nw,0);
Pxn = Px/max(Px(1:NP));
PxndB = 10*log(Pxn(1:NP));

matchval = -120;
for n = 1:NP,
  if ((PxndB(n) <= -60) & (PxndB(n) > matchval))
    matchn = n;
    matchval = PxndB(n);
  end;
  if (PxndB(n) > -60)
    matchval = -120;
  end;
end;
  
matchtime = matchn*1000/Fa
matchval

figure;
  plot(1000*(1:NP)/Fa,x(1:NP));
  grid;
  PlotTitle = sprintf('h(t) Fa=%d Hz',Fa);
  title(PlotTitle);
  xlabel('t [ms]');
  ylabel('h');

figure;
  plot(1000*(1:NP)/Fa,Px(1:NP));
  grid;
  PlotTitle = sprintf('Leistung Ph(t), Windowsize=%d Samples, Time=%g ms',Nw,1000*Nw/Fa);
  title(PlotTitle);
  xlabel('t [ms]');
  ylabel('eh');

figure;
  plot(1000*(1:NP)/Fa,PxndB(1:NP));
  set(gca,'YTick',-20*(0:6));
  xt = get(gca,'XTick');
  rval = 100;
  di = 1;
  for i = 1:length(xt)-1,
     lv = round(matchtime) - xt(i);
     if (lv <= 0)
       di = i;
       if (i > 1)
         uv = round(matchtime) - xt(i-1);
         if (abs(uv) < abs(lv))
           di = i - 1;
         end;
         break;
       end;
     end;
  end;
  di
  xt(di) = matchn*1000/Fa;
  set(gca,'XTick',xt);
  grid;
  PlotTitle = sprintf('Leistung Ph(t) 60dB-decay time=%g ms',matchtime);
  title(PlotTitle);
  xlabel('t [ms]');
  ylabel('Ph [dB]');