plot_powerspec

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  function [x_power_spec,y_power_spec,h, NFFT]= plot_powerspec(d,data,all,t_start,t_stop,plotOption, loglin)
 
  Plots a simple power spectrum of requested data

 Takes sample length by looking at difference between adjacent timestamps
  N.B. need to check this as i have found slightly different values
  depending on the timestamps selected. Might be better to take length of
  data/no. samples
 
 Plots y on log scale and x as linear
  h is the handle to the plot

 Inputs   d: complete data set
          data: data you want to plot the power spectrum of
           t_start:  start time (in case you only want to plot a subset of the data)
           t_stop  : stop_time
           all    :  1--> if you want to plot all the data
           plotOption:  string of color, etc.
               
  act 16/6/2010 : Original version
  act 3/10/2010 : Changed order of inputs so default is now to plot power
                    power spectrum of all the data
  mas 3/05/2012 : Added optional loglin parameter to allow for log-linear
  plots (which are better for the load correction).
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0001 function [x_power_spec,y_power_spec,h, NFFT]= plot_powerspec(d,data,all,t_start,t_stop, plotOption, loglin)
0002 
0003 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0004 %
0005 %  function [x_power_spec,y_power_spec,h, NFFT]= plot_powerspec(d,data,all,t_start,t_stop,plotOption, loglin)
0006 %
0007 %  Plots a simple power spectrum of requested data
0008 %
0009 % Takes sample length by looking at difference between adjacent timestamps
0010 %  N.B. need to check this as i have found slightly different values
0011 %  depending on the timestamps selected. Might be better to take length of
0012 %  data/no. samples
0013 %
0014 % Plots y on log scale and x as linear
0015 %  h is the handle to the plot
0016 %
0017 % Inputs   d: complete data set
0018 %          data: data you want to plot the power spectrum of
0019 %           t_start:  start time (in case you only want to plot a subset of the data)
0020 %           t_stop  : stop_time
0021 %           all    :  1--> if you want to plot all the data
0022 %           plotOption:  string of color, etc.
0023 %
0024 %  act 16/6/2010 : Original version
0025 %  act 3/10/2010 : Changed order of inputs so default is now to plot power
0026 %                    power spectrum of all the data
0027 %  mas 3/05/2012 : Added optional loglin parameter to allow for log-linear
0028 %  plots (which are better for the load correction).
0029 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0030 
0031 if (all==1)
0032     t_start = 1;
0033     t_stop = length(d.antenna0.receiver.utc);
0034 end;
0035 
0036 if(nargin<6)
0037   plotOption = 'b';
0038 end
0039 if(nargin<7)
0040   loglin = 0;
0041 end
0042 
0043 t_sec = (d.antenna0.receiver.utc(t_start:t_stop)-d.antenna0.receiver.utc(t_start))*24*60*60;
0044 t_sec = t_sec - t_sec(1);
0045 Fs = 1/(t_sec(3)-t_sec(2));
0046 L= length(data(t_start:t_stop));
0047 NFFT = 2^nextpow2(L);
0048 y_power_spec = (fft(data(t_start:t_stop),NFFT)/L);
0049 x_power_spec = Fs/2*linspace(0,1,NFFT/2+1);
0050 
0051 if loglin == 0
0052   eval(sprintf('h = loglog(x_power_spec, 2*abs(y_power_spec(1:NFFT/2+1)),''%s'');', plotOption));  
0053 else
0054   eval(sprintf('h = semilogy(x_power_spec, 2*abs(y_power_spec(1:NFFT/2+1)),''%s'');', plotOption));
0055 end
0056 set(gca,'fontsize',5) 
0057 return