--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m-toolbox/classes/@ao/heterodyne.m	Wed Nov 23 19:22:13 2011 +0100
@@ -0,0 +1,183 @@
+% HETERODYNE heterodynes time-series.
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% DESCRIPTION: HETERODYNE heterodynes time-series.
+%
+% The input signal is mixed down at the specified frequency. The mixed
+% signal is then (optionally) low-pass filtered and (optionally) downsampled 
+% to have the specified bandwidth.
+%
+% CALL:     b = heterodyne(a,pl)
+%
+% INPUTS:   pl   - a parameter list
+%           a    - input analysis object
+%
+% OUTPUTS:  b    - output analysis object containing the filtered data.
+%
+% <a href="matlab:utils.helper.displayMethodInfo('ao', 'heterodyne')">Parameters Description</a>
+%
+% VERSION:     $Id: heterodyne.m,v 1.22 2011/04/08 08:56:16 hewitson Exp $
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+function varargout = heterodyne(varargin)
+  
+  % Check if this is a call for parameters
+  if utils.helper.isinfocall(varargin{:})
+    varargout{1} = getInfo(varargin{3});
+    return
+  end
+  
+  import utils.const.*
+  utils.helper.msg(msg.PROC3, 'running %s/%s', mfilename('class'), mfilename);
+  
+  % Collect input variable names
+  in_names = cell(size(varargin));
+  for ii = 1:nargin,in_names{ii} = inputname(ii);end
+  
+  % Collect all AOs and plists
+  [as, ao_invars] = utils.helper.collect_objects(varargin(:), 'ao', in_names);
+  [pl, pl_invars] = utils.helper.collect_objects(varargin(:), 'plist', in_names);
+  
+  % Make copies or handles to inputs
+  bs   = copy(as, nargout);
+  
+  % Combine plists
+  pl = parse(pl, getDefaultPlist());
+  
+  
+  % Get parameters
+  t0 = find(pl, 't0');
+  f0 = find(pl, 'f0');
+  if isempty(f0)
+    error('### Please specify the heterodyne frequency with the paramter ''f0''');
+  end
+  mix = find(pl, 'quad');
+  
+  for jj = 1:numel(bs)
+    if isa(bs(jj).data, 'tsdata')
+      
+      % store input history
+      inhist = bs(jj).hist;
+      
+      % check bandwidth
+      bw = find(pl, 'bw');
+      if isempty(bw)
+        bw = bs(jj).data.fs;
+      end
+      if bw > bs(jj).data.fs
+        error('### The output bandwidth can not exceed the input bandwidth');
+      end
+      
+      % mix at f0
+      switch lower(mix)
+        case 'cos'
+          bs(jj).data.setY(bs(jj).data.getY .* 2.0 .* cos(2*pi * f0 .* (bs(jj).data.getX - t0)));
+        case 'sin'
+          bs(jj).data.setY(bs(jj).data.getY .* 2.0 .* sin(2*pi * f0 .* (bs(jj).data.getX - t0)));
+        otherwise
+          error('### Unknown quadrature specified');
+      end
+      
+      
+      % user-input filter for low pass
+      filt = find(pl, 'filter');
+      
+      % lowpass filter at bw/w
+      if ~isempty(filt) || utils.prog.yes2true(find(pl, 'lp'))
+        if isempty(filt)
+          % standard filter for low-pass
+          filt = miir(plist('type', 'lowpass', 'order', 4, 'fc', 0.4*bw, 'fs', bs(jj).data.fs));
+        end
+        bs.filtfilt(filt);
+      end
+      
+      % downsample
+      if utils.prog.yes2true(find(pl, 'ds'))
+        factor = ceil(bs(jj).data.fs / bw);
+        bs.downsample(plist('factor', factor));
+      end
+      
+      % set name and history
+      bs(jj).name = sprintf('heterodyne(%s, %s@%.01f Hz)', ao_invars{jj}, mix, f0);
+      bs(jj).addHistory(getInfo('None'), pl, ao_invars(jj), inhist);
+      % clear errors
+      bs(jj).clearErrors;
+      
+    else
+      error('### heterodyne only works on time-series AOs currently.');
+    end
+  end
+  
+  % Set output
+  if nargout == numel(bs)
+    % List of outputs
+    for ii = 1:numel(bs)
+      varargout{ii} = bs(ii);
+    end
+  else
+    % Single output
+    varargout{1} = bs;
+  end
+end
+
+%--------------------------------------------------------------------------
+% Get Info Object
+%--------------------------------------------------------------------------
+function ii = getInfo(varargin)
+  if nargin == 1 && strcmpi(varargin{1}, 'None')
+    sets = {};
+    pls  = [];
+  else
+    sets = {'Default'};
+    pls  = getDefaultPlist;
+  end
+  % Build info object
+  ii = minfo(mfilename, 'ao', 'ltpda', utils.const.categories.sigproc, '$Id: heterodyne.m,v 1.22 2011/04/08 08:56:16 hewitson Exp $', sets, pls);
+  ii.setModifier(false);
+end
+
+%--------------------------------------------------------------------------
+% Get Default Plist
+%--------------------------------------------------------------------------
+function plout = getDefaultPlist()
+  persistent pl;  
+  if exist('pl', 'var')==0 || isempty(pl)
+    pl = buildplist();
+  end
+  plout = pl;  
+end
+
+function pl = buildplist()
+  
+  pl = plist();
+  
+  % f0
+  p = param({'f0', 'The heterodyne frequency in Hz.'}, paramValue.EMPTY_DOUBLE);
+  pl.append(p);
+  
+  % t0
+  p = param({'t0', 'Modulation start time offset in s.'}, paramValue.DOUBLE_VALUE(0));
+  pl.append(p);
+  
+  % quad
+  p = param({'quad', 'The quadrature to output. ''sin'' or ''cos''.'},{2, {'sin', 'cos'}, paramValue.SINGLE});
+  pl.append(p);
+  
+  % bw
+  p = param({'bw', 'The bandwidth at the output in Hz.'}, paramValue.EMPTY_DOUBLE);
+  pl.append(p);
+  
+  % lp
+  p = param({'lp', 'Low pass filter the output data at ''bw''.'}, paramValue.YES_NO);
+  pl.append(p);
+  
+  % filter
+  p = param({'filter', ['Filter to be used to low pass the output data.<br>' ...
+    'If this parameter is set, the low pass is applied regardless to the value of the ''lp'' parameter']}, paramValue.EMPTY_DOUBLE);
+  pl.append(p);
+  
+  % ds
+  p = param({'ds','Downsample the output data.'}, paramValue.YES_NO);
+  pl.append(p);
+end