plskyplt.m

Sky lab calculate position of satellite in GNSS systems and calculate elevation and azimuth them and

function plskyplt (eph,azim,elev,cutoff)
%PLELETIM: Create skyplot
%
% The function create a plot showing the elevation and azimuths
% of GPS satellites in time (2D)
%
% Syntax:
%    plskyplt (eph,azim,elev,cutoff);
%
% Input arguments:
%    eph    - Ephemerides
%    azim   - Azimuth of satellites
%    elev   - Elevation for each satellite
%    cutoff - Cutoff elevation
%
% Output arguments:
%    none

% ----------------------------------------------------------------------
% File.....: plskyplt.m
% Date.....: 29-APR-1999
% Version..: 1.0
% Author...: Peter Joosten
%            Mathematical Geodesy and Positioning
%            Delft University of Technology
% ----------------------------------------------------------------------

% --------------------------------------
% --- Create the figure, set options ---
% --------------------------------------

h = figure('Units','normalized', ...
	   'Position',[0.2 0.3 0.6 0.6], ...
	   'Color',[0 0 0], ...
	   'Name','Skyplot (Azimuth/Elevation)', ...
	   'NumberTitle','off');

h = axes ('Units','normalized', ...
	  'Position',[0.05 0.05 0.90 0.90], ...
	  'Color',[0 0 0], ...
	  'XColor',[0 0 0], ...
	  'YColor',[0 0 0], ...
	  'Xgrid','off', ...
	  'Ygrid','off', ...
	  'Box','off');

axis square
hold on;

% -----------------------------------------
% --- Limits, grid, labels and such ... ---
% -----------------------------------------

set (gca,'Xlim',[-90 90]);
set (gca,'Ylim',[-90 90]);

set (gca,'FontWeight','bold');
set (gca,'FontSize',16);
set (gca,'LineWidth',2);

for i = 0:30:330;
  [x,y] = pol2cart (-deg2rad(i-90),90);
  plot ([0 x], [0 y],'w-');
  [x,y] = pol2cart (-deg2rad(i-92),94);
  h = text (x,y,num2str(i));
  set (h,'Color',[1 1 1]);    
  set (h,'FontSize',12);
  set (h,'FontWeight','bold');
  set (h,'Rotation',-i);
end;

for i = [0:15:90 cutoff];
  
  az = [0:1:360];
  el = (90-i)*ones(size(az));
  [x,y] = pol2cart (deg2rad(az),el);
  h = plot (x,y,'w-');
  set (h,'LineWidth',1);
  if i == cutoff;
    set (h,'LineStyle',':');
  else
    if i ~= 0;
      h = text (2,90-i+3,num2str(i));
      set (h,'Color',[1 1 1]);    
      set (h,'FontSize',12);
      set (h,'FontWeight','bold');
    end;
  end;
end;

% -------------------
% --- Actual plot ---
% -------------------

lcol = get(gca,'ColorOrder');

for i = 1:size(eph,1);

  idx1 = find(elev(i,:)>cutoff);
  
  if ~isempty(idx1);
    
    idx2 = [0 (find (idx1(1:length(idx1)-1) ~= idx1(2:length(idx1))-1)) length(idx1)];

    for j = 1:length(idx2)-1

      [x,y] = pol2cart(-deg2rad(-azim(i,idx1(idx2(j)+1):idx1(idx2(j+1)))-90), ...
		       90-elev(i,idx1(idx2(j)+1):idx1(idx2(j+1))));
      h = plot (-x,y);
      set (h,'Marker','.');
      set (h,'LineWidth',3);
      set (h,'Color',lcol(mod(i,size(lcol,1))+1,:));
      
      [tx,ty] = pol2cart (-deg2rad(-azim(i,idx1(idx2(j)+1))-90),90-elev(i,idx1(idx2(j)+1)));
      tx = tx + 5; ty = ty + 2;
      h  = text(-tx,ty,num2str(eph(i,1)));
      set (h,'Color',lcol(mod(i,size(lcol,1))+1,:));
      set (h,'FontSize',18);
      set (h,'FontWeight','bold');
      
    end;

  end
  
end;

% ----------------------
% --- End of routine ---
% ----------------------