plnumsat.m

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

function plnumsat (eph,tsat,elev,cutoff)
%PLNUMSAT: Plot number of satellites
%
% The function create a plot showing the number of satellites
% above the elevation cutoff as a fucntion of time
%
% Syntax:
%    plnumsat (eph,tsat,elev,cutoff)
%
% Input arguments:
%    eph    - Ephemerides
%    tsat   - Time (seconds)
%    elev   - Elevation for each satellite
%    cutoff - Cutoff elevation
%
% Output arguments:
%    none

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

% ----------------------------------------------
% --- Count the number of visible satellites ---
% ----------------------------------------------

numsat = zeros(size(tsat));

for i = 1:size(elev,2);
  numsat(i) = length(find(elev(:,i)>=cutoff));
end;

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

h = figure('Units','normalized', ...
	   'Position',[0.2 0.5 0.6 0.3], ...
	   'Color',[0 0 0], ...
	   'Name','Number of satellites vs. time', ...
	   'NumberTitle','off');

h = axes ('Units','normalized', ...
	  'Position',[0.05 0.10 0.90 0.80], ...
	  'Color',[0 0 0], ...
	  'XColor',[1 1 1], ...
	  'YColor',[1 1 1], ...
	  'Xgrid','on', ...
	  'Ygrid','on', ...
	  'Box','on');

hold on;

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

xlabel ('Time [sec]');
ylabel ('Number of satellites');

set (gca,'Xlim',[min(tsat) max(tsat)]);
set (gca,'Ylim',[0 max(numsat)+1]);

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

h = plot (tsat,numsat,'b-');
set (h,'LineWidth',2);

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