ndx2gps

 NDX2GPS - convert indices to gps times

 gps = ndx2gps(ndx,fs,gps0)

 ndx         index or vector of indices
 fs          sample rate
 gps0        gps time of first sample. Either a scalar or a struct
             with elements sec, ns.
 
 gps         struct (array) gps time relative to time of first sample
   (:).sec   seconds
   (:).ns    nanoseconds

0001 function gps = ndx2gps(ndx,fs,gps0)
0002 % NDX2GPS - convert indices to gps times
0003 %
0004 % gps = ndx2gps(ndx,fs,gps0)
0005 %
0006 % ndx         index or vector of indices
0007 % fs          sample rate
0008 % gps0        gps time of first sample. Either a scalar or a struct
0009 %             with elements sec, ns.
0010 %
0011 % gps         struct (array) gps time relative to time of first sample
0012 %   (:).sec   seconds
0013 %   (:).ns    nanoseconds
0014 
0015 % $Id: ndx2gps.m,v 1.1 2004/05/19 15:04:00 stuver Exp $
0016 
0017 sec = (ndx-1)/fs;
0018 if (isstruct(gps0))
0019   sec = sec + gps0.sec + gps0.ns/1e9;
0020 else
0021   sec = sec + gps0;
0022 end
0023 
0024 ns  = (sec - floor(sec))*1e9;
0025 sec = floor(sec);
0026 ns = floor(ns);
0027 gps = struct('sec',num2cell(sec),'ns',num2cell(ns));
0028 
0029 return