ogr_riseset.c

The OpenGPSRec receiver software runs on the real time operating system RTAI-Linux. It compiles with

/* ************************************************************************ 
   *                                                                      *
   *                            OpenGPS Receiver                          *
   *                                                                      *
   * -------------------------------------------------------------------- *
   *                                                                      *
   *    Module:   ogr_riseset.c                                           *
   *                                                                      *
   *   Version:   0.1                                                     *
   *                                                                      *
   *      Date:   05.08.03                                                *
   *                                                                      *
   *    Author:   G. Beyerle                                              *
   *                                                                      *
   * -------------------------------------------------------------------- *
   *                                                                      *
   * Copyright (C) 2001-2002 C. Kelley, 2003 G. Beyerle                   *
   *                                                                      *
   * This program is free software; you can redistribute it and/or modify *
   * it under the terms of the GNU General Public License as published by *
   * the Free Software Foundation; either version 2 of the License, or    *
   * (at your option) any later version.                                  *
   *                                                                      *
   * This program is distributed in the hope that it will be useful,      *
   * but WITHOUT ANY WARRANTY; without even the implied warranty of       *
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        *
   * GNU General Public License for more details.                         *
   *                                                                      *
   * You should have received a copy of the GNU General Public License    *
   * along with this program; if not, write to the Free Software          *
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.            *
   *                                                                      *
   * -------------------------------------------------------------------- *
   *                                                                      *
   * The files 'ogr_user.c', 'ogr_navdecode.c', 'ogr_navsolve.c',         *
   * 'ogr_rtproc.c' are modified versions of the files 'gpsfuncs.cpp',    *
   * 'gpsrcvr.cpp' from Clifford Kelley's OpenSourceGPS distribution.     *
   * The unmodified files can be obtained from                            *
   *             http://www.home.earthlink.net/~cwkelley                  *
   *                                                                      *
   * -------------------------------------------------------------------- *
   *                                                                      *
   *                 Track setting and rising satellites                  *
   *                                                                      *
   ************************************************************************ */

/* ******************************* changes ********************************

   dd.mm.yy -

   ************************************************************************ */

/***********************************************************************
  GPS RECEIVER (GPSRCVR) Ver. 1.02
  12 Channel All-in-View GPS Receiver Program based on Mitel GP2021
  chipset
  Clifford Kelley [e-mail]
  Copyright (c) 1996-2001 Clifford Kelley.  All Rights Reserved.
  This LICENSE must be included with the GPSRCVR code.
***********************************************************************/

/*
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

      CONDITIONS

1. Redistributions of GPSRCVR source code must retain the above copyright
notice, this list of conditions, and the following disclaimer.

2. Redistributions in binary form must contain the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.

3. All modifications to the source code must be clearly marked as
such.  Binary redistributions based on modified source code must be
clearly marked as modified versions in the documentation and/or other
materials provided with the distribution.

4. Notice must be given of the location of the availability of the
unmodified current source code, e.g.,
  http://www.Kelley.com/
or
  ftp://ftp.Kelley.com
in the documentation and/or other materials provided with the
distribution.

5. All advertising and published materials mentioning features or use
of this software must display the following acknowledgment:  "This
product includes software developed by Clifford Kelley and other
contributors."

6. The name of Clifford Kelley may not be used to endorse or promote
products derived from this software without specific prior written
permission.

      DISCLAIMER

This software is provided by Clifford Kelley and contributors "as is" and
any expressed or implied warranties, including, but not limited to, the
implied warranties of merchantability and fitness for a particular
purpose are disclaimed.  In no event shall Clifford Kelley or
contributors be liable for any direct, indirect, incidental, special,
exemplary, or consequential damages (including, but not limited to,
procurement of substitute goods or services; loss of use, data, or
profits; or business interruption) however caused and on any theory of
liability, whether in contract, strict liability, or tort (including
negligence or otherwise) arising in any way out of the use of this
software, even if advised of the possibility of such damage.
*/

/* ------------------------------- includes ------------------------------- */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <time.h>
#include <assert.h>

#include "port.h"
#include "ogr_defines.h"
#include "ogr_globals.h"
#include "ogr_structs.h"

/* ----------------------------- defines ---------------------------------- */

/* ---------------------------- prototypen -------------------------------- */

/* ----------------------------- globals ---------------------------------- */

/* ---------------------------- procedures -------------------------------- */

/*
 *  cycle through all tracked sats and determine whether their
 *  elevation angle increases or decreases
 */
void find_rising_or_setting( int tr_ch_len, int tr_ch[], ECEF rcvr_pos, double Ttr)
{
  INT16  n, ch, prn;
  double Trel, 
         az, el, az_next, el_next, 
         tOfs = 60;   // time step is 1 min
  ECEF   xmit_pos;
  
  for ( n=0; n<tr_ch_len; n++)
  {
    ch  = tr_ch[n];
    prn = Chan[ch].prn;
    
    xmit_pos = satellite_position( prn, Ttr, &Trel);
    sat_azimuth_elevation( xmit_pos, rcvr_pos, &az, &el);

    xmit_pos = satellite_position( prn, Ttr + tOfs, &Trel);
    sat_azimuth_elevation( xmit_pos, rcvr_pos, &az_next, &el_next);

// if elevation angle decreases it must be a setting event
    if ( el_next < el)
      Xmit_Info[prn].riseset = -1;
    else  
      Xmit_Info[prn].riseset = 1;
  }

  return;   
}

/*
 * select sat to be tracked next
 */
INT16 schedule_riseset( int tr_ch_len, int tr_ch[], 
  ECEF rcvr_pos, double Ttr)
{
  INT16 n, prn, prnmin = -1, nmin = -1;
  
  find_rising_or_setting( tr_ch_len, tr_ch, rcvr_pos, Ttr);

//  Ctrl->riseset_elev_min 
//  Ctrl->riseset_elev_max

//  select 
  for ( n=0; n<tr_ch_len; n++)
  {
    prn = Chan[tr_ch[n]].prn;

    if ( nmin < 0 && Xmit_Info[prn].riseset < 0)
    {
      nmin = n;
      prnmin = Chan[tr_ch[nmin]].prn;
    }

// find tracked sat with lowest elevation
    if ( nmin >= 0 && 
         Xmit_Info[prn].riseset < 0 &&
         Xmit_Info[prn].elevation < Xmit_Info[prnmin].elevation  )
    {
      nmin = n;
      prnmin = Chan[tr_ch[nmin]].prn;
    }
  }

  return (prnmin);
}


/* ---------------------------- end of file ------------------------------- */