ogrt_monosat.c

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

/* ************************************************************************ 
   *                                                                      *
   *                            OpenGPS Receiver                          *
   *                                                                      *
   * -------------------------------------------------------------------- *
   *                                                                      *
   *    Module:   ogrt_monosat.c                                          *
   *                                                                      *
   *   Version:   0.1                                                     *
   *                                                                      *
   *      Date:   09.12.02                                                *
   *                                                                      *
   *    Author:   C. Kelley, G. Beyerle                                   *
   *                                                                      *
   * -------------------------------------------------------------------- *
   *                                                                      *
   * Copyright (C) 2001-2003  C. Kelley, 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.            *
   *                                                                      *
   * -------------------------------------------------------------------- *
   *                                                                      *
   * OpenGPS is based on Clifford Kelley's OpenSourceGPS distribution.    *
   * The OpenSourceGPS distribution can be obtained from                  *
   *             http://www.home.earthlink.net/~cwkelley                  *
   *                                                                      *
   * -------------------------------------------------------------------- *
   *                                                                      *
   *                         Real-time process                            *
   *                                                                      *
   ************************************************************************ */

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

   26.01.03 - replace 'trackch' by 'RT_Ctrl->leadch'
              use fields RT_Ctrl->accum_missed & ->accum_new
   18.07.03 - Chan[].ms_count wraps at 6000 (instead of 30000)
   18.07.03 - move Ms_Count to struct Chan[]
   31.07.03 - fixed bug in find/read_preamble()
   03.08.03 - copy carrier-aided code tracking from OpenSourceGPS

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

/***********************************************************************
  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) 1996-2002 Clifford Kelley.  All Rights Reserved.
  This LICENSE must be included with the OGR 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 <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>

#include <rtai.h>
#include <rtai_sched.h>
#include <rtai_fifos.h>
#include <rtai_shm.h>

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

#include  "ogrt_defines.h"
#include  "ogrt_globals.h"
#include  "ogrt_prototypes.h"

MODULE_LICENSE( "GPL");

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

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

//static long delta_carrier[NOFCHN], delta_code[NOFCHN];

/* ------------------------------ prototypes ------------------------------ */

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

/* ------------------------------------------------------------------------- *
FUNCTION init_monosatriseset()
RETURNS  None.

PARAMETERS
  ch   channel number (0-11)

PURPOSE
  init 'monosat' and 'riseset' modes: all 12 channels track
  the same PRN tracked by channel no. 'RT_Ctrl->leadch'
* ------------------------------------------------------------------------- */

void init_monosatriseset( INT16 mode)
{
  INT16 i, ch, leadch, mask, dithermode;

  leadch = RT_Ctrl->leadch;

  i = 1;  // RT_Ctrl->monosat_cod_ofs[0] is zero!
  for ( ch=0; ch<NOFCHN; ch++)
  {
    if ( ch != leadch)
      monosat_cod_ofs[ch] = RT_Ctrl->monosat_cod_ofs[i++];
    else
      monosat_cod_ofs[ch] = 0;
  }

//  activate UPDATE mode
// 0x8000: GPS mode, early select, UPDATE mode
// 0x9000: GPS mode, early select, PRESET mode
// 0xa000: GPS mode, late select, UPDATE mode
// 0xb000: GPS mode, late select, PRESET mode

  if ( RT_Ctrl->earlylate > 0)
    dithermode = 0xa000;
  else
    dithermode = 0x8000;

  mask = (~(0x1 << leadch)) & 0xfff;
  multi_channel_select( mask);

//  all_cntl( PRN_Code[Chan[leadch].prn] | dithermode);  // add G2 load 
//  Note: writes to code and carrier DCOs take effect immediately! 
//  all_carrier( Chan[leadch].car_frq);
//  all_code( Chan[leadch].cod_frq);

// add G2 load
  multi_cntl( PRN_Code[Chan[leadch].prn] | dithermode);   

//  write to code and carrier DCOs take effect immediately! 
  multi_carrier( Chan[leadch].car_frq);
  multi_code( Chan[leadch].cod_frq);

//  all_code_DCO_preset_phase( 0);

//  256/6.5 ~  39
//  256/5.5 ~  47
//  256/4.5 ~  57
//  256/3.5 ~  73
//  256/2.5 ~ 102
//  256/1.5 ~ 171

//  *** CHECKME: does a TIC event right now interfere? ***
//  It shouldn't: only write to EPOCH_COUNT_LOAD activates PRESET  

//  preset chip phases
//  ofs = # halfchips (range) / 12 * 256

//  ofs =  73; // 3.42 halfchips
//  ofs =  85; // 3.98 halfchips
//  ofs = 102; // 4.78 halfchips

// activates PRESET at next TIC
//  all_epoch_count_load( 0);

//  update chan structure accordingly
  for ( ch=0; ch<NOFCHN; ch++)
  {
    if ( ch != leadch)
    {
      Chan[ch].state     = follow_monosat; 
      Chan[ch].prn       = Chan[leadch].prn;
      Chan[ch].n_freq    = search_min_f;
      Chan[ch].delta_frq = 1;
      Chan[ch].car_frq   = Chan[leadch].car_frq;
      Chan[ch].cod_frq   = Chan[leadch].cod_frq;
    }
    else if ( mode == trans2monosat)
      Chan[ch].state     = track_monosat;
    else
      Chan[ch].state     = track_riseset;
  }

#if 0
  multi_code_DCO_preset_phase( 0);
  multi_code_slew( 2);                     // must be non-zero
  multi_epoch_count_load( 0);
#endif

#if 0
  all_carrier( Chan[trackch].car_frq);                   // select carrier
  all_code( Chan[trackch].cod_frq);                      // 1.023 MHz chipping rate
  all_code_DCO_preset_phase( 0);
  all_code_slew( 2);                     // must be non-zero
// activates PRESET at next TIC
  all_epoch_count_load( 0);
#endif

#if 0
//  write header info to data file
  ptr = buf;

//  data file format (increment if you change something!)
  tmp = 6;                              // offset
  memcpy( ptr, &tmp, sizeof( INT16));   // 2 bytes
  ptr += sizeof( INT16);

//  header size in bytes
  headersize = MSG_HEADERSIZE;
  memcpy( ptr, &headersize, sizeof( INT16));   // 4 bytes
  ptr += sizeof( INT16);

//  data body size in bytes
  tmp = MSG_DATASIZE;
  memcpy( ptr, &tmp, sizeof( INT16));   // 6 bytes
  ptr += sizeof( INT16);

////  GPS week
//  memcpy( buf+6, &RT_Ctrl->gps_week, sizeof( INT16)); // 8 bytes

//  time of week
  memcpy( ptr, &Chan[leadch].tow_HOW, sizeof( long)); // 12 bytes 
  ptr += sizeof( long);

//  TIC
  memcpy( ptr, &RT_Ctrl->tow_tic_count, sizeof( long));  // 16 bytes
  ptr += sizeof( long);

//  which channel leads the gang?
  memcpy( ptr, &RT_Ctrl->leadch, sizeof( INT16));  // 70 bytes
  ptr += sizeof( INT16);

// +1 late arm, -1 : early arm
  memcpy( ptr, &RT_Ctrl->earlylate, sizeof( INT16));  // 72 bytes
  ptr += sizeof( INT16);

//  PRN of leading channel
  memcpy( ptr, &Chan[leadch].prn, sizeof( INT16)); // 18 bytes
  ptr += sizeof( INT16);

//  code phase offset (monosat mode)
  memcpy( ptr, monosat_cod_ofs, 12*sizeof( INT16)); // 44 bytes
  ptr += 12 * sizeof( INT16);

////  carrier offset (monosat mode)
//  memcpy( ptr, monosat_car_ofs, 12*sizeof( INT16)); // 68 bytes
  ptr += 12 * sizeof( INT16);

  rtf_put( 1, buf, headersize);  // write to FIFO
#endif

  return;