test_snr.c

This a framework to test new ideas in transmission technology. Actual development is a LDPC-coder in

/***************************************************************************
              test_snr.c  -  Module for testing the SNR-module
                            -------------------
    begin                :  2003-03-24
    authors              :  ineiti
    emails               :  [e-mail]
 ***************************************************************************/

/***************************************************************************
                                 Changes
                                 -------
 date - name - description
 03/08/x - ineiti - start
 04/03/03 - ineiti - added a small comment
 
 **************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/

char desc[] =
"Description:\n"
"So that we can compare the SNR of the matched filter with a 'real'\n"
"calculated by-hand SNR, we wrote this test-chain. The output\n"
"is once for QAM and then rotated-by-pi/4 QAM and shows the comparison\n"
"of the 'calculated-by-hand' with the 'matched-filter' SNR. Usually,\n"
"both should be within 1/2 dB of SNR, due to the small lenght of\n"
"the matched filter.\n\n";

#include "spc.h"
#include "std.h"

#define DBG_LVL 4


struct chain_t *test_chain, *test_chain_2;

void *start_it( void *arg ) {
  int i, type;

  swr_sdb_id rnd, rnd2, mafi, snr_rcv, snr_send, mid, block;

  test_chain = swr_chain_create( NEW_SPC_VAR( "random", rnd ),
                                 NEW_SPC_VAR( "snr_send", snr_send ),
                                 NEW_SPC_VAR( "midamble", mid ),
                                 NEW_SPC( "rrc" ),
                                 NEW_SPC_VAR( "block", block ),
                                 NEW_SPC_VAR( "matched_filter", mafi ),
                                 NEW_SPC_VAR( "snr_rcv", snr_rcv ),
				 CHAIN_END );

  test_chain_2 = swr_chain_create( NEW_SPC_VAR( "random", rnd2 ),
                                   OLD_SPC_IN( snr_rcv, 1 ),
                                   CHAIN_END );

  // Make both rnd-chains the same
  swr_sdb_set_config_int( rnd, "seed", 0x1234 );
  swr_sdb_set_config_int( rnd2, "seed", 0x1234 );
  swr_sdb_set_config_int( block, "size", 6000 );

  // Adjust the amplitudes
  swr_sdb_set_config_int( snr_send, "amplitude", 16384 / 4 );
  swr_sdb_set_config_int( mid, "amplitude", 16384 / 4 );

  PR( "Comparing SNR_midamble to SNR_module\n" );
  for ( type = 0; type < 2; type ++ ) {
    PR( "Type: %i\n", type );
    swr_sdb_set_config_int( snr_rcv, "type", type );
    swr_sdb_set_config_int( snr_send, "type", type );
    for ( i=0; i<50; i+=5 ) {
      swr_sdb_set_config_double( block, "sigma", i );
      swr_sdb_send_msg( rnd, SUBS_MSG_USER, NULL, -1 );
      swr_sdb_send_msg( rnd2, SUBS_MSG_USER, NULL, -1 );
      PR( "Amp: %3i:%3i, Noise: %5i:%-5i  SNR : %5.5g - %5.5g = %5.5g\n",
          swr_sdb_get_stats_int( mafi, "mid_amp" ),
          swr_sdb_get_stats_int( snr_rcv, "amp" ),
          swr_sdb_get_stats_int( mafi, "noise_var" ),
          swr_sdb_get_stats_int( snr_rcv, "var" ),
          swr_sdb_get_stats_double( mafi, "snr" ),
          swr_sdb_get_stats_double( snr_rcv, "snr" ),
          swr_sdb_get_stats_double( mafi, "snr" ) -
          swr_sdb_get_stats_double( snr_rcv, "snr" ) );
    }
  }

  return 0;
}

swr_spc_id_t spm_id;

struct thread start;
/**
 * This function is called upon "insmod" and is used to register the
 * different parts of the module to the SPM.
 */
int um_module_init(void) {

  PR_CL( desc );
  test_chain = NULL;
  if ( swr_thread_init( &start, start_it, NULL ) < 0 )
    goto first_no_stack;
  return 0;

first_no_stack:
  PR_DBG( 0, "Couldn't allocate stack\n" );
  return -1;
}

void um_module_exit( void ) {

  swr_thread_free( &start, NULL );
  swr_chain_destroy( test_chain_2 );
  swr_chain_destroy( test_chain );
}


module_init( um_module_init );
module_exit( um_module_exit );