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/*****************************************************************************
* Johns Hopkins University
* Center For Astrophysical Sciences
* FUSE
*****************************************************************************
*
* Synopsis: cf_electronics_dead_time(fitsfile *header, long nseconds,
* float *fec_rate, float *elec_dtc)
*
* Description: Scales the weighting factor to correct for the electronics
* dead time.
*
* Arguments: fitsfile *header Pointer to FITS file containing the
* header of the intermediate data file
* long nseconds The number of timeline values
* float *fec_rate An array of Front End Counter (FEC)
* rates
* float *elec_dtc Dead-time correction array (returned)
* Calls:
*
* Return: 0 on success
*
* History: 10/27/02 1.1 peb Begin work
* 11/11/02 1.2 peb Corrected function description and
* added cf_timestamp after ELEC_COR
* check.
* 12/06/02 1.4 wvd Calculate DT correction for each time
* step, then apply to photons.
* Set keyword DET_DEAD.
* 05/20/03 1.5 rdr Added proc_check call
* 08/01/03 1.7 wvd Just calculate correction; don't
* apply it. Return elec_dtc array.
* 08/04/03 1.8 wvd Convert fec_rate to type short.
* 11/26/03 1.9 wvd Change fec_rate to type float.
* 02/12/04 1.10 wvd In verbose mode, write mean DTC.
* 04/07/07 1.11 wvd Clean up compiler warnings.
*
****************************************************************************/
#include <string.h>
#include <math.h>
#include "calfuse.h"
int
cf_electronics_dead_time(fitsfile *header, long nseconds,
float *fec_rate, float *elec_dtc)
{
char CF_PRGM_ID[] = "cf_electronics_dead_time";
char CF_VER_NUM[] = "1.11";
char elecfile[FLEN_VALUE]={"\0"}, detector[FLEN_VALUE]={"\0"};
char keyword[FLEN_KEYWORD]={"\0"};
int errflg=0, status=0;
long k;
float abort, clock, state;
float mean_elec_dtc = 0.;
fitsfile *elecfits;
cf_error_init(CF_PRGM_ID, CF_VER_NUM, stderr);
cf_timestamp(CF_PRGM_ID, CF_VER_NUM, "Begin Processing");
if ((errflg = cf_proc_check(header, CF_PRGM_ID))) return errflg;
FITS_read_key(header, TSTRING, "DETECTOR", detector, NULL, &status);
/*
* Get the electronics dead-time constants.
*/
FITS_read_key(header, TSTRING, "ELEC_CAL", elecfile, NULL, &status);
FITS_open_file(&elecfits, cf_cal_file(elecfile), READONLY, &status);
sprintf(keyword, "ABORT_%s", detector);
FITS_read_key(elecfits, TFLOAT, keyword, &abort, NULL, &status);
sprintf(keyword, "CLOCK_%s", detector);
FITS_read_key(elecfits, TFLOAT, keyword, &clock, NULL, &status);
sprintf(keyword, "STATE_%s", detector);
FITS_read_key(elecfits, TFLOAT, keyword, &state, NULL, &status);
FITS_close_file(elecfits, &status);
/*
* Calculate dead-time correction.
*/
for (k=0; k<nseconds; k++) {
float xa, x, x2, x4, x6, x10;
xa = exp(-fec_rate[k]*abort);
x = exp(-fec_rate[k]*clock);
x2 = x*x;
x4 = x2*x2;
x6 = x4*x2;
x10 = x6*x4;
elec_dtc[k] = (1. + fec_rate[k]*state + 4.*(x2-x) + x6 - x10)/xa;
if (elec_dtc[k] < 1.0) elec_dtc[k] = 1.0;
mean_elec_dtc += elec_dtc[k];
}
/*
* Calculate mean dead-time correction. Write to file header.
*/
mean_elec_dtc /= nseconds;
cf_verbose(2, "Mean detector electronics dead-time correction: %f", mean_elec_dtc);
FITS_update_key(header, TFLOAT, "DET_DEAD", &mean_elec_dtc, NULL, &status);
cf_proc_update(header, CF_PRGM_ID, "COMPLETE");
cf_timestamp(CF_PRGM_ID, CF_VER_NUM, "Done processing");
return 0;
}
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