#!/usr/bin/perl
########################################################################
# otfaste.pl -- a perl script to estimate OTF obs parameters for ASTE
#   usage: type "perl otfaste.pl"
#   2006-11-15 for multi-ON/OFF observations
#   2007-10-22 WHSF support
#   2007-10-22 tdump=0.2 for WHSF
#   sawada @ NRO
########################################################################

$tapp = 4.;
$ttran = 2.;
$ttranoff = 5.;
$fcal = 16./15.;
$eta  = 4.3;
$etaq = 0.88;
$tdump = 0.1;

printf("### OTF sensitivity estimation for ASTE ###\n");

#	/* BACKEND TYPE */
printf("backend type                            (1:MAC, 2:WHSF): ");
chomp($betype = <STDIN>);

#	/* MAPPING AREA */
printf("length of mapping area (along the scans)    l1 [arcsec]: ");
chomp($len1 = <STDIN>);
printf("length of mapping area (perp. to the scans) l2 [arcsec]: ");
chomp($len2 = <STDIN>);

#	/* TIME FOR SCAN */
printf("time for scan                                 tscan [s]: ");
chomp($tscan = <STDIN>);

#	/* SEQUENCE PATTERN */
printf("number of ONs per OFF                        Nscan(SEQ): ");
chomp($nscanseq = <STDIN>);

#	/* SEPARATION BETWEEN SCANS */
printf("separation between scans              (delta)l [arcsec]: ");
chomp($deltal = <STDIN>);

#	/* MAP GRID */
printf("map grid                                     d [arcsec]: ");
chomp($dgrid = <STDIN>);

#	/* SYSTEM NOISE TEMPERATURE */
printf("system noise temperature                       Tsys [K]: ");
chomp($tsys = <STDIN>);

#	/* RESOLUTION BANDWIDTH */
printf("resolution bandwidth                            B [kHz]: ");
chomp($bandw = <STDIN>);

printf("----------------------------------------------------------------\n");
#	/* END OF INPUT */

if ($betype == 2) {
	$etaq = 0.64;
	$tdump = 0.2;
}

$vscan = $len1/$tscan;
printf("vscan=%0.1f[\"/sec]",$vscan);
printf(" (%0.1f\" per %0.1fs sample)\n",$vscan*$tdump,$tdump);

$nrow = $len2/$deltal + 1;
$tontot = $tscan*$nrow;
$toh = 2.*$ttranoff/$nscanseq + $tapp + ($nscanseq-1)/$nscanseq*$ttran;
$toff = sqrt(($tscan+$toh)*$eta*$nrow*$tscan*$deltal*$dgrid/$len1/$len2 *
	$nscanseq*$nscanseq*$dgrid/(($nscanseq-1)*$deltal+$dgrid));
printf("tOFF=%0.1f[s]",$toff);
$toff = int($toff+0.5);
printf(" -> %d[s]\n",$toff);

printf("tOH=%0.1f[s]\n",$toh);
$tobstot = $nrow*($tscan+$toff/$nscanseq+$toh) * $fcal;

printf("ttot(ON)=%0.1f[min]\n",$tontot/60.);
printf("ttot(OBS)=%0.1f[min]\n",$tobstot/60.);
printf("eta(ON/OBS)=%0.2f\n",$tontot/$tobstot);

$tcellon = $eta*$tontot*$dgrid*$dgrid/$len1/$len2;
$tcelloff = $toff*(($nscanseq-1)*$deltal+$dgrid)/($nscanseq*$deltal);
$dta = $tsys/$etaq/sqrt(1000.0*$bandw)*sqrt(1./$tcellon+1./$tcelloff);

printf("tcell(ON)=%0.2f[s]\n",$tcellon);
printf("tcell(OFF)=%0.2f[s]\n",$tcelloff);
printf("dTa*=%0.2f[K]\n",$dta);