;+ ; NAME: ; bcs_dtfac ; PURPOSE: ; to compute BSC deadtime correction factors ; CALLING SEQUENCE: ; dt_fac=bcs_dtfac(bda_index,dp_sync,type,interp=interp) ; INPUTS: ; dp_sync - DP synchronous data ; bda_index - BDA index structures ; type - method of computing correction ; OUTPUTS: ; dt_fac(4,n) - deadtime factors by which to multiply spectral counts. ; KEYWORDS: ; interp - 1 set zero deadtime factors to unity ; - 2 keep zero deadtime factors as zero ; - 3 interpolate out zero deadtime factors ; PROCEDURE ; Assumes the correction factor is LIM/ACC (type = 1) ; or SUM(LIM)/SUM(ACC) (type = 2) where the summation ; is taken over channels 1 & 2 or 3 & 4. The counts are corrected ; for their own deadtime before use. ; RESTRICTIONS: ; Must have dp_sync data ; HISTORY: ; Written by D. Zarro (ARC) Oct'92 -- based on D. Pike's DT_FACTOR ;- function bcs_dtfac,bda_index,dp_sync,type,stime,etime,interp=interp on_error,1 ;-- check inputs if (datatype(bda_index) ne 'STC') then $ message,'usage --> DT_FAC=BCS_DTFAC(BDA_INDEX,DP_SYNC,TYPE,INTERP=INTERP)' if datatype(dp_sync) ne 'STC' then begin message,'DP_SYNC data not entered; deadtime corrections not applied',/continue return,0 endif ;-- check that DP_SYNC and BDA_INDEX times overlap dok=bcs_dp_check(dp_sync,bda_index) if not dok then begin message,'DP_SYNC and BDA_INDEX times do not overlap; correction not applied',/contin return,0 endif ; ; was method supplied? ; if n_elements(type) eq 0 then type=1 type= (type < 2) & type=(type > 1) ; ; set default limited events counter deadtime ; lim_microsecs = 3.7 ; ; were times supplied? if not use all file, if yes then find indices ; in index array ; bdagen=bda_index.gen stet=(n_elements(stime) eq 0) or (n_elements(etime) eq 0) if stet then begin n1 = 0 n2 = n_elements(bdagen.time) - 1 endif else begin ttime = bdagen.time/3600./1000. + (bdagen.day - bdagen(0).day)*24. ss = where( (ttime ge stime) and (ttime le etime) ) if n_elements(ss) ge 2 then begin n1 = ss(0) n2 = ss(n_elements(ss)-1) endif else begin message,'No datasets found in that time range, returning.',/cont print,'PS. time range in this file is ',ttime(0),' to ',$ ttime(n_elements(bdagen.time)-1),$ ' Hrs UT',format='(a,f6.3,a,f6.3,a)' return,dt_fac endelse endelse ; ; and the same in the dp_sync arrays ; if stet then begin d1 = 0 d2 = n_elements(dp_sync.time) - 1 endif else begin ttime = dp_sync.time +(dp_sync.day - dp_sync(0).day)*86400L*1000L ttime = ttime/3600./1000. ; ; compensate for different start days ; if bdagen(0).day lt dp_sync(0).day then ttime = ttime + 24.0 if bdagen(0).day gt dp_sync(0).day then ttime = ttime - 24.0 ss = where( (ttime ge stime) and (ttime le etime) ) d1 = ss(0) d2 = ss(n_elements(ss)-1) endelse ; ; use chekov to correct overflows in LIM and ACC counts in all channels ; and form mean of both counts ; print,'Checking for counter overflows...' chekov,3,2,dp_sync,lim4,dum lim4 = (lim4 + dum)/2 chekov,3,3,dp_sync,acc4,dum acc4 = (acc4 + dum)/2 chekov,2,2,dp_sync,lim3,dum lim3 = (lim3 + dum)/2 chekov,2,3,dp_sync,acc3,dum acc3 = (acc3 + dum)/2 chekov,1,2,dp_sync,lim2,dum lim2 = (lim2 + dum)/2 chekov,1,3,dp_sync,acc2,dum acc2 = (acc2 + dum)/2 chekov,0,2,dp_sync,lim1,dum lim1 = (lim1 + dum)/2 chekov,0,3,dp_sync,acc1,dum acc1 = (acc1 + dum)/2 ; ; correct for their own deadtime, using only the data requested to save time ; print,'Correcting LIMited counts for counter deadtime...' dt_corr,lim_microsecs,lim4(d1:d2),dum lim4_dt = fltarr(n_elements(lim4)) lim4_dt(d1:d2) = dum dt_corr,lim_microsecs,lim3(d1:d2),dum lim3_dt = fltarr(n_elements(lim3)) lim3_dt(d1:d2) = dum dt_corr,lim_microsecs,lim2(d1:d2),dum lim2_dt = fltarr(n_elements(lim2)) lim2_dt(d1:d2) = dum dt_corr,lim_microsecs,lim1(d1:d2),dum lim1_dt = fltarr(n_elements(lim1)) lim1_dt(d1:d2) = dum ; ; form the search index array ; rm_idx = indgen(n2-n1+1) + n1 ; ; call routine to correlate INDEX and dp_sync times ; bcs_dp_sync,dp_sync,bda_index,rm_idx,dp_idx ; ; create the output factor array ; dt_fac = fltarr(4,n_elements(bdagen.time)) ; ; set all to a safe value of 1.0 ; ;-- default is to interpolate if n_elements(interp) eq 0 then interp=3 if interp eq 1 then safe_val=1 else safe_val=0 dt_fac(*,*) = safe_val if safe_val eq 1 then $ message,'setting zero deadtime correction factors to unity',/contin ; ; average the counts and form the ratios ; case type of 1: print,'Forming type 1 deadtime correction ratios in dt_fac(4,*)...' 2: print,'Forming type 2 deadtime correction ratios in dt_fac(4,*)...' endcase for i=n1,n2 do begin if dp_idx(i,0) ge 0 and dp_idx(i,1) ge 0 then begin case type of 1: begin d4=total(acc4(dp_idx(i,0):dp_idx(i,1))) if d4 eq 0. then dt_fac(3,i)=safe_val else $ dt_fac(3,i)=total(lim4_dt(dp_idx(i,0):dp_idx(i,1)))/d4 d3=total(acc3(dp_idx(i,0):dp_idx(i,1))) if d3 eq 0. then dt_fac(2,i) = safe_val else $ dt_fac(2,i)=total(lim3_dt(dp_idx(i,0):dp_idx(i,1)))/d3 d2=total(acc2(dp_idx(i,0):dp_idx(i,1))) if d2 eq 0. then dt_fac(1,i) =safe_val else $ dt_fac(1,i)=total(lim2_dt(dp_idx(i,0):dp_idx(i,1)))/d2 d1=total(acc1(dp_idx(i,0):dp_idx(i,1))) if d1 eq 0. then dt_fac(0,i) =safe_val else $ dt_fac(0,i)=total(lim1_dt(dp_idx(i,0):dp_idx(i,1)))/d1 end 2: begin d3= (total(acc4(dp_idx(i,0):dp_idx(i,1)))+$ total(acc3(dp_idx(i,0):dp_idx(i,1)))) if d3 eq 0. then dt_fac(3,i) = safe_val else $ dt_fac(3,i)=(total(lim4_dt(dp_idx(i,0):dp_idx(i,1)))+$ total(lim3_dt(dp_idx(i,0):dp_idx(i,1))))/d3 dt_fac(2,i) = dt_fac(3,i) d1=(total(acc2(dp_idx(i,0):dp_idx(i,1)))+$ total(acc1(dp_idx(i,0):dp_idx(i,1)))) if d1 eq 0. then dt_fac(1,i) = safe_val else $ dt_fac(1,i)=(total(lim2_dt(dp_idx(i,0):dp_idx(i,1)))+$ total(lim1_dt(dp_idx(i,0):dp_idx(i,1))))/d1 dt_fac(0,i) = dt_fac(1,i) end endcase endif else begin dt_fac(*,i) = safe_val endelse endfor ;-- interpolate out zero factors if interp eq 3 then dt_fac=bcs_dt_interp(dt_fac,bda_index) return,dt_fac & end