dish.cal - Function

Apply calibration to a scan (GBT only currently).

Synopsis
cal(scan, baseline, range, order, units, flipsr, fold, flipfold, proc)

Description
This function applies a calibration to the data based on information in the STATE table of the MS, in particular, it utilizes the OBSMODE column to determine a procedure type, switching signal, and switching state. In addition, information on the procedure size and procedure sequence number are used. This function is called by calib (with proc=T or proc=F).

The function applies a number of corrections:

1.

determine elevation, frequency; solve for opacity,gain correction.

2.

determine units used, solve for appropriate efficiency factor from table.

factor = $\displaystyle {\frac{e^{\tau (1/sin(elev))}}{\eta_x}}$

where $\eta_{x}^{}$ is the efficiency factor determined by the user selected units.

3.

based on procedure, calibrate data. Typically, this entails calibrating "cal on" and "cal off" phases of signal (on source) and reference (off source) observations, where the "cal" is a known noise diode. e.g.,

V_sig( $\displaystyle \nu$ ) = $\displaystyle {\frac{(V_{sig,on}(\nu) w_{sig,on} + V_{sig,off}(\nu) w_{sig,off})}{w_{sig,on} + w_{sig,off}}}$

Similarly for the reference observation, leading the difference spectrum:

T_diff( $\displaystyle \nu$ ) = < T_{sys, ref} > $\displaystyle {\frac{V_{sig}(\nu) - V_{ref}(\nu)}{V_{ref}(\nu)}}$

where, < T_{sys, ref} > is:

< T_{sys, ref}( $\displaystyle \nu$ ) > = < $\displaystyle {\frac{T_{cal}(\nu) V_{ref}(\nu)}{V_{ref,on}(\nu) - V_{ref,off}(\nu)}}$ >

Arguments

scan	scan number
	Allowed:	integer
	Default:	no default
baseline	toggle baseline subtraction on or off
	Allowed:	boolean
	Default:	F (off)
range	range for baseline
	Allowed:	channel range vector
	Default:	F (full range)
order	order of baseline fit
	Allowed:	integer
	Default:	1
units	units for calibrated result; 1=TA*, 2=TMB, 3=S
	Allowed:	integer
	Default:	1
flipsr	flip sense of signal and reference
	Allowed:	boolean
	Default:	F
fold	fold data - FSWITCH data only
	Allowed:	boolean
	Default:	F
flipfold	flip sense of fold - FSWITCH data only
	Allowed:	boolean
	Default:	F
proc	calibrate full procedure or single scan
	Allowed:	boolean
	Default:	T

Returns
T (if successful)

Example

- d.cal(9,proc=F); #calibrate only scan 9 regardless of whether it is part
                   #of a larger multi-scan procedure.

Next: dish.calib - Function Up: dish - Tool Previous: dish.bshape - Function Contents Index

	Package	dish
	Module	dish
	Tool	dish