smooth, virspec

NAME

smooth - convert backend dispersion and resampling with smoothing
virspec - convert backend dispersion and resampling

SYNOPSIS

DESCRIPTION

The command "smoonth" converts backend dispersion. The original .scn file keeps a less than 5th order polynomical for the relation between the backend channel and frequency. The command converts it to be a linear function asigned by velocity span and velcity step. This conversion is required if you want to integ several profiles with different backend dispersion functions. For this perpuse "-v_step" should be smaller than the original sampling and choose "pin" as "-v_smooth_kernel", because this combination keeps original profile as well as possible. You should not use default "-v_range" and "-v_step" for the resampling purpose. The default option does not give the same dispersion functions.
The command also changes an actual velocity resolution for the spectrum.

The data with the spurious flag are neglect for smoothing process.

The command "virspec" is the same as "smooth" but with "-v_start_type center" and "-v_smooth_kernel pin". The name comes from spectrum observed with a virtual spectrometer.

FILTER TYPE

.scn | smooth | .scn
.scn | virspec | .scn

OPTIONS

-v velocity_range | -v_range velocity_range

The range is composed of two values devided by the character ",". The unit is km/s in LSR. For example

-v_range -20,60

means velocity ranges from -20 km/s to 60 km/s.

-v_step v_for_resampling | -v_sample v_for_resampling

Resampling interval. The unit is in km/s. If you give non-positive value, the command adjust the value using "-v_width" value depending on "-v_smooth_kernel". The same value for "-v_width" value is given for bin and pin kernels. And the half value for other kernels.

-v_width velecity_width

Smoothing width in velocity. The unit is in km/s. The actual width is FWHM for the smoothing kernel function. For the pin kernel this value is meaningless. If you give non-positive value, the command adjust the value using "-v_step" value depending on "-v_smooth_kernel". The same value for "-v_step" value is given for bin and pin kernels. And the double value for other kernels.

-v_smooth_kernel hunning | gauss | box | bin | pin

Choose kernel function for smoothing.

hunning - hunning smoothing, or 1-2-1 weighting
gauss - gaussian
box - boxcar, or running mean with equal weight
bin - binning, or avaraging over the width
pin - pin-point, or delta function, or only resampling

-v_start_type center | edge | outer_edge | inner_edge

Choose the final velocity range of the resultant profile corresponding "-v_range".

center - The centers of the first and last channels of the resultant profile correspond to the velocity range.
edge - The outer edges of the first and last channels of the resultant profile correspond to the velocity range.
outer_edge - The same as "edge".
inner_edge - The inner edges of the first and last channels of the resultant profile correspond to the velocity range.

-template_scn scn_name

The scn_name paramter is the scn filename which is used as the template of setup for receiver and backend. The scn_name can be abbribiated like load command. If scn_name is "no", the command does not use any template profile.

DEFAULTS

-prm smooth.prm
-v_range 0,0: Whole range for the first profile. NEVER recomend to use the default if you use smooth to adjust the backend dispersion funcitions!
If all option values corresponding velocity, the command choose the maximum channel span with 1 km/s sampling from 0 km/s.
-v_step 0: The value is reset depending on "-v_width" and "-v_smooth_kernel". But NEVER recommend!
-v_width 0: The value is reset depending on "-v_step" and "-v_smooth_kernel".
-v_smooth_kernel bin
-v_start_type center
-template_scn no

ENVIRONMENT

BUGS

The default values should be given more properly but it is too difficult.

HISTORY

ver.3.00: 1998/4/1 T.Handa
ver.3.20: 1998/5/1 T.Handa
ver.3.30: 2000/2/10 T.Handa

MANUAL VERSION

2000/2/10 T.Handa