SPECTRAL_WINDOW Spectral window description.

Name

Format

Units

Measure

Comments

Columns

Data description

NUM_CHAN

Int Number of spectral channels Nf

Data

NAME

String Spectral window name

REF_FREQ

Double Hz FREQUENCY The reference frequency

CHAN_FREQ

Double( Nf) Hz FREQUENCY Center frequencies for each channel in the data matrix

CHAN_WIDTH

Double( Nf) Hz Channel width for each channel in the data matrix

MEAS_FREQ_REF

Int FREQUENCY Measure ref.

EFFECTIVE_BW

Double( Nf) Hz The effective noise bandwidth for each channel in the data matrix

RESOLUTION

Double( Nf) Hz The effective spectral resolution for each channel in the data matrix

TOT_BANDWIDTH

Double Hz Total bandwidth for this window

NET_SIDEBAND

Int Net sideband

(BBC_NO)

Int Baseband converter no

(BBC_SIDEBAND)

Int BBC sideband

IF_CONV_CHAIN

Int IF conversion chain

FREQ_GROUP

Int Frequency group

FREQ_GROUP_NAME

String Frequency group name

( DOPPLER_ID)

Int Doppler identifier

( ASSOC_SPW_ID)

Int(*) Associate spectral-window identifier

(ASSOC_NATURE)

String(*) Nature of association

Flags

FLAG_ROW

Bool The row flag

Notes: This table describes properties for each defined spectral window. A spectral window is both a frequency label for the associated data in MAIN, but also represents a generic frequency conversion chain that shares joint physical properties and makes sense to calibrate in a single entity.

NUM_CHAN
Number of spectral channels    
NAME
Spectral window name; user specified.
REF_FREQ
Reference frequency. A frequency representative of the spectral window, usually the sky frequency corresponding to the DC edge of the baseband. Used by the calibration system if a fixed scaling frequency is required or in algorithms to identify the observing band.  
CHAN_FREQ
Center frequencies for each channel in the data matrix. These can be frequency-dependent, to accommodate instruments such as the WVM radiometers. Note that the channel frequencies may be inascending or descending frequency order.      
CHAN_WIDTH
Nominal channel width of each spectral channel. Although these can be derived from CHAN_FREQ  by differencing, it is more efficient to keep a separate reference to this information.    
MEAS_FREQ_REF
Frequency Measure reference for CHAN_FREQ . This allow a row-based reference for this column in order to optimize the Choice of the Measure reference when Doppler tracking is used. Modified only by the MS access code.    
EFFECTIVE_BW
Effective noise bandwidth of each spectral channel  
RESOLUTION
Effective spectral resolution of each channel  
NET_SIDEBAND
Net sideband for this spectral window.
The reserved value are: -1 NoSB, 0 DSB, 1 LSB, 2 USB, 3 2SB LSB, 4 2SB USB, 5 2SB LSB SBsep, 6 2SB USB SBsep.
BBC_NO
Baseband converter number, if applicable.  
BBC_SIDEBAND
Baseband converter sideband, if applicable
IF_CONV_CHAIN
Identificaion of the electronic signal path for the case of multiple (simultaneous) IFs.
FREQ_GROUP
The frequency group to which the spectral window belongs. This is use to associate spectral windows from joint calibration purposes.
FREQ_GROUP_NAME
The frequency group name; user specified
DOPPLER_ID
Doppler identifier defining frame information for this spectral window.
ASSOC_SPW_ID
Associated spectral windows, which are related in some fashion (e.g. “channel-zero”).
ASSOC_NATURE
Nature of the association for ASSOC_SPW_ID; reserved keywords are CHANNEL-ZERO1 , EQUAL-FREQUENCY2 , SUBSET3 .
FLAG_ROW
True if the row does not contain valid data.