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java.lang.Objectuk.ac.starlink.ast.AstObject
uk.ac.starlink.ast.Mapping
uk.ac.starlink.ast.Frame
uk.ac.starlink.ast.SpecFrame
uk.ac.starlink.ast.DSBSpecFrame
public class DSBSpecFrame
Java interface to the AST DSBSpecFrame class - dual sideband spectral coordinate system description. A DSBSpecFrame is a specialised form of SpecFrame which represents positions in a spectrum obtained using a dual sideband instrument. Such an instrument produces a spectrum in which each point contains contributions from two distinctly different frequencies, one from the "lower side band" (LSB) and one from the "upper side band" (USB). Corresponding LSB and USB frequencies are connected by the fact that they are an equal distance on either side of a fixed central frequency known as the "Local Oscillator" (LO) frequency.
When quoting a position within such a spectrum, it is necessary to indicate whether the quoted position is the USB position or the corresponding LSB position. The SideBand attribute provides this indication. Another option that the SideBand attribute provides is to represent a spectral position by its topocentric offset from the LO frequency.
In practice, the LO frequency is specified by giving the distance from the LO frequency to some "central" spectral position. Typically this central position is that of some interesting spectral feature. The distance from this central position to the LO frequency is known as the "intermediate frequency" (IF). The value supplied for IF can be a signed value in order to indicate whether the LO frequency is above or below the central position.
This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public Licence for more details.
You should have received a copy of the GNU General Public Licence along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street,Fifth Floor, Boston, MA 02110-1301, USA
Nested Class Summary |
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Nested classes/interfaces inherited from class uk.ac.starlink.ast.Mapping |
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Mapping.Interpolator, Mapping.Spreader |
Field Summary |
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Fields inherited from class uk.ac.starlink.ast.Mapping |
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LINEAR_INTERPOLATOR, LINEAR_SPREADER, NEAREST_INTERPOLATOR, NEAREST_SPREADER |
Fields inherited from class uk.ac.starlink.ast.AstObject |
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AST__BAD, AST__TUNULL, pointer |
Constructor Summary | |
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DSBSpecFrame()
Creates a DSBSpecFrame. |
Method Summary | |
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boolean |
getAlignSideBand()
Get should the SideBand attribute be taken into account when aligning this DSBSpecFrame with another DSBSpecFrame. |
double |
getDsbCentre()
Get the central position of interest in a dual sideband spectrum. |
double |
getIf()
Get the intermediate frequency in a dual sideband spectrum. |
String |
getSideBand()
Get indicates which sideband a dual sideband spectrum represents. |
void |
setAlignSideBand(boolean alignSideBand)
Set should the SideBand attribute be taken into account when aligning this DSBSpecFrame with another DSBSpecFrame. |
void |
setDsbCentre(double dsbCentre)
Set the central position of interest in a dual sideband spectrum. |
void |
setIf(double ifreq)
Set the intermediate frequency in a dual sideband spectrum. |
void |
setSideBand(String sideBand)
Set indicates which sideband a dual sideband spectrum represents. |
Methods inherited from class uk.ac.starlink.ast.SpecFrame |
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getAlignStdOfRest, getGeoLat, getGeoLon, getRefDec, getRefPos, getRefRA, getRestFreq, getSourceSys, getSourceVel, getSourceVRF, getStdOfRest, setAlignStdOfRest, setGeoLat, setGeoLon, setRefDec, setRefPos, setRefRA, setRestFreq, setRestFreq, setSourceSys, setSourceVel, setSourceVRF, setStdOfRest |
Methods inherited from class uk.ac.starlink.ast.Frame |
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angle, axAngle, axDistance, axOffset, convert, distance, findFrame, format, getActiveUnit, getAlignSystem, getBottom, getDigits, getDigits, getDirection, getDomain, getDut1, getEpoch, getFormat, getLabel, getMatchEnd, getMaxAxes, getMinAxes, getNaxes, getNormUnit, getObsLat, getObsLon, getPermute, getPreserveAxes, getSymbol, getSystem, getTitle, getTop, getUnit, intersect, norm, offset, offset2, permAxes, pickAxes, resolve, setActiveUnit, setAlignSystem, setBottom, setDigits, setDigits, setDirection, setDomain, setDut1, setEpoch, setEpoch, setFormat, setLabel, setMatchEnd, setMaxAxes, setMinAxes, setObsLat, setObsLon, setPermute, setPreserveAxes, setSymbol, setSystem, setTitle, setTop, setUnit, unformat |
Methods inherited from class uk.ac.starlink.ast.Mapping |
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decompose, getInvert, getNin, getNout, getReport, getTranForward, getTranInverse, invert, linearApprox, mapBox, mapSplit, rate, rebin, rebinD, rebinF, rebinI, resample, resampleB, resampleD, resampleF, resampleI, resampleL, resampleS, setInvert, setReport, simplify, tran1, tran2, tranGrid, tranN, tranP |
Methods inherited from class uk.ac.starlink.ast.AstObject |
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annul, clear, copy, delete, equals, finalize, getAstConstantI, getB, getC, getD, getF, getI, getID, getIdent, getL, getNobject, getObjSize, getRefCount, hashCode, isThreaded, reportVersions, sameObject, set, setB, setC, setD, setF, setI, setID, setIdent, setL, show, test, tune |
Methods inherited from class java.lang.Object |
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clone, getClass, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public DSBSpecFrame()
AstException
- if an error occurred in the AST libraryMethod Detail |
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public boolean getAlignSideBand()
When astFindFrame or astConvert is used on two DSBSpecFrames (potentially describing different spectral coordinate systems and/or sidebands), it returns a Mapping which can be used to transform a position in one DSBSpecFrame into the corresponding position in the other. The Mapping is made up of the following steps in the indicated order:
- If both DSBSpecFrames have a value of 1 for the AlignSideBand
attribute, map values from the target's current sideband (given by its
SideBand attribute) to the observed sideband (whether USB or LSB). If
the target already represents the observed sideband, this step will
leave the values unchanged. If either of the two DSBSpecFrames have a
value of zero for its AlignSideBand attribute, then this step is omitted.
- Map the values from the spectral system of the target to the spectral
system of the template. This Mapping takes into account all the
inherited SpecFrame attributes such as System, StdOfRest, Unit, etc.
- If both DSBSpecFrames have a value of 1 for the AlignSideBand
attribute, map values from the result's observed sideband to the
result's current sideband (given by its SideBand attribute). If the
result already represents the observed sideband, this step will leave
the values unchanged. If either of the two DSBSpecFrames have a value
of zero for its AlignSideBand attribute, then this step is omitted.
public void setAlignSideBand(boolean alignSideBand)
When astFindFrame or astConvert is used on two DSBSpecFrames (potentially describing different spectral coordinate systems and/or sidebands), it returns a Mapping which can be used to transform a position in one DSBSpecFrame into the corresponding position in the other. The Mapping is made up of the following steps in the indicated order:
- If both DSBSpecFrames have a value of 1 for the AlignSideBand
attribute, map values from the target's current sideband (given by its
SideBand attribute) to the observed sideband (whether USB or LSB). If
the target already represents the observed sideband, this step will
leave the values unchanged. If either of the two DSBSpecFrames have a
value of zero for its AlignSideBand attribute, then this step is omitted.
- Map the values from the spectral system of the target to the spectral
system of the template. This Mapping takes into account all the
inherited SpecFrame attributes such as System, StdOfRest, Unit, etc.
- If both DSBSpecFrames have a value of 1 for the AlignSideBand
attribute, map values from the result's observed sideband to the
result's current sideband (given by its SideBand attribute). If the
result already represents the observed sideband, this step will leave
the values unchanged. If either of the two DSBSpecFrames have a value
of zero for its AlignSideBand attribute, then this step is omitted.
alignSideBand
- the AlignSideBand attribute of this objectpublic double getDsbCentre()
The value is accessed as a position in the spectral system represented by the SpecFrame attributes inherited by this class, but is stored internally as topocentric frequency. Thus, if the System attribute of the DSBSpecFrame is set to "VRAD", the Unit attribute set to "m/s" and the StdOfRest attribute set to "LSRK", then values for the DSBCentre attribute should be supplied as radio velocity in units of "m/s" relative to the kinematic LSR (alternative units may be used by appending a suitable units string to the end of the value). This value is then converted to topocentric frequency and stored. If (say) the Unit attribute is subsequently changed to "km/s" before retrieving the current value of the DSBCentre attribute, the stored topocentric frequency will be converted back to LSRK radio velocity, this time in units of "km/s", before being returned.
The default value for this attribute is 30 GHz.
public void setDsbCentre(double dsbCentre)
The value is accessed as a position in the spectral system represented by the SpecFrame attributes inherited by this class, but is stored internally as topocentric frequency. Thus, if the System attribute of the DSBSpecFrame is set to "VRAD", the Unit attribute set to "m/s" and the StdOfRest attribute set to "LSRK", then values for the DSBCentre attribute should be supplied as radio velocity in units of "m/s" relative to the kinematic LSR (alternative units may be used by appending a suitable units string to the end of the value). This value is then converted to topocentric frequency and stored. If (say) the Unit attribute is subsequently changed to "km/s" before retrieving the current value of the DSBCentre attribute, the stored topocentric frequency will be converted back to LSRK radio velocity, this time in units of "km/s", before being returned.
The default value for this attribute is 30 GHz.
dsbCentre
- the DsbCentre attribute of this objectpublic double getIf()
When setting a new value for this attribute, the units in which the frequency value is supplied may be indicated by appending a suitable string to the end of the formatted value. If the units are not specified, then the supplied value is assumed to be in units of GHz. For instance, the following strings all result in an IF of 4 GHz being used: "4.0", "4.0 GHz", "4.0E9 Hz", etc.
When getting the value of this attribute, the returned value is always in units of GHz. The default value for this attribute is 4 GHz.
public void setIf(double ifreq)
When setting a new value for this attribute, the units in which the frequency value is supplied may be indicated by appending a suitable string to the end of the formatted value. If the units are not specified, then the supplied value is assumed to be in units of GHz. For instance, the following strings all result in an IF of 4 GHz being used: "4.0", "4.0 GHz", "4.0E9 Hz", etc.
When getting the value of this attribute, the returned value is always in units of GHz. The default value for this attribute is 4 GHz.
ifreq
- the If attribute of this objectpublic String getSideBand()
public void setSideBand(String sideBand)
sideBand
- the SideBand attribute of this object
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