SimField.h

Classes

SimField -- a container for data destined for an MS FIELD table (full description)

SimFieldList -- a container for data destined for an MS FIELD table (full description)

class SimField

Interface

Public Members

SimField(uInt srcId, const MDirection& dir, Double longOffset=0.0, Double latOffset=0.0, const longOffset& name="", const longOffset& code="") : row_p(-1), src_p(srcId), rep_p(0), off_p(2,0.0), name_p(name), code_p(code), dir_p(dir)

SimField(const SimField& s)

SimField& operator=(const SimField& s)

~SimField()

Int getRow() const

void setRow(Int id)

uInt sourceId() const

const String& name() const

const String& code() const

const Vector<Double>& offset() const

const MDirection& direction() const

static Vector<Double> offset(const MDirection srcdir, const MDirection flddir)

uInt repetition() const

void setRepetition(uInt n)

Description

Prerequisite

Etymology

This is a container for describing fields to be observed in simulated observations.

Synopsis

This container describes a field to be observed in a set of simulated observations. It provides a simplified data model for a field that assumes that the field position is not moving in time and that its delay, phase, and reference directions are all the same. Furthermore, it provides an observer-oriented interface that allows one to specify the field direction in terms of offsets from a source or reference direction. This container is used to define simulated observations. Simulators would not normally create these objects directly but rather implicitly via the SimObservations class.

The field direction and the associated source ID are set at construction time and cannot be changed. No check is done to ensure that the source ID exists or is otherwise valid; this must be done at a higher level. The only writable data in this class are a row marker (via setRow(), used by SimFieldList) and an optional repetition factor. The repetition factor (set with setRepetition()) indicates how many times this field should be observed consecutively before observing slews to the next field. This value is not recorded in an MS FIELD table. (The SimpleSimulator uses this as a default repetition value if one is not set at a higher level.)

Motivation

This container provides an simplified in-memory representation of feeds that will ultimately be written to a FIELD table. The interface is oriented toward what is typical with current instruments and thus is simpler than the interface provided by the MS FIELD table.

To Do

It would probably be helpful to have a common base classes for all Sim* and Sim*List classes that are managed by SimTelescope and SimObservations

Member Description

SimField(uInt srcId, const MDirection& dir, Double longOffset=0.0, Double latOffset=0.0, const longOffset& name="", const longOffset& code="") : row_p(-1), src_p(srcId), rep_p(0), off_p(2,0.0), name_p(name), code_p(code), dir_p(dir)

Create a record. srcId is the source ID that this field is associated with. dir is normally the position of the source referenced by srcId so that longOffset and latOffset gives the relative position of the field center; however, dir will be the absolute position of the field when longOffset=latOffset=0. longOffset is the true angular offset in radians in the direction perpendicular to the celestial pole (i.e. along a great circle) of the field center from the source position given by dir. latOffset is the angular offset in radians in the direction of the celestial (north) pole of the field center from the source position.

SimField(const SimField& s)
SimField& operator=(const SimField& s)

create a copy

~SimField()

Int getRow() const
void setRow(Int id)

get and set the row ID, the row in the FIELD table containing this record. An ID less than zero means that this record has not yet been recorded.

uInt sourceId() const

return the ID of the source observed in this field

const String& name() const

return the name of the field

const String& code() const

return the code of the field

const Vector<Double>& offset() const

return the offset from the source position for this field. The first element is the longitude offset and the second is the latitude offset. Both are in radians.

const MDirection& direction() const

return the direction of the field center. (This will recorded simulataneously as DELAY_DIR, PHASE_DIR, and REFERENCE_DIR.)

static Vector<Double> offset(const MDirection srcdir, const MDirection flddir)

compute the shift between to positions. The returned vector is the same as returned from offset(). The values are only approximate.

uInt repetition() const
void setRepetition(uInt n)

get and set the number of consecutive integrations to perform on this field. A value of zero means a suitable default value should be used.

class SimFieldList

Interface

SimFieldList(uInt initsz=2, uInt stepsz=4) : n_p(0), chnk_p(stepsz), rec_p(initsz, 0)

SimFieldList(const MSField& fldt, uInt stepz=4)

SimFieldList(const SimFieldList& t)

SimFieldList& operator=(const SimFieldList& t)

~SimFieldList()

void clearIds()

SimField& operator[](Int i)

const SimField& operator[](Int i) const

uInt numFields() const

SimField& addField(uInt srcId, const MDirection& dir, Double longOffset=0.0, Double latOffset=0.0, const String& name="", const String& code="")

void initFrom(const MSField& fldt)

void flush(MSField& fldt, MSSource& srct)

Private Members

void deleteRecs()

SimField& get(Int i) const

void throwOutOfRange(uInt legallength, Int index) const

void add(SimField *fld)

uInt loadSourceInfo(MSSource& srct, SimpleOrderedMap<Int, String> &snames, SimpleOrderedMap<Int, Double> &times)

Description

Prerequisite

Etymology

This class holds a list of SimField objects.

Synopsis

This class holds a list of SimField instances which, as a group, describes a list of sources to observe. When using this class, one does not create SimField objects directly, but rather implicitly via the addSource() function. The ultimate purpose of this container is to support simulated observations. Simulators would not normally create these objects directly but rather implicitly via the SimObservations class.

An important function handled by this class is the recording of the fields to a Measurement Set. This is done with the flush() function. When it writes the data from a SimField in its list to the MS, it sets the row number of the source record via setRow(); this is used as a flag indicating that the SimField has been flushed. This allows one to later add additional setups to the list; when flush() is called again, only the new SimField data are written out. This, of course, assumes that the same output MSDataDescription is passed to the flush() function each time. If you want to write all the data to a new FIELD table, you can call clearIds() to clear all the row markers.

A list of fields can be read in from a FIELD table as well using the initFrom() method or the SimFieldList(const MSField&, ...) constructor. These will implicitly set the row markers from the input table. This allows one to add new setups to the already recorded set.

Motivation

This container provides an simplified in-memory representation of sources that will ultimately be written to a FIELD table. The interface is oriented toward what is typical with current instruments and thus is simpler than the interface provided by the MS FIELD table.

To Do

loading from an existing MS needs more testing.
It would probably be helpful to have a common base classes for all Sim* and Sim*List classes that are managed by SimTelescope and SimObservations

Member Description

SimFieldList(uInt initsz=2, uInt stepsz=4) : n_p(0), chnk_p(stepsz), rec_p(initsz, 0)

create an empty list

SimFieldList(const MSField& fldt, uInt stepz=4)

create a list and fill it with the contents of a FIELD table

SimFieldList(const SimFieldList& t)
SimFieldList& operator=(const SimFieldList& t)

create a copy

~SimFieldList()

void clearIds()

reset all the row markers used to flag the SimField members that have been recorded to a Measurement Set already. Thus, the next call to flush() will record all SimFields to the FIELD table. This should be used when writing to a new FIELD table, different from one previously read from or written to.

SimField& operator[](Int i)
const SimField& operator[](Int i) const

access the i-th field in this list.

uInt numFields() const

return the number of fields in this list

SimField& addField(uInt srcId, const MDirection& dir, Double longOffset=0.0, Double latOffset=0.0, const String& name="", const String& code="")

Add a field. srcId is the source ID that this field is associated with. dir is normally the position of the source referenced by srcId so that longOffset and latOffset gives the relative position of the field center; however, dir will be the absolute position of the field when longOffset=latOffset=0. longOffset is the true angular offset in radians in the direction perpendicular to the celestial pole (i.e. along a great circle) of the field center from the source position given by dir. latOffset is the angular offset in radians in the direction of the celestial (north) pole of the field center from the source position.

void initFrom(const MSField& fldt)

add field descriptions from an MS FIELD table

void flush(MSField& fldt, MSSource& srct)

write out all fields that have yet to be written