org.placelab.core
Class GPSMeasurement

java.lang.Object
  org.placelab.core.Measurement
      org.placelab.core.GPSMeasurement

All Implemented Interfaces:

Observable, PositionMeasurement

public class GPSMeasurement

extends Measurement

implements PositionMeasurement

A Measurement based on a reading from a GPS unit. GPSMeasurements are different from most Measurements in that they have a Coordinate included with them that is read from the GPS.

Field Summary

static int	DONT_HAVE_A_LOCK
static java.lang.String[]	gpsTypes
static int	HAVE_A_LOCK
static int	NO_INFO_RE_A_LOCK

Constructor Summary

GPSMeasurement(long timestampInMillis, Coordinate loc)

GPSMeasurement(long timestampInMillis, Coordinate loc, java.util.Hashtable fields)

GPSMeasurement(long time, java.io.DataInputStream dis)

Method Summary

java.lang.String	getField(java.lang.String fieldName)
Coordinate	getPosition()
java.lang.String	getType()
int	haveALock() Roughly the same as isValid, but also returns whether there was no info about a lock (which can be assumed to be no lock)
boolean	isLikelyAccurate() Uses a heuristic based on number of satellites and satellite angles to predict if reading is likely to be accurate.
boolean	isValid() Gets whether or not the fix data is valid for this GPSMeasurement.
byte[]	toCompressedBytes() For storage on impoverished devices
java.lang.String	toLogString() Converts the Measurement to a form which is convenient for writing to a log file.
java.lang.String	toShortString() A short string based representation for debugging purposes

Methods inherited from class org.placelab.core.Measurement

fromCompressedBytes, getTimestamp, setTimestamp

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.placelab.core.PositionMeasurement

getTimestamp

Field Detail

gpsTypes

public static final java.lang.String[] gpsTypes

HAVE_A_LOCK

public static final int HAVE_A_LOCK

See Also:

Constant Field Values

DONT_HAVE_A_LOCK

public static final int DONT_HAVE_A_LOCK

See Also:

Constant Field Values

NO_INFO_RE_A_LOCK

public static final int NO_INFO_RE_A_LOCK

See Also:

Constant Field Values

Constructor Detail

GPSMeasurement

public GPSMeasurement(long timestampInMillis,
                      Coordinate loc,
                      java.util.Hashtable fields)

GPSMeasurement

public GPSMeasurement(long timestampInMillis,
                      Coordinate loc)

GPSMeasurement

public GPSMeasurement(long time,
                      java.io.DataInputStream dis)
               throws java.io.IOException

Method Detail

getPosition

public Coordinate getPosition()

Specified by:

getPosition in interface PositionMeasurement

isValid

public boolean isValid()

Gets whether or not the fix data is valid for this GPSMeasurement. GPSMeasurements without valid fix data should not be relied upon for positioning.

isLikelyAccurate

public boolean isLikelyAccurate()

Uses a heuristic based on number of satellites and satellite angles to predict if reading is likely to be accurate.

getField

public java.lang.String getField(java.lang.String fieldName)

Parameters:

fieldName - GPS field names from NMEASentence

Returns:

the field value

getType

public java.lang.String getType()

Specified by:

getType in interface PositionMeasurement

toLogString

public java.lang.String toLogString()

Description copied from class: Measurement

Converts the Measurement to a form which is convenient for writing to a log file. The convention is to have the following form:

 TYPE=type|TIME=timestamp|OTHERFIELD=value ...
 

All necessary fields should be stored in that pipe separated format, and all values should be percentEscaped with StringUtil.percentEscape(String)

Such a format is easily converted into a HashMap form, and a Measurement should (but is not required to) provide a constructor to build itself from a HashMap created from its log string form.

Overrides:

toLogString in class Measurement

toShortString

public java.lang.String toShortString()

Description copied from class: Measurement

A short string based representation for debugging purposes

Overrides:

toShortString in class Measurement

toCompressedBytes

public byte[] toCompressedBytes()

Description copied from class: Measurement

For storage on impoverished devices

Overrides:

toCompressedBytes in class Measurement

Returns:

a compressed form of the Measurement suitable for storing on small devices such as phones

haveALock

public int haveALock()

Roughly the same as isValid, but also returns whether there was no info about a lock (which can be assumed to be no lock)

See Also:

HAVE_A_LOCK, DONT_HAVE_A_LOCK, NO_INFO_RE_A_LOCK