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Top Forums UNIX for Dummies Questions & Answers Timekeeping in Linux question ... Post 302517284 by newlinuxuser1 on Tuesday 26th of April 2011 10:40:22 AM
Old 04-26-2011
wow, 30 nanoseconds is pretty impressive! Thank for the input, I could never imagine that GPS could be used for precise timekeeping, it is an amazing technology, isn't it? WOW! It practically means, that all Internet timekeeping is done through the space! I could imagine to myself something like an atomic clock, but going with GPS is a wonderful idea!
 

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GPS::Point(3pm) 					User Contributed Perl Documentation					   GPS::Point(3pm)

NAME
GPS::Point - Provides an object interface for a GPS point. SYNOPSIS
use GPS::Point; my $obj=GPS::Point->newGPSD($GPSD_O_line);#e.g. GPSD,O=.... my $obj=GPS::Point->new( time => $time, #float seconds from the unix epoch lat => $lat, #signed degrees lon => $lon, #signed degrees alt => $hae, #meters above the WGS-84 ellipsoid speed => $speed, #meters/second (over ground) heading => $heading, #degrees clockwise from North climb => $climb, #meters/second etime => $etime, #float seconds ehorizontal => $ehz, #float meters evertical => $evert, #float meters espeed => $espeed, #meters/second eheading => $ehead, #degrees eclimb => $eclimb, #meters/second mode => $mode, #GPS mode [?=>undef,None=>1,2D=>2,3D=>3] tag => $tag, #Name of the GPS message for data ); DESCRIPTION
This is a re-write of Net::GPSD::Point with a goal of being more re-usable. GPS::Point - Provides an object interface for a GPS fix (e.g. Position, Velocity and Time). Note: Please use Geo::Point, if you want 2D or projection support. USAGE
print scalar($point->latlon), " "; #latlon in scalar context my ($x,$y,$z)=$point->ecef; #if Geo::ECEF is available my $GeoPointObject=$point->GeoPoint; #if Geo::Point is available my @distance=$point->distance($point2); #if Geo::Inverse is available my $distance=$point->distance($point2); #if Geo::Inverse->VERSION >=0.05 USAGE TODO
my $obj=GPS::Point->newNMEA($NMEA_lines); #e.g. GGA+GSA+RMC CONSTRUCTOR
new my $obj = GPS::Point->new(); newGPSD my $obj=GPS::Point->newGPSD($GPSD_O_line);#e.g. GPSD,O=.... newMulti Constructs a GPS::Point from a Multitude of arguments. Arguments can be a GPS::Point, Geo::Point, {lat=>$lat,lon=>$lon} (can be blessed), [$lat, $lon] (can be blessed) or a ($lat, $lon) pair. my $point=GPS::Point->newMulti( $lat, $lon, $alt ); #supports lat, lon and alt my $point=GPS::Point->newMulti([$lat, $lon, $alt]); #supports lat, lon and alt my $point=GPS::Point->newMulti({lat=>$lat, lon=>$lon, ...}); my $point=GPS::Point->newMulti(GPS::Point->new(lat=>$lat, lon=>$lon)); my $point=GPS::Point->newMulti(Geo::Point->new(lat=>$lat, long=>$lon, proj=>'wgs84')); my $point=GPS::Point->newMulti({latitude=>$lat, longtude=>$lon}); Note: Hash reference context supports the following keys lat, lon, alt, latitude, longitude, long, altitude, elevation, hae, elev. Note: Units are always decimal degrees for latitude and longitude and meters above the WGS-84 ellipsoid for altitude. initialize, initializeGPSD, initializeMulti METHODS (Base) time Sets or returns seconds since the Unix epoch, UTC (float, seconds) print $obj->time, " "; lat, latitude Sets or returns Latitude (float, degrees) print $obj->lat, " "; lon, long or longitude Sets or returns Longitude (float, degrees) print $obj->lon, " "; alt, altitude, hae, elevation Sets or returns Altitude (float, meters) print $obj->alt, " "; speed Sets or returns speed (float, meters/sec) print $obj->speed, " "; heading, bearing Sets or returns heading (float, degrees) print $obj->heading, " "; climb Sets or returns vertical velocity (float, meters/sec) print $obj->climb, " "; etime Sets or returns estimated timestamp error (float, seconds, 95% confidence) print $obj->etime, " "; ehorizontal Sets or returns horizontal error estimate (float, meters) print $obj->ehorizontal, " "; evertical Sets or returns vertical error estimate (float, meters) print $obj->evertical, " "; espeed Sets or returns error estimate for speed (float, meters/sec, 95% confidence) print $obj->espeed, " "; eheading Sets or returns error estimate for course (float, degrees, 95% confidence) print $obj->eheading, " "; eclimb Sets or returns Estimated error for climb/sink (float, meters/sec, 95% confidence) print $obj->eclimb, " "; mode Sets or returns the NMEA mode (integer; undef=>no mode value yet seen, 1=>no fix, 2=>2D, 3=>3D) print $obj->mode, " "; tag Sets or returns a tag identifying the last sentence received. For NMEA devices this is just the NMEA sentence name; the talker-ID portion may be useful for distinguishing among results produced by different NMEA talkers in the same wire. (string) print $obj->tag, " "; METHODS (Value Added) fix Returns either 1 or 0 based upon if the GPS point is from a valid fix or not. print $obj->fix, " "; At a minimum this method requires mode to be set. datetime Returns a DateTime object from time my $dt=$point->datetime; At a minimum this method requires time to be set. latlon, latlong Returns Latitude, Longitude as an array in array context and as a space joined string in scalar context my @latlon=$point->latlon; my $latlon=$point->latlon; At a minimum this method requires lat and lon to be set. setAltitude Sets altitude from USGS web service and then returns the GPS::Point object. This method is a wrapper around Geo::WebService::Elevation::USGS. my $point=GPS::Point->new(lat=>$lat, lon=>$lon)->setAltitude; $point->setAltitude; my $alt=$point->alt; At a minimum this method requires lat and lon to be set and alt to be undef. ecef Returns ECEF coordinates. This method is a warpper around Geo::ECEF. my ($x,$y,$z) = $point->ecef; my @xyz = $point->ecef; my $xyz_aref = $point->ecef; #if Geo::ECEF->VERSION >= 0.08 At a minimum this method requires lat and lon to be set. (alt of 0 is assumed by Geo::ECEF->ecef). GeoPoint Returns a Geo::Point Object in the WGS-84 projection. my $GeoPointObject = $point->GeoPoint; At a minimum this method requires lat and lon to be set. distance Returns distance in meters between the object point and the argument point. The argument can be any valid argument of newMulti constructor. This method is a wrapper around Geo::Inverse. my ($faz, $baz, $dist) = $point->distance($pt2); #Array context my $dist = $point->distance($lat, $lon); #if Geo::Inverse->VERSION >=0.05 At a minimum this method requires lat and lon to be set. track Returns a point object at the predicted location in time seconds assuming constant velocity. Using Geo::Forward calculation. my $new_point=$point->track($seconds); #default $point->heading my $new_point=$point->track($seconds => $heading); At a minimum this method requires lat and lon to be set. It might be very useful to have speed, heading and time set although they all default to zero. forward Returns a point object at the distance and heading using Geo::Forward calculations. my $point=$point->forward($dist); #default $point->heading my $point=$point->forward($dist => $heading); #meters => degrees At a minimum this method requires lat and lon to be set. It might be useful to have heading set although the default is zero. BUGS
Send to GPSD-DEV or GEO-PERL email lists SUPPORT
Try GPSD-DEV or GEO-PERL email lists AUTHOR
Michael R. Davis CPAN ID: MRDVT DavisNetworks.com account=>perl,tld=>com,domain=>michaelrdavis http://www.davisnetworks.com/ COPYRIGHT
This program is free software licensed under the... The BSD License The full text of the license can be found in the LICENSE file included with this module. SEE ALSO
Geo::Point, Net::GPSD, Net::GPSD::Point, Geo::ECEF, Geo::Functions, Geo::Forward, Geo::Inverse, Geo::Distance, Geo::Ellipsoids, Geo::WebService::Elevation::USGS, DateTime perl v5.10.1 2010-01-30 GPS::Point(3pm)
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