Oregon Real-time GPS Network (ORGN) partners and subscribers with valid ORGN Rover Accounts have access to Real Time Kinematic (RTK) correctors computed by Leica Spider software. These correctors are served over the internet and accessed by the user via a cell modem connected to a GPS rover in the field.

ORGN Spider provides both Network and Single Reference Station survey accuracy (dual-frequency) correctors. In addition, single frequency Differential GPS correctors are provided to users of resource/mapping accuracy GPS receivers
 

Network RTK Corrections:

A network-based RTK corrector is based on using several reference stations at once.  A network-based corrector resolves distance dependent errors including ionospheric, tropospheric, and emphemeris errors better than a corrector based upon a single reference station, thereby allowing the rover user to travel farther from the reference stations than would be possible when using a single reference station. 

A user must be within the confines of the network for a network-based corrector to be effective.

ORGN provides a network corrector called MAX, in RTCM version 3.0 format, to rovers that are RTCM 3.0-capable.  The MAX network correctors take full advantage of the additional network messages available in RTCM 3.0.

For older rovers that are not version RTCM 3.0-capable, a network corrector called i-MAX is provided using RTCM 2.3 format.

For a rover to use either the MAX or i-MAX network corrector, it must be configured by the user to send the rover position back to the ORGN processing center using the NMEA GGA format.  In other words, the rover must be set to "send GGA".

 Single Reference Station RTK Corrections:

If the user is working outside the confines of the RTK network, they will not be able to use a network-based correction effectively; however, rover users will still be able to receive a corrector based upon a single reference station (same distance dependent errors apply as when using a single base RTK from a temporary base station).  The user of a single base station solution will not be able to work as far from the reference station as when using a network-based MAX or i-MAX solution; however, the user will still realize considerable cost savings by not having to buy a base station receiver and set it up and monitor it everyday of a project.  In addition, common error sources associated with the use of a portable base station, including incorrect input of base coordinates, base antenna not plumbed correctly over station mark, and incorrect height of base antenna, are avoided by the use of a permanent ORGN reference station.

ORGN provides "nearest site" RTK correctors in RTCM 2.3 format.

For a rover to use the "nearest site" RTK correctors, it must be configured by the user to send the rover position back to the ORGN processing center using the NMEA GGA format.  In other words, the rover must be set to "send GGA".

DGPS:

Resource-grade mapping GPS users can access RTCM correctors from the network via cell phone modem.

ORGN provides single frequency "nearest site" RTCM correctors for mapping resource GPS receivers in the RTCM 2.3 format.

For a single frequency GPS receiver to use the "nearest site" RTK correctors, it must be configured by the user to send the rover position back to the ORGN processing center using the NMEA GGA format.  For example, for the Trimble GeoXT, the RT corrector type should be set to "VRS" under RT settings/External Port Settings in order to send GGA.

ORGN Rover Accounts: Partner/Subscriber Information

Real-time correction products will be provided to users with valid Rover Accounts.

All rover users will be issued a Rover Account at no direct charge during the 2007 calendar year while ongoing costs of the ORGN are being calculated.   In 2008 and after, ORGN partners will continue to receive Rover Accounts at no charge; however, rover users who are not partners may be charged a reasonable subscription fee in order to help recover ongoing maintenance and upgrade costs of the ORGN.

A partner is defined as an individual, agency, or business that contributes substantially to the infrastructure of the Oregon Real-time GPS Network (ORGN).  An individual, agency or business may qualify as a partner  of the ORGN by providing a GPS reference sensor and antenna  and/or a site for a reference station for the ORGN. 

In order to access the real-time correctors from ORGN, you will need a GPS rover that is capable of receiving real-time correctors in RTCM 2.3 or RTCM 3.0 format.

Each Rover Account will be issued a log in name and password for authentification which allows the rover to log onto the ORGN server that streams real time correctors.

It is preferable for your rover to be able to provide NTRIP authentification.  NTRIP is an acronym for "Networked Transport of RTCM via Internet Protocol" and is an application-level protocol for streaming Global Navigation Satellite System (GNSS) data over the Internet.  NTRIP is a generic, stateless protocol based on the Hypertext Transfer Protocol (HTTP).

It is also preferable for your rover to be able to send its position back to the ORGN central server by sending a GGA message via NMEA protocol.

You must also have a cellular modem or data-capable cell phone that is connected to your rover and you must purchase a data service plan from a cellular provider.  Both CDMA (example: Verizon, Sprint) and GSM (examples: Cingular, Unicel) cellular formats are capable of accessing the ORGN server that streams RTK correctors.  You should pick a cellular provider based on which provider provides the best data service coverage in the area where you will be working most. 

The rover user will be responsible for purchasing, configuring, and maintaining the appropriate GPS rover, cell modem, and cellular data service.  ORGN_Support will provide general support, but cannot provide support for configuring and using specific GPS equipment, specific cellular modems, or data service.  Please contact your GPS equipment manufacturer or vendor for GPS support and your cellular provider for cellular service support.  We will post support documents for specific equipment and FAQ's as they become available.

Hourly RINEX files at a 5 second data rate from each reference station are posted to this website and are made available on-line for a period of one month for users, then it will be archived off-line.  The RINEX files are available at no charge to all users, whether partners/subscribers or not.

If an ORGN partner is already providing RINEX files on-line for their site; i.e., the partner site is a National Geodetic Survey Coop CORS site, we will not duplicate those RINEX files on the ORGN website; however, we will provide a link to the partner's RINEX data by clicking on the station on our Station Status page or by clicking on a station on one of the clickable ORGN maps.

The nominal epoch rate for ORGN RINEX files if 5 seconds; however, users may request  RINEX files with a faster epoch rate on a project-by-project  basis, for example, an aerial photography project using airborne GPS control.  Contact ORGN_Support in advance of your project if you have such a need.  Users may also request archived RINEX data that is older than one month by contacting ORGN_Support