Albuquerque Real Time GNSS Network
ARTGN
What is it?
The Albuquerque Real Time GNSS Network (ARTGN) is a high-accuracy real-time satellite based positioning system. It has been put in place by the City of Albuquerque to provide engineering companies, surveying companies, utility companies, construction companies and myriad other users of geospatial positioning products with real-time centimeter accuracy positioning throughout the metropolitan area of the City. Both the Citizens of Albuquerque and the City Government benefit from the high accuracy, quality control and cost savings provided for positioning of a full range of infrastructure components from subdivisions, pipelines, powerlines, and roadways, to underground water valves, gas meters, street signs and topographic features. The users benefit from the significant savings that come from no longer having to expend valuable time and resources to set up a remote GNSS base station every day. The ARTGN provides the base station data so they can simply get out of their vehicle and start surveying immediately. There is no more searching for control points, setting up the equipment, connecting cables, turning it all on and entering control point coordinates. The GNSS unit they have already been using for a base station can be used more productively elsewhere. And finally, they do not have to pay someone to sit by the station all day to ensure that no one steals it.
How does it work?
The system consists of seven continuously operating GNSS base station receivers connected to a central processing facility. The base stations operate 24/7 and continuously stream GNSS observations through the internet to a central processing facility. The central processing facility turns the observations into high accuracy positioning products that are made available to users through the internet. A user fee of $200 per month pays for access to the system. The City has purchased and installed the system and is charging user fees to recoup the initial costs and pay for ongoing maintenance. The City provides users with a password which enables them to stream data from the central processing facility through the internet to their jobsite. These data products are being combined with the users GNSS observational data to produce centimeter accuracy in real time.
From the site of field operations users access the internet using mobile phones. Internet enabled mobile phones, or their card equivalents, enable the user to tap into the City IP address, enter their password and open a data stream to their GNSS receiver in the field. It is a generic system that can be used by equipment from any manufacturer. Currently both Trimble and Topcon rovers are being used on the system.
Components of the system
GNSS Base Stations:
There are currently two types of base station receivers being used and three types of antennas as listed below:
Station: RRHS_ARP
Receiver: Topcon Odyssey_RS
Antenna: Topcon TPSPG_A1+GP
Station: CNM1
Receiver: Topcon Odyssey_E
Antenna: Topcon TPSCR3_GGD CONE Chokering with conical dome
Station: TOPCON01_ARP
Receiver: Topcon Net-G3
Antenna: Topcon TPSCR.G3 TPSH L1/L2 Chokering with semi-hemispherical dome
Station: TOPCON02_ARP
Receiver: Topcon Net-G3
Antenna: Topcon TPSCR.G3 TPSH L1/L2 Chokering with semi-hemispherical dome
Station: TOPCON03_ARP
Receiver: Topcon Net-G3
Antenna: Topcon TPSCR.G3 TPSH L1/L2 Chokering with semi-hemispherical dome
Station: TOPCON04_ARP
Receiver: Topcon Net-G3
Antenna: Topcon TPSCR.G3 TPSH L1/L2 Chokering with semi-hemispherical dome
Station: TOPCON05_ARP
Receiver: Topcon Net-G3
Antenna: Topcon TPSCR.G3 TPSH L1/L2 Chokering with semi-hemispherical dome
To see the specifics of each base station refer to the "GNSS Base Stations" section above or go to the Base Stations - Detailed Info link.
Antenna Mounts:
The system has two general types of antenna mounts made either from concrete pillars or wall mounted steel pipes.
The Cerro Colorado site and the Double Eagle II sites have the concrete pillar mounts. The following diagrams illustrate this type of mount:
The antenna mount is a concrete pillar, two feet in diameter, drilled eight feet deep and about seven feet above ground. It has a 2 inch galvanized pipe inserted in the center projecting about six inches above the top.
The following figures show the antenna mounts we are using at most of the sites:
They have aluminum plates with stainless steel bolts for leveling. There is a 5/8 inch stainless steel bolt in the middle for attaching the antenna.
The wall mounted sites are illustrated by the following two figures:
The antenna mounts at New Mexico Community College (CNM) and Rio Rancho High School (RRHS) are somewhat different. The mount at RRHS is a large steel bracket mounted to a top wall of the building and the mount at CNM is very similar to the pipe mounts shown above.
To see the specifics of each base station refer to the "GNSS Base Stations" section above or go to the Base Stations - Detailed Info link.
Central Processing Facility:
The network software is installed on two Hewlett Packard ProLiant ML350 rack mounted servers. Should the process fail on one server it can be readily transferred to the other server with minimal interruption of service. Both servers are installed in the City server room at the City/County building in Albuquerque.The network software is TopNET VRS Network software which provides a variety of services and capabilities. It tracks password usage and enables data transfer using NTRIP protocol a subset of HTTP designed specifically for GNSS networks. Data from all the base stations is monitored continuously and automatic system alarms notify the system operator of any outages or excessive antenna movements. Raw base station data at fifteen second epoch intervals is being stored for later use in post-processing. This data can be obtained free from the ftp site: ftp://artgn1.cabq.gov. Different epoch intervals may be stored upon request to the City. More information about this process can be found at the RINEX Downloads page. The software provides positioning either by creating a "virtual" base station near the user or enabling a direct connection to a network base station. For more information on how these processes work, please refer to the "RTN101" articles on the More Information page.
If you have any other questions about the system please contact Cliff Wilkie the City's Geodetic Surveyor by email at Cwilkie@cabq.gov or 768-3609.
Magazine Articles:
Several spellbinding magazine articles about the ARTGN may be found at the following two links: