Frequently Asked Questions
- What is RTN? - RTN is a real time positioning network that provides centimeter or better accuracy in latitude, longitude, and 2-5 centimeter accuracy in ellipsoid height at any given time (barring geomagnetic storm/solar flare).
- What is the name of Montana RTN? - Montana State Reference Network (MTSRN)
- When did the MTSRN first launch? - March 12, 2022.
- Why is Montana investing in RTN? – RTN provides a common correction on national datum for the entire state with improved accuracy and less conversion errors. RTNs provide machine guidance for grading or superelevation and benefits construction and transportation for critical engineering infrastructure, land surveying, precision agriculture, energy & utility, mining, drones, and robotics, public safety and more.
- Who owns the MTSRN? Who are the partners in establishing RTN? - The State of Montana owns the MTSRN under the legal authority of the Montana State Library. The Montana Department of Transportation (MDT) is a major partner for establishing bulk of base stations and with Montana Tribal Nationals, city and county governments and the University of Montana. 15 stations from UNAVCO are added to the network as well.
- What software does the MTSRN use? - MTSRN is run on Trimble’s Pivot software which is hosted in Trimble’s cloud server.
- What is the datum for the coordinates? - 2011 realization of North American Datum of 1983 or NAD 83(2011), epoch 2010.0
- Do you need a geoid model to receive orthometric height? - Yes, the default output of the MTSRN is latitude, longitude, and ellipsoid height. You need a National Geodetic Survey (NGS) geoid difference model installed in your software to receive orthometric height. We recommend using the latest geoid model which is GEOID18.
- How does a rover connect to MTSRN? How does MTSRN work? - MTSRN provides RTN correction through NTRIP (Network Transport of RTCM via Internet Protocol) which supports wireless internet access through any mobile IP networks (GSM or CDMA). There are NTRIP clients in most survey/mapping grade rover receivers/data collectors with standard fields to enter NTRIP IP/Port along with login credentials. - User can login to MTSRN website (www.mtsrn.org) using the same login credentials.
- How many stations are required to provide statewide coverage through the network? - About 120 stations. However, the density of base stations may change depending on the NGS recommendations of spacing geometry, relief discrepancy (gravity dependent), and availability of construction sites and needs.
- What is subnet? - Long separation between stations prohibits creating network solution. Subnets are formed to create network solution using a cluster of closely spaced base stations.
- How many subnets exist in the MTSRN? - There are currently five (5) subnets in the network. - These are named geographically such as, NEMT for northeast Montana, or SCMT for southcentral Montana.
- What are the names of the existing subnets? - NEMT, NCMT, NWMT, SWMT, and SCMT
- What is VRS in RTN? - Virtual Reference Station (VRS) is a station created close to a Rover Receiver as if this virtual station is providing the correction to the rover. 14. What is mountpoint? - A VRS solution format, or a single base broadcast format provided by NTRIP caster is called a mountpoint. A NTRIP client rover connects to a mountpoint and receives correction from the specific mountpoint.
- What kind of solution format one can expect from subnets? - VRS is the name of network solution - VRS follows subnet name, such as NEMTVRS, or SCMTVRS - To differentiate between Trimble proprietary solution or international standard solution format, suffixes are added. For example, CMRx suffix is added (NWMTVRSCMRx) to indicate Trimble proprietary multi-constellation solution, and MSM suffix is added (NWMTVRS_MSM) to indicate multi-constellation non-proprietary international solution format. - International standard (RTCM3.1 - RTCM3.3) solution format is compatible for any rovers built in last decade.
- I have a GPS only receiver. Can I use this receiver to receive correction or connect to any mountpoint? - CMR+ and RTCM3.1 are Trimble proprietary and international solution format respectively for GPS/GLONASS only receivers. In MTSRN, for example mountpoint NEMTVRSCMR is added to indicate CMR+ , and mountpoint NEMTVRSRTCM3 to indicate RTCM3.1 VRS solutions. - Single base solution, for example BKFB is added to indicate CMR+ and BKFB_3 to indicate RTCM3.1 solution.
MTSRN Coordinator
Kazi Arifuzzaman
Montana State Library
mtsrn@mt.gov
406-444-0240
