Frequently Asked Questions

Anyone with a network-ready GNSS receiver can use the IaRTN. All corrections are made through the Internet via networked transport of RTCM via Internet Protocol (Ntrip) and Transmission Control Protocol/Internet Protocol (TCP/IP).

There are no current plans for the Iowa DOT to charge users to access the network, whether from the public or private sector.

All network users are required to register with the Iowa DOT.

Registration must be completed online, and can be accessed by the IaRTN registration link on the IaRTN home page. Once completed, your account will be activated within two working days. You will receive an email containing your username and password. New users will receive one email to confirm that email address. After the email confirmation another email will be received by the user to order a subscription. This is a free two year subscription.

A link to the IaRTN connection information.

An internal or external cell modem or a data capable cell phone with the ability to communicate with your rover and the Internet are needed to access the network corrections.

The Iowa DOT does not recommend any particular cellular provider. Cellular data coverage at the location where you will be working is the most important consideration in choosing your cellular provider.

Any brand of GNSS rover of recent manufacture capable of receiving Radio Technical Commission for Maritime Services (RCTM) 3.1, RTCM 3.2, compact measurement record (CMR), or CMR+ messages is needed. In addition, current firmware allowing connection to cellular communications is required. Consult with your rover's local distributor for questions specific to your equipment.

Yes. Glonass satellites are available to those users using the RTCM 3.1 correction messages. Glonass satellites are not available to those users using the RTCM 2.3, CMR or CMR+ correction messages.

There are no plans to provide Glonass satellites for CMR or CMR+ users. The network was based on an open-architecture format (universally open correction formats), and GNSS satellite only CMR and CMR+ formats are being provided on a temporary basis until older GNSS rovers can be replaced.

Yes. Galileo satellites and the L5 signal are available to those users using the RTCM 3.2 MSM4 correction messages. Galileo satellites are not available to those users using the RTCM 3.1, RTCM 2.3, CMR or CMR+ correction messages.

No, the network also provides single-frequency correctors suitable for use by professional quality mapping/geographic information system grade, single-frequency GNSS receivers capable of using a cellular data modem or a data-capable phone to receive correction messages.

The established datum for the IaRTN is currently NAD83(2011)(Epoch 2010.000). Originally the IaRTN was on NAD83(CORS96)(Epoch 2002.0000), but switched over to NAD83(2011)(Epoch 2010.0000) on January 7, 2013.

Assuming the standard GNSS protocols and best practice methods are employed for maximum precision (i.e., good satellite coverage, good geometry of precisions, low multipath environments) the IaRTN typically achieves an RTK accuracy of 1-2 cm horizontally and 2-3 cm vertically.

RINEX data from individual stations is available online for post-processing.

Hourly, one second sampled, RINEX data is available through the SBC Post Processing tool . In addition, RINEX data sets in user selectable time frames from one hour to 24 hours, with user-selectable sampling rates of 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30 and 60 seconds are available through the network software using the SBC Post Processing tool. RINEX 2 and files older than 90 days can be retrieved upon request.

Yes, upon prior request to the Iowa DOT, data is available with a sampling rate as small as 0.1 seconds. If the Iowa DOT is are aware of your needs beforehand, a project-specific file can be created with a sample rate to meet your needs.

In 2006, the Iowa Department of Transportation conducted a business model study to examine the potential models for the deployment and operations of a statewide Real Time Kinematic (RTK) Global Positioning System (GPS) network. The study results helped the Iowa DOT develop a business model that best suited the DOT's and the State of Iowa’s needs. Under the selected model, the network uses existing Iowa DOT facilities and wide area network (WAN) communications infrastructure. In addition, the DOT owns the network hardware and software, maintains the hardware, and contracts out the network software support/service.

After a thorough evaluation process, including a written proposal and installation of demonstration networks by competing firms, Leica Geosystems was selected to install and support the IaRTN. The first 80 base stations were installed in the last half of 2008, and the network went online Feb. 2, 2009. Data from the IaRTN base stations along Iowa’s borders are shared with other DOT RTK networks in Minnesota, Missouri and Wisconsin. In return, those three networks share the data from their base stations along the Iowa border with the IaRTN. The sharing enhances all three networks along the border areas. Currently the network consists of 103 base stations (83 Iowa DOT sites, 10 Minnesota DOT sites and 3 Wisconsin DOT sites).

In 2018, the network hardware was replaced, and the operating software was upgraded to take advantage of new technology not available in 2008. The network was upgraded to a Global Navigation Satellite System (GNSS) network, using the satellite constellations of the United States (GPS), Russia (Glonass) and the European Union (Galileo). The network provides users centimeter positioning statewide. The Iowa DOT uses the centimeter positioning for surveying, engineering and geographical information system (GIS) applications, along with machine control. The network is also available to federal, state, county, city, quasi-public and private sector users without charge. Machine control by the agricultural sector is one of the biggest network users.