California Real Time Network
Alert (4/25/2019): The GPS week number rollover on April 6 caused inaccurate positions for those using CRTN data streams with some versions of Trimble R8 receivers. Our users at the County of San Diego indicate that an upgrade to R8-3 firmware 5.40 solved the problem. Please contact your Trimble dealer for more information.
Alert (3/26/2019): It was discovered that the northern California CRTN server (22.214.171.124) was transmitting incorrect coordinates in the RTCM3 messages. This started on January 16th when we moved the server to another workstation. The problem was resolved in the late afternoon of March 26th. Anyone who relied on the CRTN coordinates over this time period will need to revisit their rover coordinates. Please contact us if you believe your surveys may have been affected by the erroneous coordinates. Note that the southern California server was not affected. Thanks to Jim Frame and Art Andrew for discovering the problem. We’re sorry for the inconvenience.
Alert (10/12/2018): We have not been receiving real-time data from the USGS SCIGN stations in southern California for the last month. This causes a significant gap in coverage in the greater Los Angeles area. We do not know when the USGS service will be restored.
The California Real Time Network (CRTN) is a multipurpose statewide GNSS network that utilizes the existing geophysical and geodetic infrastructure for two primary purposes: (1) research into earthquake, tsunami and extreme weather early warning and rapid response, and (2) to provide a public utility in support of real-time kinematic and dynamic positioning. CRTN is managed through the California Spatial Reference Center (CSRC) and overseen by the CRTN Consortium.
CRTN is a clearinghouse of high-rate real-time GNSS data obtained from multiple servers, at UNAVCO (PBO), UC Berkeley/USGS Menlo Park (BARD), USGS Pasadena (SCIGN), Caltrans (CVSRN), Orange County Public Works (OCRTN), and SOPAC (SCIGN). SOPAC and some PBO stations in southern California are supported by a dedicated communications network HPWREN.
For a list of stations and coordinates click here.
1 Hz RTCM 3.0 data are now available in NTRIP protocol from GNSS stations operated by Scripps Institution of Oceanography’s Orbit and Permanent Array Center (SOPAC). The RTCM streams contain CSRS Epoch 2017.50 (NAD83) coordinates and station metadata (antenna and receiver models, antenna height and reference point).
CRTN fulfills the requirements of the California Public Resources Codes 8856(c)(e), 8857(c), and 8858(b) for GPS-derived geodetic coordinates and orthometric heights.
Register for CRTN
CRTN offers one (free) RTCM data stream for single-base positioning with respect to the California Spatial Reference System (CSRS). Users must register with the CSRC to obtain access. To register, click here.
Multiple data streams are available to Contributing and Consortium members. For more information, click here.
Connecting to CRTN Utilizing CRTN for RTK positioning requires a survey grade dual-frequency GNSS receiver with NTRIP and an Internet connection. The user makes a connection via NTRIP, enters their CRTN username and password and receives a list of the active CGPS base stations. The user then selects the desired CGPS base station and receives the RTCM data stream for RTK surveying.
In February 2018, the CSRC published a new geodetic datum for California called “CSRS Epoch 2017.50 (NAD83)” under a Caltrans contract to SIO/SOPAC. The new epoch-date coordinates have been embedded in the RTCM 3.0 data streams since March 1, 2018.