Current updates on the service availability of individual satellites are provided in Notice Advisory to Navstar Users (NANU) messages, which are likewise available from the US Coast Guard.
Between June 15 and 29, 2013, the GPS Directorate conducted a first live transmission of CNAV navigation messages as described in the L2C L5 CNAV Test Plan. The test involved all fully operational Block IIR-M and IIF satellites transmitting L2C and, in part, L5 signals.
As part of the MGEX project, CNAV navigation data were collected during this campaign by the German Aerospace Center (DLR) and the University of New Brunswick (UNB) with a total of five globally distributed multi-GNSS monitoring stations. The binary raw data as well as post-processed RINEX-style navigation files are made publicly available through the CDDIS and can be accessed in the June 2013 CNAV campaign direcory. A detailed description of the data set is provided in a dedicated ReadMe file.The routine transmission of CNAV data started on April 28, 2014 and daily uploads of navigation data are performed since Dec. 31, 2014. CNAV data collected since the start of the pre-operational CNAV are made available on a daily basis in annual directories of the MGEX data archive for 2014 to 2017. The employed data format matches the one introduced for the CNAV test campaign and is described in the corresponding ReadMe file.
- Montenbruck O., Langley R.B., Steigenberger P. (2013) "First Live Broadcast of GPS CNAV Messages", GPS World, 24(8):14-15
- Steigenberger P., Montenbruck O., Hessels U. (2015) "Performance Evaluation of the Early CNAV Navigation Message", Navigation, 63(3):219-228, DOI: 10.1002/navi.111