# Detection of RINEX-2 Files With Mixed GPS L2P(Y)/L2C Carrier Phase Observations
## 4 Observation Data Sets and Detection Results  
The detection algorithms described above were applied to RINEX-2 observation files of DoY (day of year) 150, 2018, which were copied from the servers of four GNSS data centers (Table 2). The data center operated by Crustal Dynamics Data Information System (CDDIS) contains mainly, but not exclusively, observations of stations of the IGS. Geoscience Australia manages a database of GNSS reference stations for the realization of the Asia-Pacific Reference Frame (APREF). The German Federal Agency for Cartography and Geodesy (BKG) serves as one of the data centers of the EUREF Permanent Network (EPN). The US National Geodetic Survey (NGS) maintains a database of Continuously Operating Reference Stations (CORS) in the USA and some additional countries. Some stations provide their RINEX-2 files to more than one of the four data centers of Table 2. We deleted such redundant files, keeping just one copy--the one obtained from CDDIS. CDDIS, APREF, and EPN/BKG offer RINEX-2 and RINEX-3 observation files. Usually, if a RINEX-3 file is available, the corresponding RINEX-2 file is also present. NGS provides observations in RINEX-2 only. Detection Algorithm 1 was applied to all 2624 station files. The primary results consisted of the bias difference between non-L2C and L2C satellites according to (12) and its standard deviation according to (13). Of the stations, 94.6% had a bias smaller than 0.1 cycles with a standard deviation of less than 0.05 cycles. They were considered to be correct and not affected by the L2 quarter cycle problem (black dots in Figure 4). The remaining 143 observation files were treated as suspicious and checked by Algorithms 2 and 3. Algorithm 2 was used when the closest GPS station was not further apart as several 100 km. Algorithm 3 was applied if a corresponding RINEX-3 file was available. \begin{table}
\begin{tabular}{c c c} \hline
**Satellite** & **RINEX-2** & **RINEX-3** \\ \hline  & **carg1500.18o** & **CARG00 ESP\_R\_20181500000\_01D\_30S\_MO\_mx** \\ \hline  & L1: 130395895.177 & LIC: 130395895.176 \\ (Block IIF, L2C) & L2: 101607188.874 & L2W: 101607184.615, L2S: 101607188.624 \\  & L5: 97373552.985 & L5Q: 97373552.984 \\ \hline  & L1: 128919863.442 & LIC: 128919863.442 \\ (Block IIR, non-L2C) & L2: 100457022.515 & L2W: 100457022.516, L2S: - \\  & L5: - & L5Q: - \\ \hline \end{tabular}
\end{table} 
Table 1: Two sample data sets of corresponding RINEX-2 and RINEX-3 phase observations [cy] used to map RINEX-3 onto RINEX-2 observation codes. EUREF Permanent Network station CARG, day of year (DoY) 150, 2018, epoch 00:00:00. \begin{table}
\begin{tabular}{c c} \hline
**Data Center** & **Geographical Distribution of Stations** & **Access** \\ \hline CDDIS & Global & [[ftp://cddis.gsfc.nasa.gov/pub/gps/data/daily/2018/150/18d](ftp://cddis.gsfc.nasa.gov/pub/gps/data/daily/2018/150/18d)]([ftp://cddis.gsfc.nasa.gov/pub/gps/data/daily/2018/150/18d](ftp://cddis.gsfc.nasa.gov/pub/gps/data/daily/2018/150/18d)) \\ APREF & Mainly Australia/New Zealand & [[ftp://ftp.ga.gova/geodesy-outgoing/gpss/data/daily/2018/18150](ftp://ftp.ga.gova/geodesy-outgoing/gpss/data/daily/2018/18150)]([ftp://ftp.ga.gova/geodesy-outgoing/gpss/data/daily/2018/18150](ftp://ftp.ga.gova/geodesy-outgoing/gpss/data/daily/2018/18150)) \\ EPN/BKG & Europe & [[ftp://igb.kg.bund.de/EUREF/obs/2018/150](ftp://igb.kg.bund.de/EUREF/obs/2018/150)]([ftp://igb.kg.bund.de/EUREF/obs/2018/150](ftp://igb.kg.bund.de/EUREF/obs/2018/150)) \\ NGS & Mainly USA & [[ftp://geodesynoaa.gov/crs/rinex/2018/150](ftp://geodesynoaa.gov/crs/rinex/2018/150)]([ftp://geodesynoaa.gov/crs/rinex/2018/150](ftp://geodesynoaa.gov/crs/rinex/2018/150)) \\ \hline \end{tabular}
\end{table} 
Table 2: GPS observation data sets, RINEX-2, DoY 150, 2018. The number of detected and confirmed RINEX-2 files with L2 quarter cycle problems amounted to 72, which was 2.7% of all examined files (filled colored symbols in Figure 4).