From cec063f3601088e4cd89f0b26f342c59e797be6d Mon Sep 17 00:00:00 2001
From: Carles Fernandez <carles.fernandez@gmail.com>
Date: Sat, 1 Apr 2017 10:47:36 +0200
Subject: [PATCH] Prints fake IODE and IODC in GPS L2C-only RINEX navigation
 files

IODE and IODC are not defined in CNAV. If set to zero, tools such as
RTKLIB are not able to compute position. With this commit, we write a
fake value that changes whenever Toe in message types 10 and 11, and Toc
in types 30-37, do not match.
---
 src/algorithms/PVT/libs/rinex_printer.cc | 20 +++++++++++++++-----
 src/algorithms/PVT/libs/rinex_printer.h  |  2 ++
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/algorithms/PVT/libs/rinex_printer.cc b/src/algorithms/PVT/libs/rinex_printer.cc
index 51d1bad0c..7dcfc704e 100644
--- a/src/algorithms/PVT/libs/rinex_printer.cc
+++ b/src/algorithms/PVT/libs/rinex_printer.cc
@@ -187,6 +187,7 @@ Rinex_Printer::Rinex_Printer(int conf_version)
     }
 
     numberTypesObservations = 4; // Number of available types of observable in the system
+    fake_cnav_iode = 1;
 }
 
 
@@ -1897,9 +1898,17 @@ void Rinex_Printer::log_rinex_nav(std::fstream& out, const std::map<int,Gps_CNAV
             // -------- BROADCAST ORBIT - 1
             line.clear();
             line += std::string(5, ' ');
-            // If there is no IODE in CNAV, so we set it to zero
-            double my_zero = 0.0;
-            line += Rinex_Printer::doub2for(my_zero, 18, 2);
+            // If there is no IODE in CNAV, so we check if Toe in message Type 10, Toe in Message type 11 and Toc in message types 30-37.
+            // Whenever these three terms do not match, a data set cutover has occurred and new data must be collected.
+            // See IS-GPS-200H, p. 155
+            if ( !((gps_ephemeris_iter->second.d_Toe1 == gps_ephemeris_iter->second.d_Toe2) && (gps_ephemeris_iter->second.d_Toe1 == gps_ephemeris_iter->second.d_Toc)) ) // Toe1: Toe in message type 10,  Toe2: Toe in message type 11
+                {
+                    // Toe1: Toe in message type 10,  Toe2: Toe in message type 11,
+                    fake_cnav_iode = fake_cnav_iode + 1;
+                    if(fake_cnav_iode == 240) fake_cnav_iode = 1;
+                }
+
+            line += Rinex_Printer::doub2for(fake_cnav_iode, 18, 2);
             line += std::string(1, ' ');
             line += Rinex_Printer::doub2for(gps_ephemeris_iter->second.d_Crs, 18, 2);
             line += std::string(1, ' ');
@@ -1962,6 +1971,7 @@ void Rinex_Printer::log_rinex_nav(std::fstream& out, const std::map<int,Gps_CNAV
             line += Rinex_Printer::doub2for(gps_ephemeris_iter->second.d_IDOT, 18, 2);
             line += std::string(1, ' ');
             // No data flag for L2 P code
+            double my_zero = 0.0;
             line += Rinex_Printer::doub2for(my_zero, 18, 2);
             line += std::string(1, ' ');
             double GPS_week_continuous_number = static_cast<double>(gps_ephemeris_iter->second.i_GPS_week + 1024); // valid until April 7, 2019 (check http://www.colorado.edu/geography/gcraft/notes/gps/gpseow.htm)
@@ -1981,8 +1991,8 @@ void Rinex_Printer::log_rinex_nav(std::fstream& out, const std::map<int,Gps_CNAV
             line += std::string(1, ' ');
             line += Rinex_Printer::doub2for(gps_ephemeris_iter->second.d_TGD, 18, 2);
             line += std::string(1, ' ');
-            // no IODC in CNAV, so we set it to zero
-            line += Rinex_Printer::doub2for(my_zero, 18, 2);
+            // no IODC in CNAV, so we fake it (see above)
+            line += Rinex_Printer::doub2for(fake_cnav_iode, 18, 2);
             Rinex_Printer::lengthCheck(line);
             out << line << std::endl;
 
diff --git a/src/algorithms/PVT/libs/rinex_printer.h b/src/algorithms/PVT/libs/rinex_printer.h
index 0d1dc940e..3ad44d26b 100644
--- a/src/algorithms/PVT/libs/rinex_printer.h
+++ b/src/algorithms/PVT/libs/rinex_printer.h
@@ -277,6 +277,8 @@ private:
      */
     void lengthCheck(const std::string & line);
 
+    double fake_cnav_iode;
+
     /*
      * If the string is bigger than length, truncate it from the right.
      * otherwise, add pad characters to its right.