Rework GPSDO fix check

Accelerate startup, take advantage of new UHD sensor, fix startup
issue.

6 files changed, 145 insertions, 101 deletions

diff --git a/doc/example.ini b/doc/example.ini
index ebd4ec1..b94825c 100644
--- a/doc/example.ini
+++ b/doc/example.ini
@@ -261,11 +261,10 @@ pps_source=none
 ; possible values: ignore, crash
 behaviour_refclk_lock_lost=ignore
 
-; The maximum accepted holdover time for the gpsdo.
+; The maximum accepted holdover time for the gpsdo once it
+; started operating. Initial check interval for GPSDO lock
+; at startup is always 180s.
 ; Valid only if the refclk and pps_source are set to gpsdo.
-; This value is also used for the initial lock check, and must
-; be at least a minute so that the GPSOD has enough time to lock
-; and to start disciplining its oscillator.
 ; Units: seconds
 ; Set to 0 to disable holdover check
 ; default value: 0
diff --git a/src/output/SDR.cpp b/src/output/SDR.cpp
index 7c1b585..9be9aa2 100644
--- a/src/output/SDR.cpp
+++ b/src/output/SDR.cpp
@@ -78,6 +78,8 @@ SDR::SDR(SDRDeviceConfig& config, std::shared_ptr<SDRDevice> device) :
     RC_ADD_PARAMETER(underruns, "Counter of number of underruns");
     RC_ADD_PARAMETER(latepackets, "Counter of number of late packets");
     RC_ADD_PARAMETER(frames, "Counter of number of frames modulated");
+    RC_ADD_PARAMETER(gpsdo_num_sv, "Number of Satellite Vehicles tracked by GPSDO");
+    RC_ADD_PARAMETER(gpsdo_holdover, "1 if the GPSDO is in holdover, 0 if it is using gnss");
 }
 
 SDR::~SDR()
@@ -381,7 +383,9 @@ void SDR::set_parameter(const string& parameter, const string& value)
     }
     else if (parameter == "underruns" or
              parameter == "latepackets" or
-             parameter == "frames") {
+             parameter == "frames" or
+             parameter == "gpsdo_num_sv" or
+             parameter == "gpsdo_holdover") {
         throw ParameterError("Parameter " + parameter + " is read-only.");
     }
     else {
@@ -426,6 +430,14 @@ const string SDR::get_parameter(const string& parameter) const
             ss << stat.num_frames_modulated;
         }
     }
+    else if (parameter == "gpsdo_num_sv") {
+        const auto stat = m_device->get_run_statistics();
+        ss << stat.gpsdo_num_sv;
+    }
+    else if (parameter == "gpsdo_holdover") {
+        const auto stat = m_device->get_run_statistics();
+        ss << (stat.gpsdo_holdover ? 1 : 0);
+    }
     else {
         ss << "Parameter '" << parameter <<
             "' is not exported by controllable " << get_rc_name();
diff --git a/src/output/SDRDevice.h b/src/output/SDRDevice.h
index bd1a518..9e052b0 100644
--- a/src/output/SDRDevice.h
+++ b/src/output/SDRDevice.h
@@ -106,10 +106,13 @@ struct FrameData {
 class SDRDevice {
     public:
         struct RunStatistics {
-            size_t num_underruns;
-            size_t num_late_packets;
-            size_t num_overruns;
-            size_t num_frames_modulated;
+            size_t num_underruns = 0;
+            size_t num_late_packets = 0;
+            size_t num_overruns = 0;
+            size_t num_frames_modulated = 0;
+
+            int gpsdo_num_sv = 0;
+            bool gpsdo_holdover = false;
         };
 
         virtual void tune(double lo_offset, double frequency) = 0;
diff --git a/src/output/UHD.cpp b/src/output/UHD.cpp
index 711e218..e4b578e 100644
--- a/src/output/UHD.cpp
+++ b/src/output/UHD.cpp
@@ -362,6 +362,12 @@ SDRDevice::RunStatistics UHD::get_run_statistics(void) const
     rs.num_overruns = num_overflows;
     rs.num_late_packets = num_late_packets;
     rs.num_frames_modulated = num_frames_modulated;
+
+    if (m_device_time) {
+        const auto gpsdo_stat = m_device_time->get_gnss_stats();
+        rs.gpsdo_holdover = gpsdo_stat.holdover;
+        rs.gpsdo_num_sv = gpsdo_stat.num_sv;
+    }
     return rs;
 }
 
@@ -433,7 +439,7 @@ bool UHD::is_clk_source_ok(void) const
     }
 
     if (m_device_time) {
-        ok |= m_device_time->verify_time();
+        ok &= m_device_time->verify_time();
     }
 
     return ok;
diff --git a/src/output/USRPTime.cpp b/src/output/USRPTime.cpp
index 39b0e5a..232fa58 100644
--- a/src/output/USRPTime.cpp
+++ b/src/output/USRPTime.cpp
@@ -39,64 +39,6 @@ namespace Output {
 
 using namespace std;
 
-
-// Check function for GPS TIMELOCK sensor from the ODR LEA-M8F board GPSDO
-static bool check_gps_timelock(uhd::usrp::multi_usrp::sptr& usrp)
-{
-    try {
-        const string sensor_value =
-            usrp->get_mboard_sensor("gps_timelock", 0).to_pp_string();
-
-        if (sensor_value.find("TIME LOCKED") == string::npos) {
-
-            const string gngga =
-                usrp->get_mboard_sensor("gps_gngga", 0).to_pp_string();
-
-            std::stringstream ss(gngga);
-            std::string item;
-            std::vector<std::string> elems;
-            while (std::getline(ss, item, ',')) {
-                elems.push_back(item);
-            }
-
-            const auto num_svs = (elems.size() >= 7) ? elems[7] : "?";
-
-            etiLog.level(info) << "OutputUHD: " << num_svs << " SVs,"
-                " gps_timelock " << sensor_value;
-            return false;
-        }
-
-        return true;
-    }
-    catch (const uhd::exception &e) {
-        etiLog.level(warn) << "OutputUHD: no gps_timelock sensor: " <<
-            e.what();
-        return false;
-    }
-}
-
-// Check function for GPS LOCKED sensor from the Ettus GPSDO
-static bool check_gps_locked(uhd::usrp::multi_usrp::sptr& usrp)
-{
-    try {
-        const uhd::sensor_value_t sensor_value(
-                usrp->get_mboard_sensor("gps_locked", 0));
-        if (not sensor_value.to_bool()) {
-            etiLog.level(warn) << "OutputUHD: gps_locked " <<
-                sensor_value.to_pp_string();
-            return false;
-        }
-
-        return true;
-    }
-    catch (const uhd::exception &e) {
-        etiLog.level(warn) << "OutputUHD: no gps_locked sensor" <<
-            e.what();
-        return false;
-    }
-}
-
-
 USRPTime::USRPTime(
         uhd::usrp::multi_usrp::sptr usrp,
         SDRDeviceConfig& conf) :
@@ -104,26 +46,6 @@ USRPTime::USRPTime(
     m_conf(conf),
     time_last_check(timepoint_t::clock::now())
 {
-
-    if (m_conf.pps_src == "gpsdo") {
-        using namespace std::chrono;
-        auto now = system_clock::now();
-        auto expiry = now + seconds(m_conf.maxGPSHoldoverTime);
-        auto checkfunc = gpsdo_is_ettus() ? check_gps_locked : check_gps_timelock;
-        while (now < expiry) {
-            if (checkfunc(m_usrp)) {
-                break;
-            }
-
-            now = system_clock::now();
-            this_thread::sleep_for(seconds(2));
-        }
-
-        if (not checkfunc(m_usrp)) {
-            throw runtime_error("GPSDO did not lock during startup");
-        }
-    }
-
     if (m_conf.pps_src == "none") {
         if (m_conf.enableSync) {
             etiLog.level(warn) <<
@@ -133,8 +55,18 @@ USRPTime::USRPTime(
 
         set_usrp_time_from_localtime();
     }
-    else if (m_conf.pps_src == "pps" or m_conf.pps_src == "gpsdo") {
-        set_usrp_time_from_pps();
+    else if (m_conf.pps_src == "pps") {
+        // let verify_time handle time setup
+    }
+    else if (m_conf.pps_src == "gpsdo") {
+        if (gpsdo_is_ettus() ? check_gps_locked() : check_gps_timelock()) {
+            set_usrp_time_from_pps();
+            gps_state = gps_state_e::monitor_fix;
+            num_checks_without_gps_fix = 0;
+        }
+        else {
+            // let verify_time handle time setup
+        }
     }
     else {
         throw std::runtime_error("USRPTime not implemented yet: " +
@@ -193,6 +125,11 @@ bool USRPTime::verify_time()
     throw logic_error("End of USRPTime::verify_time() reached");
 }
 
+gnss_stats_t USRPTime::get_gnss_stats(void) const
+{
+    return gnss_stats;
+}
+
 void USRPTime::check_gps()
 {
     timepoint_t time_now = timepoint_t::clock::now();
@@ -224,11 +161,11 @@ void USRPTime::check_gps()
             // time, it has to be done in a separate thread.
             if (gpsdo_is_ettus()) {
                 gps_fix_future = std::async(std::launch::async,
-                        std::bind(check_gps_locked, m_usrp) );
+                        std::bind(&USRPTime::check_gps_locked, this) );
             }
             else {
                 gps_fix_future = std::async(std::launch::async,
-                        std::bind(check_gps_timelock, m_usrp) );
+                        std::bind(&USRPTime::check_gps_timelock, this) );
             }
         }
     }
@@ -239,11 +176,15 @@ bool USRPTime::gpsfix_needs_check() const
     if (m_conf.refclk_src == "internal") {
         return false;
     }
-    else if (m_conf.refclk_src == "gpsdo") {
+    else if (gps_state == gps_state_e::monitor_fix and
+            (m_conf.refclk_src == "gpsdo" or
+             m_conf.refclk_src == "gpsdo-ettus")) {
         return (m_conf.maxGPSHoldoverTime != 0);
     }
-    else if (m_conf.refclk_src == "gpsdo-ettus") {
-        return (m_conf.maxGPSHoldoverTime != 0);
+    else if (gps_state == gps_state_e::bootup and
+            (m_conf.refclk_src == "gpsdo" or
+             m_conf.refclk_src == "gpsdo-ettus")) {
+        return true;
     }
     else {
         return false;
@@ -308,6 +249,78 @@ void USRPTime::set_usrp_time_from_pps()
     }
 }
 
+
+// Check functionality of GPS sensors applicable to the ODR LEA-M8F board GPSDO
+bool USRPTime::check_gps_timelock()
+{
+    bool locked = false;
+
+    try {
+        const string sensor_value =
+            m_usrp->get_mboard_sensor("gps_timelock", 0).to_pp_string();
+
+        const string gngga =
+            m_usrp->get_mboard_sensor("gps_gngga", 0).to_pp_string();
+
+        std::stringstream ss(gngga);
+        std::string item;
+        std::vector<std::string> elems;
+        while (std::getline(ss, item, ',')) {
+            elems.push_back(item);
+        }
+
+        const auto num_svs = (elems.size() > 7) ? elems[7] : "0";
+        gnss_stats.num_sv = std::stoi(num_svs);
+
+        locked = (sensor_value.find("TIME LOCKED") != string::npos);
+    }
+    catch (const uhd::exception &e) {
+        etiLog.level(warn) << "OutputUHD: no gps_timelock sensor: " <<
+            e.what();
+    }
+
+    // LEA-M8F-patched UHD 3.12.0 has this additional sensor, that can
+    // be used to distinguish holdover operation. Previous versions
+    // did a config reset at startup to ensure we would not startup while
+    // in holdover.
+    try {
+        const string disc_src =
+            m_usrp->get_mboard_sensor("gps_discsrc", 0).to_pp_string();
+
+        locked &= (disc_src.find("gnss") != string::npos);
+    }
+    catch (const uhd::exception &e) {
+        etiLog.level(warn) << "OutputUHD: no gps_timelock sensor: " <<
+            e.what();
+    }
+
+    gnss_stats.holdover = not locked;
+
+    return locked;
+}
+
+// Check function for GPS LOCKED sensor from the Ettus GPSDO
+bool USRPTime::check_gps_locked()
+{
+    try {
+        const uhd::sensor_value_t sensor_value(
+                m_usrp->get_mboard_sensor("gps_locked", 0));
+        if (not sensor_value.to_bool()) {
+            etiLog.level(warn) << "OutputUHD: gps_locked " <<
+                sensor_value.to_pp_string();
+            return false;
+        }
+
+        return true;
+    }
+    catch (const uhd::exception &e) {
+        etiLog.level(warn) << "OutputUHD: no gps_locked sensor" <<
+            e.what();
+        return false;
+    }
+}
+
+
 } // namespace Output
 
 #endif // HAVE_OUTPUT_UHD
diff --git a/src/output/USRPTime.h b/src/output/USRPTime.h
index 51ca800..bc862fd 100644
--- a/src/output/USRPTime.h
+++ b/src/output/USRPTime.h
@@ -2,7 +2,7 @@
    Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Her Majesty the
    Queen in Right of Canada (Communications Research Center Canada)
 
-   Copyright (C) 2017
+   Copyright (C) 2018
    Matthias P. Braendli, matthias.braendli@mpb.li
 
     http://opendigitalradio.org
@@ -54,16 +54,24 @@ DESCRIPTION:
 
 namespace Output {
 
+struct gnss_stats_t {
+    int num_sv = 0; // Number of Satellite Vehicles used
+    bool holdover = false; // True if LEA-M8F uses its internal time reference
+};
+
 class USRPTime {
     public:
         USRPTime( uhd::usrp::multi_usrp::sptr usrp,
                 SDRDeviceConfig& conf);
 
         // Verifies the GPSDO state, that the device time is ok.
-        // Returns true if all ok.
+        // Returns true if all ok. Needs to be called so the device
+        // time gets properly set.
         // Should be called more often than the gps_fix_check_interval
         bool verify_time(void);
 
+        gnss_stats_t get_gnss_stats(void) const;
+
         // Wait time in seconds to get fix
         static const int initial_gps_fix_wait = 180;
 
@@ -72,10 +80,8 @@ class USRPTime {
 
     private:
         enum class gps_state_e {
-            /* At startup, the LEA-M8F GPSDO gets issued a hotstart request to
-             * make sure we will not sync time on a PPS edge that is generated
-             * while the GPSDO is in holdover. In the bootup state, we wait for
-             * the first PPS after hotstart, and then sync time.
+            /* In the bootup state, we wait for correct time lock and
+             * the first PPS, and then sync time.
              */
             bootup,
 
@@ -93,6 +99,8 @@ class USRPTime {
         gps_state_e gps_state = gps_state_e::bootup;
         int num_checks_without_gps_fix = 1;
 
+        gnss_stats_t gnss_stats;
+
         using timepoint_t = std::chrono::time_point<std::chrono::steady_clock>;
         timepoint_t time_last_check;
 
@@ -107,6 +115,9 @@ class USRPTime {
 
         void set_usrp_time_from_localtime(void);
         void set_usrp_time_from_pps(void);
+
+        bool check_gps_timelock(void);
+        bool check_gps_locked(void);
 };
 
 } // namespace Output