3 files changed, 17 insertions, 0 deletions
diff --git a/host/lib/usrp/b200/b200_cores.cpp b/host/lib/usrp/b200/b200_cores.cpp
index dcfd41825..31a95021a 100644
--- a/host/lib/usrp/b200/b200_cores.cpp
+++ b/host/lib/usrp/b200/b200_cores.cpp
@@ -74,6 +74,14 @@ void b200_ref_pll_ctrl::set_lock_to_ext_ref(bool external)
     _spi->restore_perif();
 }
 
+bool b200_ref_pll_ctrl::set_refclk_frequency(int refclk_kHz)
+{
+    _spi->change_perif(b200_local_spi_core::PLL);
+    bool success = adf4001_ctrl::set_refclk_frequency(refclk_kHz);
+    _spi->restore_perif();
+    return success;
+}
+
 
 b200_local_spi_core::sptr b200_local_spi_core::make(
     uhd::wb_iface::sptr iface, b200_local_spi_core::perif_t default_perif)
diff --git a/host/lib/usrp/b200/b200_cores.hpp b/host/lib/usrp/b200/b200_cores.hpp
index 54f5e5926..b97f99900 100644
--- a/host/lib/usrp/b200/b200_cores.hpp
+++ b/host/lib/usrp/b200/b200_cores.hpp
@@ -58,6 +58,7 @@ public:
 
     b200_ref_pll_ctrl(b200_local_spi_core::sptr spi);
     virtual void set_lock_to_ext_ref(bool external);
+    virtual bool set_refclk_frequency(int refclk_kHz);
 
 private:
     b200_local_spi_core::sptr _spi;
diff --git a/host/lib/usrp/b200/b200_impl.cpp b/host/lib/usrp/b200/b200_impl.cpp
index e2a0e0b70..e4ea372b3 100644
--- a/host/lib/usrp/b200/b200_impl.cpp
+++ b/host/lib/usrp/b200/b200_impl.cpp
@@ -716,6 +716,14 @@ b200_impl::b200_impl(const uhd::device_addr_t& device_addr, usb_device_handle::s
     _tree->access<std::string>(mb_path / "clock_source/value").set("internal");
     _tree->access<std::string>(mb_path / "time_source/value").set("internal");
 
+    //GPS installed: use external ref, time, and init time spec
+    if (_gps and _gps->gps_detected()) {
+      const int freq = _gps->gps_refclock_frequency();
+      if (not _adf4001_iface->set_refclk_frequency(freq)) {
+        throw uhd::value_error("Could not set refclk frequency to " + std::to_string(freq));
+      }
+    }
+
     // Set the DSP chains to some safe value
     for (size_t i = 0; i < _radio_perifs.size(); i++) {
         _radio_perifs[i].ddc->set_host_rate(default_tick_rate / ad936x_manager::DEFAULT_DECIM);