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+/*! \page page_gpsdo_x3x0 Internal GPSDO Application Notes (USRP-X3x0 Models)
+
+\tableofcontents
+
+This application note describes the use of the board-mounted GPS
+Disciplined OCXO, as used with the USRP X300/X310. For information
+regarding the GPSDO that is compatible with the USRP N2xx or E1xx,
+please see \ref page_gpsdo.
+
+\section gpsdox_specs Specifications
+
+-   **Receiver type**: 50 channel with WAAS, EGNOS, MSAS
+-   **10 MHz ADEV**: 5e-11 over \>24h
+-   **1PPS RMS jitter**: \<50ns 1-sigma
+-   **Holdover**: \<20us over 3h
+
+<b>Phase noise</b>:
+
+ Offset  |   OCXO Phase noise power
+---------|----------------------------
+1Hz      |-75dBc/Hz
+10Hz     |-110dBc/Hz
+100Hz    |-132dBc/Hz
+1kHz     |-142dBc/Hz
+10kHz    |-145dBc/Hz
+100kHz   |-150dBc/Hz
+
+<b>Antenna Types:</b>
+
+The GPSDO is capable of supplying a 3V for active GPS antennas or
+supporting passive antennas.
+
+\section gpsdox_install Installation Instructions
+
+To install the GPSDO, you must insert it into the slot on the board near
+the 10 MHz Reference SMA. Keep in mind that the two sides of the GPSDO
+have a different number of pins. When inserting the GPSDO, make sure to
+press down firmly and evenly. When turning on the USRP X3x0 device, a
+green LED should illuminate on the GPSDO. This signifies that the unit
+has successfully been placed.
+
+<b>NOTE: The pins on the GPSDO are very fragile. Be sure to press down
+evenly, or the pins may bend or break. Once the GPSDO is in place, we
+very highly discourage further removal, as this also risks damaging the
+pins.</b>
+
+\section gpsdox_using Using the GPSDO in Your Application
+
+By default, if a GPSDO is detected at startup, the USRP will be
+configured to use it as a frequency and time reference. The internal
+VITA timestamp will be initialized to the GPS time, and the internal
+oscillator will be phase-locked to the 10MHz GPSDO reference. If the
+GPSDO is not locked to satellites, the VITA time will not be
+initialized.
+
+GPS data is obtained through the **mboard_sensors** interface. To
+retrieve the current GPS time, use the **gps_time** sensor:
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
+    usrp->get_mboard_sensor("gps_time");
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The returned value will be the current epoch time, in seconds since
+January 1, 1970. This value is readily converted into human-readable
+format using the **time.h** library in C, **boost::posix_time** in C++,
+etc.
+
+Other information can be fetched as well. You can query the lock status
+with the **gps_locked** sensor, as well as obtain raw NMEA sentences
+using the **gps_gprmc**, and **gps_gpgga** sensors. Location
+information can be parsed out of the **gps_gpgga** sensor by using **gpsd**
+or another NMEA parser.
+
+
+*/
+// vim:ft=doxygen: