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+/*! \page page_gpsdo Internal GPSDO Application Notes (USRP-N2x0/E1X0 Models)
+
+\tableofcontents
+
+This application note describes the use of integrated GPS-disciplined
+oscillators (GPSDOs) for the USRP N-Series and E1xx. For information
+regarding the GPSDO that is compatible with the USRP X-Series, please
+see: \ref page_gpsdo_x3x0
+
+
+\section gpsdo_specs Specifications
+
+-   **Receiver type**: 50 channel with WAAS, EGNOS, MSAS
+-   **10MHz ADEV**: 1e-11 over \> 24h
+-   **1PPS RMS jitter**: \< 50ns 1-sigma
+-   **Holdover**: \< 11us over 3h
+-   **Phase noise**:
+    -   **1Hz:** -80 dBc/Hz
+    -   **10Hz:** -110 dBc/Hz
+    -   **100Hz:** -135 dBc/Hz
+    -   **1kHz:** -145 dBc/Hz
+    -   **10kHz:** \< -145 dBc/Hz
+
+<b>Antenna Types:</b>
+
+The GPSDO is capable of supplying a 3V for active GPS antennas or
+supporting passive antennas.
+
+\section gpsdo_install Installation Instructions
+
+Instructions for mounting the GPSDO kit onto your USRP device can be
+found here: http://www.ettus.com/content/files/gpsdo-kit_2.pdf
+
+\subsection gspdo_install_post Post-installation Task (N-Series only)
+
+<b>Note:</b> The following instructions are only necessary for UHD 3.4.\*
+and below.
+
+This is necessary if you require absolute GPS time in your application
+or need to communicate with the GPSDO to obtain location, satellite
+info, etc. If you only require 10 MHz and PPS signals for reference or
+MIMO use (see \ref page_sync), it is not necessary to perform this step.
+
+To configure the USRP to communicate with the GPSDO, use the
+`usrp_burn_mb_eeprom` utility:
+
+    cd <install-path>/lib/uhd/utils
+    ./usrp_burn_mb_eeprom --args=<optional device args> --values="gpsdo=internal"
+
+    -- restore original setting --
+    ./usrp_burn_mb_eeprom --args=<optional device args> --values="gpsdo=internal"
+
+\section gpsdo_use 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 10 MHz 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: