diff options
Diffstat (limited to 'host/docs')
| -rw-r--r-- | host/docs/gpsdo.rst | 18 | ||||
| -rw-r--r-- | host/docs/sync.rst | 13 |
2 files changed, 24 insertions, 7 deletions
diff --git a/host/docs/gpsdo.rst b/host/docs/gpsdo.rst index a0f2d67da..5680e0699 100644 --- a/host/docs/gpsdo.rst +++ b/host/docs/gpsdo.rst @@ -11,11 +11,17 @@ to the Jackson Labs Firefly-1A device unless noted otherwise. ------------------------------------------------------------------------ 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: -80dBc/Hz, 10Hz: -110dBc/Hz, 100Hz: -135dBc/Hz, 1kHz: -145dBc/Hz, 10kHz: <-145dBc/Hz +* 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:** -80dBc/Hz + * **10Hz:** -110dBc/Hz + * **100Hz:** -135dBc/Hz + * **1kHz:** -145dBc/Hz + * **10kHz:** <-145dBc/Hz ------------------------------------------------------------------------ Installation @@ -35,6 +41,7 @@ To configure the USRP to communicate with the GPSDO, use the usrp_burn_mb_eeprom utility: :: + $ cd <install-path>/share/uhd/utils $ ./usrp_burn_mb_eeprom --key=gpsdo --val=internal @@ -53,6 +60,7 @@ GPS data is obtained through the mboard_sensors interface. To retrieve the current GPS time, use the "gps_time" sensor: :: + usrp->get_mboard_sensor("gps_time"); The returned value will be the current epoch time, in seconds since diff --git a/host/docs/sync.rst b/host/docs/sync.rst index fe37a66dd..fb9f7a1df 100644 --- a/host/docs/sync.rst +++ b/host/docs/sync.rst @@ -105,8 +105,17 @@ and the user can also parse this string to determine GPS time: Method 3 - internal GPSDO ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ USRPs with internal GPSDOs properly configured will automatically -configure themselves to set the VITA time to current UTC time. See the -GPSDO application note for more details. +configure themselves to set the VITA time to current UTC time. +See the `GPSDO Application Notes <./gpsdo.html>`_ for more details. + +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +Method 4 - MIMO cable +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +A USRP can synchronize its time to another USRP via the MIMO cable. +Unlike the other methods, this does not use a real "pulse per second". +Rather, the USRP sends an encoded time message over the MIMO cable. +The slave device will automatically synchronize to the time on the master device. +See the `MIMO Cable Application Notes <./usrp2.html#using-the-mimo-cable>`_ for more detail. ------------------------------------------------------------------------ Synchronizing channel phase |