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| -rw-r--r-- | host/docs/usrp1.rst | 22 | ||||
| -rw-r--r-- | host/docs/usrp_nxxx.rst | 18 |
2 files changed, 35 insertions, 5 deletions
diff --git a/host/docs/usrp1.rst b/host/docs/usrp1.rst index be684e20e..9038616a8 100644 --- a/host/docs/usrp1.rst +++ b/host/docs/usrp1.rst @@ -89,3 +89,25 @@ Windows - install driver On Windows, a driver must be installed the first time the USRP1 is attached to the host computer. A download link for this driver can be found on the UHD wiki page. Download and unpack the driver, and direct the Windows driver install wizard to the .inf file. + +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +Hardware setup notes +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +------------------------------------------------------------------------ +External Clock Modification +------------------------------------------------------------------------ +The USRP can be modified to accept an external clock reference instead of the 64MHz onboard reference. + * Solder SMA (LTI-SASF54GT) connector to J2001 + * Move 0 ohm 0603 resistor R2029 to R2930 + * Move 0.01uF 0603 capacitor C929 to C926 + * Remove 0.01uF 0603 capacitor C924 + +The new external clock needs to be a square wave between +7dBm and +15dBm + +To configure UHD for the new reference clock, modify host/lib/usrp/usrp1/clock_ctrl.cpp: + +:: + + static const double master_clock_rate = <YOUR_NEW_REFERENCE_FREQUENCY>; + diff --git a/host/docs/usrp_nxxx.rst b/host/docs/usrp_nxxx.rst index 1c270df08..575f0ff70 100644 --- a/host/docs/usrp_nxxx.rst +++ b/host/docs/usrp_nxxx.rst @@ -227,19 +227,27 @@ The LEDs reveal the following about the state of the device: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Ref Clock - 10MHz ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -Using an external 10MHz reference clock requires a signal level between -+5dBm and +20dBm at 10MHz applied to the Ref Clock SMA port on the front panel. +Using an external 10MHz reference clock, square wave will offer the best phase +noise performance, but sinusoid is acceptable. The reference clock requires the following power level: + +* **USRP2** 5 to 15dBm +* **N2XX** 0 to 15dBm ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PPS - Pulse Per Second ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -Using a PPS signal for timestamp synchronization requires a 5Vpp square wave signal +Using a PPS signal for timestamp synchronization requires a square wave signal with the following amplitude: + +* **USRP2** 5Vpp +* **N2XX** 3.3 to 5Vpp + +Test the PPS input with the following app: + +* <args> are device address arguments (optional if only one USRP is on your machine) -Test the PPS input of the USRP2 with the following app: :: cd <prefix>/share/uhd/examples ./test_pps_input --args=<args> -* <args> are device address arguments (optional if only one USRP is on your machine) |