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+========================================================================
+UHD - USRP1 Application Notes
+========================================================================
+
+.. contents:: Table of Contents
+
+------------------------------------------------------------------------
+Specify a non-standard image
+------------------------------------------------------------------------
+The standard USRP1 images installer comes with two FPGA images:
+ * **usrp1_fpga.rbf:** 2 DDCs + 2 DUCs
+ * **usrp1_fpga_4rx.rbf:** 4 DDCs + 0 DUCs
+
+By default, the USRP1 uses the FPGA image with 2 DDCs and 2 DUCs.
+However, a device address parameter can be used to override
+the FPGA image selection to use an alternate or a custom FPGA image.
+See the images application notes for installing custom images.
+
+Example device address string representations to specify non-standard firmware and/or FPGA images:
+
+::
+
+    fpga=usrp1_fpga_4rx.rbf
+
+    -- OR --
+
+    fw=usrp1_fw_custom.ihx
+
+    -- OR --
+
+    fpga=usrp1_fpga_4rx.rbf, fw=usrp1_fw_custom.ihx
+
+------------------------------------------------------------------------
+Missing and emulated features
+------------------------------------------------------------------------
+The USRP1 FPGA does not have the necessary space to support the advanced
+streaming capabilities that are possible with the newer USRP devices.
+Some of these features are emulated in software to support the API.
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+List of emulated features
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+* Setting the current device time
+* Getting the current device time
+* Transmitting at a specific time
+* Transmitting a specific number of samples
+* Receiving at a specific time
+* Receiving a specific number of samples
+* End of burst flags for transmit/receive
+* Notification on late stream command
+* Notification on late transmit packet
+* Notification on underflow or overflow
+* Notification on broken chain error
+
+**Note:**
+These emulated features rely on the host system's clock for timed operations,
+and therefore may not have sufficient precision for the application.
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+List of missing features
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+* Start of burst flags for transmit/receive
+
+------------------------------------------------------------------------
+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 R2030
+ * Move 0.01uF 0603 capacitor C925 to C926
+ * Remove 0.01uF 0603 capacitor C924
+
+The new external clock needs to be a square wave between +7dBm and +15dBm
+
+After the hardware modification,
+the user should burn the setting into the EEPROM,
+so UHD can initialize with the correct clock rate.
+Run the following commands to record the setting into the EEPROM:
+::
+
+    cd <install-path>/share/uhd/utils
+    ./usrp_burn_mb_eeprom --args=<optional device args> --key=mcr --val=<rate>
+
+The user may override the clock rate specified in the EEPROM by using a device address:
+Example:
+::
+
+    uhd_usrp_probe --args="mcr=52e6"