View source for USRP X300 and X310 Configuration Guide

==Introduction==
Application Note Number: AN-5501

Authors: John Smith and Jane Smith

Last Modified Date: 2016/04/15

Reference: https://www.ettus.com/kb/detail/usrp-x300-and-x310-configuration-guide

==Overview==
The Ettus Research USRP X300/X310 is a high-performance, modular software defined radio (SDR) platform that combines two extended-bandwidth daughterboard slots covering DC – 6 GHz with up to 120 MHz bandwidth, multiple high-speed interface options (PCIe, dual GigE, dual GigE), and a large user-programmable Kintex-7 FPGA in a convenient desktop or rack-mountable half-wide 1U form factor.  These features are provided in a flexible product that can be configured to meet to specific requirements of your application.  This document can be used as a guide as you select the most ideal options.

==Configuration Matrix==
Ettus Research recommends using  the flowchart and table below to guide you through the decision making process.  It highlights each decision point to be made as you configure a USRP X300/X310.  A general recommendation is made for each decision point, based on high-level application criteria.  Additional information for each decision point is also is also provided in this document.

[[File:Config flow 2.png|700px|center]]

<center>* Figure 1 - USRP X300/X310 Configuration Flow</center>

{| class="wikitable" style="margin: auto;"
!colspan="4"|Table 1 - USRP X300/X310 Configuration Matrix 
|-
!Decision Point
!Options
!Recommendation
!Your Choice
|-
|USRP ™ X300 or X310?
|USRP X300
USRP X310
|USRP X310 for larger FPGA (XC7K410T)
|
|-
|rowspan="4"|Interface Type
|rowspan="4"|1 GigE
10 GigE

PCIe

ExpressCard
|Max throughput( Desktop) -> 10 GigE
|-
|Minimum Latency ->PCIe
|-
|Min Latency (Laptop) -> ExpressCard
|-
|Provided with X3xx -> 1 GigE
|-

|rowspan="5"|RF Daughterboard
|rowspan="5"|WBX-120

SBX-120

CBX-120

Legacy DBs
|Choose by frequency:
|rowspan="3" style="vertical-align:top;"|Daughterboard A:
|-
|50 MHz – 2.2 GHz ->  WBX-120
|-
|400 MHz – 4.4 GHz -> SBX-120
|-
|1.2 GHz – 6 GHz -> CBX-120
|rowspan="2" style="vertical-align:top;"|Daughterboard B:
|-
|DC – 30 MHz -> LFRX/LFTX 
|-

|Power Cords
|Yes/No
|Outside the US/Japan?

Purchase a International Power Cord Kit
|
|-
|High-Accuracy GPSDO
|Yes/No
|Purchase GPSDO for high-accuracy clocking
|
|-
|GPSDO Antenna Kit
|Yes/No
|Purchase GPS Antenna for best clock accuracy and global timing alignment
|
|-
|GPIO Kit
|Yes/No
|Purchase GPIO Kit for external control& debug functionality
|
|-
|rowspan="2"|MIMO Components
|rowspan="2"|OctoClock/

OctoClock-G
|OctoClock if using an external 10 MHz/PPS source
|rowspan="2"|
|-
|OctoClock-G for fully integrated system with internal 10 MHz/PPS source
|-
|Rackmount
|Yes/No
|Desktop setup: No
|
|-

|}


==Choosing USRP X310 vs USRP X300==
In terms of host bandwidth, interface options, and all other hardware features the USRP X300 and USRP 310 are identical. However, the USRP X310 provides a larger FPGA, a Xilinx XC7K410T, as opposed to XC7K325T.  While both options provide a significant amount of free resources for custom FPGA development, the XC7K410T provides additional design margin, which translates to ease of development and future expandability.   Most users choose the USRP X310 for their development.

{| class="wikitable" style="margin: auto;"
!colspan="3"|USRP X300 and X310 FPGA Resource Summary
|-
|rowspan="2"|Resource Type
|USRP X300 (XC7K325T)
|USRP X310 (XC7K410T)
|-
|Count
|Count
|-
|DSP48 Blocks
|840
|1540
|-
|Block Rams (18kB)
|890
|1590
|-
|Logic Cells
|326,080
|406,720
|-
|Slices (logic)
|50,950
|63,550
|-
|}

For up-to-date information on FPGA resource utilization in the stock FPGA design, please see "USRP 300/X310 FPGA Resources" in the Ettus Research knowledge base (ettus.com/kb).

==Choosing an RF Daughterboard==
With the increased sample rates used by the USRP X300 and USRP X310, these new device can support extended-bandwidth daughterboards.  The WBX-120, SBX-120, and CBX-120 are recommended to take advantage of the full bandwidth capability of the USRP X300 and X310.  The WBX-120, SBX-120, and CBX-120 have been upgraded from their predecessors (40 MHz) to use 120 MHz baseband filters.  You can select your daughterboard based on the center frequency of your primary application.

{| class="wikitable" style="margin: auto;"
!Daughterboard
!Frequency Range
!Bandwidth
|-
|WBX-120
|50 MHz - 2200 MHz
|120 MHz
|-
|SBX-120
|400 MHz - 4400 MHz
|120 MHz
|-
|CBX-120
|1200 MHz - 6000 MHz
|120 MHz
|-
|}

If your application is in the HF frequency range, the LFRX and LFTX are recommended for up to 30 MHz of bandwidth per channel.  The BasicRX and BasicTX are ideal for configurations that use an external frontend for tuning and filtering with either an IF or baseband interface.

The USRP X300 and X310 are backward compatible with legacy daughterboards except for the RFX Series and XCVR2450.  Please note, while there are two daughterboard slots, the USRP X300/X310 can only support a single TVRX2.


If you plan to transmit or receive over the air, you should also purchase an antenna.

==Choosing a Host Interface==

The USRP X300/X310 provide three interface options – 1 Gigabit Ethernet (1 GigE), 10 Gigabit Ethernet (10 GigE), and PCI-Express (PCIe). Generally, Ettus Research recommends using 10 GigE to achieve the maximum throughput available from the USRP X300/X310.  PCIe is recommended for applications that require the lowest possible latency, which is a desirable characteristic for PHY/MAC research.  If your application does not require the full bandwidth of the USRP ™ X300 and X310, the 1 GigE interface serves as a cost-effective fall-back option.  Ettus Research provides a complete interface kit for each of these options, which is also shown in Table 3.

{| class="wikitable" style="margin: auto;"
!colspan="4"|Table 3 - Interface Performance Summary
|-
!Interface
!Throughput (MS/s @ 16-bit)
!Target
!Recommended Kit
|-
|1 Gigabit
|25 MS/s
|Desktop/Laptop
|Components provided with USRP X300/X310 kit.
For additional connections, purchase the following:
[https://www.ettus.com/product/details/1GIGE-KIT SFP Adapter + GigE Cable]
|-
|10 Gigabit
|200 MS/s
|Desktop
|[https://www.ettus.com/product/details/10GIGE-KIT 10 GigE Interface Kit]
|-
|PCI-Express 
(PCIe, 4 lane)
|200 MS/S
|Desktop
|[https://www.ettus.com/product/details/PCIE-KIT PCI-Express Desktop Kit]
|-
|Express Card
(PCIe, 1 lane)
|50 MS/s
|Laptop
|[https://www.ettus.com/product/details/ECARD-KIT ExpressCard Kit]
|-
|}


[[File:Connectivity 2.png|700px|center]]

<center>Figure 2 - Host Interface Options</center>

==International Power Supply Options==
The power supply provided with the USRP X300/X310 kit is packaged with a power cord that is compatible with power outlets in the US/Japan.  If you are not using the USRP X300/X310 in the US/Japan, we recommend purchasing the International USRP X300/X310 Power Cord set.  

==Option: GPS Disciplined, Oven-Controlled Oscillator (GPSDO)==
The USRP X300 and USRP X310 provide the option to integrate a high-accuracy GPS-disciplined oscillator (GPSDO).  The GPSDO improves the accuracy of the internal frequency reference to 20 ppb, or 0.1 ppb if the GPS is synchronized to the GPS constellation.  When synchronized to the GPS constellation, all USRP ™ devices will also be synchronized in time within 50 ns.

{| class="wikitable" style="margin: auto;"
|
!Internal TCXO
!GPS-Disciplined Clock
|-
|Frequency Reference
|TCXO
|OCXO
|-
|Frequency Accuracy
|± 2.5ppm
± 2,500 Hz @ 1 GHz
|± 20 ppb
± 20 Hz @ 1 GHz
|-
|Frequency Accuracy
|
|± 0.01ppb
|-
|(GPS-Disciplined)
|
|~ ± 0.01 Hz @ 1 GHz
|-
|GPS Time Sync Accuracy
|
|±50ns to UTC Time**
|-
|10 MHz Reference Phase Drift with GPS Sync
|
|<±20ns After 1 Hour**
|-
|}

==Option: Antenna Kit for GPSDO==
The GPSDO Mini Kit will improve the accuracy of the USRP reference clock, even if it does not receive signals from the GPS Constellation.  However, to achieve the best accuracy possible, and to achieve global timing alignment across multiple USRPs, Ettus Research recommends the GPSDO Mini Antenna Kit.

==Option: General Purpose Input/Output (GPIO) Kit==
The USRP X300 and X310 include a DB15 connector on the front panel that provides convenient access to GPIO signals.  Each pin can be configured as an input or output, uses 3.3V-level logic, and is protected with basic anti-static circuitry.  These pins can be used to control external devices like RF switches and amplifiers, trigger software events on the host, or even provide basic debugging functionality.  The USRP GPIO Kit is an affordable option that provides access to these signals with a DB15 cable and a breakout board.  The breakout board allows the user to connect external devices through a terminal block.  The user can also solder wires and components into the dedicated prototyping area.

==Option: Cables for MIMO Expansion==
Multiple USRP X300/X310s can be synchronized for coherent operation by sharing a common 10 MHz and 1 PPS signal.  We recommend using a star-distribution topology with an OctoClock or OctoClock-G, as seen in Figure 4.  This requires matched length cables to be used for both 10 MHz and 1 PPS.

For more information about MIMO operation, please see the MIMO and Synchronization Application Note.
[[File:8mimo.png|700px|center]]
<center>Figure 4 - Star-Distribution of 10 MHz/PPS Signals with OctoClock</center>

==Option: USRP X300/X310 Rackmount==
The USRP X300/X310 was designed to use a convenient half-wide 1U rack-mount form factor.  This allows developers to build high-density MIMO systems in a neat and well organized setup.  If the user will be developing in a lab environment, or building a high-channel count system, the 1U Rackmount Assembly is recommended.  However, if the user plans to work with the USRP X300/X310 on a desk, the rackmount is not required.  Rubber standoffs are mounted on the USRP X300/X310 to avoid direct contact and surface scratching.



[[Category:Application Notes and White Papers]]