Universal Software Radio Peripheral

Lore & Background

The USRP product family includes a variety of models that use a similar architecture. A motherboard provides subsystems such as clock generation and synchronization, FPGA, ADCs, DACs, host processor interface, and power regulation. A modular front-end, called a daughterboard, is used for analog operations such as up/down-conversion, filtering, and other signal conditioning. This modularity permits the USRP to serve applications that operate between DC and 6 GHz. In stock configuration the FPGA performs several DSP operations, providing translation from real signals in the analog domain to lower-rate, complex, baseband signals in the digital domain. The code for the FPGA is open-source and can be modified to allow high-speed, low-latency operations to occur in the FPGA.

The USRP hardware driver (UHD) is the device driver provided by Ettus Research for use with the USRP product family. It supports Linux, macOS, and Windows platforms. Several frameworks including GNU Radio, LabVIEW, MATLAB and Simulink use UHD. The functionality provided by UHD can also be accessed directly with the UHD API, which provides native support for C++. Any other language that can import C++ functions can also use UHD. This is accomplished in Python through SWIG, for example. UHD provides portability across the USRP product family; applications developed for a specific USRP model will support other USRP models if proper consideration is given to sample rates and other parameters.

Reader's Guide

The USRP family is notable for its role in democratizing software-defined radio through open-source hardware and software. The article states that many USRP products are open source hardware, with board schematics for select models freely available, and all USRP products are controlled with the open source UHD driver. USRPs are commonly used with the GNU Radio software suite to create complex software-defined radio systems. The modular daughterboard architecture allows the USRP to serve applications from DC to 6 GHz, making it adaptable to a wide range of frequencies. The product line includes networked, bus, and embedded series, each targeting different use cases—from high-performance MIMO systems (via the networked series) to standalone operation (via the embedded series). The UHD driver's cross-platform support and API accessibility (C++, Python via SWIG) have fostered a broad ecosystem of users, including research labs, universities, and hobbyists. The article also notes that National Instruments sells the NI USRP 292x series, functionally equivalent to the USRP N210, and that MATLAB and Simulink support certain models. The open-source FPGA code allows advanced users to implement custom high-speed, low-latency operations directly in hardware.

Did You Know?

• The USRP family was designed for accessibility, and many products are open source hardware.
• The USRP N200 and N210 use a Gigabit Ethernet interface to transfer up to 50 MS/s of complex baseband samples.
• The Embedded Series (e.g., E310) uses a Zynq SoC platform and Analog Devices AD9361 RFIC for standalone operation without an external PC.
• The original USRP and USRP2 are discontinued; the USRP2 was replaced by the USRP N200 and N210.