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NI Universal Software Radio Peripheral (USRP) are computer-hosted RF transceivers used for development and exploration of software-defined radios. NI USRP transceivers can transmit and receive radio-frequency signals in a several bands and can be used for applications in communications education and research. Paired with NI LabVIEW software, NI USRP transceivers provide affordable solution that offers access to real-world signals to enable interactive development and a hands-on approach to teaching.
Table of Contents
- Software-Defined Radio
- Common Applications
- Hardware Overview
- Software Overview
- Why NI?
- Additional Resources
Software-Defined Radio
NI USRP hardware and LabVIEW software offer flexibility, functionality, and affordability to deliver an ideal software-defined radio prototyping platform for educational laboratories and physical layer communications research.
LabVIEW, running on a Gigabit Ethernet-connected host computer, provides the signal processing engine for the modulation and demodulation of signals streaming to and from NI USRP hardware. Toolkits extend LabVIEW software offer functional blocks for many common analog and digital modulation techniques and signal processing algorithms optimized for real-world radio signals.
Figure 1. NI USRP hardware interfaces with LabVIEW software to provide an accessible software-defined radio.
Common Applications
NI USRP hardware, LabVIEW software, and relevant courseware form an ideal solution for hands-on laboratory learning. In introductory communications courses, this platform provides the opportunity for students to gain a high-level understanding of an entire communications system with access to real-world signals. When exposed to more advanced digital communications topics, students can implement and optimize elements of a communications system by implementing each algorithm themselves in either LabVIEW or the .m file syntax supported by the LabVIEW MathScript RT Module. This approach scales directly to research areas including dynamic spectrum access, whitespace, and physical- and MAC-layer research. The NI USRP platform is also useful in simple transmit or receive applications for building custom protocols or logging spectrum to disk.
Hardware Overview
Following a common software-defined radio architecture, NI USRP hardware implements a direct conversion analog front end with high-speed analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) featuring a fixed-personality FPGA for the digital downconversion (DDC) and digital upconversion (DUC) steps. The receiver chain begins with a highly sensitive analog front end capable of receiving very small signals and digitizing them using direct downconversion to in-phase (I) and quadrature (Q) baseband signals. Downconversion is followed by high-speed analog-to-digital conversion and a DDC that reduces the sampling rate and packetizes I and Q for transmission to a host computer using Gigabit Ethernet for further processing. The transmitter chain starts with the host computer where I and Q are generated and transferred over the Ethernet cable to the NI USRP hardware. A DUC prepares the signals for the DAC after which I-Q mixing occurs to directly upconvert the signals to produce an RF frequency signal, which is then amplified and transmitted.
Figure 2. The NI USRP 2920 system level diagram.
Software Overview
LabVIEW is a graphical dataflow programming language well-suited for designing and implementing communications algorithms. At the most fundamental level, LabVIEW software uses the NI-USRP driver to both specify NI USRP hardware configuration and send and receive properly formatted baseband I/Q data. The LabVIEW Modulation Toolkit and the LabVIEW MathScript RT Module provide additional communications-specific functions and native .m file script support to LabVIEW. Blocks for channel coding, pulse shaping, simulating channel impairments, creating visualizations, and more make the LabVIEW Modulation Toolkit essential to most applications. Included examples offer a starting point for implementing a communications link using a variety of modulation schemes and are ready for use out of the box. The LabVIEW MathScript RT Module supports .m file syntax to allow for maximum code portability and reuse. You can rapidly integrate simulations built using .m file syntax into a hardware-based system for validation. Both the LabVIEW Modulation Toolkit and LabVIEW MathScript RT Module are included with every NI USRP hardware kit.
Figure 3. NI LabVIEW Modulation Toolkit provides additional communications-specific functions.
Why NI?
National Instruments offers technical support for NI USRP hardware, which carries a standard one-year extendable warranty. NI is committed to delivering a fully assembled and tested software and hardware platform with CE (European Conformity) certification. The tools are well-documented with step-by-step instructions to assist you from the time the box is opened to the time you transmit and receive your first signals. Paired with LabVIEW and application-specific courseware, NI USRP hardware offers a complete and accessible solution for RF and communications teaching and research.
Additional Resources
Learn How to Build a Software-Defined Radio Over-the-Air Link With NI LabVIEW and USRP Hardware
Download the NI-USRP driver for LabVIEW
Find NI-USRP example LabVIEW VIs
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