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2 An Introduction to Software Defined Radio With LabVIEW and NI USRP

3 Hands-on Course Objectives Exercise 1 Acquire an RF signal using USRP Introduction to the LabVIEW environment Configuring the USRP software defined radio Acquiring an RF signal using NI USRP Exercise 2 Demodulate & listen to live FM radio LabVIEW programming fundamentals Integrating digital signal processing functions Exercise 3 Using Mathscript code and pre-built IP

4 What is LabVIEW? LabVIEW is a graphical programming environment used by millions of engineers and scientists to develop sophisticated measurement, test, and control systems LabVIEW can integrate with wide variety of hardware devices, including the NI USRP

5 NI RF Test Platform Optimized APIs Cellular, Wireless, & GPS Test Toolkits ( a/b/g/n, GSM, EDGE, WCDMA, RFID, WiMAX, GPS, etc.) Soft Front Panels Reference Architectures Multicore Processing VSAs & VSGs FPGA I/O & Co-processing Amplifiers & Attenuators Switching Power Meters

6 The Next 30 Years: Expanding LabVIEW into System Design Design Verification Product Verification Research/Mod eling Design/Simul ation Verification/Va lidation Manufacturing

7 Introduction to SDR Acquire a spectrum using NI-USRP API Introduction to the LabVIEW environment Configuring the USRP software defined radio Acquiring an RF signal using NI-USRP

8 From Concept to Prototype Rapidly! Graphical System Design Platform Design Simulate Prototype LabVIEW Graphical System Design offers one tool, integrated flow Shorter learning curve Easier system integration Reduce the time to hardware rapid prototyping!

9 Getting Started in LabVIEW

10 LabVIEW Programs are Called Virtual Instruments (VIs) LabVIEW VIs contain three main components: 1. Front Panel 2. Block Diagram 3. Icon/Connector Pane

11 Front Panel & Controls Palette Numeric Control Controls Palette - contains the controls and indicators you use to create the front panel

12 Block Diagram & Functions Palette Math Function Front panel objects appear as terminals on the block diagram Contains the VIs, functions, and constants you use to create the block diagram

13 Dataflow Programming Block diagram execution Dependent on the flow of data Block diagram does NOT execute left to right Node executes when data is available to ALL input terminals Nodes supply data to all output terminals when done

14 LabVIEW Help Utilities Context Help Hover over function blocks for just-in-time help Help»Show Context Help Shortcut Keys: <Ctrl-H>

15 LabVIEW Help Utilities LabVIEW Help Select Help»LabVIEW Help Use the Detailed help link or button in the Context Help window Right-click an object and select Help from the shortcut menu

16 What is a Software Defined Radio? Software-Defined Radio (SDR) refers to the technology wherein software modules running on a generic hardware platform are used to implement radio functions..

NI USRP Software Defined Radio Tunable RF Transceiver Front Ends Frequency Range

4 GHz (NI-2922) Signal Processing and Synthesis NI LabVIEW to develop and explore

signals Applications FM Radio TV GPS GSM ZigBee Safety Radio OFDM Passive Radar

17 NI USRP Software Defined Radio Tunable RF Transceiver Front Ends Frequency Range 50 MHz 2.2 GHz (NI-2920) 2.4 GHz & 5.5 GHz (NI-2921) 400 MHz 4.4 GHz (NI-2922) Signal Processing and Synthesis NI LabVIEW to develop and explore algorithms NI Modulation Toolkit and LabVIEW add-ons to simulate or process live signals Applications FM Radio TV GPS GSM ZigBee Safety Radio OFDM Passive Radar Dynamic Spectrum Access 1 Gigabit Ethernet to PC Plug-and-play capability Up to 25 MS/s baseband IQ streaming

18 NI USRP Software Defined Radio RF Transceiver Baseband IQ Software Processing

19 SDR Components Tx Digital to Analog RF Upconversion Modulation RX RF Downconversion Analog to Digital Demodulation Signal Processing

20 NI-USRP Driver Software RX Settings

21 Signal Processing (PC) Receiver Path Software Radio Example TX SMA RX? SMA BUS

22 Signal Processing (PC) Receiver Path Software Radio Example TX SMA Amp DA C How fast? How many bits? BUS RX SMA Amp AD C 5GS/s for Wifi!?

23 Example: Sampling at 5 GS/s 2.5 GHz 50 MHz 0 Hz 2.4 GHz Signal of interest has 50 MHz bandwidth When we sample at 5 GS/s, we get all the data between GHz Only interested in 2.4 GHz +/- 25 MHz At this sampling rate, we collect much more data than we need How do we get around this?

24 Mixing

25 Signal After Mixing 50 MHz 0 Hz After mixing, signal of interest has 50 MHz bandwidth, but now it is a much lower frequency At this lower frequency, an ADC can capture the signal

26 Introduction to I and Q Acos( 2 f ct ) Acos( )cos(2 fct) I Acos( ) Q Asin( ) Acos( 2 f ct ) Asin( )sin(2 fct) I cos(2 fct) Qsin(2 fct) Note: I and Q capture Amplitude and Phase information

By summing two orthogonal data streams and a carrier, we get a phase

27 IQ Modulator An IQ modulator multiplies I and Q by the carrier and carrier - 90 degrees, respectively. By summing two orthogonal data streams and a carrier, we get a phase modulator (any angle in the phase plane). If we add amplitude control, we get a vector modulator (any point in the phase plane). LO

28 Signal Processing (PC) Software Radio Receiver I( t)cos(2 f t) Q( t)sin(2 f t) c c RX Mixe r I(t) AD C BUS SMA Amp 0 o 90 o Tunable Oscillator f c Mixe r Q(t) RF Signal IQ Mixing Baseband f c = center frequency of interest AD C 100 MS/s ADC

29 Signal Processing (PC) Receiver Path Software Radio Example RF Signal IQ Mixing Baseband RX 1 SMA Switc h BUS RX 2 SMA Amp Tunable Oscillator Mixe r 0 o 90 o Mixe r LPF LPF 20 MHz LPF Low pass filters chosen to be below 50MHz Nyquist criteria Act as anti-aliasing filters Switch added to handle multiple different antennas 2 sampling chains effectively samples the signal twice AD C AD C 100 MS/s ADC 2 Sampling chains

30 Signal Processing (PC) Receiver Path USRP Example RF Signal IQ Mixing Baseband RX 1 SMA Switc h BUS RX 2 SMA Amp 900 MHz Tunable Oscillator Mixe r 0 o 90 o Mixe r LPF LPF 20 MHz LPF AD C AD C 100 MS/s ADC 3.2 Gb/s 1 Gb Etherne t Data Rate Calculation: 100 Million Samples/sec x 16 bits/sample x 2 = 3.2 Gigibits/second BUS = 1 Gb Ethernet down-conversion is needed to ~ 25 MS/s or less.

31 RX Control Signal Processing (PC) Receiver Path: USRP Example RF Signal IQ Mixing Baseband RX 1 SMA Switc h FPGA BUS RX 2 SMA Amp 900 MHz Tunable Oscillator Mixe r 0 o 90 o Mixe r LPF LPF 20 MHz LPF AD C AD C 100 MS/s ADC Onboard Signal Processing Onboard Signal Processing 1 Gb Etherne t Data Rate Calculation: 100 Million Samples/sec x 16 bits/sample x 2 = 3.2 Gigibits/second BUS = 1 Gb Ethernet down-conversion is needed to ~ 25 MS/s or less.

Switc h Tunable Oscillator FPGA BUS RX 2 SMA Amp Mixe r 0 o 90 o LPF AD C Onboard Signal

32 RX Control TX Control Signal Processing (PC) Radio NI USRP System Diagram RX 1 TX SMA 1 Amp Mixe r 0 o 90 o LPF DA C Onboard Signal Processing Mixe r LPF DA C Onboard Signal Processing Switc h Tunable Oscillator FPGA BUS RX 2 SMA Amp Mixe r 0 o 90 o LPF AD C Onboard Signal Processing Mixe r LPF AD C Onboard Signal Processing Tunable Oscillator NI USRP-2920 System Diagram

33 NI USRP-2920 Hardware Diagram 5. Gain 1. Device Name 4. Antenna 6. # Samples/ Buffer 2. IQ Rate 3. Carrier Frequenc y Analog RF Transceiver Fixed Function FPGA PC

34 USRP Configuring in 6 Parameters 1. Device Name IP address of one or multiple USRP 2. IQ Rate Quadrature sampling rate, equivalent to bandwidth 3. Carrier Frequency Frequency of interest 4. Antenna Select which antenna port to receive from 5. Gain Amplification of signal before digitizing the signal 6. Fetch size how many samples to acquire each fetch

35 Power (db) NI USRP RF Receive Parameters IQ Rate ~ Bandwidth 1 MHz 50 MHz 94.7 MHz Frequency

36 Power (db) NI USRP RF Receive Parameters Carrier Frequency 1 MHz 50 MHz 94.7 MHz Frequency

37 Power (db) NI USRP RF Receive Parameters Gain 1 MHz 50 MHz 94.7 MHz Frequency

38 NI USRP RF Receive Parameters number of samples IQ 1 _ rate Time Domain * number _ samples fetch _ time

39 NI-USRP Driver Software Initialize Configur e Start Read IQ Stop Close

40 Exercise 1 buffered finite Acquisition

41 Demodulating Live FM Demodulate & listen to live FM radio LabVIEW programming fundamentals Integrating digital signal processing functions Using.m file script inside LabVIEW

42 Common Data Types Found in LabVIEW

43 Reviewing the Block Diagram Wire: Waveform Datatype Wire: Error Cluster

44 Waveform Data Type The waveform data type is used by LabVIEW to display and store periodic signal measurements. t0 Initial time of waveform dt Sample period Y Array of data samples Baseband IQ : Y is an array of complex numbers representing I and Q samples

45 Arrays An array consists of elements and dimensions Elements: data that make up the array Dimension: the length, height, or depth of an array Consider using arrays when you work with a collection of similar data and when you perform repetitive computations 49

46 Introduction to Clusters Data structure that groups data together Data may be of different types Analogous to struct in ANSI C Elements must be either all controls or all indicators Thought of as wires bundled into a cable Uses: Grouping variables Error handling Modulation toolkit

47 Loops While Loop Terminal counts iterations Always runs at least once Runs until stop condition is met For Loop Terminal counts iterations Runs according to input N of count terminal While Loop For Loop

48 Demodulating Broadcast FM Radio FM radio can be demodulated in 3 steps: 1. Detect carrier phase 2. Unwrap the phase (remove discontinuities) 3. Compute the derivative (change in phase frequency) Baseband IQ Demodulated FM Detect phase Unwrap phase Differentiate phase

49 Unwrapping Phase Polar numbers consist of magnitude and phase Phase values from -180º to 180º Discontinuities exist as phase wraps back around Unwrap phase to eliminate discontinuities

50 Exercise 2A Demodulate and Listen to FM Radio

51 Demodulated Broadcast FM Mono Audio Left + Right 19 khz Stereo Pilot Stereo Audio Left - Right RBDS Direct Band Audos Subcarrier 0 30 Hz 15 khz 23 khz 38 khz 53 khz 57 khz khz khz khz 92 khz 99 khz

52 LabVIEW Models of Computation Dataflow C HDL Code Textual Math Multi-Rate DSP Simulation Statechart LabVIEW LabVIEW LabVIEW LabVIEW `` Desktop Real-Time FPGA MPU/MCU Personal Computers PXI Systems CompactRIO Single-Board RIO Custom Design

m file script language Terminate statements with a semicolon to disable immediate output

53 Math with the LabVIEW MathScript Node Implement equations and algorithms textually Input and output variables created at the border Generally compatible with popular.m file script language Terminate statements with a semicolon to disable immediate output (Functions»Programming» Structures»MathScript) Prototype your equations in the interactive LabVIEW MathScript Window.

54 Frequency Demodulation Algorithm Detect phase Unwrap phase Differentiate phase

55 Exercise 3A Use a MathScript RT node

56 Communications Design in LabVIEW Modulation Toolkit Analog and Digital modulation formats AM, FM, PM ASK, FSK, MSK, GMSK, PAM, PSK, QAM Custom Visualization 2D and 3D Eye, Trellis, Constellation Modulation Analysis BER, MER, EVM, burst timing, frequency deviation, ρ (rho) Impairments Additive White Gaussian Noise (AWGN) DC offset, Quadrature skew, IQ gain imbalance, phase noise Equalization, Channel Coding, Channel Models

57 Exercise 3B Use Use Prebuilt IP

58 Digital Communications Explore a digital communications system Open and run a digital communications reference design Identify the part of a more advanced LabVIEW block diagram Overview of the modulation & demodulation process

59 Downconversion Demodulation Channel Decoding Source Decoding Source Coding Channel Coding Modulation Upconversion Digital Communication System Communications Channel

60 Digital Communication System NI Modulation Toolkit NI Modulation Toolkit

61 Digital Communication System NI Modulation Toolkit NI USRP NI Modulation Toolkit NI USRP

Communications Design in LabVIEW Modulation Toolkit Analog and Digital

Custom Visualization 2D and 3D Eye, Trellis, Constellation Modulation

Impairments Additive White Gaussian Noise (AWGN) DC offset, Quadrature

62 Communications Design in LabVIEW Modulation Toolkit Analog and Digital modulation formats AM, FM, PM ASK, FSK, MSK, GMSK, PAM, PSK, QAM Custom Visualization 2D and 3D Eye, Trellis, Constellation Modulation Analysis BER, MER, EVM, burst timing, frequency deviation, ρ (rho) Impairments Additive White Gaussian Noise (AWGN) DC offset, Quadrature skew, IQ gain imbalance, phase noise Equalization, Channel Coding, Channel Models

63 Advanced Digital Communications Topics

64 Packet-based Communication Link System Setup RF Signal Center Frequency: 915MHz Modulation Format: PSK packets Bit Rate: 400kbps NI USRP-2920 Transmitter NI USRP-2920 Receiver USRP control (Tx & Rx) Modulate Tx signal Demodulate Rx signal Reconstruct message

65 Packet-based Communication with LabVIEW

66 Packet Structure GUARD BAND SYNC SEQ PCKT NUM DATA PAD Field Length [bits] Description Guard Band 30 Allow initialization of Rx PLL, filters, etc Sync Sequence 20 Frame and Symbol Synchronization Packet Number 8 Range: Used for reordering of packets and detection of missing packets Data Variable length data field. Length detected dynamically at Rx end Pad 20 Allows for filter edge effects.

67 Transmitter Block Diagram

68 The Received Signal

69 Receiver Block Diagram

70 Demonstration : Packet Based Transceiver

Digital Communications Bundle Bundle Contents Two NI USRP-2920 + Toolkits MIMO Cable Digital Comm Lab Manual Target Courses Communication Systems

71 Digital Communications Bundle Bundle Contents Two NI USRP Toolkits MIMO Cable Digital Comm Lab Manual Target Courses Communication Systems Digital & Wireless Communications Software Defined Radio (SDR) Key Benefits Affordable Accessible NI Supported TX & RX Real RF Signals Scales to Research

Germany LabVIEW software and the NI USRP hardware are key components of this research project, allowing the team to

72 NI USRP Research Case Study: Cognitive Radio & Whitespace Large Scale Cognitive Radio Testbed Prototyping cognitive radio in LabVIEW Spectral sensing with blind detection Database driven geo-location with GPS Deployed in Munich, Germany LabVIEW software and the NI USRP hardware are key components of this research project, allowing the team to rapidly prototype and successfully deploy the first cognitive radio test bed of this kind. Dr. Paulo Marques, COGEU Aveiro, Portugal

NI USRP Research Case Study: Physical Layer

Murat Torlak Continuously monitoring multiple

802.11b beacon signals Identification of

73 NI USRP Research Case Study: Physical Layer Prototyping Dr. Murat Torlak Continuously monitoring multiple wifi channels Demodulation and descrambling of b beacon signals Identification of hotspots, tracking relative power levels Demodulate Descramble b SSID Decoding Carrier Detection Frequency Offset Estimation & Correction Demodulation & Descrambling Interpret the frame for SSID

74 Summary LabVIEW offers a graphical approach, shortening the design process, and tight hardware/software integration that allows for seamless transition from design to test NI provides a full spectrum of RF / Communications solutions: RF Test, Research and Education LabVIEW and NI USRP is an accessible, easy-to-use software defined radio platform

75 Next Steps Learn more about NI SDR and RF platforms Visit /sdr Download references from the Code sharing community Learn more about LabVIEW

76 NI LabVIEW Certifications Certified LabVIEW Architect Certified LabVIEW Developer On May 16 th, FREE Certified LabVIEW Associate Developer!! Certified LabVIEW Associate Developer

77 Thank you Questions

Spectral Monitoring/ SigInt

RF Test & Measurement Spectral Monitoring/ SigInt Radio Prototyping Horizontal Technologies LabVIEW RIO for RF (FPGA-based processing) PXI Platform (Chassis, controllers, baseband modules) RF hardware