This document discusses software defined radios (SDR) and challenges in testing SDR systems. SDRs use reconfigurable hardware and software to support different wireless functions and standards. Testing SDRs is challenging due to the mixed-signal nature and potential for impairments throughout the system. Software defined instruments on a PXI platform can test multiple standards using one hardware configuration by changing software. MaxEye Technologies provides SDR test and measurement solutions using National Instruments hardware and LabVIEW to generate and analyze signals for various digital video standards.

1. SDR System Level Test Challenges and
Measurement Solutions

2. SDR Overview
 SDR is a set of Hardware and Software technologies providing reconfigurable
architectures for network and wireless terminals.
 The purpose is therefore to use the same Hardware for different functions, through a
dynamic configuration according to the operational context.
 SDR provides an efficient and comparatively inexpensive solution to the problem of
building multi-mode, multi-band, multi-functional wireless devices that can be
enhanced using software upgrades
 Software-defined radios (SDR) utilize a combination of FPGAs, DSPs and analog/RF
designs to achieve the radio’s system performance.
 The mixed-signal nature of these SDR designs can introduce system integration
testing complexities when the baseband hardware and RF hardware are integrated
and tested together.
 SDR’s overall system performance can be impacted by an accumulation of
baseband, analog and RF design impairments, which can make issues difficult to
isolate in the system integration testing phase.

3. SDR Block Diagram

4. SDR Test Challenges
 Many factors can contribute to error along the mixed-signal transmitter chain and in
turn, affect waveform quality and the SDR’s overall error vector magnitude (EVM)
performance.
 EVM is a measure of waveform quality and is typically used as a metric for wireless
transmitter performance.
 For example, the D/A converter may introduce nonlinearities and the D/A converter clock
may introduce jitter.
 Additionally, local oscillator (LO) phase noise, IF/RF filters, and nonlinear gain/phase
distortion from the IF/RF up-converter and power amplifier may introduce waveform
distortion to the SDR’s EVM performance.
 Need for instrumentation capable of working across the digital and RF elements in the SDR
design, and that allows for probing at every stage along the mixed-signal chain.
 Need for software-defined approach to instrumentation by using coding and modulation
software to generate and measure signals through modular, general-purpose RF
instrumentation.

5. Software Defined Instruments
 Software Defined Instruments (SDI) perform signal analysis and measurements in the
software that are performed in the hardware traditionally using one embedded processor for
each standard.
 Using SDI we can perform multiple standard measurements using one hardware.
 PXI platform is ideal for SDR testing as it is PC-based and SDR multimode testing can be done
using single hardware.
 The functionality of PXI instruments is defined in software so a single PXI RF instrument can
test multiple communications standards by simply changing the software running on the
system controller.
 PXI controllers employing the latest dual-core and quad-core processors can easily process
the most complex communications algorithms.
 As communications standards continue to scale the amount of data transferred, it is
important to base a communications test platform on a high-throughput bus to transfer the
data.
 PXI is based on the PCI and PCI Express buses, providing up to 12 GB/s of system bandwidth.

6. NI PXI RF Platform
 With the modular nature of PXI, you can upgrade a single component of a system. For example,
you can increase the performance of all of the instruments in a PXI system by upgrading to a
controller with a higher-performance processor.
 This type of upgrade is not possible with stand-alone instruments where the embedded
processor is not user-accessible or upgradable. Moreover, because PXI is a multivendor
platform, the modular components of a system can come from multiple vendors.

7. SDR Multimode Transmitter Testing
• SDI enables user to perform measurements at various stages in SDR transmitter chain. For e.g., digital baseband IQ before
DAC and analog IQ after DAC, analog IF and RF output signals can be measured and analyzed using single instrument.
• This enables probing and debugging the complete SDR transmitter signal chain to verify the performance of the individual
components.
• Modulation Accuracy Measurements
– Error Vector Magnitude (EVM)
• Average and Peak EVM Results
– Frequency Offset
– Clock Offset
– IQ Gain Imbalance
– Quadrature Skew
– IQ Offset (Carrier Leakage)
– Channel Frequency Response
– Modulation Error Ratio (MER)
– Average and Peak Power
– Various Measurement Traces (EVM vs Symbols, EVM vs Subcarriers, Constellation Graph, Spectral Flatness)
• Spectral Measurements
– Channel Power
– Adjacent Channel Power
– Spectral Emission Mask

8. SDR Multimode Receiver Testing
• SDI enables user to perform receiver measurements at various stages in
SDR Receiver chain. For e.g., digital baseband IQ after ADC and analog IQ
before ADC, analog IF and RF output signals can be given as an input to the
Receiver.
• This enables probing and debugging the complete SDR Receiver signal
chain to verify the performance of the individual components.
• Receiver Measurements
– Receiver Sensitivity Measurements
• BER before and after channel coding
• PER (Packet Error Rate) or FER (Frame Error Rate)
– Maximum Input Level
– Power Control
– Receiver Selectivity

9. MaxEye Digital Video Test and Measurement Solutions
 MaxEye Technologies Digital Video Test and Measurement solutions are powered
by National Instruments LabVIEW software, NI RFSG (NI PXI 5673/5673E, NI PXI
5672) and NI RFSA (NI PXI 5663/5663E, NI PXI5661)Hardware.
 Enables testing of multiple digital video and audio standards testing using one NI
PXI RF hardware. Ideal solution for multimode Digital Video SDRs.
 The following are the digital video broadcasting toolkits currently being supported
by MaxEye Technologies.
• DVB-T /H
• DVB-T2
• ISDB-T/Tb
• CMMB
• DTMB
• ATSC and ATSC-M/H
• DAB/DAB Plus/T-DMB
• DRM/DRM Plus
• DVB-S (under development)
• DVB-S2 (under development)

10. Product Overview
 MaxEye Digital Video Signal generation software is an ideal test tool for generating
the test signals with different configurations to completely test the receiver during
design, verification and manufacturing floor to characterize the receiver
performance.
 MaxEye Digital Video analysis toolkit is an ideal tool for analyzing the signal quality
of the transmitted signal.
 Toolkit provides various measurement traces to enable the engineers to analyze,
troubleshoot and validate the transmitter signal issues.
 The toolkit measurements can be used to calibrate the Digital Video Transmitter
components.
 The MaxEye Digital Video analysis toolkit provides standard based modulation
accuracy, power measurements and spectral measurements to enable engineers
for evaluating, designing, manufacturing transmitters, amplifiers, tuners,
repeaters, modulators and gap-fillers.

11. Product Features - Generation
 Real time streaming of the generated waveform using NI RFSG streaming mode.
This enables testing of the receiver continuously for hours. (Typical DTG testing
requires 5 minutes of video to be played in real-time)
 Multi-carrier signal generation – Generation of multiple DVB carriers using single
NI RFSG. This reduces the complexity of the test setup and test automation
simpler.
 MaxEye test and measurement solution enables user to do the following tests
 Receiver Design, Verification and Manufacturing Tests
 Receiver Functionality Tests
 RF Components and Transmitter Testing
 Supports MPEG TS file as an input to the toolkit for testing the video and audio
quality of the receiver. The TS file bitrate is adjusted according to the signal
configuration.

12. Product Features - Analysis
 Supported Measurements
 Modulation Accuracy Measurements
 Data MER, Pilot MER
 Data EVM, Pilot EVM
 Peak EVM, Peak EVM Symbol Position, Peak EVM Subcarrier Position
 Frequency Offset
 Clock Offset
 IQ Gain Imbalance, Quadrature Skew
 Carrier Suppression
 Constellation Trace
 EVM vs Symbols, EVM vs Subcarriers Trace
 Channel Frequency Response (Spectral Flatness)
 Average and Peak Power
 Spectral Measurements
 Channel Power
 Adjacent Channel Powers
 Spectral Emission Mask

13. Generation Front Panel

14. Analysis Front Panel

15. For more information about our products and services
please contact
ramesh@maxeyetech.com
Phone: +91 9448067717
info@maxeyetech.com
Visit our website
www.maxeyetech.com