rf streaming, analysis and playback in aerospace & defense ...aerospace & defense symposium...

© 2012 Agilent Technologies

Aerospace & Defense Symposium

RF Streaming, Analysis and Playback in Aerospace & Defense Applications

Presented by: Jim Taber, X-COM Systems



2© 2012 Agilent Technologies


Agenda

Interference in Many Forms

Use-Cases in Long-Duration Interference Testing

Challenges with Traditional Approaches

Alternative Approaches to Long-Duration Interference Testing

Tools for Interference Testing

Case Study

Mitigation Strategies

Summary



3

Interference Comes in Many Forms

• Not always easy to see or determine the culprit

• Alternative approaches may be required

Signal Processing Tools are Often Required

• Understand the nature of the interference

• Understand its impacts on system performance

Captured Interference is Information

• Provide undeniable proof of what actually happened

• Use to stress and margin test victim receivers

Interference Test





Interference

Photo: Courtesy of the LA Times

\ˌin-tə(r)-ˌfir\ : to hinder or impede; come into collision or be in opposition





The Need for Interference Test

Radio

Conversations

Telemetry

Links

Flight

Range Ops

System

Interoperability

SIGINT

Spectrum

Monitoring

Required: Seconds, Minutes or Days of Seamless RF Signal Capture



6

Interoperability

• Design compliance – vendor adherence

to a published standard

• Margin testing - Receiver performance

in presence of interference

Compatibility

• Operational compliance – Transceiver

performance in the presence of other

mission critical RF assets

• Impacts from and on other RF assets

Goals of Interference Testing





Jammer

Interference in Many Forms

In-BandOut-of-Band

In

Channel

Out of

Channel

Co-ChannelAdjacent

Channel

Noise Floor

Fundamental

Harmonic

High Power Tx

Intermodulation

Culprits• Co-Channel

• Adjacent Channel

• PIM and Rx De-sense

• Harmonics/Spurs

• Deliberate Jamming

Victim





Use-Cases for Interference Test

#1. Record in theater and playback in the lab

• Characterize the nature of interference

– 100% capture provides understanding of who, what, when and where

– Record environment at victim and culprit locations simultaneously

– Extract and post-process interesting portions from long-duration captures

• Replay and Simulate environment using real-world signals

– Test receiver in presence of interference

– Evaluate mitigation techniques





Use-Cases for Interference Test

#2. Record in the lab and playback in the lab

• Compatibility testing during long-duration integration test

• Anechoic chamber and direct inject measurements

#3. Create in the lab and playback on the range

• Interoperability testing

• Single and multi-channel environment simulation





Challenges with Traditional Approaches

ADC DSP RAM µP

Display

RF

Input

If the system fails to capture the event, it’s gone forever

Signal Analyzer Block Diagram

(simplified)

PreselectDown-

ConvertDigitize Store Process

• Monitoring stops while the receiver is post-processing

• Events lasting longer than the available memory are lost

• Trigger settings valid only for one set of conditions

Continuous

Processing

Batch

Processing

Real-Time LVDS Interface





Interference Testing – Alternative Approach

for Long-Duration Signals

RF Down Conversion

Signal Playback

Waveform Digitization

Signal Capture

Data Formatting& Storage

RF Up Conversion

Waveform Generation

Signal Analysis &

Signal Creation

• Vector Signal Analyzer w/

Streaming IQ Interface

− Broad frequency coverage

− Wide acquisition bandwidth

− High dynamic range

• IQ Data Recorder−Real Time Data Tagging

−High Speed Offloading

−Data Protection

• Visualize & ID Signals

• Replay Very Large Files

• Create New Signals from

Original Data

• Convert Digital IQ to Analog

• Vector Signal Generator

− Broad frequency coverage

− Wide bandwidth IQ

− High dynamic range

Analyze and Simulate

100% Capture, Analysis, Simulation and Replay RF Data





MXG


Capture

Stream Digital

I/Q Samples

LVDS

Playback

Analog

Base Band Generation

I

Q

PXA

MXA

EXA

PSG

ESG

IQC CPG

or

or

or

or

Analog

Record and Playback Real-Life Signals with Exceptional

Signal Fidelity Using Agilent VSAs and VSGs

Victim

SW Tools

Spectro-X

89600B

RFEditor

Matlab

Analyze & Simulate

Datapack (2-16TB)





MXG


Gapless Capture

IF Out

Non-Streaming Playback

I

Q

PXA PSG

ESG

PXI Chassis PXI QARB [optional]

or

or

Analog

For Wider Streaming Bandwidths up to 100MHz Use the

PXI Digitizer, embedded controller and RAID drive

Victim

SW Tools

Spectro-X

89600B

Dataviewer

Signal Studio

IQ ToolsAnalyze & Simulate

100MHz BW*

M9036A

embedded

Controller

M9021 PCI interface

M9202A 2GSa/s

Digitizer

JMR 32TB

RAID

M9330A AWG





SW Tools for Interference Testing

Spectro-X Signal Analysis Software

• Visualize stored data as a “Motion Picture”

• Search engines to ID and fingerprint waveforms

• “Clip and Save” for replay in Agilent VSA SW

89600B Vector Signal Analysis Software

• Supports over 75 standards and modulation types

• Bit-level modulation analysis

RF Editor Signal Creation Software

• Create new signal scenarios from recorded files

• Clip, stitch, translate, filter and loop waveform libraries

89600B VSA Software

Spectro-X Analysis

RF Editor Software



15

Case Study – Interference Test

• 10 Minutes of Continuous Capture

• Visually Inspect for Interference

• Zoom into Interesting Time Ranges

• Signal Process

Region #1

Region #2

Region #3

PXA

IQC-2110

Datapack

Spectro-X

LVDS

SAS





Case Study – Time Range 1

Select Time of Interest

Question: How often do

signals like this one occur?

Spectrogram

Zoomed

Spectrogram

Zoom on Signal of Interest

IEEE 802.11b

Analyze Signal of Interest

88 µs

Time Overview



17

Case Study – Region 1 Interference

Carrier Search

• Finds all signals above a

specified power threshold

• Prune results to isolate

signals of interest

17

Find Everything Sort on Signal

Characteristics



18


Carrier Search

• 137,000 total carriers found over

time range

Search Pruning

• 5,000 matching our criteria for

hopping radio

Carrier Statistics

• Center Frequency

• Bandwidth

• Start Time

• Duration

• Power

Spectrogram for each Result

Hop Freq vs Time

10.2 Seconds



19


Region #2Culprit Easy to See

Questions:

• What’s the interfering signal?

• What’s the impact on the

801.11g signal quality?

Time Overview



20


Wireless Standard Search

• Correlate training sequence in

wireless standards

• User-definable carrier frequency and

correlation

• Stepping allows searching “near”

specified carrier frequency



21


Wireless Standard Search

• 92,000 instances of IEEE

802.11a/g found

Good

Correlation

Poor

Correlation

Interference of Reference Sequence

Question: What’s the impact

on this 802.11g signal?

Reference

Sequence

Interferer

Reference

Sequence

Payload



22


89600B: Time before Interference 89600B: Time during Interference

Extract Portions of Dataset for Time-

Correlated Vector Signal Analysis with

89600B VSA Software

Spectro-X Spectogram

45 dB



23


Region #3

Questions:

• How many instances occurred?

• Which ones are not like the

others?

Zoom on Signal of Interest

Signal appears to be a 10 MHz LFM Chirp

Spectrogram

Zoomed

Spectrogram

Time Overview



24


Arbitrary Waveform Search

• Find occurrences of signals that look

like a reference waveform

• Reference can be extraction from

data set or simulated (e.g. Matlab)

• User-definable correlation and

carrier frequency

Reference Waveform






Arbitrary Waveform Search

• 20,000 occurrences matching the reference

“Good” Pulse 99% Correlation

“Bad” Pulse 21% Correlation



26


-75

-60

-45

-30

-15

0

Ma

gn

itu

de

(d

Bm

)

Relative Freq (MHz)

-20 -16 -12 -8 -4 0 4 8 12 16 20

Re

lati

ve

Tim

e (

µs

ec

)

0

5

10

15

20

25

30

35

40

45

50

Time Origin

00:00:0.078028

Freq Origin

2 GHz

Spectrum Phase v Time

Freq v TimeAmplitude v Time

Export Pulse to 89600B VSA SW to Show Why its Different





Case Study – Interference Results

Region #1

• Found 137,000 total carriers

– Pruning extracted frequency agile radio with 5,000 hops

– Hopper operated for 10.2 seconds starting 11:31am

– Hop pattern was extracted and plotted using Excel

Region #2

• Identified an IEEE 802.11g transmission

– Interferer began disrupting communications at 11:34 am for 5 seconds

– 89600B VSA analysis found that EVM went from 2.6% when interference was not present to nearly infinite when the interferer was present

Region #3

• Located 20,000 occurrences of an arbitrary carrier that looked like a LFM radar chirp

– Correlation analysis found that one pulse looked different (21% match) at 11:38:46.692am

– 89600B VSA analysis found that this was a 10.7us wide non-linear chirp

Region #1

Region #2

Region #3





Mitigation Strategies

Filtering – Improve receiver preselection

Shielding – Reduce impact of culprit radiation

Spatial Separation – Take advantage of path loss

Re-banding – Find compatible open channels

Temporal Compliance – Timing of culprit and victim

PIM Studies – ID interference and use hand-held tools to locate

Margin Testing – How much is enough to mitigate interference effects



29

Tools – Signal Editing and Creation

Choose Recordings

From Library

Loop segments

at specific

intervals

Add frequency shifted

copies of original signal

Filter signals to

reduce transition

transients

Create composite IQ file

Independent, parallel

tracks can be precisely

time synchronized

Build New Scenarios from Existing Recordings



30

Extract time segment of “good” WLAN operation (no interference)

Overlay the interference waveform

Build new signal environment to simulate and test

• Attenuate culprit

• Sum with “good” WLAN signal

• Simulate scenario and replay into victim receiver

Mitigation Example for 802.11g Interference



31


EVM still impacted, but

worse-case acceptable






Datapack

IQC-2110 CPG-2110

Vector-PSG

Create RF Environments using Recorded Waveforms

• IQC-2110 formats data for replay by CPG-2110 baseband generator

• CPG-2110 generator converts signal from digital IQ to analog IQ

• Vector PSG up converts the IQ waveform to carrier frequency

Victim

Rx

LVDS



RF Interference – Video

http://www.youtube.com/watch?v=IiWP7xuYuJw&feature=player_embedded

http://www.youtube.com/watch?v=IiWP7xuYuJw&feature=player_embedded





RF Signal Capture

X-SeriesAgilent X-Series Vector Signal Analyzers

• Widest frequency coverage 3.6 to 50 GHz

• Up to 40 MHz streaming bandwidth (160 MHz internal)

• High dynamic range – what you see, is what you record

X-COM RF Signal Recorder• Plug-compatible with Agilent X-Series VSAs

• Over 10 hours of continuous recording at 40 MHz

analysis bandwidth

• Inputs for data markers, IRIG-B timing and GPS tags

IQC-2110





X-Series Option Configurations for

Streaming to X-COM Signal Recorders

Streaming

BW

PXA

(N9030A)

MXA

(N9020A)

EXA

(N9010A)

40 MHz

B1X + MPB

or

B40 + MPB

B40 + MPB B40 + MPB

25 MHz B25 B25 + DP2 B25 + DP2

10 MHz DP2 DP2

Note: Option B1X provides 160 MHz analysis BW internal to instrument

Option MPB is required for 40 MHz, recommended for 10 and 25 MHz options





RF Signal Playback

PSG – E8267DAgilent PSG, ESG and MXG Vector Signal Generators

• Broad frequency coverage from 100 kHz to 44 GHz

– Playback recording at original or arbitrary carrier

– High fidelity IQ modulator for realistic signal

simulation

X-COM Continuous Playback Generator

• IQ outputs drive Agilent VSG

• 16 bit I and 16 bit Q, baseband outputs

• Supports continuous playback of up to 150 MHz wide

signals

CPG-2110





E8267D

RF Signal Capture / Playback

Agilent PXIe Digitizer

• Directly Digitize X-Series IF outputs

• 50 MHz and 100 MHz recording bandwidths

• Search and Analyze captures in Spectro-X

• Cost-Effective Solution

Agilent AWG and Vector Signal Generator

• Replay interesting signals up to 1 GHz wide

• 16 MS of on-board memory

M9202A

M9330A

+

N9030A

+



38

Interference Comes in Many Forms

• Not always easy to see or determine the culprit

• Alternative approaches may be required

Signal Processing Tools are Often Required

• Understand the nature of the interference

• Understand its impacts on system performance

Captured Interference is Information

• Provide undeniable proof of what actually happened

• Use to stress and margin test victim receivers

Interference Testing Summary

Photo: Courtesy of Flickr.com





Q&A





RF Streaming Contacts

X-COM Systems

Jim Taber

Director of Sales & Marketing

+1 571-612-5490

[email protected]

www.xcomsystems.com

Agilent Technologies

John Hansen

Senior Applications Engineer

+1 707-577-4721

[email protected]

www.agilent.com

mailto:[email protected]

http://www.xcomsystems.com/

mailto:[email protected]

http://www.agilent.com/

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