21 feb 13 webcast

© 2013 Agilent Technologies

EW Testing: Capture, Measurement, and Emulation

Presented by: Walt Schulte, Agilent Technologies

© 2013 Agilent Technologies 2


Problem

• Jamming is a response to an identified radar signal

• Jamming techniques take time to work

• You must therefore capture and analyze an entire jamming event


Measurement Challenges: Dynamic PRI

1. 2.

• Signal Source: PRI increasing from 50 us to 100 us in 100 pulses

• Signal Analyzer: RBW < .3 x min PRF

Single sweep, delta marker:

PRF = 12.750 kHz Single sweep, delta marker:

PRF = 17 kHz



Measurement Challenges: Dynamic PRI

• Limited analysis time

• Scalar only: no doppler/phase

• Painful automation



Measurement Challenges: Dynamic Doppler

• Sweep times too slow relative to rate of doppler change

• Display shows a swept spectrum over entire sweep time


• Capture the Event

• Measure the Event

Solution

PXA

89600

VSA



Solution: Test Setup

DUT

(Jammer)

Agilent X-Series

Analyzer

LAN

Computer

w/Agilent 89600

VSA

• Digitize

• Record

• Analyze

Caution: Max. input

power +30 dBm (1 Watt)



Alternative Setup

DUT

(Jammer)

Agilent X-Series

Analyzer running

VSA internally

• Digitize

• Record

•Analyze

Caution: Max. input

power +30 dBm (1 Watt)



Agenda

Transmitter Test

• Capture

• Measurement

Receiver Test

• Emulation



Capture: Span/Record Length

1

10

100

1000

1 10 100 1000

Cap

ture

Len

gth

(sec)

Measurement Span (MHz)

PXA Capture Length vs. Span

Spanxfs 28.1



Capture: Span

rtBW /35.

devchirpBW -or-

1.

2. xBWfs 5

3. 28.1/sfspan

.35/30ns ~ 12 MHz

5 x 12 MHz = 60 MHz

60 MHz/1.28 = 46 MHz

46 MHz ~ 50 MHz


• Multiple options available

• Most flexible is “IF Mag”

• Use negative trigger delay

Capture: Triggering on the First Pulse

89600 VSA



Capture: Recording the Signal



Capture: Recording Length



Capture: Recording the Signal

Record

89600 VSA



Agenda

Transmitter Test

• Capture

• Measurement

Receiver Test

• Emulation



Measurement: J/S, PRI



Velocity Technique Measurement

Po

we

r

Dopp



Measurement: Frequency Resolution


Signal Processing So Far…

• Gated FFT

• Sample period of

15.625 ns

• Correspondingly, a 64

MSa/s sample rate

• We get much better

frequency resolution

through zero padding

5 us gate time. N = 5 us / 15.625 ns/Sa ~ 300 samples

300 samples padded out to 406,601 FFT points



Frequency Resolution

N

ff s 64 MHz / 409,601 ~ 150 Hz



Measurement: Gated Spectrum

GHzft cN 10,1

kHzft cN 822.4,



Using the VSA to Process Doppler

0 5 10 15 20 25 30 35 40-1000

0

1000

2000

3000

4000

5000

6000

Dop

ple

r (H

z)

Pulse Number

Carrier Frequency: 10 GHz



More Helpful Measurements: OBW

5 us PW, gated FFT of 900 MHz chirp



More Helpful Measurements: Band Power

Band Power Marker: Based on the OBW, how much jamming power is in-band?



More Helpful Measurements: Spectrogram



Deep-Memory Record / Playback

Record and Playback 100% of Long Duration RF Signals (No Gaps)

minutes days hours

+ High Fidelity Signal

Acquisition and Generation

Continuous Capture and Playback

Modern Equipment

S i g n a l R e c o r d e r s E x t e n d T i m e


Turning Data into Information

30

Record 100% of Signal Content (minutes, hours, days)

Identify Signals of Potential Interest

Replay “Interesting”

Portions

Analyze/ Demod

RF Environment

Take Appropriate Action

Raw Data

Info

“Stare” at spectrum for extended periods of time

Operate on very large data sets

Recreate with high signal fidelity

Leverage investment in existing signal analysis tools using open-format data files

X-Series + IQC

89601B

CPG + VSG

Spectro-X



Agenda

Transmitter Test

• Capture

• Measurement

Receiver Test

• Emulation


W H Y S I M U L AT E R A D A R F O R E W T E S T ?

EW Test Challenges • You need some way of determining whether the

jammer will respond to emitters known to be in a

particular theater

• Captured enemy radars are relatively rare

• Test ranges exist, but it’s expensive to fly and difficult

to schedule

• Flight testing occurs much later in the design process

Simulation Benefits • Cost effective

• Sufficient realism

• Time-efficient

• Test much earlier in the process


What Radar Parameters Should Be

Simulated?

• Antenna Properties

• Pulse Parameters

• Pulse Repetition Interval

• Power Levels


•Bore-Sight – Maximum gain of the

antennas main lobe or beam pointing at the

target.

•Bearing Angle - The bearing angle of the

target can be determined by moving the

antenna beam to the maximum return.

•Beam width – ½ Power points in the main

lobe measured in angular width AZ/EL

degrees.

•Side Lobe Level - the level of energy on

the side lobes relative to the main lobe or

beam

•Back Lobe – the energy emitting in the

opposite direction of the main beam.

A N T E N N A P AT T E R N P R O P E R T I E S A N D D E F I N I T I O N S


E X A M P L E 1 – C I R C U L A R A N T E N N A S C A N

(Elevation)

Degrees

Reciever

Vertical

Location

Receiver

Horizontal Location

(Azimuth) - Degrees

Circular ScanY

°

0°

+90°

+180°

+270°

Scan Rate RPM

X°


E X A M P L E 2 – C O N I C A L A N T E N N A S C A N Feed horn nutating in a small circular orbit


E X A M P L E 3 – B I D I R E C T I O N A L R A S T E R A N T E N N A S C A N


Amplitude seen by the jammer due to scan

38

N7620B Signal Studio for pulse building


Pulse Repetition Interval

Choice of PRI • Crucial for range or doppler

measurement

• Helps reduce

mainlobe/sidelobe clutter

• Helps eliminate ground moving

targets

• Reduces range/doppler

ambiguities, blind zones and

blind speeds

• Aids in power management

• Helps reduce POI

• Mode switching

EW systems use radar PRI for identification


PRI Switching

B A

C t

A B

rf

1

PW

Range

C

uR


Pulse Parameters

• Pulse width: affects average power for a given peak power, affects time-bandwidth product and range resolution

• Rise Time/Fall Time: affected by analog BW of the radar

• Modulation-on-pulse: chosen for range resolution desired

• Jitter: may be intentional to eliminate blind speeds or clutter, may be due to thermal fluctuations or system impairments from power supplies


Scenario Name

Source Parameters

Pulse Envelope properties – tr, tf, PW

Pulse Width Patterns

PRI Patterns

Modulation on Pulse Properties – Chirp, Barker, FSK, etc

Antenna Scanning Type

Antenna Radiation Type

Antenna Beam Width – AZ, El

Antenna Null Depth

Receiver Location

S C E N A R I O D ATA B A S E – I M P O R T I N G & E X P O R T I N G

Intelligence

Database Spreadsheet Simulation at RF (emulation)


Agilent N7620B Signal Studio

For Pulse Building Software

43

I Q

Features

• flexible GUI

• Complex pulse/PRI patterns/antenna scans

• wideband modulation on pulse

• corrected test signals

• .csv importing

• COM API



Summary

Transmitter Test

• Capture

• Measurement

Receiver Test

• Emulation



Summary

• More information can be found on our website:

www.agilent.com/find/pxa PXA Signal Analyzer

www.agilent.com/find/psg PSG Signal Generator

www.agilent.com/find/vsa 89600 VSA Software

www.agilent.com/find/n7620b Signal Studio for Pulse Building

www.agilent.com/find/n6171b MATLAB

www.agilent.com/find/xcom X-com systems

• The application note entitled “Making Wideband Measurements” (5990-

9108EN) is found here:

http://cp.literature.agilent.com/litweb/pdf/5990-9108EN.pdf

• VSA trial licenses available!

http://www.home.agilent.com/agilent/download.jspx?cc=US&lc=eng&nid=-

33713.958604&pageMode=DL

http://www.agilent.com/find/pxa

http://www.agilent.com/find/psg

http://www.agilent.com/find/vsa

http://www.agilent.com/find/n7620b



http://www.agilent.com/find/xcom




http://www.home.agilent.com/agilent/download.jspx?cc=US&lc=eng&nid=-33713.958604&pageMode=DL



21 feb 13 webcast

Documents

agilent technologies

agilent technologies

pxa capture length

signal record

negative trigger delay

signal source

entire sweep time

pulses signal analyzer