JED - April 2014 - 52

E W101
RCS chamber or by computer simulation. Such data can also be measured
in an operational environment, but
like all such "open air" data gathering, it is challenging to separate the
desired data from the environmental
conditions.
As shown in Figure 1, the collected data is processed using special
software to determine the dominant
scattering points. The return from
each of these scattering points is
characterized in terms of its phase,
amplitude, Doppler shift and position
as a function of the aspect angle.
This data is stored in a data base from
which DRFM channels can be driven
to generate an accurate, dynamic
target return.

CONTROL
A/D

MEMORY

D/A

DOPPLER
MODULATOR
C
O
M
B
I
N
E
R

CONTROL
A/D
FROM
RCVR

MEMORY

D/A

DOPPLER
MODULATOR

X

X

TO
XMTR

CONTROL
A/D

MEMORY

D/A

DOPPLER
MODULATOR

LO

DRFM CONFIGURATION

The Journal of Electronic Defense | April 2014

52

Figure 2 is a block diagram of an
older DRFM system designed to genFigure 2: Older systems can generate complex targets with multiple DRFMs, each of which can replicate
erate complex false targets. There are
one or two scatterers.
multiple DRFM cards, each of which
can generate one or two returns. Each DRFM digitizes the signal
dynamic scenarios depicting various targets through many typiinput from a receiver and modifies it to represent the return from
cal engagements. These testing scenarios must include realistic
the target's scatterers. The output has the proper amplitude,
multi-point scattering returns with the proper amplitude, phase
phase and Doppler shift for its assigned scattering point (see
and position characteristics to test all of the radar's hardware
Figure 3). It also has a time delay appropriate to the distance
and software features.
from the radar with the current target aspect angle. The RF
outputs of the DRFMs are combined and coherently retransmitWhat's Next
ted to the target radar.
Next month, we will discuss EA against frequency-hopping
radars. For your comments and suggestions, Dave Adamy can
With the introduction of FPGAs, a single DRFM board can
be reached at dave@lynxpub.com. a
generate returns for 12 scattering points. Each scattering point
signal has a unique modulation that
has the Doppler shift and range delay
appropriate to its relative location
in the current target orientation
with the current velocity and three
dimensional angular velocities.
DOPPLER
RANGE
MODULATOR
Each of these scattering point
GENERATOR
DELAY
channels also applies the modulaQUADRATURE
FROM
A/D
GENERATION
RCVER
tion required to perform the applied
C
DOPPLER
RANGE
O
MODULATOR
deceptive jamming technique, which
GENERATOR
DELAY
M
must be different for each point to
B
D/A
I
TO
fool the jammed radar.
DOPPLER
RANGE
GENERATOR

MODULATOR

DELAY

JAMMING AND RADAR TESTING
This discussion has been presented in terms of deceptive jamming, but it can be equally important
for the testing of modern radars.
In order to test a radar that has
processing capable of detecting complex radar returns, it is, of course,
necessary to generate accurate

DOPPLER
GENERATOR

MODULATOR

N
E
R

XMTR

RANGE
DELAY

Figure 3: A single DRFM unit with FPGA technology can emulate 12 scatterers, with control and Doppler
shift functions on the board.



JED - April 2014

Table of Contents for the Digital Edition of JED - April 2014

The Monitor
Washington Report
World Report
Interview: Rich Sorelle
The Electromagnetic Battle Management (EMBM) Challenge
Technology Survey: Radar Jammers
Show Preview: EW Europe 2014
The View From Here
Conferences Calendar
Courses Calendar
From the President
EW 101
AOC News
Index of Advertisers
JED Quick Look
JED - April 2014 - cover1
JED - April 2014 - cover2
JED - April 2014 - 3
JED - April 2014 - 4
JED - April 2014 - 5
JED - April 2014 - The View From Here
JED - April 2014 - 7
JED - April 2014 - Conferences Calendar
JED - April 2014 - 9
JED - April 2014 - Courses Calendar
JED - April 2014 - 11
JED - April 2014 - From the President
JED - April 2014 - 13
JED - April 2014 - 14
JED - April 2014 - The Monitor
JED - April 2014 - 16
JED - April 2014 - 17
JED - April 2014 - 18
JED - April 2014 - 19
JED - April 2014 - 20
JED - April 2014 - 21
JED - April 2014 - 22
JED - April 2014 - 23
JED - April 2014 - Washington Report
JED - April 2014 - 25
JED - April 2014 - World Report
JED - April 2014 - 27
JED - April 2014 - Interview: Rich Sorelle
JED - April 2014 - 29
JED - April 2014 - The Electromagnetic Battle Management (EMBM) Challenge
JED - April 2014 - 31
JED - April 2014 - 32
JED - April 2014 - 33
JED - April 2014 - 34
JED - April 2014 - 35
JED - April 2014 - 36
JED - April 2014 - 37
JED - April 2014 - 38
JED - April 2014 - 39
JED - April 2014 - 40
JED - April 2014 - Technology Survey: Radar Jammers
JED - April 2014 - 42
JED - April 2014 - 43
JED - April 2014 - 44
JED - April 2014 - 45
JED - April 2014 - 46
JED - April 2014 - Show Preview: EW Europe 2014
JED - April 2014 - 48
JED - April 2014 - 49
JED - April 2014 - 50
JED - April 2014 - EW 101
JED - April 2014 - 52
JED - April 2014 - 53
JED - April 2014 - AOC News
JED - April 2014 - 55
JED - April 2014 - 56
JED - April 2014 - Index of Advertisers
JED - April 2014 - JED Quick Look
JED - April 2014 - cover3
JED - April 2014 - cover4
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