Page 171 - Radar Technology Encyclopedia

161 ECM, velocity-measurement ELECTRONIC INTELLIGENCE (ELINT)

ity-tracking gate by reradiating the target signal at a high jam-
Table E3
mer-to-signal ratio and then pulls the captured gate off the ECM against Tracking Radar
true target doppler signal. A primary tactic with VGPO is to
pull the doppler gate off and then momentarily shut off the ECM type Effects of ECM on ECCM techniques
jammer, forcing reacquisition of the target by the radar or radars
seeker. The doppler pull-off rate can be calculated to avoid Special jammers:
early recognition and counter by the victim, but spectral anal- · Blinking Upset AGC cir- Fast AGC, wide
ysis and audio indications can reveal the presence of VGPO (noise) jam- cuits, break track dynamic range
and, in the case of tracking radars and given enough time, mer (multiple SSJs) receivers
manual tracking can defeat the VGPO. Modern doppler · Skirt Saturate receiver Multiple track file
radars and missile seekers can be expected to contain effec- frequency maintenance
tive and automatic countermeasures to simple VGPO; for this jammer
reason, the technique is seldom used alone but is combined in · Image fre- Generate large Improved AFC, S
a repertoire of other deceptive jamming techniques. PCH, quency tracking errors or and D channel phase
SAL jammer break track matching
Ref.: Chrzanowski (1990), p. 123; Schleher (1986), p. 160. · Two- Generate large RF preselection filter
frequency tracking errors or
Table E3 jammer break track
ECM against Tracking Radar Chaff Prevent target Doppler filtering and
detection, false tar- MTI, multiple track
Effects of ECM on
ECM type ECCM techniques get generation file maintenance
radars
Passive decoys Generate false tar- Multiple track file
Barrage noise: gets, track file satu- maintenance
· SOJ Prevent target Low-sidelobe anten- ration
acquisition nas from Barton (1991), pp. 12.18–19.
Deny target range Sidelobe cancela-
· SSJ and ESJ tion, coherent inte- ELECTRONIC INTELLIGENCE (ELINT) is “informa-
gration, jammer tion that is the product of activities in the collection and pro-
strobe processing cessing, for subsequent intelligence purposes, of potentially
(track on jamming),
hostile, non-communications electromagnetic radiations
mainlobe canceler
which emanate from other than nuclear detonations and
(ESJ)
radioactive sources.” The primary ELINT activities collect
Spot noise: Deny target range, As above, plus wide
data on all types of radar, but navigation systems, command
SSJ and ESJ receiver saturation dynamic range
and control links, data links, and test range instrumentation
receivers
(telemetry) may be included as well.
Repeater (SSJ and ESJ):
ELINT data may be used in several different ways:
· Simple type Generate false tar- Multiple track file (1) Operational capability: to evaluate the operational capa-
gets (delay acquisi- maintenance, target bility of radar and associated equipment as revealed by an
tion), track file signature analysis
analysis of key observable radar characteristics and parame-
saturation
ters, including functions performed, modes, and performance.
· Range-gate Break track As above, plus (2) State-of-the-art assessment: by observing existing capa-
pull-off dynamic track
bilities and features and comparing these with past records, an
(RGPO) filtering
assessment of the technical progress made within a given
· Velocity-gate Break track As above, plus time period may be made. Also, a review of the key features
pull-off dynamic track
and performance may imply future trends and the ability to
filtering
pursue certain technological radar solutions.
· Cross-polar- Generate large Planar antennas and (3) Electronic order-of-battle: wide-area electronic surveil-
ization jam- tracking errors or radomes, polarization
lance can result in an accurate, timely geographically based
mer break track diversity
inventory of a potential enemy’s radar deployment. Such an
· Cross-eye Generate large Multiple-phase-cen- inventory may reveal potential strategic options available to
jammer tracking errors or ter antennas, sepa-
the potential enemy, or indicate changes in strategic or tacti-
break track rate transmit and
cal intent.
receive antennas
(4) Electronic countermeasures (ECM): all of the uses indi-
· Surface- Generate large Narrow-beam anten-
cated above may serve to materially assist the ELINT host
bounce tracking errors or nas, target signature
party in the development of new ECM techniques and equip-
break track analysis
ment that may be required to respond effectively to observed