JED - December 2013 - 28

The Journal of Electronic Defense | December 2013


in the general direction of the threat, "in
order to direct a more precise countermeasure or counterfire toward a threat, you
had better know its location with much
greater accuracy." The response speed of
the detector is also critical in order to
provide timely target-type and friendor-foe information.
Although the HARLID sensor is considered an appropriate solution for detecting individual pulses from multiple lasers
simultaneously and accurately determining their location, laser warning systems
specifically designed to detect beam-rider
threats will use a different sensor technology which, as described by Desfonds,
may in some cases be avalanche photodiodes (APDs) fabricated in either InGaAs or
Silicon, depending on the specific requirements of the customer. APDs can have a
detection range between 0.4 and 1.1 μm
with a wide range of sensitivity and speed.
As explained by Desfonds, "The more
sensitivity you have, the more sensitive
you are to the baseline or environmental
light as well, but, given that it's often
a question of life and death whether
your system detects the person that's
targeting you or not, everyone usually
wants us to push the sensitivity to the
maximum, wherever possible, to get that
last little photon of light." In the end,
he observes, it will always come down to
a tradeoff, and be up to the final system
designer to mix and match the sensor
capabilities and sensitivities of PINs
and APDs to best meet the requirement.
"Beyond the sensors, there is a lot of
art involved in how you process these
signals and how you make decisions to
trigger the right responses."
Desfonds says one of the biggest challenges he sees ahead for sensor technology is cost. "These are complex systems
to build, requiring great precision, such
as plus or minus 0.8-degree AOA accuracy.
But, at the same time, there's significant
disparity in the types and value of the
platforms customers are looking to protect, ranging from multi-million dollar
aircraft to individual light-armored vehicles, to perhaps protection for unmanned
vehicles and drones. Although we've succeeded in being able to cost-effectively
manufacture these high-end devices in
volume, there's still a transition point
in terms of cost and budget pressures

where we need to talk about lower-end
equipment with less resolution in order
to meet cost limitations."
ISR's Gephart agrees. "Over time, we're
seeing semiconductor laser technology
advancing steadily, but in addition to
keeping pace with the capabilities of
emerging threats, we also have to continually take advantage of new technology that can help drive down size,
weight, power (SWAP) and ultimately
cost." Along these lines, he says a major
principle behind their detector technology development is achieving as much
commonality of design as possible, with
technologies that can support multiple
applications, platforms and operational
domains. He also points out that another
cost-addressing feature of their systems is
that they're compatible with the Multiple
Integrated Laser Engagement System, Airto-Ground Engagement System II (MILESAGES II) training system, which allows
them to be used in simulated tactical
combat exercises and significantly reduce
training overhead costs. The training system is used by the US military and other
armed forces around the world.
In terms of the evolving threat,
Desfonds says they are indeed seeing
more and more laser systems operating
in the longer wavelenth (2 and 3 μm) range
which allow them to be used more stealthily on the battlefield. As a result, Excelitas
has already begun working internally to
develop longer wavelength capabilities
through different chip technologies. "The
HARLID was designed from the outset to
be upgradeable, and future versions will
likely offer extended range capabilities."

Rotary-wing aircraft were among
the first platforms to receive the benefits of laser warning technology. And
today, according to Erich Wagenbauer,
Key Account Manager, Airborne SelfProtection Division of Cassidian (Ulm,
Germany), a division of EADS, "laser
warning systems are even more important
for protection and situational awareness,
especially in the asymmetric battlefield."
Cassidian makes the Advanced Laser
Threat Alerting System (ALTAS)-2QB
system fielded on German Army CH-53
helicopters as well as other aircraft, and
perhaps most revealing regarding the size
and scope of the threat, is Wagenbauer's
observation that "users of the system
have actually learned through its use
that there are many more laser threats
on today's battlefield than they thought.
And the number is still growing."
The ALTAS-2QB detects laser rangefinders and target designators in the 0.5 -
1.65 μm range as well as missile beamrider
threats from 0.8 - 1.1 μm. Its sensitivity is
less than 15 W/m2 for rangefinders and designators, and less than 1 mW/m2 for beamriders, with a false alarm rate of less than
one per eight hours. The system can be
integrated with an onboard Defensive Aid
Subsystem (DAS) to deliver pre-processed
laser threat information for pilot display
and deployment of countermeasures, as
well as with the EADS' Airborne Missile
Protection System (AMPS).
In the US, ISR Systems' AN/AVR-2B is
the standard laser warning system for all
US Army helicopters and is also fielded
on a number of US-made helicopters in


JED - December 2013

Table of Contents for the Digital Edition of JED - December 2013

The View From Here
Conferences Calendar
Courses Calendar
From the President
The Monitor
World Report
Seeing the Light: Laser Warning Systems Facing Increasingly Lethal Threats
2014 EW/SIGINT Resource Guide
EW 101
AOC News
Index of Advertisers
JED Quick Look
JED - December 2013 - cover1
JED - December 2013 - cover2
JED - December 2013 - 3
JED - December 2013 - 4
JED - December 2013 - 5
JED - December 2013 - The View From Here
JED - December 2013 - 7
JED - December 2013 - Conferences Calendar
JED - December 2013 - 9
JED - December 2013 - Courses Calendar
JED - December 2013 - 11
JED - December 2013 - From the President
JED - December 2013 - 13
JED - December 2013 - 14
JED - December 2013 - The Monitor
JED - December 2013 - 16
JED - December 2013 - 17
JED - December 2013 - 18
JED - December 2013 - 19
JED - December 2013 - 20
JED - December 2013 - 21
JED - December 2013 - 22
JED - December 2013 - 23
JED - December 2013 - World Report
JED - December 2013 - 25
JED - December 2013 - Seeing the Light: Laser Warning Systems Facing Increasingly Lethal Threats
JED - December 2013 - 27
JED - December 2013 - 28
JED - December 2013 - 29
JED - December 2013 - 30
JED - December 2013 - 31
JED - December 2013 - 32
JED - December 2013 - 2014 EW/SIGINT Resource Guide
JED - December 2013 - 34
JED - December 2013 - 35
JED - December 2013 - 36
JED - December 2013 - 37
JED - December 2013 - 38
JED - December 2013 - 39
JED - December 2013 - 40
JED - December 2013 - 41
JED - December 2013 - 42
JED - December 2013 - 43
JED - December 2013 - 44
JED - December 2013 - 45
JED - December 2013 - 46
JED - December 2013 - 47
JED - December 2013 - 48
JED - December 2013 - 49
JED - December 2013 - EW 101
JED - December 2013 - 51
JED - December 2013 - 52
JED - December 2013 - 53
JED - December 2013 - AOC News
JED - December 2013 - 55
JED - December 2013 - 56
JED - December 2013 - Index of Advertisers
JED - December 2013 - JED Quick Look
JED - December 2013 - cover3
JED - December 2013 - cover4