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Case Study: ITT’s Dual I2 & IR Enhanced Night Vision Goggle (ENVG)
ITT’s Enhanced Night Vision Goggle (ENVG) is the industry’s first system that combines both image intensification (I2) and thermal long wave IR sensing in a single overlay image. The ENVG provides soldiers, marines and airmen on the ground unprecedented situational awareness when exposed to obscurants from total darkness like being in a cave or in limited visibility from fog, white out dust storms or battle field smoke. This is the first time that a goggle has ever been able to show orange (heat) features over green (light) background in a single image presented to the eye.
ITT is the military’s sole-source provider for the ENVG, now designated the AN/PSQ-20. It is a single tube with a second sensor that the soldier or marine can toggle between or use in selectable fused modes to see an I2 image, an IR image or the two images combined.
The ENVG is the first stop on the Army’s roadmap to an all-digital goggle for the soldier. In such a system, there would be full pixel-by-pixel fusion of the I2 and IR imagery. That’s a few years down the road, so the best possible way to fuse the images now is optically.
“In our device, the fusion takes place inside the goggle,” said Mark Oyler, AN/PSQ-20 program manager. “Look at it this way: When a pilot is using a night vision goggle and also looking at the heads-up display, he’s doing what’s called brain fusion. His brain is creating a single fused image of the two displays. The ENVG does the same thing as an optical overlay.”
The ENVG is designed to augment the existing capabilities of AN/PVS-14 monocular night vision devices that are spread liberally among the forces, and the plan is to distribute the more capable PSQ-20s to every platoon operating in Afghanistan and Iraq. About 250 have been delivered and are in use by the 10th Mountain Division at Fort Drum, N.Y., a light infantry division that has deployed units for combat and peacekeeping operations in Somalia, Haiti, Bosnia, Kosovo, the Horn of Africa, Afghanistan and Iraq. Thousands more ENVGs are under contract, and an export version is also planned.
In October 2009, the magazine C4ISR Journal selected the AN/PSQ-20 as one of the five category winners in its Big 25 C4ISR awards, picking the ENVG as the most important sensor development of the last year.
The capabilities of the ENVG are all part of what Oyler calls having “overmatched protection.”
OVERMATCHED PROTECTION:
At its most fundamental level, overmatched protection means giving soldiers and marines the ability to detect and engage the enemy before the enemy knows that they’re there.
“Our devices have to see farther and operate under more conditions so that we can engage the enemy and then get out of harm’s way before the bad guys can start shooting,” said Oyler. “The Army is determined on maintaining that overmatch. It’s obvious why.”
In the case of night vision equipment, one way to accomplish that is by maximizing the advantages of the technology while minimizing its limitations. For ENVG, that means combining the advantage of I2 technology to provide clear target identification and the advantage of thermal imaging to provide improved target detection. The two technologies of I2 and IR act as a natural yin and yang to maximize advantages and to minimize limitations when operating in certain combat environments.
For example, image intensifiers can’t see through smoke. IR sensors can.
IR sensors can’t see through glass. Image intensifiers can.
Image intensifiers can’t sense in the absence of light. IR sensors can.
With the ENVG, ITT has developed and fielded a system that sees both through smoke and in the complete absence of light – something that still takes two pieces of hardware to accomplish, except when using the AN/PSQ-20.
“Let me put you into a current situational environment in Afghanistan where soldiers are searching caves,” said Oyler. “You need a bit of light for night vision to operate properly, but many caves have a complete absence of light. The night vision goggle has the capability to produce its own light, but you’ll give yourself away if there’s somebody else in the cave also using an I2 sensor system. Even if their goggle isn’t very good, you’ll look like a beacon in the night.”
That’s where the complementary capabilities of the thermal sensor become advantageous.
“The thermal sensor doesn’t require light to operate,” said Oyler. “So going into the cave, you key into the visual image from the I2 sensor first and then to the heat signature when you hit an absence of light. You retain awareness of what’s going on in the cave without giving your position away.”
However, it wasn’t always that image intensifiers and thermal sensors were able to coexist in such a way.
“The whole concept of sensor fusion has been around at least since the early ’90s, when Texas Instruments was developing sensor-fused suites,” said Don Morello, director of U.S. government marketing for ITT. “They combined daylight TV with millimeter wave radar and other sensors to present one picture to the user. That combined the sensors electronically; we call it muxing (or multiplexing). But they were big and bulky, and needed to be driven around the battlefield. So, it didn’t really have utility and none for the dismounted soldier.”
So for many years, image intensifiers and thermal sensors were developed and procured within individual stovepipes.
“The Army was working with both technologies and with two different industrial bases; one set of companies made image tubes and goggles, and another set made thermal devices,” said Morello. “And the Army treated them like separate business areas. Back in the early ’80s, they were competing with each other, and thermal was going to be the death knell of I2. It didn’t happen that way though. It became obvious that these are not competing technologies; they are complementary. It was a huge paradigm change that led to the combining of the strengths of each individual sensor while minimizing their limitations.”
ITT picked up this challenge some years ago and is now delivering the AN/PSQ-20 in a system the dismounted soldier can wear with comfort and ease for the duration of a night’s mission, about 7.5 hours.
MEETING THE KEY PERFORMANCE PARAMETERS
The state of ENVG today is due to ITT’s investigation of night vision technologies over quite a long period of time. It seems logical that the I2 and IR sensors would have been brought together long before now, but “it’s not an easy nut to crack,” said Oyler.
First, the alignment of the two sensors is critical as the I2 image is overlaid with the IR image.
“Packaging the sensor combination was a huge challenge that gets into all sorts of technical issues related to image registration, image latency and in making sure that the overlaid images are accurate and tracked with the movement of the soldier’s head,” said Morello.
Second, the combined sensors result in a slightly heavier system, so weight reduction is essential. The AN/PSQ-20 weighs less than 2 pounds and already falls within Army weight limitations for the next-generation ENVG. Next, configuration of the head-mount has to create a good center of gravity to limit neck fatigue for the wearer. ITT has accomplished that by affixing the goggle to the front of the helmet and the battery pack to the rear.
Battery life is another key issue, especially because the dual-sensor ENVG does use more power than a single-sensor model like the PVS-14. ITT is leveraging its electronics technologies and working with battery vendors to maximize battery usage for fused operations or I2/IR-only operations.
The AN/PSQ-20 program managers consider all of these things key performance parameters (KPP), which means that they all must be met successfully before the unit is ready for use.
An additional KPP for the Army relates to the support of the AN/PSQ-20, in that the Army wants this more complex, enhanced night vision goggle to be maintained by the manufacturer and expects that the contractor will invest whatever resources are necessary to maintain operational readiness of the ENVG.
“Originally, there was discussion that the government would conduct a certain level of depot maintenance like they do with the PVS-14, where they can take apart a system and replace an image tube,” said Morello. “But the ENVG is much more complex than that system. It is not field-replaceable, and the criticality of the test equipment is major. The performance level of the goggle is set so high that it requires specialized pieces of equipment for testing and for setting the sensor alignment and sensor levels.”
To handle maintenance for the Army, ITT has created an extensive supply chain trail and repair operation to maintain the operational readiness of the ENVG. Even with that network in place, Morello can remember only one valid AN/PSQ-20 field return coming back for maintenance, and that’s because it was damaged by an IED.
TWO SENSORS WITH BETTER RELIABILITY THAN ONE
The AN/PSQ-20 is a particularly noteworthy technological achievement because of the reliability of its two sensors. Together, the dual sensors have just as good a reliability rate as the single-sensor PVS-14.
“Building a night vision system and keeping its performance high throughout its operating environment takes special knowledge and understanding, even when you’re talking about a single-sensor goggle,” said Oyler. “With the ENVG, we’ve demonstrated world-class performance and reliability that is as high as I’ve seen on any single-sensor system.”
That comes from the manufacturability brought to the program by ITT, which has traveled the learning curve necessary to design a dual-sensor goggle with optics of the highest order and to manufacture them in quantity.
An example of manufacturability can be found in the AN/PSQ-20’s image tube. The ENVG was originally designed around a small, lightweight 16 mm tube that turned out to be more complicated and expensive to build because it was a low-volume item. (The several hundred ENVG’s delivered so far have all incorporated the 16 mm tube.)
With an Army mandate to begin delivering the dual-sensor goggle in greater quantities, ITT will now build the AN/PSQ-20 with the same 18 mm image tube that goes into the PVS-14. The rugged reliability of the PVS-14 image tube combined with ITT’s advanced dual-sensor optics will give the Army a next-generation ENVG that can be cost-effectively manufactured in quantity. ITT is already the world’s largest manufacturer of image tubes for the AN/PVS-14, and the company has invested in the additional capacity necessary to also build the tube for the AN/PSQ-20.
Even more importantly, the AN/PSQ-20 with the 18 mm image tube won’t weigh any more than ones manufactured with the 16 mm image tube. That’s because ITT has worked in combination with other parts of the organization to develop more compact electronics and has learned to package other parts of the goggle in such a way that volume and weight are reduced.
“We’ve responded in a number of ways to increase production of the ENVG,” said Morello. “One of them has been finding a way to use a high-volume 18 mm tube, which has high performance and still meets weight requirements. We will probably be able to ship three times as many ENVG’s by making that switch. We’re well-known for producing high volumes of product, and the ENVG will follow in that pattern.”
THE FIRST STEP TO DIGITAL ENVG
The AN/PSQ-20 is the stepping stone that will soon lead to an all-digital system with fully fused sensor images, as opposed to the optical overlay of the present system. Such a system will also have an uplink/downlink capability, so a soldier sitting at a desk can view the same image as the soldier searching a building.
ITT is already developing such a system, which is called ENVG (D) for “digital” which will permit visual data to be imported and exported in a net-centric environment. Prototypes of the system have already been provided to the Army for evaluation.
The ENVG (D) is a leap in technology, as it replaces the standard image intensification tube with a new digital sensor, the MicroChannel Plate Complementary Metal-Oxide Semiconductor (MCPCMOS). The MCPCMOS sensor provides outstanding image-intensified video, enabling digital fusion with thermal infrared video. This allows full digitally fused video to be exported to the digital battlefield for intelligence exploitation as well as the ability to import video, giving the soldier enhanced situational awareness on the battlefield.
With the Enhanced Night Vision Goggle and the next-generation ENVG (D), ITT will work to ensure that U.S. armed forces and their allies have overmatched protection in any conflict they chose to fight.
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