Scott Eagle Attack teardown and comment from Fraser - Page 1
Forum section: electronics / general

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:09:47 pm
content: I recently purchased a pair of faulty Scott Eagle attack fire fighting cameras as repair projects and to find out what technology resides inside this model of camera.The specification of the camera is pretty humble but good enough for its intended duties. It uses a fast frame rate 160 x 120 pixel A-Si core and displays the scene on a 2.5" Colour LCD display. A single button switches the camera on and off and it includes centre spot temperature measurement. The LCD display also provides artificial colour overlays for temperature warnings. A DVR option is available for training and 'black box' purposes.The cameras were received today and both were repaired soon afterThis is a thread detailing the teardown of the Scott Eagle Attack camera with some comment from me on its design.Some background on the Eagle Attack camera.......The Eagle Attack thermal imaging camera dates back to 2012 and is designed to be a highly portable lightweight personal fire fighting thermal camera. Fire fighters often have to share thermal imaging cameras amongst a team. This is due to the high cost of this technology. With time, production costs have reduced and manufacturers have offered "personal thermal cameras" that they hope fire brigades will issue to large numbers of fire fighters as personal equipment rather than sharing. In order to progress this plan, companies such as Scott designed and built affordable cameras that often used commercial “off the shelf” modules where possible to keep costs low. Designing and building the electronics package for a thermal camera can be both time consuming and expensive. This situation has lead to the "screwdriver camera manufacturer" ..... a somewhat disparaging description but not totally unfair. A "screwdriver camera manufacturer" designs a thermal camera around modules that may be purchased already built and configured and needing only to be wired up and placed in a suitable casing with only some minor power control electronics to be manufactured in addition to the casing plastics etc. As we will see, the Eagle attack is just such a camera design.So what will we see inside the Eagle Attack ?1. The imaging core is the venerable L3 (was Raytheon) Thermal Eye 3600AS A-Si technology core providing 160 x 120 pixel resolution with a refresh rate of 30fps. The core is capable of up-scaling the image to 640 x 480 pixels using its on-board video processing. The lens is Germanium and provides a 50 Degree HFOV at F1.02. The 2.5" LCD monitor is a "commercial off the shelf" product that uses an Intersil Techwell TW8817 LCD driver to process the composite video coming from the Thermal Eye 3600AS core. This LCD monitor is basically a skeleton chassis composite video monitor for integration into any product that requires such. There are unused options on the monitor such as the menu and image adjustment buttons.3. A small bespoke SCOTT power and interconnection hub PCB is used to connect the cameras various parts together. The PCB is connected to the battery, power button. Thermal Eye core, monitor and camera I/O port (for PVR use)4. A custom designed case with Germanium window protects the contents from water and dirt. It also has to be fire and impact resistant for its role as a fire fighting camera.Well I think its time to move on to the pictures.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:16:19 pm
content: Disassembly begins......

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:24:37 pm
content: Inside the casing......the journey begins......

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:28:19 pm
content: Continued......

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:32:17 pm
content: The imaging core .......L3 Thermal Eye 3600AS A-Si 160x120 pixels 30fps

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:39:04 pm
content: Continued.....

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:42:18 pm
content: Continued....

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:47:20 pm
content: Power and connection hub PCB.....

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:51:29 pm
content: The LCD driver and LCD panel.........

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 09:58:32 pm
content: Testing the core and some pictures for scale......

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 10:19:42 pm
content: Datasheets for the L3 Thermal Eye 3600AS core and the Intersil Techwell TW8817 LCD monitor board

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 10:30:49 pm
content: For anyone wondering if there is a manufacturers "Splash Screen" at power on and where it is created....Yes there is a Splash Screen that appears for just a couple of seconds after switching the camera on. The graphic is loaded into the Thermal Eye Core using the configuration GUI that connects to the core via its USB port. The battery gauge graphic is also produced within the Thermal Eye core and monitors the battery voltage. The Thermal Eye 3600AS core was designed to be easily integrated into a camera system tole with the minimum of additional components needed. This is proven by the relative simplicity of the Eagle Attack design. The TE 3600AS could just as easily be serving a very different role in a rifle sight with a more powerful lens and electronic viewfinder display. They are great little modulesFraser

author: Fraser
author_rank: Super Contributor
timestamp: November 17, 2020, 11:00:55 pm
content: As can be seen from the above pictures, the waterproof casing design for the Eagle Attack camera has performed well as I found no evidence of water ingress. This means the most interesting and valuable part of the cameras, namely their cores, are in ‘as new’ physical conditionI have said it before, fire fighting cameras can be a great source of affordable professional grade thermal imaging cores .... provided you know your topic and choose carefullyFraser

author: Bill W
author_rank: Super Contributor
timestamp: November 18, 2020, 10:56:09 am
content: Quote from: Fraser on November 17, 2020, 10:30:49 pmThis family from L3 were designed to allow quite a lot of 'camera' level customisation to suit the various camera builders and their end users. So while very much a 'screwdriver' job mechanically and electrically there was a lot of access for setup.As you have seen the battery level indication is provided from the core, but also custom temperature-colour mapping.This even extended (via that high density P1 I suspect) to intercepting the image processing at various locations, although I am not sure who, if anyone, actually used it.This was the time the e2v Argus cameras went over to ULIS and built from the sensors upwards.Bill

author: Fraser
author_rank: Super Contributor
timestamp: November 18, 2020, 12:24:27 pm
content: Bill_W,As you so rightly state, the 3xxxAS and 4xxxAS cores are very versatile modules. I was surprised and pleased with the level of configuration available to anyone in possession of the L3 Thermal Eye GUI. These cores can be ‘dumbed down’ for the simpler applications or fine tuned to meet more demanding roles. The inclusion of high and low gain combined with temperature warning thresholds and highlighting made them a decent choice for fire fighting cameras. In fact the cores documentation discusses various roles in which the core can serve and fire fighting is detailed. It is clear that the design team were tasked with producing a multi-role thermal imaging core series that would appeal to multiple markets and offer a high level of customisation to imaging system manufacturers. The cores would be just as effective guiding a firefighter around a smoke and fire filled factory as they would cruising at 10000 feet aboard a UAV monitoring forest fires or fulfilling a military reconnaissance role. A sort of Swiss Army knife of thermal imaging coresThere have been discussions on the forum regarding the FFC event, its duration and whether it may be stopped in order to do a video recording without interruption etc. The Thermal Eye 3xxxAS and 4xxxAS offer a configurable FFC event interval and also the ability to deactivate it. I was also pleased to see the very useful image inversion options to permit an inverting supplemental lens to be catered forThere is so much to ‘play’ with in that GUI but at the end of the day, these cores are designed to deliver nice quality thermal imaging to the user in whatever role they serve in.On the mechanical design front, the separate microbolometer/lens combination on a flexible ribbon cable makes these cores an excellent proposition where an unusual case shape or lens position is needed. The case can be short and wide or long and thin without any modifications to the core and the 3600AS PCB set was reduced in size to enable more compact case designs. Of course modern imaging cores are smaller but when the 3600AS was released, I suspect designers were very impressed with its size and versatility. The only problem was its country of Origin and the red tape that was involved in procuring this very nice series of cores. Bearing in mind the cores versatility and usefulness in military applications, I can understand caution in its international distribution though.A final comment, the imaging produced by the 3600AS cores from the Eagle Attack displayed impressively low levels of column noise in my brief testing last night. The A-Si cores have had a history of higher column noise than VOX based microbolometers but these 3600AS cores seem very well behaved in that respect. I know that ULIS have continued to develop the A-Si microbolometers to reduce the image noise levels to those approaching VOX based FPA levels. Quite an achievement.Bill_W, I know you achieved great things with the ULIS microbolometers but I would be interested to hear whether you were disappointed with the decision to drop the Thermal Eye core from ARGUS designs. It is a lot of years ago now but the Thermal Eye cores would surely have made life easier for you in the development team ? Or did the ‘ground up’ building of an imaging core around the ULIS microbolometers provide a freedom to enhance performance beyond that offered by the COTS L3 offerings ? The move to in-house imaging core design certainly did not adversely effect ARGUS camera performance as the Argus 4 proves. I suppose building and programming a thermal imaging core provides insight into core behaviour and the ability to ‘fine tune’ the design whereas a COTS core from Raytheon/L3 was more of a fixed building block that, though highly configurable, was not open source firmware or hardware so could not be modified easily. That said, as you mentioned, the Thermal Eye 3600AS core has an expansion port for those who wish to incorporate more sophisticated image processing etc. I am guessing that port was provided as a safety net for applications that needed specialist signal processing, such as in some military applications of such a core. The port certainly provides plenty of access to the signal processing chain within the core. The modern Seek Thermal OEM cores offer similar, but in the software domain, rather than hardware.

author: Fraser
author_rank: Super Contributor
timestamp: November 18, 2020, 12:55:23 pm
content: For those interested in such, the FFC event on the Thermal Eye 3600AS core is momentary, that is to say, hardly noticeable apart from the click of the flag solenoid ! The core also offers image enhancement features that effectively combines frames to reduce temporal noise but this is at the expense of motion blur. A nice feature to have though and there are many levels of enhancement to choose from.Fraser

author: Bill W
author_rank: Super Contributor
timestamp: November 22, 2020, 05:42:30 pm
content: Quote from: Fraser on November 18, 2020, 12:24:27 pmThere were several considerations at the time, it was not an open and shut decision.For a CoreAs you say simplicityThe existing relationship and core performance from L3/RaytheonInterfacing was not an issue, once NDA were signed you got the whole software interfacing data, and circuits, and access to the designers. In many ways better than 'open source'. Argus2 and Argus3 BST have the Raytheon sensor PCB circuit design on an e2v designed PCB.Against a CoreRaytheon were slow in going 'lead-free' and IIRC the BST cores never did.Fixed lumps to design around, especially other cores than the Raytheon ASi. As you know the Argus3 is big due to the fixed size of various core parts while with all the design done in house ergonomics could win out as long as there was enough PCB area.US export red tape was bad and getting worse. France do not care.We did look at ULIS based cores as well, but they were very big, pricey and high power.Adding functions such as better 'fire' video processing, colour video overlays, image and video capture and direct LCD drive meant you would end up duplicating parts and power consumption. For example Argus3 has two full D to A video encoders, one in the core (unused) and another on the e2v Argus PCB for the colour output.Limited maximum imaging temperatures. With many camera builders using the same core, you knew their operational limits and could deliberately exceed them in a specmanship battle.Was it right ? Yes. The 3600AS / 4500AS did address some of these issues, maybe even at our behest, but by then Argus4 was up and running with the ULIS sensor in it.It also probably kept Argus in thermal imaging for another 15 years as the cost of core was a very high, fixed, US$ denominated, part of the camera price. Using a sensor much improved margins (although at the expense of added development costs) and more costs were in GBP.

author: Fraser
author_rank: Super Contributor
timestamp: November 22, 2020, 07:28:11 pm
content: Bill,Thank you for your insight into the thought processes behind the decision to go with ULIS.Fraser