AVON-ISI NVISION XT (3500) Thermal Camera by Fraser  - Page 1
Forum section: electronics / general

author: Fraser
author_rank: Super Contributor
timestamp: March 17, 2017, 03:19:06 pm
content: A new camera joins my collection.This camera is made by AVON-ISI and is designed for fire fighter use.The model is the NVISION XT but it looks to be the same as the ISI 3500.This is possibly due to the fact that AVON bought ISI so they may have just renamed the models.ISI previously produced the '2500' and the '3500'. Both were 160 x 120 pixel A-Si camera cores and some checking of specifications leads me to believe that the thermal cores used in these cameras are the Raytheon/L3 2500AS and 3500AS respectively. Hence their model names. The 3500AS core is an enhancement of the older 2500AS and, on paper at least, has a better NETD figure (100mK Vs 50mK).For those unaware, Raytheon/L3 produce 'Core kits' amongst many other Thermal Imaging products. The 'core kit' comprises all the main components needed to produce a thermal camera minus the display, power management and any custom processing or control electronics desired. The cores are effectively 'Plug & Play', only needing the connection of a suitable display and power supply in order to work.It is difficult for a single core configuration to meet the needs of all OEM's, so different lens options were available at time of order and the core may be configured via its RS232 or USB interface (depending upon model). These cores are VERY versatile and similar have been used in personal weapons sights, several Fire fighting cameras and Military UAV's (Drones).I purchased this particular camera as I strongly suspected that it contained the excellent Raytheon/L3 core and I knew that it could likely be re-configured to better meet my needs. Buying fire fighting cameras can be risky if you are looking for a Microbolometer core in particular. Many used Fire brigade cameras contain a BST core. Though very good, it is not the microbolometer based technology that some prefer. I just wanted a configurable Raytheon XX00AS series core !In the auction pictures the camera appeared to be in excellent condition as most fire fighting cameras have a hard life and receive plenty of knocks before disposal. The camera arrived this week and is in every bit as good condition as I had hoped. It has the odd scratch on its case but the rubber bumpers look like new and the whole camera has the look of a unit that was treated with great respect and care. It may have been used for training or in a service that used it very infrequently. I tested the provided battery expecting to have to rebuild it. Nope, the battery is rated at 4.5Ah and that is about what it is providing when tested. Wonderful ! Another indicator that this camera has not seen heavy use. If I do ever need to rebuild the battery, the case comes apart easily thanks to being screwed together. It contains 6 X 'A' size 4.5Ah Panasonic Ni-Mh cells.Some may wonder whether 160 x 120 pixels are enough for a decent image from a thermal camera. I have always said that my minimum is 160 x 120 pixels as that DOES produce a decent image in may scenarios. This camera proves my point. My pictures of its screen do not do it justice. The images produced are excellent ! Sensitivity is more than enough as the camera clearly shows the plaster 'dabs' behind my house plaster board dry lining. A test I use on all my cameras. Some fail it miserably ! The NVISION XT also has a X2 zoom function that performs well.Also worthy of note is that fire fighting cameras are normally multi-range devices. That is to say, they have a high sensitivity mode up to say 150C which is perfect for room searching in the hunt for life, and then they have at least one lower sensitivity setting that enables imaging of areas that are at very high temperatures due to fire. A most versatile tool. They do not, however, normally provide the user with any fine tuning capability. They are full auto for ease of use. Their full auto modes are normally pretty effective though.Time for some pictures I think......

author: Fraser
author_rank: Super Contributor
timestamp: March 17, 2017, 03:21:24 pm
content: Continued

author: Fraser
author_rank: Super Contributor
timestamp: March 17, 2017, 03:25:15 pm
content: Well now for the display pictures. Not great photography on my part!The LCD has some 'dust' marks on it that I will need to clean off after removing the face plate. Nothing serious though.I will be opening the camera for a look inside soon, but for now, just external pictures.I am very pleased with this compact thermal camera. Thanks to the pedigree of its imaging core, it s a very capable thermal imaging unitI should also comment on its build quality. It is excellent. The cases are held together with quality stainless steel socket head screws and the design is very neat indeed.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: March 17, 2017, 03:33:02 pm
content: Camera brochure

author: sam1275
author_rank: Frequent Contributor
timestamp: March 17, 2017, 03:46:11 pm
content: Hi Fraser,It looks like a good oneOne thing you didn't mention, which is my favorite part of Fire fighting TICs, is that they have a very wide FOV compare to average thermal cameras.Also they are rugged and built to last in a hazard environment.Sam

author: Fraser
author_rank: Super Contributor
timestamp: March 17, 2017, 03:50:39 pm
content: Yes indeed Sam,This camera has a 50 Degree FOV and it is designed to survive being dropped and drenched with water !I attach a picture taken of firefighters that was captured with the L3 3500AS coreI should state that as the number of pixels decreases, it is not unusual for an OEM to decrease the FOV to maintain the displayed target detail. That is to say a 320x240 pixel camera may have a 40 Degree FOV, and a 160x120 pixel camera may have a 20 Degree FOV to provide similar image detail but over a smaller field of view. 50 Degrees is quite a large FOV for 160x120 pixels but with a decent core and image processing it still works.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: March 17, 2017, 05:33:28 pm
content: The Raytheon/L3 3500AS core brchure