Smartphone in the NVD zone: minimize visibility in NVD
Previously, the author prepared a number of materials on the selection and configuration of smartphones that are planned to be used in combat zones, in particular, the last two materials talked about how to perform basic "combat" settings necessary to prevent accidental or remote activation of wireless modules, and also more deep settings that minimize the risk of independent smartphone activity and increase the convenience of working with it in various lighting conditions.
In principle, this was the planned end of the series, but on the YouTube channel TurNav, which I have mentioned several times, several videos were published showing how visible a smartphone and its owner can be through a night vision device (NVD).
Well, there are ways to minimize these risks, and we’ll talk about them today.
So, in a smartphone we have several sources of visible light - this is the screen and the camera flash, which can also be used as a flashlight. Also, a smartphone can have several sources of infrared radiation - this is the camera lidar and the backlight of the Face ID facial recognition module, but not all smartphones have this.
Apparently, this shot shows Face ID in action.
Accordingly, the screen and the Face ID backlight reveal the owner from the front of the smartphone, and the lidar and the camera flash from the back.
The back side of the smartphone
First of all, it is necessary to eliminate the possibility of accidental use of the camera and its flash, which can be used as a flashlight.
It is absolutely necessary to remove the camera and flashlight shortcuts from the lock screen, if they are there, then you need to remove them from the drop-down menu curtain, accordingly, also, if they are there, and finally remove them from the main screen, which opens when you unlock your smartphone.
It is best if the camera and flashlight shortcuts are located in the application menu in a separate folder.
In this case, it will be almost impossible to turn them on by accident – you will have to accidentally turn on the screen, accidentally unlock the smartphone, accidentally go to the application menu, accidentally open the desired folder and accidentally launch the camera or flashlight shortcut in it – too long a chain of accidents for it to be implemented in practice.
Also, in the menu “Settings / Additional functions / Side button” you need to turn off the “Double press” menu or assign another function to it.
It is worth noting that other smartphone models may have other ways of turning on the camera and flashlight, but here you need to look at the specific smartphone model.
However, there is another way to minimize the risks of turning on the lidar and camera flash - this is to purchase a case with a curtain for your smartphone.
An opaque curtain is guaranteed not to let in any lidar light, as for the flash, you have to look at it in each specific case, but most likely it won’t be visible either.
In addition, remember that in Samsung smartphones you can completely disable access to the camera for all applications, including the standard camera application, but this button does not interfere with turning on the flashlight separately.
Taken together, all these actions guarantee, with a probability close to 100%, that you will not reveal yourself with the help of the accidentally turned on lidar and camera flash/flashlight of your smartphone.
Screen and Face ID
Let's start with the fact that Face ID is not available on all smartphones, and of those that have it, it is not always equipped with infrared backlighting, however, in the same Samsung smartphones, when recognizing a face, the smartphone can forcibly increase the brightness of the screen, so it is better to turn off this function, and in general, what kind of face recognition is there in a war zone?
In the settings menu “Security and privacy / Biometric data / Face recognition” you need to disable the item “Unlock with face recognition”, and at the same time (just in case) the item “Increase screen brightness”.
After we got rid of Face ID, we still had to deal with the increased screen brightness, and here we can’t do without the smartphone’s standard tools.
In the previous article, we talked about how you can dim the screen below the minimum brightness in Samsung smartphones using the “Maximum dimming” setting.
In the menu “Settings / Accessibility / Advanced options / Accessibility button” you need to select “navigation bar”, and then in the menu “Choose actions” you need to select in sequence: “Invert colors”, “Adjust color”, “Zoom”, “Maximum dimming”, “Mute all sounds”.
The "Maximum Darkness" option, as the name suggests, darkens the screen as much as possible - a very convenient feature for working in the dark.
However, when the eyes get used to the darkness, the brightness of the smartphone screen with the “Maximum dimming” function turned on seems too high, that is, it both blinds and at the same time unmasks the owner to an outside observer, especially one equipped with night vision devices.
Backlight from smartphone screen
It is impossible to reduce the brightness even more for an unjailbroken and hardware-imperfect smartphone, but there is a solution - you need to use a third-party application that applies a darkening filter to the image.
In particular, the author used the Darker app because the Screen Filter app previously used with the Samsung Galaxy S7 Edge smartphone turned out to be incompatible with the Samsung Galaxy S22 Ultra.
Once again, applications like Darker or Screen Filter reduce the brightness of the screen not by reducing the brightness of the backlight, but by using a color filter. However, in fact, visually, the brightness can be reduced to almost zero, although there are some nuances.
For example, you can’t turn on the standard Samsung color inversion together with Darker, because in this case the dark filter will turn into a light one and the screen, on the contrary, will “shine”, that is, if you use Darker or a similar application, it’s better to remove the “Color Inversion” setting from the menu altogether.
It’s better not to set the brightness level in the Darker application to “0” and not to enable it in autoload, otherwise you’ll have a hard time turning it off later.
A great combination is to have the Darker brightness level set to "10%" and also have the "Maximum Dimming" setting enabled - this allows you to quickly adjust the two minimum brightness levels without having to fiddle with other settings.
From left to right: minimum brightness + maximum dimming + Darker at "10%", minimum brightness + maximum dimming, just minimum brightness (two smartphones in different modes were photographed in pairs with a third smartphone in complete darkness, so the image is a little blurry).
At the level of minimum brightness + maximum dimming + Darker at the level of “10%”, when the eyes adapt to the darkness, the cards are quite readable, but there is practically no backlight from the smartphone.
The Darker app also allows you to set color filters on the image according to the user's choice, for example, red or green.
It should be noted that the author tested the Darker application only on a smartphone with an Amoled display, I don’t know how it will work with other types of displays – you need to try it on other smartphones or look for information on thematic resources.
Conclusions
By using a combination of standard smartphone settings, special cases and additional darkening filter applications, you can minimize the risk of detection of your smartphone and its user in the dark, including with the use of night vision devices.
At the same time, it is possible to set the minimum comfortable image brightness to ensure efficient and safe work with it in complete darkness.
Information