Microphone non-linearity is recognized as a gateway for establishing secret communication channels and as a malicious backdoor for injecting hidden voice commands. In the previous article, Ultrasonic Jammers: All You Need to Know, some representative microphones jamming methods were explained - like RF jammers, audio jammers and ultrasonic jammers.
Ultrasonic jammers provide an efficient barrier to any harmful activity, information leakage or unauthorized information access. The jammer produces an ultrasonic signal which passes on to the microphone's membrane via the amplifier and a low-pass filter. When the membrane captures this signal, it leaks into the audible frequency range of the device and makes audio input to the microphone useless. After the ultrasonic jammer signal capturing, a distortion field is created inside the microphones. Typical range of ultrasonic jammers could be up to 10m. As the amplitude of incoming signal is higher, the distortion field inside the microphone is stronger.
In comparison with other available technologies, ultrasonic jammers are much more powerful and effective. Some of their unique advantages are easy installation anywhere in the meeting room or other premises, silent work in ultrasonic range - inaudible to human ears and disabling the recording capabilities of electronic devices.
According to the mobility criteria, there are two main types of ultrasonic jammers – portable and fixed.
Portable ultrasonic jammers have different sizes and shapes. They can be small - pocket size, or larger that can be carried in backpacks or suitcases. Portable ultrasonic jammers generally have DC power supply, correlated with their size, construction, power consumption, etc.
Small packet size ultrasonic jammers are easy for manipulation, they have lower power consumption, short battery life of about an hour and shorter ranges. They are to use (one button activation) and can be easily concealed.
Larger ultrasonic jammers are more elaborate. Having in mind more complex construction, their size is bigger, and they cannot be hidden in pockets. Provisioning of additional jamming features needs optimal power supply sources. This means that portable ultrasonic jammers have high power consumption and need high-capacity batteries which enable several hours of jamming signal transmission. Their transportation needs to be in appropriate suitcases or backpacks. Fixed ultrasonic jammers are generally applicable in premises where their active mode is requested for several hours a day. Their shapes and sizes can be different, as well as supported jamming features. Sometimes, their construction can also be adjusted in compliance with the specific customer needs.
Conference room jammers are rudimentary representatives of fixed jammers, or even a combination of fixed and portable jammers.
Nowadays, panels for conference rooms with hidden built-in ultrasonic jammers or high-tech looking ultrasonic jammers are the most favorable for conference rooms. The size of the conference room influences the size and performances of the ultrasonic jammer. This results in complex construction and enables implementation of some additional ultrasonic jammer performances.
To achieve some unique capabilities, manufacturers of conference room jammers usually:
When analyzing the radiation pattern generally, ultrasonic jammers can be omnidirectional and directional. Omnidirectional ultrasonic jammers transmit ultrasonic signals in all directions - 360°. In this way, radiated energy is spreading in the horizontal plane. Their deployment in small conference rooms results in intensive multipath propagation. Omnidirectional jammers are providing uniform angular coverage of ultrasonic jamming signals.
Directional ultrasonic jammers transmit ultrasonic frequencies in one direction, covering a specific sector with the strong jamming signal. They are an optimal solution that can cover “guest” sectors in the conference room and protect meeting premises from information leakage.
In addition to these structural features and technical measures, several ultrasonic jammers can be deployed in big conference rooms to cover blind spots – omnidirectional and directional, fixed and portable, remotely controlled or a combination of above-mentioned choices. When needed, some of the portable jammers may work as fixed jammers in conference rooms too. They can be plugged into power supplies or powered by batteries.
Jamming effectiveness depends on the power of the jamming signal, distance between the jammer and the microphone, type of the microphones and structural attenuation. Structural attenuation is very important for indoor coverage. Influenced by obstacles, it affects reception of transmitted ultrasonic jamming signals and highly shortens the range. Choice of the abovementioned combinations of ultrasonic jammers is tailored from case to case, according to the conference room volume, interior organization, shape and features of available ultrasonic jammers (like range, direction, remote control capabilities and other specificities).
Commonly, conference room jammers are hidden from a curious glance, but in some specific scenarios their appearance is not concealed intentionally so they are built-in on dominant positions. When their purpose determines specific types of implementation, conference room jammers have different patterns, offering high-tech, sophisticated or even decorative look in order to fit the interior landscape - like picture, trace, lamp etc.
Furthermore, there are some operational measures performed by the end user, such as choosing the optimal deployment positions for the conference room ultrasonic jammers - on the wall, ceiling or on the tables. These operational measures can improve some jamming performances like range, directions, angular coverage and signal strength.
Conference room ultrasonic jammers are available today more than ever. They have great potential in keeping information safe, protecting its leakage and unauthorized access. Their implementation is applicable to different environments, not only conference rooms, but even theaters, concert halls, cinemas, finance premises and other locations where it is important to keep communication secure, prohibit its recording or other malicious activities and potential threats.