The invention present disclosure relates to a method for preventing the voice of at least one person in a vehicle from being intercepted. At least one loudspeaker in the vehicle is activated, wherein the at least one loudspeaker is used to generate audio signals which have at least one frequency that is higher than the threshold frequency for sound that is audible to the at least one person, and the audio signals are used to interfere with the reception of a signal by means of at least one microphone when the at least one person uses their voice to articulate.

A system for interacting with a thermal detector includes at least one unmanned aerial vehicle and a sensor mounted to the at least one unmanned aerial vehicle. The sensor is configured to determine the presence of a component of the thermal detector and to generate a signal indicative of the presence of the component. The system also includes a beam emitter mounted to the at least one unmanned vehicle and in communication with the sensor. The beam emitter includes a beam source configured to direct a beam of thermal radiation to the thermal detector in response to the signal from the sensor.

A system and method of down converting microwave (RF) signals into lower frequencies are disclosed, such that associated electronics can more precisely analyse the signals. Exemplary embodiment, can be applied to multiple RF bands by using several optical wavelengths.

A wireless sound-emitting device includes a housing adapted to be coupled to a wall at a source of electric power, a loudspeaker positioned at a periphery of the housing, a control module outputting an electric audio signal to the at least one loudspeaker, and a wireless communications module in electrical communication with the control module. The loudspeaker emits acoustic signals in a direction parallel to the wall, when the housing is coupled to the wall, with the acoustic signals reflecting off the wall. The device may produce a sound masking noise or play a sound recorded on an internal memory. The device may include an electric plug or be adapted to replace an electric outlet faceplate. The device may have electric pass-through outlets and may be powered by the source of electric power. The device may be controlled remotely, for example via an Internet of Things (IoT) platform.

Systems and methods of friendly jamming for securing wireless communications at the physical layer are presented. Under the assumption of exact knowledge of the eavesdropping channel, a resource-efficient distributed approach is used to improve the secrecy sum-rate of a multi-link network with one or more eavesdroppers while satisfying an information-rate constraint for all links. A method based on mixed strategic games can offer robust solutions to the distributed secrecy sum-rate maximization. In addition, a block fading broadcast channel with a multi-antenna transmitter, sending two or more independent confidential data streams to two or more respective users in the presence of a passive eavesdropper is considered. Lastly, a per-link strategy is considered and an optimization problem is formulated, which aims at jointly optimizing the power allocation and placement of the friendly jamming devices for a given link under secrecy constraints.

A flight interference apparatus enabling it to block intrusion by a miniature unmanned aerial vehicle which is remotely piloted by radio communication into an area to be protected, suppress influence on communication within and outside the area, and reduce the number of required antenna devices. The flight interference apparatus includes one or a plurality of antenna devices which radiate a jamming signal from a directional antenna, and the directional antenna includes a radiating element which radiates a jamming signal of a predetermined frequency band and a reflector which gives directionality to the jamming signal in its radiation direction.

A speech reproduction device for reproducing speech based on a received speech signal so that the reproduced speech is intelligible in a clear speech zone and unintelligible in a masked speech zone includes an audio processing module configured for receiving the speech signal; a set of speech loudspeakers configured for reproducing the speech based on one or more speech loudspeaker signals; and a set of masking sound loudspeakers configured for producing a masking sound based on one or more masking sound loudspeaker signals, wherein the masking sound masks the speech in the masked speech zone; wherein the audio processing module includes a speech signal analysis module configured for producing one or more analysis signals based on spectral and/or temporal characteristics of the speech signal; wherein the audio processing module includes a masking sound generator configured for producing one or more masking sound signals based on the one or more analysis signals.

A communication system is provided having multiple transmit antennas for transmitting respective transmit signals with spatial diversity to reduce multipath fading. The communication system communicates with at least one receiver for receiving the transmit signals with no additional processing required at the receiver. In some embodiments, the communication system includes an associated receiver for receiving and analyzing various signals.

The communication system in the present invention is able to help reduce the effects of multipath fading without modifications to the receiver. Prior art attempts to reduce the effects of multipath fading require some form of additional processing at the receiver.

The invention is particularly useful when deployed in a Managed Access Service (MAS) system or a jamming system. In particular, such a system can be used in a facility (such as a prison, school, government building, etc) to prevent cellphone usage.

A system for near field communications is provided. The system can include a near field generator configured to generate a near field detectable signal comprising information. The system can include a near field detector configured to receive the near field detectable signal and output the information. The system can include an Electro-Magnetic (EM) shield surrounding the near field generator to block EM radio frequency (RF) signals in the vicinity of the near field generator from interfering with operations of the near field generator. The EM shield does not prevent communication of the near field detectable signal between the near field generator and the near field detector. The EM shield can be configured to reduce magnetic field loss from eddy currents in the EM shield as the near field detectable signal passes through the EM shield.

Systems and methods are described herein for monitoring an on-board cellular network infrastructure. In one aspect, a controller and one or more noise generation units can be used to inhibit passenger devices from connecting to ground-based cellular stations while on-board. The noise generation unit can be configured to generate a noise signal. If a loss of power to an on-board cell station is identified, the noise generation can generate a different noise signal in response.