A data network has at least three line branches connected via a common star node to distribute message signals from one of the line branches onto the other line branches, wherein connected to at least one of the line branches is at least one bus-user device is configured to generate in a corresponding transmit mode by a corresponding transmit unit at least one of the message signals, wherein in the corresponding bus-user device, the transmit unit has a current source circuit which, in generating the message signal (16), is configured to inject an electric current into electrical lines of the line branch to which the bus-user device is connected, and via the current source circuit the lines are connected to an internal impedance value of the current source circuit that in transmit mode is constantly greater than 10 times the value of the characteristic impedance, for example greater than 500 Ohms.

A radio transmitter adjusts its radio frequency (RF) fingerprint to defeat RF fingerprinting identification without destroying the content of its transmissions. The radio transmitter comprises a frequency-upconverter configured to upconvert a baseband or intermediate-frequency signal to an RF signal, and an amplifier to amplify the RF signal to produce a transmission signal. An RF fingerprint control circuit changes the non-linear behavior of the frequency-upconverter or the amplifier in order to change the RF fingerprint. The transmitter may create RF fingerprint “personalities” to be paired with different radio protocol behaviors and subscriber terminal identification codes (e.g., MAC addresses or SMSIs) for generating different radio identities.

A near field communication system can include a near field generator configured to generate a near field detectable information signal. The near field generator and supporting circuitry also produces incidental electromagnetic radiation. A masking signal transmitter is used with the near field generator and radiates a masking electromagnetic signal. The masking electromagnetic signal may substantially mask the incidental electromagnetic radiation.

Systems, methods, and apparatus for identifying, tracking, and disrupting UAVs are described herein. A tracking system can receive sensor data associated with an object in a particular airspace from one or more radio frequency sensors. The tracking system can analyze the sensor data relating to the object to identify a type of RF signal being used by the object. A portable countermeasure device can generate one or more disruption signals on one or more targeted bands of spectrum based on the type of RF signal being used by the object.

Systems and methods for identifying a synthetic track are provided. In one embodiment, a method can include receiving, by one or more computing devices, a plurality of emissions from one or more platforms. The emissions can be generated in an emission sequence and are generated to create a track indicative of an object travel path. The method can further include determining, by the one or more computing devices, whether an irregularity associated with the track exists based at least in part on one or more of the emissions. The method can include rejecting, by the one or more computing devices, the track as an actual object travel path when it is determined that the irregularity associated with the track exists.

The present disclosure discloses a signal sending method and device. The method includes: receiving, by a base station, an uplink pilot signal sent by authorized user equipment, and determining a direction vector parameter and a first channel fading parameter of a channel calculating, according to the direction vector parameter and the first channel fading parameter, a first signal beamformer parameter, determining a transmission area of an artificial noise signal according to the direction vector parameter, and calculating a second signal beamformer parameter; and processing a to-be-transmitted signal by using the first signal beamformer parameter and the second signal beamformer parameter, and transmitting the processed signal. In this way, in a non-target direction, energy leakage of the secrecy signal to the authorized user equipment is relatively small, and transmitted artificial noise signals are concentrated in an area with a relatively high secrecy signal leakage risk.

Systems, apparatuses, and methods are described for a privacy blocking device configured to prevent receipt, by a listening device, of video and/or audio data until a trigger occurs. A blocker may be configured to prevent receipt of video and/or audio data by one or more microphones and/or one or more cameras of a listening device. The blocker may use the one or more microphones, the one or more cameras, and/or one or more second microphones and/or one or more second cameras to monitor for a trigger. The blocker may process the data. Upon detecting the trigger, the blocker may transmit data to the listening device. For example, the blocker may transmit all or a part of a spoken phrase to the listening device.

Methods, systems, and devices for wireless communications are described. A base station may indicate for a first device to transmit random information in the direction of an adverse device on at least partially overlapping time and frequency resources that are also used for receiving a downlink message from the base station. By transmitting the random information in the direction of the adverse device, the first device may cause entropy overhead to the adverse device, impacting an ability of the adverse device to decode portions of the downlink message transmitted to and intended for the first device. Accordingly, the first device may receive the downlink message and may concurrently transmit the random information in the direction of the adverse device on time and frequency resources that at least partially overlap with time and frequency resources used for receiving the downlink message based on receiving the indication from the base station.

A sound masking system according to the invention is disclosed in which one or more sound masking loudspeaker assemblies are coupled to one or more electronic sound masking signal generators. The loudspeaker assemblies in the system of the invention have a low directivity index and preferably emit an acoustic sound masking signal that has a sound masking spectrum specifically designed to provide superior sound masking in an open plan office. Each of the plurality of loudspeaker assemblies is oriented to provide the acoustic sound masking signal in a direct path into the predetermined area in which masking sound is needed. In addition, the sound masking system of the invention can include a remote control function by which a user can select from a plurality of stored sets of information for providing from a recipient loudspeaker assembly an acoustic sound masking signal having a-selected sound masking spectrum.

Methods and systems fort operating one or more light sources to project adversarial patterns generated to disorient a machine learning based detection system, comprising generating one or more adversarial patterns configured to disorient the machine learning based detection system and operating one or more light sources configured to project one or more of the adversarial pattern(s) in association with the targeted object in order to disorient the machine learning based detection system.