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.

Distance-based authentication is provided for mitigating undesirable interaction and/or attacks upon ranging systems, such as those involving vehicle entry or secure payment. As may be implemented in accordance with one or more embodiments, a leading edge of one or more pulses in a waveform of a signal is obscured as part of distance-based authentication. For instance, noise may be generated via a noise modulation circuit and combined with some or all of a leading edge of a pulse. Distance-based authentication is provided by transmitting a signal with a waveform having the obscured portion of the leading edge, which operates to mitigate detection of the polarity of the leading edge or otherwise of the leading edge itself.

A financial device includes: an insertion part to which a medium is inserted; a random number generation unit configured to generate an signal including information on a copying prevention number for preventing copying of a medium according to an on signal; a detection unit installed near the insertion part and configured to generate a detection signal by detecting the existence of the medium; a determination unit configured to determine whether the medium is completely inserted or is being removed based on the detection signal; a controller configured to generate the on signal to make the random number generation unit operate, wherein the controller generates an off signal to make the random number generation unit not operate when it is determined that the medium is completely inserted and generates the on signal to make the random number generation unit operate again when it is determined that the medium is being removed; and a card reader unit installed at one position of a movement path of the inserted medium and configured to recognize information included in the medium.

A monitoring system using cooperative jamming and spoofing according to an embodiment of the present disclosure includes a spoofing relay to amplify and relay an illegal signal detected from an illegal transmitter according to a preset amplification coefficient, a cooperative jammer to transmit a jamming signal for changing the quality of a communication channel to an illegal receiver with a preset transmit power, and a monitor to calculate the amplification coefficient and the transmit power so that an information monitoring amount is maximum based on the illegal signal received from the spoofing relay.

Disclosed is an anti-eavesdropping method for the Internet of Vehicles (IoV) based on intermittent cooperative jamming. The method comprises: on the premise of effectively preventing an illegitimate user V.sub.e from information eavesdropping, first establishing optimization problems for the purpose of minimizing an energy consumption of a cooperative jamming user V.sub.j; analyzing unique communication characteristics of the IoV based on the Wireless Access in Vehicular Environments (WAVE) protocol, to obtain time structures of physical-layer data packets in the IoV and physical-layer data packet duration; and calculating the shortest physical-layer data packet duration in the IoV; then solving an optimal cooperative jamming scheme for any available power range for the cooperative jamming user V.sub.j; and finally, conducting, by the cooperative jamming user V.sub.j, periodic repetition according to the solved optimal cooperative jamming schemes in a period of data transmission between legitimate users, until transmission between the legitimate users ends.

Disclosed is a low-altitude unmanned aerial vehicle surveillance system. According to an embodiment, monitoring is performed using a balloon main body filled with gas and staying in the air; radar; camera units being provided outside the balloon main body, and including a camera taking an image of a subject; radio frequency detectors; and sound detectors and correspondingly, interceptor means is included. As interceptor means, a jammer, a jamming gun, and a spoofing device corresponding to jamming are disclosed.

A radio frequency (RF) communications system may include an RF transmitter having multicarrier transmitter circuitry that transmits frequency bands over a frequency range. A controller may selectively transmit real information over at least one of the frequency bands and selectively transmits fake information within the frequency range. The controller's operation is based on embedded machine learning model and real-time effectiveness feedback from built-in spectral analyzer. An RF receiver receives the real information from the RF transmitter.

The game table reading system comprises reading antennas for each of a plurality of reading areas of a game table, read-restriction antennas for each of the plurality of the reading areas, the read-restriction antennas restricting the RFID tag embedded in a game token placed in the corresponding reading area from being read by the reading antenna corresponding to the other adjacent reading areas, a reading control device that controls the reading antennas, and a read-restriction control device that controls the read-restriction antennas. The read-restriction control device causes the read-restriction antennas corresponding to the reading areas adjacent to the reading areas corresponding to the reading antenna that the reading control device causes to read, in synchronization with the reading control device.

Embodiments of communication systems are disclosed for protecting communication between an implanted device ID and an external device ED. Optionally, the ID communicates over the TET channel by modulating a load on the channel. While the ID is communicating the ED optionally adds noise to the TET channel, inhibiting malicious interception of the communication. Using knowledge of the noise signal, the ED cleans the noise from the TET signal to recover the communication from the ID. In some embodiments, the TET link is used to pass an encryption key and/or to verify communications over a radio channel. The TET channel may be authenticated. For example, authentication may include a minimum energy and/or power transfer.

A controller for controlling wireless communication between a node and a master device in a wireless network; wherein the controller comprises a processor arranged for: determining a first directionally restricted jamming area relative to the node; determining a second directionally restricted jamming area relative to the master device; controlling a first directional antenna to transmit a first jamming signal in the first determined directionally restricted jamming area during a predetermined time period; and controlling a second directional antenna to transmit a second jamming signal in the second determined directionally restricted jamming area during the predetermined time period.