An apparatus for preventing a relay attack that includes a microcontroller, a receiver, and a transmitter. The receiver is configured to receive a challenge message from a verifier. The challenge message has a challenge message frequency at a first challenge message frequency during a first time slot. The transmitter is configured to transmit a response message to the verifier. The response message has a response message frequency at a first response message frequency during the first time slot. The first response message frequency is different than the first challenge message frequency. The challenge message frequency is at a second challenge message frequency and the response message frequency is at a second response message frequency during a second time slit. The second challenge message frequency is different than the second response message frequency.

An electronic jamming circuit and method used to place a protective area around a person or vehicle so that an explosive device cannot be triggered are described. A wideband code division multiple access (WCDMA) device in proximity to an explosive device is prevented from being triggered by a WCDMA communication by disruption of the ability of the WCDMA device to synchronize with, and thus cannot decipher, the communication. The jammer device may operate by forcing timing circuits in the WCDMA device to lock onto a jamming signal.

Generally discussed herein are systems, apparatuses, and methods for generating a replica of a first signal with a notch at one or more desired frequencies. In an example, an apparatus can include a pulse cataloger configured to analyze the first signal and to provide phase modulation information about the first signal, a direct digital synthesizer having an output and configured to modulate a second signal using the phase modulation information and to provide the second signal at the output. The second signal can include a representation of the first signal with a frequency notch at a particular center frequency within the bandwidth of the second signal.

A hybrid electronic warfare and communications system (EW/COMM) eliminates the space, power, weight, and cost of a dedicated communication system by exchanging messages with other nodes in a network as phase modulations of radar jamming signals. Some embodiments impose message phase modulations onto CW jamming signals, while other embodiments interleave message phase modulations with pseudorandom phase modulations of the jamming signals. Message chip rates can be matched to pseudorandom phase modulation chip rates. Messages are thereby obfuscated as either phase noise or random phase modulation of the jamming signals. Messages can be encoded as BPSK or QPSK modulations. Messages can be preceded by pre-established headers known to other nodes, and distinguished thereby from random noise modulations. Some embodiments include a dedicated COMMS module and/or antenna, while other embodiments implement the communications function mostly or entirely in software. Messages can be encrypted before transmission and decrypted after reception.

Method and system of electronic countermeasure comprising an airborne RF and IR decoy, being an independent, autonomous flying body that flies on its own, using its own aerodynamics, rotatable blades and fins, being applied as protection against Radio Frequency (RF) and infrared (IR) threats. Such an aircraft decoy comprises a body; a rotatable blade or vane disposed on the body; a power source capable of generating electrical current in response to rotation of the blade or vane; a wideband radar jammer responding to a radar signal with a wideband phantom radar signature corresponding to a phantom target; corner reflectors generating strong radar reflections corresponding to the phantom target; and an infrared source emitting a phantom infrared signature corresponding to a heat signature of the phantom target. Data stored within the decoy is destroyed automatically upon impact.