Abstract: A receiver and associated methods are described. The receiver comprises a first oscillator 14, a second oscillator 16, a controller 18 operable to control frequencies to which the first and second oscillators are tuned, and a discrimination circuit 24 operable to receive and monitor transmitted signals; wherein the discrimination circuit is configured to receive a signal at a first transmission frequency determined based on a first tuned frequency to which the first oscillator is tuned, and to determine, in a capture time period, whether data is being transmitted at the first transmission frequency; wherein the controller is configured to tune, in a tuning time period, the second oscillator to a second tuned frequency; and wherein the tuning time period is shorter than the capture time period.

Abstract: Disclosed is a method of producing an output signal from a signal generator, comprising: determining a driving input to the signal generator, the driving input for driving the signal generator to provide a predetermined output signal, wherein the output signal includes at least one frame, the at least one frame comprising an active period and a dummy period and wherein the active period and dummy period are determined by the driving input. Also disclosed is a method of producing an output signal from a signal generator, comprising: receiving a synchronisation signal; obtaining an input signal for controlling the signal generator to generate an output signal comprising at least one frame wherein the at least one frame comprises at least one active period and at least one dummy period; producing the output signal comprising a series of frames; and, synchronising the output signal with the synchronisation signal by varying a duration of the at least one of the dummy period or active period.

Abstract: A communications system is described which comprises a transmission unit including a transmission circuit 12 operable to output a transmission signal to a ground antenna 22 driven, in use, into a ground formation, and an impedance adjusting unit 20 electrically connected between the transmission circuit 12 and the antenna 22 and operable to adjust the transmission output impedance. A ground antenna 22 is also described comprising a single rod or stake including a first active section 30, a second active section 32 spaced apart from the first section 30 and collinear or coaxial therewith, and an insulating section 34 located between the first and second sections 30, 32, holding the first and second sections 30, 32 in a spaced, collinear or coaxial relationship.

Abstract: A container has a base, sides and a top, the base, sides and top together defining a void within which items can be located in use, an electromagnetic shield fully surrounding at least part of the void to provide an electromagnetic shield between an exterior of the container and items located within the said part of the void, an antenna located within the said part of the void and a signal generator connected to the antenna and operable to apply a signal to the antenna to cause the transmission of an impeding signal within the said part of the void to impede the reception of signals transmitted from locations external to the container by items located within the said part of the void.

Abstract: A communications system comprising an ECM signal transmission arrangement for generating and transmitting an ECM signal, a first controller operable to control the ECM transmission arrangement such that the transmitted signal takes a pulsed form including a plurality of first periods in which the ECM signal is transmitted separated by second periods in which the ECM signal is not transmitted, a radio signal receiver arrangement forming or including a bandpass filter and arranged to receive a radio signal, and a second controller operable to control the signal received by the receiver arrangement to take a pulsed form including a plurality of third periods in which the radio signal is received by the receiver arrangement separated by fourth periods in which the radio receiver does not receive the radio signal, wherein the first and second controllers are synchronised such that the second periods are synchronised with the third periods, at the radio signal receiver arrangement such that the pulsed signal receiv

Abstract: A communications system comprising an ECM signal transmission arrangement for generating and transmitting an ECM signal, a first controller operable to control the ECM transmission arrangement such that the transmitted signal takes a pulsed form including a plurality of first periods in which the ECM signal is transmitted separated by second periods in which the ECM signal is not transmitted, a radio signal receiver arrangement forming or including a bandpass filter and arranged to receive a radio signal, and a second controller operable to control the signal received by the receiver arrangement to take a pulsed form including a plurality of third periods in which the radio signal is received by the receiver arrangement separated by fourth periods in which the radio receiver does not receive the radio signal, wherein the first and second controllers are synchronised such that the second periods are synchronised with the third periods, at the radio signal receiver arrangement such that the pulsed signal receiv

Abstract: A communications system comprising a signal transmission arrangement for outputting a first signal for transmission, a first controller operable to control transmission of the first signal such that the transmitted signal takes a pulsed form including a plurality of first periods in which the first signal is transmitted separated by second periods in which the first signal is not transmitted, a radio signal receiver arrangement including or forming a bandpass filter and arranged to receive a second signal, and a second controller operable such that during a plurality of third periods the second signal is processed by at least part of the radio receiver arrangement, the third periods being separated by fourth periods in which the radio receiver arrangement does not process the second signal, wherein the first and second controllers are synchronized such that the second periods are synchronized with the third periods, at the radio signal receiver arrangement, such that the pulsed signal received by the receiver

Abstract: A communications system comprising a signal transmission arrangement for outputting a first signal for transmission, a first controller operable to control transmission of the first signal such that the transmitted signal takes a pulsed form including a plurality of first periods in which the first signal is transmitted separated by second periods in which the first signal is not transmitted, a radio signal receiver arrangement including or forming a bandpass filter and arranged to receive a second signal, and a second controller operable such that during a plurality of third periods the second signal is processed by at least part of the radio receiver arrangement, the third periods being separated by fourth periods in which the radio receiver arrangement does not process the second signal, wherein the first and second controllers are synchronised such that the second periods are synchronised with the third periods, at the radio signal receiver arrangement, such that the pulsed signal received by the receiver

Abstract: A protection device comprises a covering including at least a layer of ballistics material, and a layer of an electromagnetic screening material.

Abstract: A protection device comprises a covering including at least a layer of ballistics material, and a layer of an electromagnetic screening material.