Abstract: A method for detecting unauthorised radio communications devices, the method including the steps of filtering received radio frequency signals into desired signals having a frequency band characteristic of an unauthorised radio communications device and undesired signals having a different frequency band characteristic of an authorised radio communications device, comparing respective levels of the desired and undesired signals with respective predetermined threshold levels, and generating detection signals indicative of the presence of the unauthorised radio communications device only if the desired signals exceed their predetermined threshold level and the undesired signals do not exceed their predetermined threshold level, thereby passively discriminating between the authorised and unauthorised radio communications devices, and interference therebetween.

Abstract: A switch having two apertured plates one of which is movable relative to the other to occupy spaced switch positions, the apertures being arranged in the plates so that in each switch position two or more pairs of apertures are aligned and all others are masked, wherein light transmitted through a selected one of the two or more aligned aperture pairs in a particular switch position is visible through an external switch position indicating window to thereby provide an unambiguous indication that the movable plate is positively registered in the particular switch position.

Abstract: An electronic warfare target simulator is a small, low power, programmable target simulator for Defence electronic warfare operators to use for training in Electronic Warfare deception and jamming techniques and to aid in the calibration of radio direction finding equipment. The invention includes methods and apparatus for the replay of stored data and the generation of electronic noise or tones to be transmitted in open air to deceive or jam target receiving intercept electronic warfare operators and their equipment.