Abstract: A compliant contact for insertion in a plated hole in a circuit board is machined from a single piece of metal with a shank at one end, which projects through the hole, and a socket at its opposite end, which can be crimped about a conductor inserted in it. Rearwardly of the shank, the contact has an entry region with two convex surfaces tapering away from one another rearwardly to a compliant region. The compliant region has two flat sides and a slot extending between the sides, which divides the region into two resilient blades, each of which has a flat, parallel outer surface. The flat outer surfaces are divided from the flat sides by turned edge portions formed as a part of a common surface of circular section.

Abstract: In the modulation and demodulation of a plurality of frequency separated channels on a radio frequency carrier by digitally coded speech or data, the speech or data is modulated on a digitally generated sub-carrier by quadrature phase shift keying and after conversion to analogue form the modulated sub-carrier is mixed with an RF carrier of fixed frequency to produce the signal for transmission. Reception and demodulation of the transmitted signal are effected by the reverse processes. Frequency multiplication is effected after the digital to analogue conversion by producing analogue samples of very short duration and applying them to a suitable filter. Frequency division during the analogue to digital conversion is effected by sub-sampling.