Abstract: A method and apparatus for performing frequency acquisition. Frequency acquisition is accomplished by utilizing binary-search techniques with a controller (13), variable digital oscillator (16), frequency detector (11) an incrementor (19) and decrementor (21) and control registers (22). The frequency detector (11) generates an output indicating the relative speed of the variable oscillator (16) with reference to a externally provided signal. Depending on the output of the frequency detector (11 ), the arithmetic logic circuitry (19, 21) will increase or decrease the value in a control register (22), resulting in a corresponding increase or decrease in speed of the variable oscillator (16). The magnitude of changes to the control register (22) is gradually reduced as the steps of frequency detection and arithmetic updates are repeated until the variable oscillator (16) has reached the proper frequency.

Abstract: An optical transmission device comprising a body, a tapered surface disposed in the body, and means for attaching an optical transmission means to the body. In the preferred embodiment, the optical transmission means is a hollow waveguide. The tapered surface has an inlet aperture for receiving radiation and an outlet aperture. The diameter of the outlet aperture of the tapered surface is smaller than the inner diameter of the hollow waveguide.