Abstract: A free-space laser communication system and method for compensating for the atmospheric effects and target motion of a target that may occur during free-space laser communication between of a pair of the systems. Each system makes use of a plurality of narrow infrared (IR) laser beams, a means for pointing and tracking the laser, an adaptive optics system and a communications transceiver. Optionally turbo coding techniques may be used to encode data transmitted by each of the systems. The laser communication system is less susceptible to adverse weather effects that could otherwise negatively influence the operation of an optical communication system.

Abstract: A method and apparatus for measuring the frequency of a desired resonant mode of a crystal arrangement, or other two-port device, during an automated operation. The crystal arrangement, or other two-port device, is placed into a test circuit and subjected to a sinusoidal test signal of known frequency. Based upon the output response of the crystal arrangement to the test signal, the frequency of the test signal is changed such that the test signal rapidly converges on a desired mode of operation of the crystal arrangement. This is accomplished by first noting a desired increase in amplitude of the output response of the crystal arrangement, followed by measuring an error signal related to the desired crystal arrangement mode of operation. When the error equals a predetermined value the frequency of the sinusoidal test signal is the frequency of the desired mode.