Abstract: A technique for reducing or eliminating effects of frequency and phase offset in a communications system includes implementing a demodulator having a Kalman filter based phase-locked loop for phase-shift keying or quadrature amplitude modulated signals. In an acquisition mode of operation, the Kalman filter based phase-locked loop continuously updates an error correction signal until an error between a received version of a predetermined signal transmitted using phase-shift keying or quadrature amplitude modulation and the predetermined signal is at or near zero. In a tracking mode of operation, the Kalman filter based phase-locked loop adjusts the error correction signal to maintain the error between the received signal and a predicted signal at or near zero.

Abstract: A cabinet having brackets disposed to support shelves behind glass panes of the front wall of the cabinet in a location concealed behind one horizontal mullion. The cabinet has at least two other vertical walls having a plurality of pre-drilled screw holes for attaching brackets, and at least one shelf which fits behind the front wall and between the vertical walls. Each bracket is generally L-shaped, having a flat vertical leg bearing a plurality of holes for passing a fastener and a flat horizontal leg for supporting a shelf. The vertical leg has two short extensions projecting beyond the horizontal leg, thereby stabilizing the bracket against tilting responsive to weight being imposed thereon. The horizontal leg has a neck adjoining the vertical leg which enlarges to form a broad head. The head is rounded and is of width no greater than that of the vertical leg. Distal ends of the short extensions and of the main section of the vertical leg are also rounded.