Abstract: A HVAC controller for controlling the comfort level of at least a portion of a building is described. In one illustrative embodiment, an HVAC controller for controlling the comfort level of at least a portion of a building by activating and deactivating one or more HVAC components is provided. The HVAC controller may include a special purpose save a wire terminal that provides a multiplexed or otherwise encoded control signal. The HVAC controller may be configured to multiplex, for example, two or more of a call for heat (W) signal, a call for cool (Y) signal, and/or a call for fan (G) signal onto the special purpose save a wire terminal of the HVAC controller. This may free up a wire in a four wire installation to carry, for example, a common (C) signal. A demultiplexer module may be provided adjacent to the one or more HVAC components to demultiplex the multiplexed control signal.

Abstract: An amplifier switch controller is provided for use in a headend cable transmission system having first and second amplifiers and amplifier input and output paths connected to one of the first and second amplifiers, which becomes the currently activated amplifier. The amplifier switch controller comprises an input sampler for sampling a combined signal on the input signal path and measuring an input signal level. The amplifier switch controller also comprises an output sampler for sampling the amplified combined signal on the output signal path and measuring an output signal level. A program means receives the input and output signal levels and determines whether the currently activated amplifier is not functioning properly. If it is not functioning properly, the program means generates a control signal to a switch.

Abstract: A combiner-amplifier is provided which has first current feedback amplifier which amplifies a first received signal by a predetermined gain value. A second current feedback amplifier amplifies a second received signal by the predetermined gain value. A combiner is operatively coupled to the first and the second current feedback amplifiers to combine the amplified first received signal with the second received signal together to generate a combined signal which is attenuated by the predetermined gain value such that the combined signal has approximately a unity gain over the first and the second received signals within a bandwidth of at least 45 megahertz.

Abstract: A clock recovery circuit includes a tuned-tank circuit for receiving RZ data signals, a comparator for converting an analog clock signal produced by the tuned-tank circuit to a digital clock signal, and a positive feedback of the digital clock signal to the tuned-tank circuit for self-regenerating the clock signal.