A system and method in accordance with the invention communicator remotely with remotely controllable down hole tools in a well bore at a drilling installation. At the surface, high energy pressure impulses directed into the tubing or the annulus, or both, being at a level to propagate through an interface between very different impedances zones, such as an upper level gas zone and a lower level of mobile fluid media extending down into the desired downhole location. The pressure impulses, provided by directionally gating along the longitudinal confining path a pressure impulse initially having sharp leading and trailing edges, reach the downhole location as physical perturbations forming a discernible pattern that can be detected by one or more energy responsive transducers. With combinations of these signals, one of a number of separate control devices can be remotely actuated. The system avoids the need for physical or electrical connections and concurrently greatly reduces the likelihood of accidental operation.

 
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> Automatic gain control and low power start-of-packet detection for a wireless LAN receiver

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