to access adjacent oil bearing sands here the use of paired different signal transducers enables more reliable detection of lower amplitude signal levels moreover the signal patterns can employ a number of variables based on pressure time chamber volume and orifice configuration to enable more code combinations to become available for example using a pressure regulated source the starting impulse can be given varying waveforms by changing pressure e g from 2 000 psi to 3 250 psi using the same chamber size the stored pattern of the remote microprocessor will have been coded to detect the changed signal waveforms likewise chamber volume can also be varied within a signal sequence to provide predictable modulation of downhole wavetrains in a preferred embodiment the time gap between the time windows in the first example is determined by the duration needed to establish non overlapping u201c sensing windows u201d at the remotely controlled device as seen in fig8 a as the shock impulse travels along the well bore 40 energy components in the media 50 will be more slowly propagated than energy components moving along the tubing 20 or casing 26 the sensing windows and therefore the initiating time windows are however spaced enough in time for propagation and reception of the slowest of the received signal sequences without overlap of any part of the.