An apparatus and method of communicating in a tubular system (20) through a
media (65) disposed therein and actuating a controllable device (58) are
disclosed. The apparatus and method utilize a transmission apparatus (16)
at a transmission node that is in communication with the media (65). The
transmission apparatus (16) generates pressure impulses that are
propagated through the media (65). The pressure impulses may be either
positive or negative pressure impulses depending upon the selected
transmission apparatus. The pressure impulses are detected by a reception
apparatus (77) at a reception node. The detection apparatus may detect the
pressure impulses as variation in the media (65) or as variation in the
tubular system (20) caused by the pressure impulses. Once the detection
apparatus (77) has detected the appropriate pressure impulse or pattern of
pressure impulses, a signal may be generated to actuate the controllable
device (58).