Modulating a code sequence in a borehole communication system

A technique usable with a well comprises receiving a code sequence 82 indicative of information to be communicated downhole, modulating the code sequence to remove a portion of spectral energy of the code sequence located near zero frequency to create a signal 88 and generating a stimulus in fluid of the well to communicate the signal downhole. Further disclosed is a dual purpose sensor used for receiving commands as part of a borehole telementry system (2, figs.1 and 2) and also used for monitoring downhole parameters (3, figs. 1 and 2) such as pressure, flow rate, etc. Specifically discussed is using a downhole flow meter to receive commands (6, figs. 1 and 2) downhole in the well, where the same flow meter is also used as a permanent monitoring device to monitor a production flow (8, figs.1 and 2). The command received downhole by the sensor can be used to actuate a downhole tool and in response to the tool acting upon the command stimuli can be transmitted uphole indicative of a measurement taken by the sensor.