The real drum trigger monitor and amplified tone module is an electronic percussion instrument, satisfying the desire of drummers to have realistic electronic drums with the audible drum sound coming directly from the instrument triggering the sound being heard. In particular, the invention provides apparatus and methods for low-pressure, high-speed direct injection of compressed natural gas into a combustion chamber of an engine. Subsequently received packets that have a received signal strength below the minimum level may then be rejected. Set data for setting a predetermined dose amount is entered into the control means, convert data for obtaining an actual dose amount from the monitor signal is entered into the control means by a memory means.