A test weight system includes a first assembly having a first body member and a plurality of ear members arranged about the first body member. The weaving apparatus includes a frame assembly and a weaving mechanism contained within the frame assembly. The projection is made of material identical to that of the edge. In a location identification phase, the current location in a global area is identified by the GPS module, and the current location in a local area is identified on the basis of the location recognition model selected from the identification result and the image sequence obtained at the time. Based upon measurements of the desired quality or qualities of the raw natural gas, the electronic controller selectively varies the flow of methane gas to provide a blend of raw natural gas and methane gas that possesses desired quality or qualities to the engine. The method includes estimation of the interfering signals.