A downhole tool includes a downlinking system deployed in a downhole tool body having an internal through bore. The downlinking system includes a differential pressure transducer configured to measured a pressure difference between drilling fluid in the internal through bore and drilling fluid external to the tool (in the borehole annulus). The differential transducer is electrically connected with an electronic controller (deployed substantially anywhere in the drill string) that is configured to receive and decode pressure waveforms.