A system and method are provided for providing electromagnetic (EM) measurement-while-drilling (MWD) telemetry capabilities using an existing mud-pulse MWD tool. An EM tool intercepts the output from the mud-pulse tool and generates an EM signal that mimics a mud-pulse pressure signal. The EM signal...http://www.google.fr/patents/US7573397?utm_source=gb-gplus-shareBrevet US7573397 - System and method for downhole telemetry
