Patent ID: 9719345
Date: 2017-08-01
CPC Classifications: E21B

Claim:
1. A wireless communications system for a downhole drilling operation, comprising: (a) surface communications equipment comprising a surface electromagnetic (EM) communications module with an EM downlink transmitter configured to transmit an EM downlink transmission at a frequency between 0.01 Hz and 0.1 Hz, and an EM uplink receiver configured to receive an EM uplink transmission; and (b) a downhole telemetry tool mountable to a drill string and having a downhole EM communications unit with an EM downlink receiver configured to receive the EM downlink transmission, and an EM uplink transmitter configured to transmit the EM uplink transmission at a frequency that is higher than the EM downlink transmission frequency; wherein the EM downlink transmission contains an encoded downlink message having a structure comprising in sequential order: a fixed header, a pause, and a data packet.