System and method for multi-frequency downhole bus communication

Abstract

A bottom hole assembly includes a single wire bus, a legacy sensor coupled to the single wire bus, and at least one high frequency communication sensor coupled to the single wire bus. The high frequency communication sensor injects a high frequency signal alternating between high frequency synchronization pulses and high frequency data signals onto the single wire bus. A first high frequency pass filter coupled between the at least one high frequency communication sensor and the single wire bus is also included. The high frequency pass filter passes the high frequency signal to the single wire bus from the high frequency communication sensor. The bottom hole assembly includes a first high frequency blocking filter coupled between the legacy sensor and the single wire bus. The high frequency blocking filter blocks the high frequency signal from the high frequency communication sensor from disturbing a legacy signal at the legacy sensor.

What is claimed is: 
     
         1 . A method for synchronizing a deep reading resistivity tool transmitter and a deep reading resistivity tool receiver coupled to a single wire bus, comprising:
 transmitting a first electromagnetic signal from the deep reading resistivity tool transmitter into a formation;   receiving the first electromagnetic signal at the deep reading resistivity tool receiver from the formation; and   conducting legacy sensor communication using legacy sensors coupled to the single wire bus.   
     
     
         2 . The method of  claim 1 , further comprising sampling the first electromagnetic signal from the deep reading resistivity tool transmitter at time intervals established by a high frequency pulse transmitted by the deep reading resistivity tool transmitter to the single wire bus. 
     
     
         3 . The method of  claim 2 , further comprising sampling the first electromagnetic signal from the deep reading resistivity tool receiver at the time intervals established by the high frequency pulse transmitted to the deep reading resistivity tool receiver from the single wire bus. 
     
     
         4 . The method of  claim 2 , wherein legacy signals provided to and from the legacy sensors are undisturbed by the high frequency pulse transmitted along the single wire bus. 
     
     
         5 . The method of  claim 2 , wherein conducting the legacy sensor communication comprises filtering a multi-frequency signal from the single wire bus using a high frequency blocking filter to block transmission of the high frequency pulse to the legacy sensors. 
     
     
         6 . The method of  claim 2 , wherein sampling the first electromagnetic signal from the deep reading resistivity tool receiver comprises: filtering a multi-frequency signal from the single wire bus using at least one high frequency pass filter to block transmission of the legacy signal to the deep reading resistivity tool transmitter and the deep reading resistivity tool receiver; receiving the high frequency pulse signal at the deep reading resistivity tool transmitter and the deep reading resistivity tool receiver; and storing samples of the first electromagnetic signal transmitted by the deep reading resistivity tool transmitter and received by the deep reading resistivity tool receiver when the deep reading resistivity tool transmitter and the deep reading resistivity tool receiver receive the high frequency pulse from the at least one high frequency pass filter. 
     
     
         7 . The method of  claim 2 , wherein the high frequency pulse comprises a 1 MHz signal with low harmonics. 
     
     
         8 . The method of  claim 2 , comprising communicating between the deep reading resistivity tool transmitter and the deep reading resistivity tool receiver using a high frequency data signal on the single wire bus, wherein the high frequency data signal comprises a same frequency as the high frequency pulse, and the high frequency data signal does not disturb the legacy sensor communication at the legacy sensors.