Phase-shift-keying technique

With the downhole power available and the signal detection threshold at surface, Figure 4-254b gives the maximum depth that can be reached by the technique as a function of frequency. Assuming that phase-shift keying is used with two cycles per bit, in a 10 fi m area (such as the Rocky mountains) a depth of 2 km (6,000 ft) could be reached while transmitting 7 bits/s. 

BPSK modulation technique— binary phase-shift keying QPSK modulation technique—quadrature phase-shift keying BER bit error rate. 

Fewer EXAFS works have been devoted to the study of catalytic systems under reaction conditions due, as already said, to inherent limitations of the technique at high, working temperatures characteristic of catalytic reactions. Among these, a majority include studies of Cu/ZnO (Cu/Si02) in methanol synthesis.The solid state physics of the active copper phase in methanol synthesis is a rather intriguing problem which has not achieved consensus concerning the oxidation state and the hosting of the Cu phase characteristics. The EXAFS works mentioned above elucidated mainly the importance of the metallic state in the reaction. Similarly, the metallic state has been shown to be of importance in the water gas shift reaction (WGS) in Cu, Au, and bimetallic Pd-Cu systems supported on ceria. The importance of ceria vacancies on the activation of water and of the metal (and more precisely, of the metal at support boundaries) for CO activation appear as key elements for this reaction. The bimetallic Pd-Cu work analyses the modulation of Pd behaviour by effect of the alloy with the base... 

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