| 摘要 |
An apparatus for making orientation measurements in a drill string within a well bore comprising a tubular housing (22) adapted for insertion into the drill string and first (13) and second (15) measuring devices in the housing for measuring first and second orientation characteristics, respectively, of the drill string. A signal generator (23) is responsive to the two measuring devices to provide a signal which is representative of the orientation characteristics measured. The measuring devices are operated alternately so that the signal from the signal generator is alternately representative of the first and second orientation characteristics. The signal from the signal generator, when the latter is controlled by the first measuring device, is different from the signal when the latter is controlled by the second measuring device so that it is readily apparent which of the two measuring devices is reporting.
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