| 摘要 |
<p>1476990 Acoustic signalling SUN OIL CO 23 Aug 1974 [23 Aug 1973] 37113/74 Heading G4F Measuring-device signals at the bottom of a well drill pipe 1, Fig. 1, are telemetered acoustically to the surface along the pipe via intermediate repeaters 4 &c., the carrier frequencies at the input and output of a repeater being different. One pattern of frequencies is illustrated. In the embodiment carrier frequencies of some 1000 Hz are utilized. The sensor-transmitter device 3 incorporates time-division-multiplexing, analogue-to-digital conversion and frequencyshift-keying of carrier f 1 , Fig. 2 (not shown). A repeater unit circuit includes, a piezo-electric pick-up, filters, and a ring modulator acting as a frequency-changer, Fig. 3 (not shown). Repeater construction. Fig. 6.-The repeater is constructed to be withdrawable by a grappling hook from the surface. Acoustic waves reach pick-up 40 from pipe 1 via fins 96, tube 97, balls 105, housing 100 and plate 104. The transmitter is a dynamic loud-speaker in a housing 113.</p> |
