| 摘要 |
1420895 Signalling by sound waves MOBIL OIL CORP 13 Feb 1974 [12 March 1973] 6537/74 Heading G4F In a system for transmitting the measurement data from one or more down-well detectors D1 ... D4 to the surface, the data is sent by acoustic signals in the well liquid and by phaseshift keying utilizing a motor 11, a data pulse changing the speed of the motor from a predetermined value, a control pulse is generated on the occurrence of a predetermined phase shift in the acoustic signal to terminate that motor speed change, and the control pulse changes the motor speed to return it to its predetermined value but with a shift in phase of the acoustic signal. In the embodiment the analogue data from the detectors is multiplexed and converted into serial digital form. In the absence of a " 1 " data bit motor 11 is controlled by retroactive phase-locking to a stable clock 12, Fig. 2 (not shown); a " 1 " data bit into control unit 32 causes disabling of the phase-locking loop and acceleration of motor 11 which is thereafter decelerated to effect 180 degrees phase-shift keying, Fig. 3 (not shown). |
