| 摘要 |
1,238,165. Calibrating telemetry systems. J. TERRY. March 14, 1969 [March 15, 1968], No. 13646/69. Heading G1U. A multichannel telemetering system for transmitting voltages from a number of capacitive pick-ups, e.g. mechanically responsive Piezoelectric devices 1a-1n to remote metering and/or recording devices 7, 10 incorporates facilities for enabling the individual channels to be tested and calibrated. Associated with each pick up device 1a-1n is a unit 2a, 2n incorporating a matching device 23 for coupling the output from the pick up to the telemetry channel and variable capacitor 13 and relay controlling switch 11, by means of which a standardizing voltage can be impressed on the pick up from an oscillator 6 in the remote control unit 4 of the system. The oscillator output amplititude and variable capacitor are adjusted to provide a voltage at the pick up corresponding to that which the pick up would produce under given input conditions. By observing this on the metering or recording arrangements, the performance of the system can be checked. The remote unit 4 comprises, in addition to the oscillator 6, general power supplies 9, a control unit 8, and an amplifier unit 5a for receiving the signal from the matching unit 23 and passing it to the metering and recording arrangements 7, 10. The units 2a are assembled in closed fluid tight boxes to resist external environment. The matching unit 23 incorporates a unity gain differential FET arrangement of very high input impedence to reject common mode signals, Fig. 3 (not shown), has a wide pass band and symmetrical low impedence outputs. The outputs from the unit are applied to unit 5a incorporating amplifier 66 and associated test and protection circuit 96, Fig. 4 (not shown). The amplifier circuit 66 contains an operational amplifier (72) to which the output from unit 23 is applied whose zero level is adjustable (75, 76). The operational amplifier output is applied to a temperature compensated transistor arrangement (85, 87) to provide an output across an adjustable potentiometer 94 enabling calibration adjustment to be effected. This output is applied to measuring unit 7 or magnetic recorder 10. The measuring unit 7, Fig. 6 (not shown) incorporates an amplifier (169) of adjustable zero, followed by a full wave diode bridge arrangement for providing a rectified output to a meter (184). Facilities are provided for applying the output from the oscillator 6 (shown in detail in Fig. 5) to the unit for calibrating comparison. Details of the switching interconnections of and operating procedure for the system are given, Fig. 8 (not shown). |
