Improvements in or relating to apparatus for investigating the sub-soil or sub-structure and for the location and examination of subterranean deposits

摘要

502,025. Locating conductors; current meters. RUHL, JUN., A., MACHTS, L., MACHTS, R., and NICKEL, B. Dec. 9, 1937, No. 24542. Convention date, May 31. [Class 37] [Also in Group XL] High-frequency apparatus for geophysical survey comprises a portable arrangement of a transmitter and receiver structurally combined as a unit, the transmitter or receiver as a whole being rotatable to effect minimum coupling between them, such adjusted position being indicated on meters. In general, a low power transmitter and highly sensitive receiver are employed, and the transmitter may be modulated. As shown, the transmitter comprises a single valve oscillator and frame aerial 1 located in a casing which is rotatable on pivot 6 by a worm 9. During transport the transmitter casing is latched in its horizontal position. Under operating conditions the receiver frame aerial 12 is in a plane parallel to pivot axis 6 and the transmitter frame aerial 1 is at right-angles to receiver aerial. Additional aerials at right-angles to 1, 12 may be employed. The receiver comprises four separately tuned high-frequency amplifier stages connected to the frame aerial 12, the last high-frequency stage including a parallel circuit for preventing back coupling. The highfrequency stages are inductively coupled at 21 to a low-frequency circuit which includes a telephone or loud-speaker receiver. A further low-frequency stage comprises a rectifier 24 and two series-connected meters 26, 26 one giving' a deflection, for example, four times that of the other for the same current, the " coarser instrument being also provided with range shunts. A continuous-current circuit 28 including a variable resistor provides a neutralizing current for setting the instrument zero. The sensitivity of the receiver can be tested by relatively adjustable plates 32, 33 connected with the frame aerial 12. The control knobs together with that for the zero setting are preferably located in the remote end wall of the cabinet to reduce capacitative disturbance. Carrying arms for the apparatus comprise projecting shafts upon which gripping tubes are mounted on ball bearings, the arms being above the centre of gravity so that the receiver aerial, for example, remains horizontal. Fig. 5 shows the meters fed from parallel-connected secondaries, each meter having its own rectifier 24. Only the meter 25 is provided with a zero neutralizing current circuit, the meter 26 having a disconnectible and variable shunt 53. For transport purposes the transmitter and frame part 5 can be detached, and can be made to slide in relation to the receiver. It is stated that in addition to locating a change in the subsoil, the direction of the course of an inhomogeneity can be determined by pivoting the transmitter around the point occupied by the receiver.