Abstract: A measuring-while-drilling system having a downhole, motor-driven acoustic signal generator includes a motor speed control circuit featuring feedback compensation which accounts for varying loading conditions on the motor. The acoustic signal generator is motor driven at speeds for imparting to well fluid an acoustic signal having phase states representative of data derived from measured downhole conditions. The motor control circuit includes circuitry which forms a phase locked loop for driving the motor at a reference phase and at a substantially constant carrier frequency producing speed in the absence of data of one logic state and also includes circuitry for temporarily changing the speed of the motor, according to a pre-programmed function, to effect a predetermined amount of phase change in the carrier signal upon data of the predetermined logic state.

Abstract: A fluid lifting apparatus operable by air pressure applied alternately to first and second pairs of cylinders each of said cylinders having a main body part, a barrel and a bottom chamber in communications with a bottom inlet. Pressuring of the main body part of the chamber, closes a check valve at the inlet and forces fluid from the main body part, through a fluid flow valve, through the chamber and up the barrel to a production tubing segment and hence to the next higher cylinder. Emptying of the main chamber closes the fluid flow valve to prevent air from the production tubing. However, the valve is positively opened once fluid flow in the bottom chamber from the inlet is reinstituted. Air vent means to the surface and/or to the well annulus rapidly depressurizes the cylinders and hence speeds cycling between the alternate cylinder pairs.

Abstract: A programmable system controller stores in memory a sequence of program words directly simulating a planar ladder diagram characterizing the desired operation of a controlled system. The ladder diagram is a set of n rung-by-m column arrays of contacts interconnected with particular controlled devices of the system. The program words are read out of the memory in a sequence to directly represent the ladder diagram on a rung-by-rung basis for each column. The controller includes an interface unit coupled to a set of input switches for providing switch signals that are indicative of the operating status of the machine. A data processing unit is provided with an accumulator having a plurality of at least n storage units respectively corresponding to each rung of the ladder diagram.