Abstract: A modular multistage centrifugal compressor with plural rotors on a common drive shaft driven by a high speed drive. A throttled leakage path between adjacent stages of the compressor reduces the axial loading on the rotors, which have axial freedom on the common drive shaft, to essentially zero. This same throttled leakage path flows between stages in the area around the common drive shaft, eliminating the need for interstage shaft seals. The compressor accommodates a family of drive sources including motors, diesel and gas engines, CNG engines and direct drive turbines.

Abstract: A time change or moving target indication system utilizing charge-coupled devices (CCD's) for signal processing in which successive integrated samples from individual detectors are loaded into adjacent CCD storage buckets and then clocked to an output device. The output device is any suitable differencing arrangement which samples the charge stored in adjacent buckets and gives an output proportional to the difference. The system of the invention allows the successive signals from individual detectors to pass through virtually identical elements in the signal processing chain so as to reduce the effects of transfer inefficiency on the accuracy of the MTI subtraction process. Further, the signal spectrum from an individual detector output may be shifted to higher frequencies during the readout process so as to reduce the effects of any 1/f noise that may be present in the output device.