Abstract: A microprocessor-based controller for an extraction type steam turbine-generator unit capable of selecting from a variety of predetermined control strategies and implementing corresponding valve position control loops by generating appropriate valve position control signals in accordance with operator-chosen setpoint signals and turbine operating level signals. In a particular control strategy, automatic system frequency correction is achieved in a load control mode upon separation of the turbine-generator from the utility power grid, by detecting turbine speed deviation beyond predetermined limits and correcting turbine speed to synchronous speed without the need for operator intervention.

Abstract: A protective relay for detecting high-impedance ground faults on a three-wire distribution system. The protective relay operates independently of the current in the ground path by using the positive and negative sequence currents to detect a fallen conductor. The ratio of the negative sequence to positive sequence current is calculated and when this ratio exceeds a predetermined value, a trip signal is produced.

Abstract: A method of time scheduling mode dwell times corresponding to a multiplicity of targets, displaced in angle, range and velocity, in the frame time of an agile beam coherent radar without reducing the performance of the radar is disclosed. Targets corresponding to a plurality of target mode dwell times scheduled to a common time interval are grouped into a set of pulse repetition frequencies (PRF's) which make the targets visible in both range and doppler. The radar is varied to a different of the set for each coherent integration time of the common time interval. The mode dwell times of the targets of a PRF grouping are interleaved in their corresponding coherent integration time by time positioning the different target time event patterns with respect to the fixed interpulse period thereof to avoid eclipsing of the time events.

Abstract: A signal quality monitor, and a protective relay system using the monitor, which utilizes both AC and DC signals from the receiver agc stage to monitor a plurality of different signal parameters. A signal responsive to the noise in the communication channel which transmits at least one of the protective relay signals used in a protective relay comparison function, is also used in the trip circuits of the associated circuit interrupter to continuously adapt or modify the trip level in response to channel noise.

Abstract: A guided missile subsystem including a Kalmanized radar track loop driven by acceleration signals of the missile generated by an inertial measuring unit (IMU), and a missile control loop driven by estimates of the relative kinematics of the missile and target computed by the radar track loop is disclosed. The IMU driven Kalmanized radar track loop accommodates the use of a high performance radar, like a synthetic aperture radar, for example, which operates to measure radar data at a low rate on the order of 1 Hz, to generate estimates of relative target and missile kinematics to drive the control loop at rates compatible with high performance missile kinematics. The Kalmanized track loop effects an exchange of IMU errors for "dynamic lag" errors of conventional track loops which cannot be modeled very well, and can change very rapidly.

Abstract: An electronically agile multi-beam radar including a clutter positioning system for positioning the band of clutter signals in the derived doppler frequency spectrum of each of the individual beams is disclosed. The radar is operative to switchedly transmit a plurality of beams directionally separated by time sharing the illuminating power thereof. Each beam includes at least one transmission of a plurality of R.F. pulses constituting a radar look. The radar is also operative to receive echo R.F. pulses of the look from each transmitted beam dispersed in time with echo R.F. pulses of the looks of the other transmitted beams of the plurality.

Abstract: An adaptive filter for enhancing the discrimination of targets from clutter and noise and suitable for use in a pulse doppler radar signal processor which processes successive echo pulse period signalling in accordance with range cell samples is disclosed. One embodiment of the filter has a delayed lattice configuration including a plurality of cascadedly coupled lattice stages, each adapted to operate on the range cell samples of first and second complex signal inputs. The adaptive filter embodiment provides rapid and low cost updating of the lattice stage weighting coefficients so that varying clutter spectrums may be effectively dealt with. Moreover, the lattice filter embodiment is insensitive to average clutter motion and to transmitter phase and gain instabilities. It further permits the use of variable interpulse period operation in radars that are unambiguous in range.

Abstract: A microprocessor-based controller for an extraction type steam turbine-generator unit capable of selecting from a variety of predetermined control strategies and implementing corresponding valve position control loops by generating appropriate valve position control signals in accordance with operator-chosen setpoint signals and turbine operating level signals. In a particular control strategy, automatic compensation of megawatt output is achieved during the extraction mode of turbine operation by summing a megawatt setpoint signal from a feedback loop with a feedforward extraction valve setpoint signal and a megawatt reference signal, which sum is then applied to the turbine control valves to enable tight megawatt control during the extraction operation.

Abstract: An apparatus and method for removing a transient exponential noise signal from a sinusoidal signal. The effects of the transient are removed by sampling the sinusoidal signal, averaging the transient over a time interval corresponding to an integral number of cycles of the sinusoidal signal, and subtracting this average from the sample at the midpoint of the time interval. The result is a compensated sinusoidal signal wherein the effects of the transient have been removed. The time interval is progressively moved ahead to produce a complete compensated signal by subtracting the average of the exponential from the value thereof at the midpoint of each successive time interval.

Abstract: A digital signal processing system and more especially a programmable bulk memory included therein comprising a plurality of memory sections independently controlled and simultaneously operative for transferring blocks or vectors of digital data words directly between selected memory sections and external data handling units while maintaining the corresponding variety of data handling throughput rates thereof without the need for input-output buffer type memories coupled therebetween is disclosed. A method of addressing the sections of addressable memory locations for accessing therefrom and storing therein blocks of data words in accordance with predetermined sequences is also disclosed.

Abstract: A system for adaptively adjusting a radar's receiver attenuation of input signals having a wide dynamic range to maintain the attenuated signals within a predetermined range for radar post processing operations is disclosed. The system includes an automatic gain control (AGC) loop governed by a computed logarithmic signal representative of the measured clutter content of the input signals received over the time interval of a radar look and a compatible reference logarithmic signal to generate a logarithmic adjustment signal for the receiver attenuation. The AGC loop includes selectable loop gains which are selected as a function of the computed logarithmic signal. More specifically, one set of loop gains is selected when the computed logarithmic signal is equal to or greater than a threshold level, and another set of loop gains is selected when the computed logarithmic signal is less than the threshold level.

Abstract: A protective relay for providing an infinitely variable family of curves for use in ground-fault protection. In one embodiment, the protective relay includes a saturable reactor across the output terminals thereof. The saturable reactor impedance varies in accord with the load or fault current such that a trip characteristic based on the zero sequence current and the load or fault current is obtained. The trip characteristic is selected by a potentiometer that limits the amount of dc current to the saturable reactor. Once established by setting the potentiometer, the trip characteristic defines the amount of 3I.sub.O neutral current, as a function of three-phase current, necessary to operate the protective relay. Varying the potentiometer setting provides the infinite family of curves.

Abstract: A system for interfacing a digital computer with an analog gimbal control loop rate integrating gyro for controlling the movement of inner and outer gimbaled elements is disclosed. The purpose of the interface system is to permit an increase in the agility of the analog control loop without imposing unreasonable data rate requirements on the digital computer. In operation, the digital computer generates a rate command signal which is stepwise updated at designated time intervals and provided to the analog gimbal control loop to govern the rate output thereof.

Abstract: A method of forming the far-field beam pattern of an antenna at short ranges is disclosed. More specifically, the antenna beam pattern is rotated through a rotational angle about the line-of-sight of a source of radar signalling located at a near-field range away from the antenna. Measurements of the field of the antenna are taken at predetermined angular increments during the rotation thereof. The far-field beam pattern of the antenna is formed by deriving discrete values thereof for corresponding angle increments along the angular rotation. Preferably, a multiplicity of antenna field measurements are selected about each selected angular increment based on a predetermined angular spacing. The discrete beam pattern value corresponding to each selected angular increment is derived as the weighted summation of the multiplicity of antenna field measurements associated therewith.

Abstract: A microprocessor-based controller for an extraction type steam turbine-generator unit capable of selecting from a variety of predetermined control strategies and implementing corresponding valve position control loops by generating appropriate valve position control signals in accordance with operator-chosen setpoint signals and turbine operating level signals. The extraction mode of turbine operation is subdivided into a provided set of mutually exclusive extraction control loops, each of which can be placed in service in a bumpless fashion upon transition from any other extraction control loop in a predetermined sequence. Upon a return from the manual mode of turbine operation to the automatic mode, a particular extraction control loop is automatically placed in service without the need for operator intervention.

Abstract: A subranging analog-to-digital converter is disclosed having digitally controlled subranging for eliminating switching gain and switching paths in the analog section thereof. The digitally controlled subranging apparatus may be applied to either a single time-shared quantizer embodiment or a converter embodiment including a plurality of simultaneously operated quantizers. In either case, the conversion is formed in a series of quantizer operations on a sampled analog signal input for forming a final accumulated digital word conversion representative thereof. Another aspect of the present invention includes the addition of apparatus in a subranging A/D converter for maintaining the pre-alignment of the various conversion dynamic subranges thereof. In this aspect, the subranges of the converter are prealigned to affect a unique set of digital conversion codes of subranged conversions of the analog signal input value corresponding to the conversion threshold transition regions between the pre-aligned subranges.

Abstract: A dual transport channel charge coupled device for coherently processing two analog signals in a bandwidth compression mode of operation, especially for use in a high resolution coherent radar system, is disclosed. An input charge injection stage is included for each transport channel. The input stages are dependently operative to simultaneously inject charge quantities correspondingly representative of concurrent samplings of the two analog signals being processed into their corresponding associated transport channels. Each transport channel comprises N multi-phase controlled stages in an in-line arrangement with the stages of one transport channel respectively corresponding to the stages of the other, the stages being operative to transport the simultaneously injected charge quantities concurrently along their corresponding channels.

Abstract: An improved latching-type comparator operative in a selected one of two exclusive states is disclosed. In one state, the operational state, a gain stage is rendered operative to amplify at least one intermediate current signal generated by an input stage in response to the comparison of a pair of input signals. At least one drive current signal is generated by the gain stage in response to the comparison and is buffered by a corresponding buffer stage to render both an output signal and a signal representative thereof. In the other state, a latch stage is rendered operative unresponsive to the comparison and governed by the signal representative of the output signal to sustain the drive current signal in a state to latch the output signal. A switching stage governed by at least one latch signal effects the selection between the gain and latch stages by conducting operating current exclusively from the selected stage to a constant current stage.

Abstract: A differential protective relay for protecting devices on an ac electrical power system. The protected devices can include a transformer, a generator, or a station bus. The differential protective relay evaluates the current flowing into and out of the protected device only during the period when the current transformers are not saturated. The differential protective relay also detects internal faults accompanying external faults by evaluating the ratio between the current flowing into and out of the protective device. When this ratio exceeds a predetermined limit the protective relay evaluates the difference between the current flowing into and out of the device to determine if this difference is sufficiently large to trip the relay. When a current transformer associated with the differential protective relay is saturated, the differential protective relay produces a restraint signal to restrain tripping.

Abstract: A passive electro-optical target recognition system which utilizes additional signature measurements of an active nature to enhance the discrimination of desired targets from detected candidate targets in the field of view thereof is disclosed. Candidate targets are detected by the passive target recognition system from passive image radiation received from the field of view of its one or more passive sensors. A laser beam generated substantially at a predetermined wavelength is positioned to illuminate individually each of the detected candidate targets. An active sensor tuned to the predetermined wavelength receives the active laser radiation separately reflected from the individually illuminated candidate targets. An active signature is derived for each of the detected candidate targets from its received active image radiation. Accordingly, a desired target is discriminated from the detected candidate targets in the field of view of the passive sensor based on the derived active target signatures thereof.