Abstract: The disclosure is of a system for driving gas-filled segment-type display panels including a plurality of groups of cathode electrodes, each having an anode electrode. The circuit includes means for holding the anodes at a relatively low potential for a short period of time after drive signals are applied thereto and to selected cathode electrodes. During this period of time, current flow charges a capacitor and raises the potential of the anodes to a potential at which ionization and cathode glow can occur. The circuit includes transistors utilized as resistors to hold off cathodes which are not intended to glow.

Abstract: A digital open-loop canceller is used to decorrelate one signal from anot in such applications as coherent sidelobe cancellers and moving target indicators. The invention measures the correlation between a complex main input signal and a complex auxiliary input signal in digital form. It divides the correlation coefficient by the average value of the auxiliary signal magnitude squared, multiplies the ratio by the auxiliary signal and subtracts the result from the main input signal to cancel correlated components.

Abstract: Sets of at least three geophones are oriented in different directions perpendicular to the longitudinal axis of a seismic cable in which they are assembled, so that at least one geophone in each set will detect substantially vertically-propagating reflected seismic signals when the cable is rotated in any orientation about its longitudinal axis. Arrangements may be provided to selectively enable the one geophone of each set that has its axis most nearly oriented to the vertical.

Abstract: The specification discloses a radar sensor for detecting short-range, slowly moving objects and using the range versus time data to develop a prediction of the time at which the range of the object will be at a minimum to the sensor. The sensor uses a pulse transmission of a radio frequency signal with object reflections being received and detected. Subsequent signal processing eliminates returns from clutter and stationary objects so that signals from low velocity objects can be detected. Computations are performed in a digital processor to compute an estimate of the time and of the range when the object will be closest to the sensor.

Abstract: An automatic thresholding reference and detection circuit which generates a signal in time which is a replica of the radar return signal's doppler spectrum. The radar signal return is processed by a target signal channel having a narrow bandwidth filter which produces a fine resolution replica of the signal spectrum, and by a reference signal channel having a wider bandwidth filter, which produces a smeared (or average) replica of the signal spectrum. The output of the reference signal channel is a threshold signal which, when compared to the output of the target signal channel, allows only the target signals to be passed for further processing and rejects clutter and thermal noise.

Abstract: Improvement in electro-fluid vibrator means used for generating seismic waves in the earth in which the flow of pressurized fluid to the vibrator is controlled in accordance with the resultant holddown pressure on the baseplate in contact with the earth, so that there is always a positive pressure on the baseplate, preventing it from being lifted off the surface of the earth. Force measuring means are provided in the holddown means. So long as this force is large and positive (in the direction to hold the baseplate to the earth) no control is required. When this positive force becomes less than a preselected value, the pressure fluid system is controlled to reduce the maximum pressure of, or rate of flow of, pressure fluid to the vibrator. The force measuring system can conveniently utilize the compliances in the holddown system as the force measuring elements.

Abstract: A side scan sonar system which records return echoes in a manner which realistically displays the spatial relationship between the sonar transducer and the echo producing topographical feature on the sea floor. The system includes a dual channel strip chart recorder having a continuous transverse belt carrying a pair of equally spaced writing styli. The belt circulates at a constant speed with each stylus moving across the paper, first in one direction and then in the opposite direction. One of the styli records starboard channel data when that stylus is moving across the paper toward the right, while the other stylus records port channel data when that stylus is moving across the paper toward the left.

Abstract: A first variable tracking gate is generated which activates a sample and hold circuit connected to receive incoming signals from a doppler radar receiver and apply output signals therefrom to a threshold circuit which in turn supplies a signal to a range counter each time the signal from the sample and hold circuit exceeds a predetermined threshold, whereupon an output from the range counter decreases the range at which the tracking gate is generated. A second tracking gate, generated a short time after the beginning of the first tracking gate, activates a second sample and hold circuit connected to receive signals from the radar receiver and supplies signals through a second threshold circuit to the range counter to increase the range of the first gate when the signal from the second sample and hold exceeds a predetermined threshold and signals from the first sample and hold circuit are below the predetermined threshold.

Abstract: A system is disclosed for removing a periodic interfering signal from an electrical signal which may also include a data signal such as a seismic signal. A digital representation of the interfering signal, comprising a series of digital words, is generated and a nulling signal formed from this digital signal is subtracted from said electrical signal. The amplitude difference between said electrical signal and the nulling signal is determined and the digital words comprising the digital representation of the interfering signal are changed by a function of the difference between said electrical signal and said nulling signal, to reduce said difference.

Abstract: An airborne geophysical measurement and recording system and apparatus in which radar signals are focused onto terrain below an aircraft flying in a straight line between microwave tower sites. The echo signals are detected and signals produced and recorded on a strip chart recorder indicating path profile and terrain reflectivity. In addition, atmospheric pressure, temperature and humidity data are recorded as functions of aircraft altitude, so that atmospheric refractivity gradients can be calculated, either by an on-board computer or later, and this factor taken into account during path design or performance simulation.

Abstract: A Doppler radar system in which quadrature Doppler signals are derived to eld directional information. The quadrature signals are derived by demodulating the return signals with respective odd and even harmonics of the sinusoidal signal used to frequency modulate the RF carrier.

Abstract: A low power radar mounted on the train interrogates passive transponders located along the track. Inductive coupling arrangements associated with the radar and each of the transponders inhibits responses from transponders other than the one immediately underneath the radar, and also for indicating failure of transponders.