Abstract: Method and apparatus for decoding Huffman encoded words are disclosed which include the use of logic gates connected in the form of a binary decoding tree which includes branches, interior and leaf nodes. Bits of the encoded word are sequentially supplied to gates of the binary tree. Simultaneously, gate enable signals are supplied to gates of the binary tree. Both the data bits and enable signals are supplied to gates at increasingly higher levels of the binary tree. When an output is obtained from a gate associated with one of the leaf nodes of the tree, the process of sequentially supplying data bits and enable signals to gates of the binary tree is repeated for the next encoded word. The original data words are regenerated by use of outputs from said gates associated with leaf nodes of the binary tree.

Abstract: CW intrusion detection method and apparatus are shown comprising first and second CW Doppler radar systems which include first and second antennas, respectively. The first antenna is located adjacent ground level for illumination of a protected area adjacent the ground. The second antenna is located directly above the first antenna a spaced distance therefrom, and illuminates the same protected area adjacent the ground. In response to movement of an intruder along the ground in the protected area, first and second Doppler difference frequency signals are obtained from the first and second radar systems. Using the first and second Doppler difference frequency signals, a signal proportional to distance of the moving intruder from the first antenna is generated.

Abstract: A directionally controllable sled for downhill snow skiing has a unitary plastic body which includes a bottom member formed with a pair of downwardly and longitudinally extending elongated runners along opposite sides thereof. The pair of runners are spaced generally flat bottom surfaces and have inwardly facing plane control surfaces extending generally perpendicular to the bottom surfaces and intersecting along facing edges which are effective for directional control of the sled by the user during sled movement. The runners are formed with smoothly curved outwardly facing sides which are substantially less effective than the inwardly facing runner edges for directionally controlling the sled.

Abstract: A system for obtaining air movement is disclosed which includes a dome which is supported a spaced distance above the earth to provide for the inlet of air from a location outside the dome. A passage or tunnel is provided which has an air inlet beneath the dome in substantially axial alignment with the dome axis and an air outlet outside the dome, with the passage or tunnel outlet below the level of the air inlet thereof. Cooling elements of refrigeration means are located in the passage or tunnel for cooling air therein and producing gravity flow of air down the passage or tunnel from the air inlet to the air outlet of the passage or tunnel. Air enters the passage or tunnel air inlet with a cyclonic motion due to Coriolis acceleration, and wind-operated means are located under the dome for operation by the cyclonically moving air. A generator is located in a chamber beneath the passage or tunnel and is coupled to the wind-operated means under the dome for operation thereby.

Abstract: Radiographic imaging method and apparatus are disclosed which include a gas gap formed between closely spaced dielectric and photoconductor surfaces, across which gap a uniform strength electric field is applied. Counting gas is supplied to the gas gap, and penetrating radiation, such as X-ray radiation, is directed onto the photoconductor through an object to be examined. Photons absorbed in the photoconductor induce electron-hole pairs resulting in increased localized conductivity thereof and localized intensification of the electric field across the gas gap to a level for production of gas discharge across the gap. Ion amplification by Townsend cascade enhances charge transfer in the gas gap. An apertured platen may be provided against which dielectric imaging paper is held by gas pressure to facilitate formation of the narrow, substantially uniform width, gas gap. A charge image is produced on the dielectric imaging surface which then is developed using conventional xerographic developing techniques.

Abstract: Digital data compression method and means are disclosed which allow for transmission of digital data over a short time period and/or narrow bandwidth transmission line. Also a maximum amount of information may be stored on a movable recording medium using data compression method of this invention. Digital signals to be stored and/or transmitted first are compressed using a finite-impulse response digital compression filter which generates estimated signal values which are subtracted from actual signal values to provide a sequence of difference signals. The difference signals are encoded using a truncated Huffman type encoding method and means, and the encoded signals are transmitted to a remote receiver and/or are recorded. The receiver includes a decoder and digital reconstruction filter for exact reproduction of transmitted digital signals. The invention is well adapted for storage and/or transmission of three lead electrocardiogram (ECG) signals, recording and playback of music, and the like.

Abstract: A system for enhancing the quality of a signal received by a mobile FM transmitter by reducing the adverse effects of multipath transmission to the receiver. A pair of antennas is provided, and each antenna is arranged to receive transmitted signals that traverses a different path. The signal produced in the receiver by one antenna is compared with a reference threshold and when the amplitude of the signal falls below the reference threshold, the receiver switches to the other antenna. The signal amplitude is sensed in a high frequency portion of the receiver, i.e. before detection or demodulation, so that switching between antennas occurs rapidly and is normally not perceived by the user of the receiver.

Abstract: A system for obtaining air movement is disclosed which includes a basin of water covered by a solar energy-transmitting dome a spaced distance over the basin. The basin is located on a mountainside, adjacent a cliff, or the like. a surface type heat exchanger is located in the water adjacent the bottom of the basin, and an air inlet passage is provided having one end which terminates above the water surface beneath the dome and an opposite end connected to the heat exchanger. A long air outlet passage in the form of a flexible tube made of canvas, plastic sheet, or the like, is connected to the outlet from the heat exchanger, which outlet passage extends downwardly along the mountain slope, cliff, or the like. Venturi tubes are located along the air outlet passage, and vane-driven devices are positioned at the venturi tubes for operation by the cooled air flowing downwardly therethrough. An air valve at the bottom end of the air outlet passage controls the rate of air flow therethrough.

Abstract: Method and apparatus for obtaining quantitative velocity profile measurements and for displaying the same are disclosed. From such velocity measurements, instantaneous volume flow within a vessel across which the measurements are obtained is calculated. In one operating mode, a real-time display of quantitative velocity profiles is provided together with a scrolling display of a plurality of total instantaneous volume flow measurements. In another operating mode, velocity profiles obtained at corresponding points in successive cardiac cycles are averaged to obtain a plurality of average velocity profiles which are selectively displayed under operator control. In this mode of operation, a fixed display of total instantaneous volume flow measurements obtained over a period of time which includes at least one cardiac cycle is provided.

Abstract: A geophone is disclosed which includes at least two transducers having axes which are perpendicular to each other for sensing vertical and horizontal in-line components of seismic waves. In one arrangement, the geophone includes a signal processor which includes active circuit elements responsive to the transducer output for suppressing ground roll components included in the transducer outputs. At least one of transducer output signals with ground roll signal components suppressed therefrom is connected to a remote location for recording. When more than one signal is to be sent from the geophone to the remote recording location, a mulliplexer is provided at the geophone for transmission of a plurality of geophone output signals to the remote location over a single transmission path, such as a dual-conductor transmission line. Analog and digital versions of the geophone are disclosed.

Abstract: A phase-lock loop is disclosed for synchronizing an oscillator signal with a train of input signal pulses, some of which may be missing. The phase-lock loop is of particular use in a decoder for decoding digitally encoded data employing a self-clocking coding scheme. The decoder generates a clock from the input signal stream for use in the decoding process.

Abstract: A digital decoder for Miller encoded signals is disclosed comprising a resettable counter which is clocked at a frequency which is a large multiple of the base frequency of the Miller encoded signal. Transitions in the Miller encoded data stream are used to reset the counter. Digital signal storage means are provided for storing a digital signal having a value substantially equal to the value to which the counter is advanced in one Miller unit of time. Output logic circuit means responsive to outputs from the counter and digital signal storage means produces a binary output signal indicative of the decoded Miller encoded input signal. Means are provided for recurrently updating the contents of the digital signal storage means to adjust for variations in the base frequency of the Miller encoded input signal.

Abstract: An ultrasonic transmitting and/or receiving transducer is disclosed which includes a piezoelectric body with electrodes at opposite faces thereof. At least one of the electrodes is in the form of an elongated strip conductor such that the transducer also functions as a lossy delay line. The beam pattern of the transducer is dependent upon the delay of the delay line. A high permeability member such as a ferrite body is located adjacent the elongated strip conductor to increase the distributed inductance of the delay line and, consequently, the delay thereof. The permeability of the ferrite body is controlled by use of a drive coil adjacent thereto. By time varying the drive current to the coil, the acoustic beam pattern is time varied. By using a spiral shaped elongated strip conductor on a cylindrical shaped piezoelectric body, a focusing transducer is provided.

Abstract: Digital data compression method and means are disclosed which allow for transmission of digital data over a short time period and/or narrow bandwidth transmission line. Also a maximum amount of information may be stored on a movable recording medium using data compression method of this invention. Digital signals to be stored and/or transmitted first are compressed using a finite-impulse response digital compression filter which generates estimated signal values which are subtracted from actual signal values to provide a sequence of difference signals. The difference signals are encoded using a truncated Huffman type encoding method and means, and the encoded signals are transmitted to a remote receiver and/or are recorded. The receiver includes a decoder and digital reconstruction filter for exact reproduction of transmitted digital signals. The invention is well adapted for storage and/or transmission of three lead electrocardiogram (ECG) signals, recording and playback of music, and the like.

Abstract: Individually useable wave-powered pumping means, solar distillation means, and cyclonic wind generating means, together with a system which employs each of them for harnessing natural energy sources are disclosed. Wave and solar energy, together with Coriolis acceleration are employed in the system which includes a basin for water situated near an ocean, or othe such body of water, having a surface subject to wave action. A solar energy transmitting cover is provided over the basin for solar heating, and evaporation of water contained therein. Vapor condensing means are located adjacent the bottom of the basin, and an upwardly extending inlet conduit, or passageway, connects the condenser to a source of water vapor above the water surface of the covered basin. Cooled air, and distilled water, are discharged from the condenser to a location outside the covered basin.

Abstract: Method and apparatus for transferring digital data in a bit stream consisting of digital data words each of which words includes data bits and a parity bit are disclosed. Except for the word parity bits, the stream is transferred without additional overhead bits such as start and stop bits employed in an asynchronous transmission data format or synchronizing characters employed in a synchronous transmission data format. Method and apparatus for locking onto the parity bit of such a bit stream are disclosed which allow for digital data transfer in this format.

Abstract: A plural channel playback system comprising magnetic recording tape movable past a reproducing transducer head having at least one transducing element for each track is shown together with skew detecting means. At least two of the tracks are recorded with digital data signals comprising equal length data words with a parity bit, with the parity bits being simultaneously recorded along the tracks. Parity bit lock-on circuits are responsive to outputs from two tracks, which lock-on circuits generate word clock pulses in synchronization with the recorded parity bit signals. A phase detector responsive to word clock pulses from the parity bit lock-on circuits produces an error signal output proportional to the phase difference between said word clock pulse inputs thereto, which error signal is related to skew. The azimuthal position of the reproducing head relative to the recording tape is adjusted either manually or automatically to minimize the error signal.

Abstract: A recording-playback system is disclosed wherein analog signals are converted to digital form which then are compressed and encoded using a variable length code. The encoded signals are temporarily stored in a buffer memory from which they are read out to a variable speed recorder for recording thereof. The rate at which the encoded signals are read out to the recorder and the recording speed are controlled in direct proportion to the percent fullness of the buffer memory for recording with substantially constant bit density on the recording medium. The ratio of the buffer memory read out rate and recording speed may be selected for recording with a substantially maximum bit density. A playback unit for the system includes a variable speed playback for playing back the recorded digital signals. The signals are temporarily stored in a buffer memory, from which memory they are read out to a decoder which operates at a substantially constant word rate.

Abstract: Method and apparatus for locking onto the parity bit of a bit stream of equal length words, each of which words includes a parity bit, are disclosed. The bit stream is shifted through a data shift register which includes a plurality of word length sections. Parity of bits contained in the first section of the data shift register is checked every bit interval of the bit stream. Two parity bit shift registers are provided, the first of which is one word in the length and the second of which is of the same length as the data shift register. The output from the parity checking means is connected to serial inputs of said first and second parity bit shift registers through a logic gate controlled by the serial output from the first parity bit shift register.