Showing papers on "Signal published in 1981"

Frequency-Independent and Frequency-Dependent Nonlinear Models of TWT Amplifiers

Abstract: Simple two-parameter formulas are presented for the functions involved in the amplitude-phase and the quadrature nonlinear models of a TWT amplifier, and are shown to fit measured data very well. Also, a closed-form expression is derived for the output signal of a TWT amplifier excited by two phase-modulated carriers, and an expression containing a single integral is given when more than two such earriers are involved. Finally, a frequencydependent quadrature model is proposed whose parameters are obtainable from single-tone measurements.

Concentrating zone method in heterogeneous immunoassays

Abstract: Method and apparatus are provided for performing immunoassays employing a device comprising a relatively small test zone referred to as an immunosorbing zone, and a relatively large liquid absorbing zone in liquid receiving relationship with said immunosorbing zone. The immunosorbing zone includes a member of an immunological pair ("mip")--ligand and antiligand--bound to a support. A signal producing system is employed in conjunction with said device having as one component a signal label bound to a mip. The signal producing system provides for production of a detectible signal in the immunosorbing zone in relation to the amount of analyte in a sample.

Interpolation and decimation of digital signals—A tutorial review

Abstract: The concepts of digital signal processing are playing an increasingly important role in the area of multirate signal processing, i.e. signal processing algorithms that involve more than one sampling rate. In this paper we present a tutorial overview of multirate digital signal processing as applied to systems for decimation and interpolation. We first discuss a theoretical model for such systems (based on the sampling theorem) and then show how various structures can be derived to provide efficient implementations of these systems. Design techniques for the linear-time-invariant components of these systems (the digital filter) are discussed, and finally the ideas behind multistage implementations for increased efficiency are presented.

Digital signal processing for sonar

Abstract: This paper is a tutorial which describes "main stream" sonar digital signal processing functions along with the associated implementation considerations. The attempt is to promote further cross-fertilization of ideas among digital signal processing applications in sonar, radar, speech, communications, seismology, and other related fields.

Television viewing center system

Abstract: At least two television reception tuners are used in a viewing center system, one for the television signals and the other for supplementary information transmitted during the blanking intervals and separated in the reception center by a data separation stage. A programmable control stage including a microprocessor accepts information not only from the data separator, but also from a manual remote control input device and from a timing control stage. A signal source switching unit for both the audio part and the composite video part of television signals is controlled by the microprocessor and interconnects signal sources including the tuners and auxiliary equipment, such as recording devices, a local camera, television games, and so on, with audio and video output devices. A digital data bus provides control to the various input and output devices.

An overview on the time delay estimate in active and passive systems for target localization

Abstract: Sonar and radar systems not only detect targets but also localize them. The process of localization involves bearing and range estimation. These objectives of bearing and range estimation can be accomplished actively or passively, depending on the situation. In active sonar or radar systems, a pulsed signal is transmitted to the target and the echo is received at the receiver. The range of the target is determined from the time delay obtained from the echo. In passive sonar systems, the target is detected from acoustic signals emitted by the target, and it is localized using time delays obtained from received signals at spacially separated points. Several authors have calculated the variance of the time delay estimate in the neighborhood of true time delays and have presented their results in terms of coherence function and signal and noise autospectra. Here we analyze these derivations and show that they are the same for the case of low signal-to-noise ratio (SNR). We also address a practical problem with a target-generated wide-band signal and present the Cramer-Rao lower bound on the variance of the time delay estimate as a function of commonly understood terms such as SNR, bandwidth, observation time, and center frequency of the band. The analysis shows that in the case of low SNR and when signal and noise autospectra are constants over the band or signal and noise autospectra fall off at the same rate, the minimum standard deviation of the time delay estimate varies inversely to the SNR, to the square root of the product of observation time and bandwidth, and to the center frequency (provided W^{2}/12 f\min{0}\max{2} \ll 1 , where W = bandwidth and f_{0} = center frequency of the band). The only difference in the case of a high SNR is that the standard deviation varies inversely to the square root of the SNR, and all other parameter relationships are the same. We also address the effects of different signal and noise autospectral slopes on the variance of the time delay estimate in passive localization.

Signal Delay in RC Tree Networks

Abstract: In MOS integrated circuits, signals may propagate between stages with fanout. The MOS interconnect may be modeled by an RC tree. Exact calculation of signal delay through such networks is difficult. However, upper and lower bounds for delay that are computationally simple are presented here. The results can be used (1) to bound the delay, given the signal threshold; or (2) to bound the signal voltage, given a delay time; or (3) to certify that a circuit is "fast enough", given both the maximum delay and the voltage threshold.

Method of and apparatus for determining very accurately the position of a device inside biological tissue

Abstract: A method of and apparatus for determining very accurately the position of a device inside biological tissue comprising a detecting instrument with a probe, which probe generates a small magnetic field which can be disturbed by a magnetically permeable metal in the device inside the tissue when a narrow end of the probe is positioned immediately adjacent to tissue containing the metal, whereby after the metal-carrying device is inserted in the tissue, the end of the probe is used to precisely locate the device by scanning the tissue until the magnetic field is disturbed which causes the instrument to emit a signal.

Health education system

Abstract: A computer controlled interactive instruction system for teaching an individual comprising a peripheral having at least one sensor for producing a signal representing a function which has been or is to be manually performed by the individual, a first device for storing a sequence of signals representing instructions relating to the correct manner of performing the function, a first display coupled to the storing device for displaying the instructions, a second device for storing video and associated audio signals representing both pictorial and oral representations of the correct manner of performing the function, a second display for displaying the pictorial representation, and a computer coupled to the peripheral, the first and second storage devices and the first and second displays for causing an ordered sequence of the instruction signals in the first signal storage device to be displayed by the first display whereby the individual may learn to recognize and to perform the function, for receiving the signals from the peripheral and detecting correct or incorrect performance of the function by the individual and for causing appropriate ones of the stored video signals to be displayed by the second display and the associated audio signals to be produced to illustrate the correct performance of the function if incorrectly performed by the individual whereby telling, showing and coaching of the individual in the recognition and performance of the function may be accomplished.

Ink jet recording device

Abstract: PURPOSE:To prevent a plugging in an ink flow channel by circulating a diluent and cleaning an ink flow channel during nonrecording time and adjusting the concentration and viscosity of ink with a diluent during recording time. CONSTITUTION:A high-level detection signal Sb from a recording state detection means 18 is output to a control circuit 19 and this circuit 19, based on the said signal Sb and a detection signal Sa from a concentration/viscosity detector 17 provided inside a subtank 5, outputs control signals Sc, Sd controlling the operation of an ink valve 3 and a diluent valve 4 respectively during recording time. Ink or a diluent is supplied into a tank from tanks 1, 2 for adjustment of the concentration/viscosity of ink and then ink is caused to spurt from an ink gun 10. While during nonrecording time, low-level signal Sb is outputted to the circuit 19 from the detection means 18, outputting a control signal Sd to open the valve 4, so that a diluent in a tank 2 is supplied to a tank 5 and a diluent is run through a pipe 9 for cleaning an ink flow channel and a gun 10.

Solid-state image sensor with exposure controller

Abstract: A solid-state image sensor which detects the quantity of light incident on image sensor cells during exposure and performs exposure control in accordance with an exposure value thus obtained The solid-state image sensor is provided with a photoelectric converter having a plurality of non-destructive readout type image sensor cells arranged in a matrix form; an exposure detector for reading out stored information of predetermined ones of the image sensor cells during exposure, obtaining an added value of the stored information thus read out and detecting that the added value reaches a predetermined level; an exposure controller which is supplied with the detected signal from the exposure detector to control at least one of the charge storage time of each image sensor cell by an optical signal, the intensity of light incident on the image sensor cell and the photosensitivity of the image sensor cell; and a scanner for scanning the photoelectric converter to read out stored information of the image sensor cells during exposure

Two-wire bus-system comprising a clock wire and a data wire for interconnecting a number of stations

Abstract: A computer system comprises a number of stations which are interconnected by means of a clock bus wire (20) and a data bus wire (22) which both form a wired logic function of the signals generated thereon by the stations (32, 34). During the clock pulses, the signal on the data bus wire is stationary; it may change between the clock pulses. Start and stop conditions are formed by a signal combination between clock bus wire and data bus wire (60 and 62, respectively) which is not permissible in a data stream. If there is more than one master station so that a composite clock signal occurs on the clock bus wire, the clocks of the relevant master stations are each time resynchronized to the actual transitions in the composite clock signal.

Apparatus and method for providing a logical exclusive OR/exclusive NOR function

Abstract: Circuits are illustrated using CMOS design techniques for incorporating N and P channel transistors into a circuit to obtain the functions of exclusive OR and exclusive NOR signal generation. This is accomplished by utilizing a given logic value signal as a control signal to pass the other input signal for three of the four possible logic value conditions. The fourth condition must generate the output signal from a selected one of the input signals, through the use of an inverter.

Satellite-based vehicle position determining system

Abstract: A system for determining the positions of a plurality of vehicles traveling on or above a defined sector of the earth's surface comprises a transponder carried by each vehicle for transmitting a uniquely coded beacon signal in response to a general interrogation signal, at least three repeater-carrying satellites at spaced orbital locations above the earth for receiving and retransmitting the beacon signals produced by the vehicles, and a ground station for periodically transmitting the general interrogation signal and for receiving and processing the beacon signals retransmitted by the three satellites in order to determine vehicle position. In order to avoid signal overlap and equipment saturation at the ground station, each vehicle transponder includes means responsive to the general interrogation signal for inhibiting the transmission of further beacon signals by the transponder for a predetermined time interval following the response of the transponder to the general interrogation signal. In a preferred embodiment of the invention, the inhibited interval of the vehicle transponders may be varied automatically in response to a command signal transmitted by the ground station.

The Correction of I and Q Errors in a Coherent Processor

Abstract: A method is presented for correcting the gain and phase imbalances and the bias errors of the in-phase and quadrature channels of a coherent signal processor [1] by means of coefficients which are derived from measurements of a test signal. The residual errors after correction depend upon the signal-to-noise ratio (S/N) of the test signal and the degree of filtering used in deriving the correction coefficients.

Battery operated access control card

Abstract: An access control card for use in an access control system. A battery, a wireless signal sensor such as an antenna for receiving coded wireless signals such as coded radio frequency signals generated by a card reader, a clock connected to the battery and including a receiver are connected to the antenna for supplying a received signal based upon the coded radio frequency signal. A memory for stores first and second stored codes, and a transmit circuit connected to the antenna, to the clock and to the memory compares the first stored code to the received signal and transmits the second stored code when there is a match between the received signal and the first stored code.

High impedance fault detection apparatus and method

Abstract: Apparatus is provided for detecting the presence of a high impedance arcing fault on an electrical circuit, particularly a high voltage power line. Detection of a high impedance fault is realized by monitoring the high frequency components of the alternating current in the circuit, and evaluating the high frequency components of each cycle of the alternating current using a microcomputer operating in accordance with a program of instructions, to determine the occurrence of a significant increase in magnitude of the high frequency components, and then to determine whether the increase exists for a prescribed period of time and follows a prescribed pattern. The high frequency components are monitored using a current-to-voltage transducer coupled to the electrical circuit, bandpass filters coupled to the transducer, and an analog-to-digital converter providing digitized samples of the filtered transducer output voltage signal.

Blood sugar analyzer having fixed enzyme membrane sensor

Abstract: A blood sugar analyzing apparatus has a reaction cell which houses a fixed enzyme membrane sensor and a measuring electrode which receives a blood specimen which causes a chemical reaction between the blood specimen and said fixed enzyme membrane for measuring the blood sugar concentration in the specimen on the basis of a reaction current signal generated in the sensor by the chemical reaction. The analyzing apparatus has a microcomputer for calculating a conversion coefficient used for converting the reaction current into a blood sugar concentration value by introducing a standard solution having a known blood sugar concentration, for storing data representing the value of said conversion coefficient, for calculating a blood sugar concentration value of a test specimen based upon the stored conversion coefficient value and reaction current from the test specimen. A display and printer provide a read-out of the blood sugar concentration value obtained. The microcomputer controls temperature and timing of the measurement process, as well as other control functions.

System for overlaying a computer generated video signal on an NTSC video signal

Abstract: A system for overlaying a computer generated video signal on an NTSC video signal includes horizontal and vertical pulse processor circuits for generating a horizontal start signal and a vertical reset signal, respectively, in accordance with NTSC standards, and a clocking system for receiving the vertical reset signal and the horizontal start signal and for generating control signals to control the read out of video data from the video generator of a computer so that it is read out at an NTSC rate. The system further includes a video insert keyer circuit for combining the NTSC video signal and the computer generated video signal and for generating a composite video signal for transmission to a monitor or standard television.

Airborne radar jamming system

Abstract: A radar jamming signal generated by equipment carried by a target aircraft, is launched onto the leading end of a towed single wire transmission line so as to travel the length of the line as a nonradiating surface wave. A drogue radiator is attached to the trailing end of the line for radiating the jamming signal transversely of the towed line so as to be received by and cause jamming of tracking and/or fire control radar. The length of the single wire transmission line is selected so that the trailing radiator causes the jamming signal to emanate from a position sufficiently behind the aircraft so as to be outside the destructive radius of weapon fire directed at the apparent source of the jamming signal by fire control radar. A ventriloqual-like deception of the radar is thus achieved. A wave launcher couples the jamming signal to the leading end of the transmission line and for this purpose includes an electrically conducted horn-shaped structure, a tunable coaxial feed end at the constricted end of the horn structure, an inner transition conductor connecting the inner conductor of the coaxial feed to a leading end of the single wire transmission line, and a plurality of annular dielectric lenses and dielectric guides cooperatively shaped and fitted to the horn structure in a manner that effectively matches the bounded electromagnetic transmission wave characteristics of the coaxial feed cable with the surface wave transmission characteristics of the single wire transmission line. Coacting with the ventriloqual-like radiation of the jamming signal from the trailing end of the transmission line is an anti-integration network that hides the return radar signal reflected off the target aircraft in a signal energy “hole” created for such purpose in a secondary low level noise signal transmitted directly from the aircraft.

Driving simulator apparatus

Abstract: Apparatus for vehicle driving simulation including a cabin capable of being swivelled and having therewith a screen, control devices and the driver's seat, from where the road picture can be observed and controlled. The cabin is capable of being swivelled around an axis which is parallel to the viewing direction and above the center of gravity of the driver. The cabin is driven by a power drive dependent upon the signal of the centrifugal acceleration via a control amplifier and by use of a measuring device, a tipable back which is driven by a power drive dependent upon the acceleration signal via a control amplifier, elastic buffers which support the driver's seat and a vibrator which is intermittingly switched on dependent upon the rotation signal via a frequency divider and a control amplifier.

Acousto-optic signal processing: Convolution and correlation

Abstract: The use of acousto-optic devices in real-time signal convolution and correlation has increased dramatically during the past decade because of improvements in device characteristics and implementation techniques. Depending on the application, processing can be implemented via spatial or temporal integration. Two-dimensional signal processing (including image processing) is possile, in spite of the inherent one-dimensional nature of the acousto-optic device as a spatial light modulator.

Dual band communication receiver

Abstract: Diclosed is a dual band communication receiver for use in a burst communication sytem. The receiver is capable of esentially simultaneous reception at a first carrier frequency (L), such as L-band and a higher carrier frequency (H), such as S-band, using distinct codes and replying in the frequency band received. A typical system is composed of a transponder and an interrogator. The incoming coded signal is down converted to an i.f. frequency compatible with surface acoustic wave (SAW) convolvers. The i.f. signal is then divided between two SAW convolvers, each having a convolution interval of two times the message symbol length (2T). Reference signals A and B are composite signals comprised of alternate L-band and H-band signals, each having a time period equal to T and each L- or H-band signal operating at a 50% duty cycle. Reference signals A and B are time reversed to the input signals applied to the convolver and are orthogonal to one another. Each of the convolver outputs are processed through log video detection circuits to reduce the dynamic range followed by peak detecting and stretching to reduce the pulse bandwidth. The outputs from each peak detection and stretching circuitry are coupled to a smaple-and-hold circuit which are in turn divided such that one path is to synchronization and interrogation sidelobe suppression (also referred to as sidelobe inhibit, ISLI or control signal) matched filters designed to look for the particular symbol sequences between the two convolver channels characteristic of the preamble and ISLI signals. The synchronization signal and the sidelobe suppression signal are used in order to determine if a valid preamble has been detected by the receiver and if the receiver is in a desired portion of the interrogator radiation pattern; if so, then a timing or address signal and the remaining portion of the message which contains the data is clocked into a memory.

Remote lighting-control apparatus

Abstract: A main control device comprises a plurality of lighting-control signal generators for generating lighting-control signals whose contents can be analogously varied, and a keyboard for specifying the contents of mode signals corresponding to those of the lighting-control signals. The lighting-control signals are supplied to the terminal control devices through a signal line. Mode signals and address signals are supplied to the terminal control devices through the signal lines. A terminal control device selected by the address signal selects a lighting-control signal corresponding to a mode signal. The selected lighting-control signal controls the lighting of a lighting load by phase control.

Application of Kalman Filtering in Computer Relaying

Abstract: During the first cycle following a power system fault, a high speed computer relay has to make a decision usually based on the 60 Hz information, which is badly corrupted by noise The noise in this case is the nonfundamental frequency components in the transient current or voltage, as the case may be For research and development purposes of computer relaying techniques, the precise nature of the noise signal is required The autocorrelation function and variance of the noise signal was obtained based on the frequency of occurrence of the different types of faults, and the probability distribution of fault location A new technique for modelling the signal and the measurements is developed based on Kalman Filtering theory for the optimal estimation of the 60 Hz information The results indicate that the technique converges to the true 60 Hz quanitities faster than other algorithms that have been used The new technique also has the lowest computer burden among recently published algorithms and appears to be within the state of the art of current microcomputer technology

Amplitude modulation using digitally selected carrier amplifiers

Abstract: An amplitude modulator (10) is disclosed which generates an amplitude modulated carrier signal by selectively combining varying numbers of other carrier signals. A circuit (20) is included which provides plural carrier signals of like frequency and phase where the number of carrier signals being provided is dependent upon the level of an input signal. A combiner circuit (22) combines the plural carrier signals to thereby provide a combined signal which is the desired amplitude modulated carrier signal. In one embodiment (FIG. 3) the carrier signals which are combined are all equal in amplitude. In another embodiment (FIG. 4) the amplitudes of some of the carrier signals are weighted in a binary progression. In yet another embodiment (FIG. 9) the carrier signals are all frequency modulated whereby the output signal has both a varying frequency and amplitude.

Ripple detector for automotive alternator battery charging systems

Abstract: Detector (28) monitoring the voltage ripple in the rectified electrical output signal of an alternator (22) in a multiphase alternator battery charging system. A circuit monitors the undulating alternator output signal and produces a signal level in response. To correct the detector operation for various magnetic phenomena present in the alternator, a first circuit measures the rotational speed of the rotor and produces a proportional signal. A second circuit determines the excitation current supplied to the field coil. The measurement and determination are separately weighted and combined to form a corrected comparison threshold value. A variable threshold circuit combines the signal proportional to the rotational speed of the rotor and the determined field coil excitation current to produce a combined signal level. Comparison means compare the signal level from the monitored alternator output signal with the combined signal level and produce an output signal level indicative of the detection of a voltage ripple in excess of the combined signal level. The output signal is corrected for the effects of significant alternator performance characteristics.