Showing papers on "Signal published in 1973"

Amplifying and processing apparatus for modulated carrier signals

Abstract: A power amplifying and signal processing system for modulated carrier signals separately processes the amplitude component of the system input signal and the component of frequency or phase or both frequency and phase, and later recombines the separately processed components to provide an output signal. The amplitude and phase transfer functions of the system can be accurately controlled. The input signal is fed to a power amplifier whose output provides the output for the system. The input and output signals of the system are fed by separate paths to a comparator which compares those signals and emits an error signal to a controller. The controller regulates the amplitude and phase, or both, of the power amplifier''s output to null the error signal. One or both of the signal paths to the comparator may have in it a non-linear function generator which acts upon the signal fed by that path to the comparator. The system may also have a frequency translator and phase shifter interposed between the system input terminal and the power amplifier''s input to shift the frequency or phase or both of the signal applied to the power amplifier''s input.

Object tracking and orientation determination means, system and process

Abstract: A field (e.g., a magnetic field) which nutates about a pointing vector is used to both track or locate an object in addition to determining the relative orientation of this object. Apparatus for generating such a field includes mutually orthogonal coils and circuitry for supplying an unmodulated carrier, hereafter called DC signal, to one coil and an AC modulated carrier signal, hereafter called AC signal, to at least one (usually two) other coil, such that the maximum intensity vector of a magnetic field produced by the currents in the coils nutates about a mean axis called the pointing vector direction of the field. The generated field is sensed in at least two orthogonal directions at the object to be tracked and whose orientation is to be determined. The sensed signals provide an indication of the direction and orientation of the object relative to the coordinates of the generating means.

Optimum processing for delay-vector estimation in passive signal arrays

Abstract: For the purpose of localizing a distant noisy target, or, conversely, calibrating a receiving array, the time delays defined by the propagation across the array of the target-generated signal wavefronts are estimated in the presence of sensor-to-sensor-independent array self-noise. The Cramer-Rao matrix bound for the vector delay estimate is derived, and used to show that either properly filtered beamformers or properly filtered systems of multiplier-correlators can be used to provide efficient estimates. The effect of suboptimally filtering the array outputs is discussed.

Guidance system for a horizontal drilling apparatus

Abstract: A drilling apparatus for forming a horizontal borehole substantially parallel to a first drilled horizontal borehole which has a signal generating apparatus inserted into the first borehole. A horizontal drill is inserted into the subterranean strata adjacent the first drilled borehole and operated until it is in the formation. A signal receiver contained in the horizontal drill apparatus will then receive a signal generated by the signal generating apparatus. The signal generating apparatus will always be maintained a fixed distance behind or in front of the horizontal drilling apparatus. The signal receiver in the horizontal drill will also include an antenna sensitive to direction which can orient itself with the signal generating apparatus. Knowing the angle between the horizontal drill and the signal generating apparatus, along with the distance along the first borehole between the horizontal drill and the signal generating apparatus, will provide sufficient data to calculate the distance between the first horizontal borehole and the drilling apparatus.

Some aspects of band-pass filtering of surface waves

Abstract: Narrow band-pass filtering of multi-mode surface-wave signals can be used to extract information concerning the group velocities and spectral amplitudes of each mode. A detailed examination of narrow band-pass filtering shows the effect of epicentral distance and the shape of the group-velocity curve upon the filtered signal. With this knowledge, the filtered signal can be used to make accurate estimates of the spectral amplitudes of each mode. A rectangular and a Gaussian filter are considered in detail. A numerical example is provided to indicate the values and limitations of the technique for determining the spectral amplitudes of each mode.

Radio telephone system

Abstract: A portable duplex radio telephone system includes at least one base station transmitter having a predetermined base transmission range, and a plurality of portable or mobile units each having a predetermined portable maximum transmission range predeterminately shorter than the base transmission range. Satellite receivers are deployed about the base station within the base station transmission range for receiving transmissions from the portable units. The base station transmitter transmits signals on a signalling channel and on at least one communications channel. Each transmitter signalling and communications channel has a frequency that is paired or associated with a receiving frequency of the satellite receivers. In a multiple base station system, the portable receiver has means for scanning the base station transmitter signalling frequencies and for tuning the portable transmitter to the signalling frequency associated with the frequency of the strongest signalling signal received from the base transmitter. When communication is initiated, the portable transmitter and receiver are automatically retuned to one of the communications channels as determined by the strongest signalling frequency received by the portable receiver and by channel availability. Means are also provided in the system to continuously locate a portable unit and switch the operating frequency thereof as the portable unit moves between base station transmitter coverage areas. Further means are provided to automatically reduce the output power of each portable transmitter to the minimum level required for satisfactory communications in order to reduce battery drain and the interference caused by the portable transmitters.

Burner control system

Abstract: A burner control apparatus for use with a furnace installation that has an operating control to produce a request for burner operation, a flame sensor to produce a signal when flame is present in the monitored combustion chamber, and one or more devices for control of ignition and/or fuel flow. The burner control apparatus comprises lockout apparatus for de-energizing the control apparatus, a control device for actuating the ignition and/or fuel control devices, and a timing circuit that provides four successive and partially overlapping timing intervals of precise relation, including a purge timing interval, a pilot ignition interval, and a main fuel ignition interval. The present invention further includes a burner control system which verifies the proper operation of certain sensors in a burner or furnace including particularly the air flow sensor. Additionally, the present system also prevents an attempt to ignite a burner if a condition is detected which indicates that the air flow sensor has been bypassed or wedged in the actuated position.

Method and apparatus for monitoring and counteracting excess brain electrical energy to prevent epileptic seizures and the like

Abstract: This invention pertains to a biomedical detecting and control apparatus wherein electrical signals in the brain of mammals are continuously monitored by electrodes implanted in certain critical places in the brain wherein excess electrical energy is manifest during epileptic seizure conditions as well as during psychic storms of some types of mental illness. Such signals are processed via electrical systems of various circuits for inversion, comparison, vector analog addition, filtering, modulation, level set, safety level limits and self test to provide a controlled signal output which automatically reduces or eliminates the excess electrical energy at the point of detection. The points of detection and control may be, but do not have to be, the same spots on the brain. The probes may be near the surface of the brain or deep set in the brain depending upon the area affected. In addition to the method, there is described an electronic device which is contemplated to be housed in a small housing outside the body of the mammal and connected through wire conductors connected to the electrodes at the point of detection and at the other end of the conductors to outlet connectors in the housing providing the point of control.

An Introduction to the Analysis and Processing of Signals

Abstract: Part 1 Signal analysis: periodic signals - the Fourier series aperiodic signals - the Fourier transform, use of the Laplace transform sampled-data signals random signals - Gaussian signals signal comparison. Part 2 Signal processing: signals and systems modulation and sampling filters signal recovery, detection and prediction - the Weiner filter, the Kalman filter.

Radiating line transmission system

Abstract: A radiating transmission line system employs a pair of leaky coaxial cables which are spaced from each other and extend along a tunnel to propagate radio signals. The signals to be propagated are fed to both cables in such a manner that the signals in one cable are in antiphase to the signals in the other cable. This reduces attenuation of the signal in the cable.

Liquid crystal display system with integrated signal storage circuitry

Abstract: Liquid crystal display systems having display panels in which a matrix array of reflective electrodes, as well as the individual addressing circuitry (field effect transistor) and electrical storage circuitry (capacitor) for each cell of the display panel, are formed on semiconductor backplates such that each reflective electrode forms one element or plate of the capacitor for the corresponding cell. Each field effect transistor is utilized to address an associated element of the matrix array, and the associated storage capacitor maintains the applied potential across the liquid crystal cell for a period sufficient for scattering centers to be formed in the liquid crystal material.

The theory and application of conductance probes for the measurement of liquid film thickness in two-phase flow

Abstract: The thickness of a rapidly moving, wavy film of water can be continuously measured and recorded using a probe, which consists of two surface-mounted parallel conductors across which a high frequency AC signal is applied. A theory is given which allows prediction of the electrical conductance of the probe as a function of the film thickness and shows how the useful range of particular probe designs can be assessed. The theory, which can be applied to probes in either flat or curved surfaces, also includes the effect of a step change in the film thickness, so that the resolution of the probe may be predicted.

Emergency communication system

Abstract: The specification discloses an emergency communication system which includes a portable unit for being carried by a wearer. The portable unit includes a radio transmitter and receiver and is operable to selectively transmit and receive coded radio signals. A console is operable to receive the coded radio signals transmitted from the portable unit and in response thereto for transmitting an emergency signal via a leased telephone line to a remote central station. The central station receives the emergency signals and implements a call for assistance and generates an acknowledge signal. The console receives the acknowledge signal and transmits a coded acknowledge signal to the portable unit. The portable unit receives the coded acknowledge signal and operates a vibrator to notify the wearer that assistance is being provided. Switches are provided on the console which may be actuated by the wearer during a predetermined time period after generation of the acknowledge signal, in order to cancel the summoning of assistance by the central station.

Electronic identification system

Abstract: An electronic detection and identification system operating with correlated microwave frequencies wherein a transmitter continuously transmits a beam of electromagnetic energy, in a predetermined direction, so as to impinge on an identification tag suitably attached on a passing object. The identification tag derives a harmonic signal from the impinging beam and radiates a beam of energy, at the harmonic frequency, which is pulse modulated in accordance with a preset identification code. The receiver receives the reflected beam and generates signals representative of the code modulation.

Data acquisition, storage and display system

Abstract: Medical data including temperature, respiration rate and pulse rate are measured and stored in an acquisition unit incorporating a circulating register for storing data covering many patients. An analog temperature signal is converted into binary coded decimal for visual presentation on a display of the acquisition unit. The display data is then stored in the acquisition unit memory by actuating a RECORD switch. An analog respiration rate signal and an analog pulse rate signal are also converted into binary coded decimal for sequential display and storage in the acquisition unit memory. Medical data from external sources may similarly be stored in the acquisition unit memory. This recording procedure is repeated for any number of patients desired up to the storage limit of the acquisition memory. Data stored in the acquisition unit is then transferred into a printer unit that accesses each memory location and prints the data on a separate label for each individual patient. The printer includes a hard wired minicomputer which reads in data from the acquisition unit and compares it with identifying codes for controlling a digital printer. Medical data for each patient stored in the acquisition unit is temporarily stored in a random access memory and sequentially compared with each of a plurality of identifying codes for control of the digital printer. After all patient data in the acquisition unit has been transferred into the printer memory, a signal is generated to enable clearing of the acquisition unit memory for subsequent use thereof.

An adaptive array for interference rejection

Abstract: An adaptive array that rejects undesired or interfering signals is presented. The array pattern is controlled by an adaptive feedback system based on a steepest descent minimization of mean-square error. Error is defined as the difference between the array output and a locally generated reference signal. Minimization of mean-square error is closely related to maximization of signal-to-noise ratio (SNR). A two-element adaptive array has been built, and its experimental performance is discussed. Typical patterns for various desired and interfering signals are shown, as well as measured transient response. Finally, some experiments showing the array behavior with modulated signals are described. The results show that such an antenna system is capable of automatically rejecting interfering signals, subject only to certain basic constraints. No a priori information about the angles of arrival of the signals is required, Detailed knowledge of the waveforms of the desired and interfering signals is also not needed, although the spectral characteristics of the desired signal must be known.

Maximum‐likelihood signal processing for a vertical array

Abstract: This paper presents the maximum‐likelihood signal processor for steering a vertical array in the vertical direction. The major application is to the estimation of the depth of a distant narrow‐band continuous point source in the waveguide. The eigenfunctions of the guide are used to match the array to the received signal The error of the depth estimate is derived as a function of the aperture and geometry of the array, the covariance function of the ambient noise received by the array, and the observation period; assuming that the source and medium are stationary during that period. The processing technique can be applied to any perfect waveguide in which a signal source is detected by an array of sensors.

Electro-optical transmission line

Abstract: An electro-optical transmission line for use in an interconnection system wherein an electrical signal is converted to an optical output signal by a light-emitting diode and the optical light signal is transmitted by an optical fiber bundle to a light receiving diode which converts the optical signal back to an electrical signal. The optical bundle is terminated at its ends in sleeves which are threadedly engaged with coaxial electrical contact assemblies.

Bioelectrical impedance measuring system

Abstract: A bioelectrical impedance measuring system that measures and indicates the impedance of a biological subject, such as one or more human extremities. The system measures and indicates a basal impedance value of the measured subject, and also indicates short temporal variations in the basal value. In the system an excitation signal, derived from an electrical signal source, is coupled to the subject by excitation electrodes and a resulting subject output signal is sensed by receiver electrodes. The subject output signal is electronically subtracted from a reference signal derived from the signal source, and the resulting signal is used to drive a display unit. The system includes a null detector connected to the display unit input, and an automatic gain control unit responsive thereto, connected in the subject output signal path to automatically maintain the system in a nulled condition. With the output of the system adjusted to a null condition the value indicated is proportional to the basal impedance of the subject. The automatic gain control unit includes a lock function generator to hold the variable gain at an instantaneous null establishing a basal value for a desired measurement episode. Consequently, any variations in the nulled signal are indicative of variations in the impedance of the subject. A range indicator is associated with the gain control unit to verify that the subject output signal is within the dynamic range of the gain control unit.

Single stage power amplifiers for multiple signal channels

Abstract: There is disclosed apparatus for amplifying, for example, four separate stereo or audio information channels by means of a common power amplifier. Each audio channel is modulated on a respective carrier signal and then applied to a common amplifier which is of a wide-band circuit configuration. Certain filtering and scanning techniques are also implemented to enable multiple channel amplification without the necessity of individual, separate amplifiers.

Inertially stabilized gimbal platform

Abstract: An inertially stabilized gimbal platform is disclosed wherein the gyros used in such system operate about their mechanical null positions and control the gimbal drive means through an electronic control section. The electronic control section includes a control signal which is combined with the gyro output to provide a drive signal for the gimbal drive means. The control signal is proportional to the offset between the electrical null position and the mechanical null position of the gyro. The control signal may be modified in accordance with platform command signals to orient the platform in a desired attitude.

Automatic vehicle-monitoring system

Abstract: A plurality of public-transport surface vehicles such as buses, each identified by an individual number, are equipped with transmitters for sending out that identification number together with heading and positional data conveying information on direction of travel and momentary distance from a point of departure; the transmitted information may also indicate the state of occupancy of the vehicle. This information is received at transit points along the route, each transit point including circuits for determining from the directional and distance data the distance of an approaching vehicle from that point. If the transit point is a passenger station, the shortest vehiclular distance or distances are registered with the accompanying identification and occupancy data in one or more stores for display to waiting passengers. The directional and distance data can also be intercepted by a traffic-control post to detect the approach of vehicles at an intersection as an aid in the operation of traffic lights. The data-evaluating equipment at any such transit point includes a comparator determining whether a newly arriving signal is from a vehicle whose data have already been registered in a store thereof, i.e. whether the transmitting vehicle is among those closest to that point at the instant of reception.

Hexagonal Multiple Phase-and-Amplitude-Shift-Keyed Signal Sets

Abstract: Selection of a particular signal set array for a bandwidthConstrained multiple phase-and-amplitude-shift-keyed (MPASK) communication system for a linear additive Gaussian noise channel requires consideration of factors such as average and/or peak power versus symbol error probability, signal amplitude dynamic range, simplicity of generation and detection, and number of bit errors per symbol error (Gray code properties). A simple technique is presented for generating and optimally detecting the honeycomb (hexagonal.) signal set, i.e., the signal set that has the tightest sphere-packing properties. The symbol and bit error probability performance of this set is compared to other two-dimensional signal sets that have been investigated in the literature, and is shown to be slightly superior from an average power standpoint. The paper concludes with a comparison of all of these signal sets from the standpoint of the factors listed above.

Device for promoting formation of bone material

Abstract: A device for promoting the formation of bone material in the region of the bone structure of a living being by the application of an A.C. signal, including at least two metal electrodes, which can be inserted into the bone, and an A.C. signal source, which has at least two connecting wires. Each of the connecting wires is connected to a corresponding one of the metal electrodes. A locking element is connected to the end of each connecting wire and a corresponding receiving element is disposed on each of the electrodes. By interlocking of the locking element with the corresponding receiving element, the connection between the connecting wire and the corresponding electrode is effected.

Stimulation control apparatus for an ink jet recorder

Abstract: A drive circuit for a stimulation transducer suppresses generation of satellite drops in an ink jet recorder. The drive circuit is an oscillator which tracks the resonant frequency of the stimulation transducer. As the resonant frequency of the transducer changes during normal operation, the frequency of the driving signal also changes, so that the power output of the transducer remains essentially unchanged. This provides accurate regulation of the filament length for the jets being stimulated and unexpectedly also suppresses generation of satellite drops. The drive circuit comprises an amplifier, a load resistor and positive and negative feedback paths to the input terminals of the amplifier. The load resistor is incorporated within the negative feedback path as well as within the supply path for the stimulation transducer. In general the impedance of the stimulation transducer is minimum at the resonant frequency thereof, so that for any shifting of the resonant frequency there is an increase in the input impedence to the transducer. This produces a voltage variation across the load resister which in turn alters the negative feedback to the amplifier. Means are provided for adjusting the negative feedback signal so as to maintain the amplifier in a state of continuous oscillation. The frequency at which this oscillation occurs is the frequency at which the impedance of the transducer is minimum, and therefore the drive circuit tracks the resonant frequency of the stimulation transducer.

A computer system for the measurement of cell and nuclear sizes.

Abstract: SUMMARY A semi-automated system has been developed for the measurement of cell (perikaryal), nuclear and nucleolar areas. The system consists essentially of a Graf/Pen data tablet (with its associated acoustical stylus and tablet electronics), an optical input system such as a camera lucida, and a small digital computer. The perikaryal, nuclear and nucleolar outlines are traced in sequence with the stylus which, on contacting the tablet surface, emits a high frequency acoustic wave that is sensed by X and Y strip microphones along the left and upper edges of the tablet. The acoustic signal is converted by a simple program into a series of X and Y coordinates which are sampled at several points around the perimeter of the profile. When the stylus tip re-enters a 1 mm stationary window set up around the starting point, the measurement is automatically terminated and the data for this profile is printed out and stored in memory for subsequent statistical analysis. The system has an overall accuracy of about 1% and in practice it has been possible to measure objects at least ten times more rapidly than by any of the other currently available methods. The hardware and software features of the system are detailed and a number of additional uses for the system are described.

FM demodulator circuits

Abstract: There is disclosed an FM demodulator including first and second phase locked loops for demodulating a first and second FM signal contained in a composite signal. The loops employ frequency feedback whereby one loop controls the input to the other loop and vice versa to assure that said first and second signals are separately demodulated relatively independent of their power ratio as present in said composite signal.

Physiological waveform detector

Abstract: A physiological waveform detector such as for cardiac R-wave and blood pressure uses a comparator to compare the derivative of the waveform signal with a reference signal representing some percentage of the magnitude of the derivative of the waveform. If the derivative is of sufficient magnitude to trip the comparator a timing circuit begins counting. If the comparator remains tripped for a predetermined interval, the waveform is considered to be the desired one. Means are provided for detecting waveform peaks and valleys. The detector recognizes desired waveforms by two characteristics, one being magnitude and the other being duration.