Showing papers on "Signal published in 1977"

Interpretation of myoelectric power spectra: A model and its applications

Abstract: Some essential elements of a mathematical model describing the power spectrum of myoelectric signals are presented. The influences of electrode cofiguration and of biological parameters such as muscle-fiber radius, action-potential conduction velocity, spread of synapses over the innervation zone, number of fibers per motor unit, and electrode-to-muscle distance are expressed in terms of filter functions modifying the shape of the power spectrum of the generator signal. Signal processing for parameter identification is described and results are listed. A few applications are discussed.

Optimum Reception in an Impulsive Interference Environment--Part II: Incoherent Reception

Abstract: Because communications systems are seldom significantly interfered with by classical white Gaussian noise, it is necessary to consider other, appropriate (and tractable) interference models, if realistic estimates of system performance are to be obtained for the general spectral-use environment. For this purpose, Middleton's recently developed canonical statistical-physical model of "impulsive" interference is applied to real-world communication channels. The principal features of this model are first summarized, including the statistical relations required for the solution of signal detection problems. [Excellent agreement of these model statistics with correspondingly measured statistics is also noted.] The model for narrow-band impulsive interference (Class A noise, a subset of the overall model) is next specifically applied to an important class of coherent signal detection problems. Algorithms for error probabilities in optimum detection are then obtained, along with performance bounds, for the same error probabilities. Since it is known that in order to gain significant improvement over current receivers, the number of (essentially) independent samples of the received interference waveform must be enlarged (i.e., large "processing gains"), the performance results here are given parametrically in the number of samples, or equivalently, in the time-bandwidth product. Performance of current suboptimum receivers is then obtained and compared to the optimum performance. It is shown that very substantial savings in signal power and/or spectrum space can usually be achieved by using the indicated optimal algorithms. Since physical realization of the completely optimum detection algorithms cannot, in general, be economically realized, the somewhat more conservative, corresponding locally optimum Bayes detection (LOBD) receivers are derived. In general, these LOBD structures require adaptive, highly non-linear filters, preceding the conventional correlation detector elements characteristic of optimum receivers for Gaussian interference. Performance for these non-linear, optimum threshold systems is then determined, specifically in Part I for coherent reception.

Label modified immunoassays

Abstract: Methods and reagents are provided for immunoassays employing as reagents a labelled receptor, where the label is capable of providing a detectable signal, and modifying reagents, capable of modifying the signal obtained from the label. When ligand (ligand analog for monoepitopic ligands) is present in the assay medium, a complex is formed which inhibits interaction between the label modifying reagent and the label. By measuring the signal obtained in the presence of a known amount of ligand in the assay medium and comparing that signal with the signal obtained with an unknown sample suspected of containing ligand, one can qualitatively or quantitatively determine the amount of ligand in the unknown. For determinating anti(ligand) the assay is carried out in substantially the same way, except a source of ligand or ligand analog must be provided.

Low-power, infrared information transmission system

Abstract: A low-power infrared information transmission system, the transmitter of which is compact, portable and capable of being powered by a low-voltage battery power source for an extended period of time, utilizes a unique infrared light pulse position modulation technique. The system is capable of transmitting information from a DC signal to a relatively high frequency AC signal. The system is utilized, for example, to transmit medical information from medical electrodes affixed to a patient via a portable infrared transmitter to a receiver unit which monitors and analyzes the patient's condition; to provide a remote control unit such as the controller for a video game or a TV on/off/channel selector, and, to provide a portable communications device such as a portable microphone or telephone set.

Electronic combination door lock with dead bolt sensing means

Abstract: The electronic combination door lock uses a push button keyboard in combination with a door provided with a dead bolt manually operable by an outer turning knob. The electronic circuitry for the keyboard compares an input code with a stored code and generates an enabling signal only if the input code is the same as the stored code. The outer turning knob is restrained from being manually moved to retract the dead bolt when the door is in its locked condition. This restraining of the outer knob is removed by the enabling signal which requires very little energy so that the dead bolt can then be manually retracted. Since the major portion of the work involved in unlocking the door is a manual operation, very little electrical energy is required for the keyboard and circuitry and a battery can thus be used to thereby eliminate complicated wiring to exterior power sources. Further major features of the invention include the ability to store several different combinations and to reprogram or change such combinations by means of the keyboard itself. The combination itself can comprise any number of digits within the capacity of memory storages in the electronic circuit.

Data acquisition system

Abstract: A data acquisition system utilizing a microcomputer and incorporating a plurality of monitors each adapted to produce an electrical signal indicative of a physical condition of apparatus to be monitored. The electrical signals are fed via multiplexing equipment and analog-to-digital converters into the microcomputer which is equipped with print-out means. The system is such that the level of any one or all of the signals from the respective monitors can be printed out as well as a change in the condition of any signal. Means are incorporated into the computer for calculating and printing the trend (i.e., the slope of a plot of signal amplitude versus time) of a succession of stored signals from any monitor which would indicate a probable malfunction of a device being monitored and the probable time to failure. In the case where the signals from the monitors comprise vibration signals, the system performs an automatic frequency spectrum analysis whenever a probable or actual malfunction is detected.

Recording method and device therefor

Abstract: PURPOSE:To simplyfy the construction of the device, easily make it multi-nozzle, enable the recording method high speed, and further obtain a distinct recorded image free from the occurrence of satellite dot and fogging by using a thermal energy effect on the ink jet recording method. CONSTITUTION:Recording medium 11 applied with a predetermined pressure by the pump 10 from the recording medium supply unit 9 is supplied to recording head 6 via valve 12. Electric heat converter 8, such as, thermal head is secured to the head 6 at a predetermined position of nozzle 7, and the recording information signal converted to pulse signal of ON-OFF by signal treating means 14 is applied to the converter 8. The converter 8 is instantly heated, and the thus produced heat energy acts upon the medium 11 in the proximity of the converter 8. The medium instantly brings forth the change of its condition to eject small drops 13 of the medium 11 from the orifice 15 of the nozzle, and the small drops 13 are flown and adhere to the recording medium 16 which moves in the direction of an arrow.

Medical patient condition monitoring system

Abstract: A medical patient condition monitoring system includes a portable battery-operable transmitter module which transmits monitored conditions of the patient via infrared energy to the receiver input stage of a medical monitoring and display unit. In one embodiment, the transmitter module which may be worn on the patient's person includes medical electrodes which are coupled to the patient's skin to receive electrical signals generated by the patient's anatomy. A voltage-controlled pulse position modulator circuit is coupled to the medical electrodes for generating pulses controllably positioned in time from a reference frequency in dependence upon the amplitude of the signal generated by the medical electrodes. An infrared light-emitting device is coupled to the output of the pulse position modulator circuit for generating infrared energy bursts in synchronism with the pulses generated by the modulator circuit. A receiver module having an infrared photodetector device located in the patient's room receives the infrared energy, and provides an electrical signal pulsed in synchronism with the bursts of infrared energy. A demodulator circuit coupled to the photodetector device generates an output signal which corresponds to the electrical signals received via the medical electrodes. This output signal is coupled to the monitoring and/or display unit for monitoring the patient's condition.

Coherent Two-Photon Excitation by Multiple Light Pulses

Abstract: We have studied Doppler-free two-photon excitation of atoms with a train of phase-coherent standing-wave light pulses, originating from the same laser pulse. Quantum interference effects produce narrow spectral fringes which have a physical origin similar to that of Ramsey fringes. Linewidths much less than the Fourier-transform limit of an individual light pulse have been observed for the sodium $3S\ensuremath{-}5S$ transition; and a dramatic enhancement of the resonant signal is possible.

Auto theft detection system

Abstract: A system is disclosed for locating missing vehicles. Each vehicle broadcasts a locator signal when queried from a central station by an encoded call signal having a code characteristic of the vehicle. Indicators responsive to the locator signal are provided to determine the location of the missing vehicle.

Rejection of flow noise using a coherence function method

Abstract: A method has been developed for rejecting transducer flow‐noise interference. The method makes use of coherence‐function relations between simultaneous pressure measurements at three transducers in the signal field and extracts from the flow‐noise background the power spectrum of the signal as received at each transducer. The signal in question can be periodic or stationary random. The coherence function relations are derived on the basis of a multivariate, random‐process model. The theory indicates that for a single source or for a group of completely coherent sources, the three transducers can be placed at arbitrary locations in the signal field. For a group of sources that are not completely coherent, the transducers must be located close together relative to the distance from the group. In any case, however, the flow noises at the transducers must be mutually independent. Successful results were obtained in laboratory tests of the method. In these tests a 10–15‐dB reduction in flow‐noise interference was attained. The method can also be used to reduce other types of noise such as instrument electronic noise.

Method and apparatus for eccentricity correction in a rolling mill

Abstract: A method and apparatus is disclosed for eccentricity correction in a rolling mill, in which prior to rolling, the eccentricity of the back-up rolls is measured and recorded both initially and each time the back-up rolls are changed. In an analog loop, constant roll gap is maintained by bidirectionally displacing the back-up rolls so as to maintain constant roll force in accordance with a reference roll force signal, the displacements being such as to neutralize the measured and recorded eccentricity. In a digital feedback loop, controlled by a digital computer, roll force is maintained constant in accordance with changes in the gauge of the work product, with the displacement of the back-up rolls producing a change in roll opening. The analog and digital control loops are cooperatively combined, so that the change in roll opening resulting from digital control, produces a new roll force reference for the analog loop. Effectively then, the intercooperation of analog and digital loops simultaneously produces roll eccentricity and gauge change compensation.

Continuous electrocardiogram monitoring method and system for cardiac patients

Abstract: A system which is capable of allowing an attending physician to continuously monitor the electrocardiogram (ECG) signals produced by a cardiac patient. The signals, generated by the patient, are first recorded in real time over a predetermined time period established by the physician. At the conclusion of the predetermined time period a monitoring station is automatically alerted by telephone and commences receiving the patient's real time ECG signals directly. The recorded ECG signals are then transmitted in a compressed time fashion to the monitoring station simultaneously with the real time ECG signals. The monitoring station receives the compressed time and the real time transmitted signals and following analysis thereof transmits a report of selected portions of the ECG to the physician. Upon instructions from the physician, the monitoring station either returns the recording apparatus to its normal operational status for a predetermined time period, or continues to receive and analyze the real time ECG signal until the patient's signal is sufficiently stable and then returns the recording apparatus to its normal operational status. This process repeats continuously. The physician communicates directly with the monitoring station and with the patient as may be required. The system and method provides close and complete monitoring of the patient with complete ECG data retrieval and individualized close patient surveillance.

Digital processing and calculating ac electric energy metering system

Abstract: A metering system for electric utility power line measurements includes voltage and current signal inputs that are randomly sampled and converted to binary representations. A system sequence controller and calculator provides programmed control for processing digital control and data signals and for producing digital calculations of electric energy parameters from the binary representations of the instantaneous signal values. Memory registers totalize and accumulate digitally calculated values for producing visual displays and output signals that correspond to electric energy parameters to be measured.

Vehicle operator security system

Abstract: A portable infrared signal generator is actuatable by a motor vehicle operator at a distance from the vehicle to generate digitally coded infrared signal pulses in accordance with either a first or a second predetermined digital code A receiver on the motor vehicle is effective to receive the infrared signal pulses, decode them and actuate apparatus responsive to the first digital code to unlock a power door lock and power a light effective to illuminate at least a part of the vehicle or responsive to the second digital code to actuate an alarm Both the first and second digital codes contain a common identifying portion substantially unique to the particular motor vehicle, which portion may be permanently stored in the generator and receiver by the connections of the input/output terminals of a microprocessor chip mounted on a printed circuit board to one of two voltage sources on the printed circuit board The receiver includes a photodiode connected in a circuit to operate in the photovoltaic mode so that the infrared pulses can be distinguished from strong background illumination for operation in daylight as well as at night The receiver further includes a lens and reflector for receiving the infrared pulses over a wide incoming angle The apparatus may include a sleep mode in which the reception of a predetermined number of signals not containing the code unique to the motor vehicle actuates apparatus to prevent unlocking of the doors and to actuate the alarm

Signal processing for the multistate myoelectric channel

Abstract: In the multistate myoelectric channel, a single myoelectric signal source is used to control a multifunction powered prosthesis. The selection of a prosthesis function requires a receiver to process the myoelectric signal, contaminated with noise, and to decide on the basis of the received signals which function is desired. Thus the channnel cleady presents a problem of choice of receiver and of decision strategy. Previous sotutions to this problem have been basically empirical. In this paper we seek the optimum receiver where optimum is in the minimum probability of error sense. First a model is developed for the bipolar myoelectric signal to provide information about the relevant signal parameters and statistics. Using this information the Bayes minimum probability of error receiver is derived for an orbitrary signal parameter set. The optimum signal parameter set is then found for the Bayes receiver, and the receiver performance calculated. The receiver performance is measured and compared with the calculated performance. A significant performance improvement is seen in the optimum receiver over a more conventional receiver.

Digital frequency-translated, plural-channel vestigial sideband television communication system

Abstract: A television communication system distributes plural VSB digitally encoded TV channels via an optical transmission link to one or more distribution terminals. At the headend the frequency band of each of the VSB signals is shifted down to baseband and transmitted in digital format. At each station along the network, the digitized baseband VSB television signal is converted into analog format and then reshifted through an up-converter to its original IF band so as to be compatible with the television receiver circuitry of the subscribers served by the distribution station. Advantageously, the present invention may employ optical communication techniques for coupling the digitally encoded frequency-shifted VSB television signals between stations. To maintain signal strength and quality, repeater units may be located in the optical communication link. Each repeater converts an incoming optical signal to an electrical signal for amplification and then reconverts the improved electrical signal back into optical form for further transmission along the link.

Real-time adaptive power control in satellite communications systems

Abstract: An adaptive transmitter power control for use in satellite communications systems wherein at least two ground stations communicate serial streams of binary data via a satellite transponder whose power-output is functionally dependent upon received signal strength. At least one of the ground stations includes a quality monitor which makes a real-time determination of the quality of the received signal, and generates signal quality indications in accordance with this determination. These signal quality indications are continuously communicated back to the corresponding transmitting station along with the serial stream of binary data. An encoder multiplexes the normal binary data and the signal quality indications into single, combined signal for transmission over only a single communications channel. The normal binary data and the signal quality indications are reconstructed at the transmitting station, where the signal quality indications are used to control the power level of the transmitted signal.

Weighted capacitor analog/digital converting apparatus and method

Abstract: An array of binary weighed capacitors, an additional capacitor having a capacitance value equivalent to that of the least of the binary weighted capacitors, a voltage comparator, switches for interconnecting the capacitors with certain predetermined voltage levels and the comparator, and a sequencing circuit are included. One side of all of the capacitors is connected to one input terminal on the comparator and the other side has applied thereto the signal to be quantized. Switch sequencing combines divided portions of a reference voltage with the signal to be quantized for presentation to the input of the comparator which thereby provides a serial digit output connected to the sequencing circuit. In this fashion, a linear conversion between an analog and a digital signal is made by the sequencing circuit. A nonlinear converter between digital and analog signal presentation is also disclosed.

Pattern-recognized structures in bounded turbulent shear flows

Abstract: It is now well established that coherent structures exist in turbulent shear flows. It should be possible to recognize these in the turbulence signals and to program a computer to extract and ensemble average the corresponding portions of the signals in order to obtain the characteristics of the structures. In this work only the u-signal patterns are recognized, using several simple criteria; simultaneously, however, the v or w signals as well as uv or uw are also processed. It is found that simple signal shapes describe the turbulence structures on the average. The u-signal pattern consists of a gradual deceleration from a local maximum followed by a strong acceleration. This pattern is found in over 65% of the total sample in the region of high Reynolds-stress production. The v signal is found to be approximately 180° out of phase with the u signal. These signal shapes can be easily associated with the coherent structures that have been observed visually. Their details have been enhanced by quadrant truncating. These results are compared with randomly generated signals processed by the same method.

Variable angle electronic halftone screening

Abstract: An electronic signal representing the density of a scanned image is electronically halftoned by combining the pictorial signal with a rectangular array of halftone screen values to form an electronic halftone image. The electronic screen function represented by the array of halftone screen values is rotated at variable angles to the original electronic image by defining a repetitive rectangular matrix representative of any predetermined halftone cell approximating a parallelogram and incorporating a shifting parameter for the repetitive rectangular matrix. An efficient, high speed, partial-dot halftoning technique is performed by indexing the screen function rectangular array, under the supervision of the shifting parameter, against the scanned image values for a realtime serial combination of the functional values.

Fluid dispensing control system

Abstract: In this fluid dispensing control system, the size of a container to be filled is established by a set of photosensors mounted on the dispenser housing. Discrimination circuitry distinguishes between ambient light level and light reflected from the container that is placed under the spout. Delay and lock-out circuitry is provided to insure that an erroneous size-indicating signal is not generated as the container is moved into position, and to insure that the size-indicating signal does not change once pouring has begun. Timer circuitry controls the pouring duration and insures complete, uniform filling of each size container. Counter and display circuitry tallies the number of containers, of each size that have been filled, and indicates the total volume of fluid that has been dispensed.

Fluid flow meter

Abstract: A fluid flow rate meter is disclosed for measuring the flow of fluid in a partially filled conduit or channel, including an electromagnetic probe adapted for mounting in the conduit below the low water mark thereof to produce a sensed velocity signal, and a liquid height pressure transducer including an air tube having a bubble-producing opening adjacent the probe for generating a liquid height signal that modifies the sensed velocity signal to produce a resultant signal that corresponds with the average velocity of fluid flow, whereby a more accurate measurement of the rate of fluid flow is obtained. The average velocity signal is multiplied with a conduit area signal obtained from the height signal by a function generator circuit which takes into account the maximum diameter of the conduit (or maximum height of the channel). A percent flow signal is modified by a second function generator in accordance with the area of the conduit.

Method of and apparatus for measurement of blood flow using coherent light

Abstract: An apparatus for measuring the flow parameter of blood flowing in an organ includes a laser and associated optics which effect the illumination of tissues. The laser light, scattered by the tissues, emerges with a spectrum broadened by Doppler effect due to motion of red blood cells in the micro-circulation vessels. The light from the tissues is fed to a photomultiplier tube or photodiode via a pinhole mask and interference filter. The photomultiplier tube or photodiode, as a result of beating of various components of the light it receives, produces as its output signals a homodyne or heterodyne spectrum or both. These output signals are fed, via a low pass filter, to a differentiator, which differentiates the output signals from the multiplier tube or photodiode, which are passed by the filter, with respect to time. The output of the differentiator is fed to a root-mean-square (RMS) detector. The low pass filter passes, for example, signals having a frequency up to about 20 KHz. The output (R) from the detector, which represents the blood flow (average percolation) in the tissues plus shot noise, a constant (S), is fed to a digital voltmeter. The voltmeter produces a visible read-out indicative of the output from the detector. The output from the detector is also fed to a calculating circuit which also receives a signal corresponding to the mean current (I) produced by the photomultiplier or photodiode, the calculating circuit effecting a solution to the equation ##EQU1## Fnorm is a normalized output signal representation of blood flow parameter.

Infant bed and apnea alarm

Abstract: A hospital bed or mattress for neonatal infants with a respiration monitor and alarm to detect apnea. No sensor or other appliance is attached to the infant. The bed comprises a base or frame structure with a soft resilient membranous top or cover, e.g., of sheet rubber. The closed air space below the pan is vented to the outside as by a small hole or tube, the average air pressure inside being about atmospheric. The baby's breathing causes slight rhythmic displacements of portions of the body, which in turn transmit small dynamic "recoil" forces proportional to acceleration to the flexible membrane on which the baby rests. The resulting diaphragm-like displacements modulate the air pressure inside. Breathing is sensed by monitoring this acoustic signal by a vented pressure microphone or by sensitive anemometer means connected to the vent. Acoustic and electrical filtering are used to discriminate against higher-frequency signals from the heart-beat and from ambient vibration. Cessation of the respiration signal for a predetermined period of time actuates an alarm.

Central system for controlling remote devices over power lines

Abstract: A system for use in a facility, such as the home, equipped with a common power distribution system, for controlling, from a central location, the operation of a plurality of remote devices. The system includes a central control unit including a memory for storing user-entered command information, preset instructions, time-of-day information, and remote-device selection information. The time-of-day information is compared with the current time-of-day and, in the presence of a time match, the command information and the remote-device selection information is modulated in a serial binary format onto a carrier signal which is coupled directly to the electrical system. A receiver/demodulator unit coupled to the electrical system and to a remote device receives the information from the central control unit and, if the command information is intended for the remote device with which the receiver/demodulator unit is associated, acts on such command information for controlling the operation of the remote device. The system also includes a receiver/demodulator/transmitter unit coupled to the power distribution system and to a remote device including a sensor for receiving and demodulating interrogation signals from the central control unit, for transmitting to the central control unit a signal indicative of the status of the remote device, and for receiving and demodulating command signals for controlling the operation of the remote device; a portable control unit for transmitting command information to the central control unit; and a unit for converting speech to a signal modulated with command information for transmission to the central control unit.

Robust Wiener filters

Abstract: The performance of minimum mean-square-error estimation filters for signals in additive noise can deteriorate considerably for deviations of the actual signal and noise power spectral densities (PSD's) from assumed, nominal densities. We consider two classes of PSD's which are useful models for the signal and noise when their PSD's are not precisely known. For these classes, robust filters which are saddlepoints for mean-square- error performance are derived. The robust filters achieve their worst performance for pairs of least-favorable signal and noise PSD's for which they are the optimum filters. It is shown by a numerical example that the robust filter can be very useful in maintaining a reasonable error performance over the whole of the classes of PSD's.