Showing papers on "Signal published in 1991"

Exploitation of spectral redundancy in cyclostationary signals

Abstract: It is shown that the cyclostationarity attribute, as it is reflected in the periodicities of (second-order) moments of the signal, can be interpreted in terms of the property that allows generation of spectral lines from the signal by putting it through a (quadratic) nonlinear transformation. The fundamental link between the spectral-line generation property and the statistical property called spectral correlation, which corresponds to the correlation that exists between the random fluctuations of components of the signal residing in distinct spectral bands, is explained. The effects on the spectral-correlation characteristics of some basic signal processing operations, such as filtering, product modulation, and time sampling, are examined. It is shown how to use these results to derive the spectral-correlation characteristics for various types of man-made signals. Some ways of exploiting the inherent spectral redundancy associated with spectral correlation to perform various signal processing tasks involving detection and estimation of highly corrupted man-made signals are described. >

Pulse responsive device

Abstract: A pulse responsive device, for example, a pulse rate meter or pulse oximetry device, is disclosed, which includes a light emitter and a light sensor for receiving light from the emitter after transmission through, or reflection from, body tissue to give an electrical signal varying according to blood flow or other fluid pulsations. A movement transducer gives an additional electrical signal representing body movements or vibrations, but independent of blood flow pulsations. This movement transducer may include a light emitter and sensor responsive to a different wavelength from the light emitter and light sensor used for measuring, and varying with, blood flow or other fluid pulsations. The pulse responsive device compares the two electrical signals produced to cancel out the movement or vibration noise fro the signal obtained from the light sensor which obtains measurements which vary with blood or other fluid flow pulsations.

Temperature controlled rf coagulation

Abstract: Radiofrequency medical devices for ohmic heating of tissue of a patient include a temperature sensor (29) carried by and in thermally conductive relationship with a thermally conductive electrode (28). The sensor (29) is connected for feedback to a control circuit (6) that modulates RF power applied to the electrode according to the signal received from the temperature sensor (29). The control circuit (6) and RF power supply alternate between two operating modes. In the first mode the RF power supply applies RF power to the electrode (28). In the second mode the control circuit (6) senses a signal from the temperature sensor (29) in the absence of RF signal. The control circuit (6) compares the signal from the temperature sensor (29) to a set value and modulates the RF power applied to the electrode (28) in accordance with the set value.

The complex backpropagation algorithm

Abstract: The backpropagation (BP) algorithm that provides a popular method for the design of a multilayer neural network to include complex coefficients and complex signals so that it can be applied to general radar signal processing and communications problems. It is shown that the network can classify complex signals. The generalization of the BP to deal with complex signals should make it possible to expand the line of applications of this powerful nonlinear signal processing algorithm. >

Sound signal reproducing device

Abstract: PURPOSE:To apply tone control of a high frequency range automatically by adjusting the amplification factor of the high frequency component in response to the level of the high frequency component of an input sound signal. CONSTITUTION:Input sound signals of left and right channels (L), (R) are added by an adder circuit 12 to form an (L+R) signal, only a high frequency component is extracted through an HPF 13 and converted into a DC voltage in response to the level of the high frequency component by a rectifier circuit 14 and a smoothing circuit 15. The DC voltage is amplified by an amplifier circuit 16 to form a control voltage of a high frequency adjustment circuit 2. The left/right channel sound signals inputted to a sound signal processing circuit 1 are subject to high frequency component adjustment by using the control voltage of the circuit 2 and the control voltage by manual adjustment through the use of a variable resistor 10a. Then the signal is adjusted manually by the adjustment circuit using a bus 3, a balancer 4 and a variable resistor 5 and the sound is outputted from speakers 8, 9 through amplifier circuits 6, 7.

Data communication apparatus

Abstract: A data communication apparatus wherein the stealthiness has been enhanced by significantly increasing the time required for a wiretapper to decrypt an encrypted text. The data communication apparatus is constituted by connecting a data transmitting apparatus and a data receiving apparatus via a transmission path. The data transmitting apparatus receives a first predetermined initial value (key information) and information data, generates a multi-valued signal the level of which varies substantially like a random number, and converts the multi-valued signal to a modulated signal of a predetermined modulation format for transmission. The data receiving apparatus demodulates the modulated signal to output the multi-valued signal, and then reproduces the information data from the multi-valued signal and a second predetermined initial value (key information) that is received.

CDMA subtractive demodulation

Abstract: Subtractive CDMA demodulation optimally decodes a coded information signal embedded in many other overlapping signals making up a received, composite signal. A radio receiver correlates a unique code corresponding to the desired signal to be decoded with the composite signal. Moreover, after each information signal is successfully decoded, it is recoded and removed from the composite signal. Subtractive CDMA demodulation is enhanced by decoding the composite signal in the order of strongest to weakest signal strength. The individual information signals are spread using block error correction codes which are correlated with the composite signal using Fast Walsh transforms. Correlated signals identified as the largest transform component are removed from the composite signal and the remaining composite signal is reformulated using an inverted Fast Walsh transform. Any residual error or interference caused during the extraction of a transform component is removed by recorrelating the composite signal using the index of that transform component.

Occupant sensing apparatus

Abstract: An occupant sensing apparatus for use in an occupant restraint system comprises a film having an electrical characteristic with changeable states and a contact member. When an occupant sits in a vehicle seat, the contact member pushes on the film and changes the state of the electrical characteristic. An electric circuit is connected to the film for providing a first signal when the film indicates an occupant is not present, a second signal when an occupant is present, and a third signal if the film and the circuit become disconnected. The occupant restraint system is enabled when either an occupant is present or an electrical fault condition occurs. In accordance with another embodiment of the invention, an array of sensors located in the seat determines the occupant's position and weight and controls deployment of the occupant restraint system in response to the determined position and weight.

Single sensor adaptive drive circuit for rearview mirror system

Abstract: An automatic rearview mirror system having a reflective element that is actuatable between at least two different reflective conditions by a control that discriminates between glare-causing and nonglare-causing light simultaneously sensed by a single light sensor. The control includes a processor that is more responsive to decreasing levels of light than to increasing levels of light to produce a signal that is indicative of the slow-transient characteristic of the light sensed by the single light sensor. The processor may include a very slow signal processor that is always operative and a somewhat faster-slow signal processor, which may be selectively inhibited when the mirror is fully colored, or when a differential circuit indicates that the difference between the glare and the non-glare light sensed by the light sensor exceeds a predetermined level. The differential circuit may additionally limit the differential between the glare and the nonglare lights sensed by the light sensor.

Integrated radio satellite response system and method

Abstract: A radio response system including a broadcast station, a satellite relay, a processing center, and a plurality of user terminals. Each user terminal has a broadcast receiver, a communications interface device, a controller and a data transmitter. The broadcast station broadcasts a program signal. The broadcast receiver receives the program signal. The communications interface device communicates the program signal to a user. The controller generates a user-data signal from identification information transmitted in connection with the program signal and/or timing, location and frequency information needed for identifying the program signal, and a user-input signal generated in response to the program signal. The data transmitter transmits the user-data signal at a carrier frequency as a transmitted-data signal. The satellite relays the user-data signal to the processing center.

Apparatus and method for adaptively compressing successive blocks of digital video

Abstract: The compression of successive blocks of digital data is optimized by selecting between different compression algorithms or different data formats on a block-by-block basis. In one application, digitized interlaced video signals are processed for transmission in a compressed form. A set of pixel data presented in a field format is compressed to provide a first compressed video signal. The set of pixel data is also presented in a frame format and compressed to provide a second compressed video signal. Errors are evaluated in the first and second compressed video signals. The compressed video signal having the least error is selected for further processing. The technique is repeated for successive sets of pixel data and the selected signals are encoded to identify them as field formatted or frame formatted signals. The encoded selected signals are then combined to provide a compressed video signal data stream for transmission. Apparatus for receiving and decoding the signals is also disclosed.

Electro-surgical HF instrument for contact coagulation - has monitoring circuit evaluating HF voltage at electrodes and delivering switch=off signal

Abstract: The surgical instrument is connected to the h.f. leads output (33,34) of a h.f. generator (10) via a h.f. coupling transformer (11) to supply the electrodes (16,17,16',17'). A monitoring circuit (20) detects the voltage at the latter and evaluates it to deliver a switch-off signal to the h.f. generator. The monitoring circuit includes a differential circuit (21) with a d.c. voltage at its input that is proportional to the amplitude curve of the h.f. electrode voltage. Its output signal is delivered to a switch-off unit (23) actuating the h.f. generator. ADVANTAGE - Technically simple circuitry ensuring reliable automatic switching off of power after completion of contact coagulation. This ensures optimal result in each case.

Signal recognition system and method

Abstract: Apparatus and method for recognizing a signal, receives the signal and samples it at a plurality of sampling points to produce a plurality of signal values. A statistical moment of the signal is calculated using the signal values according to formula (I) where N = the number of sampling points; n = 1 < n < N; X = the signal value of the signal at the sampling point; ν = a mean of the signal values; σ = a standard deviation of the signal values; and k = an integer greater than 1. The calculated statistical moment is then compared with a plurality of stored signal identifications and the received signal is recognized as similar to one of the stored signal identifications. Preferably, the calculated statistical moment is used to create a feature vector which is quantized, and a weighted sum of the quantized feature vector is used to access a memory which stores the signal identifications.

Apparatus for segmenting encoded video signal for transmission

Abstract: A vide signal encoding system includes apparatus for segmenting encoded video data into transport blocks for signal transmission. The transport block format enhances signal recovery at the receiver by virtue of providing header data from which a receiver can determine re-entry points into the data stream on the occurrence of a loss or corruption of transmitted data. The number of re-entry points are maximized by providing secondary transport headers embedded within encoded video data in respective transport blocks.

Dual indifferent electrode pacemaker

Abstract: An endocardial lead having first and second spaced apart electrodes resides in a patient's heart The first electrode is a sensing electrode and the second electrode is a carrier signal driving electrode The lead has a conductor coupling a source of alternating current carrier signals of a predetermined frequency to the second electrode A third electrode is in electrical contact with body tissues A cardiac pacer apparatus includes a pacer can which functions as a fourth electrode and has a plastic top wherein the third electrode is located Said third electrode acts in cooperation with the first electrode to form a pair of sensing electrodes The sensing electrode pair is further coupled to a sense amplifier for receiving an amplifying modulated electrical signals developed across the sensing electrode pair A demodulator and filters circuit for demodulating the modulated carrier signal and recovering the modulating signal therefrom is connected to the output of the sense amplifier The modulating signal is proportional to instantaneous stroke volume of the patient's heart and the demodulator and filters circuit develops a control signal therefrom called a stroke volume signal The control signal is applied to the pulse generator so as to control the rate of stimulating pulses

Spread spectrum digital data transmission over TV video

Abstract: A co-channel communication system allows transmission of one or more data signals in an active or visible portion of a video raster in a manner that is imperceptible to a viewer. More particularly, the data signal is transmitted over a preselected active video lines of a video raster. In order to reduce the perceptibility of the data signal, the video lines over which the data signal is transmitted is varied according to a random sequence. In an alternate embodiment, the data is also modulated at relatively low modulation levels, for example, by converting the data signal to a spread spectrum signal.

Analysis of mismatch effects among A/D converters in a time-interleaved waveform digitizer

Abstract: High-speed A/D conversion can be achieved by employing a parallel array of M A/D converters interleaved in time, each working at 1/Mth of the sampling rate. Theoretically, the resolution of the structure is given by the resolution of the A/D converters in the array (subconverters). In practice, however, mismatches among the subconverters lead to a decrease in the resolution. The effect of such mismatches is analyzed in terms of a signal-to-noise ratio defined as the ratio between the energy of the input analog signal and the energy of the error signal due exclusively to these mismatches. The analysis shows that the distortion is comparable to that generated by nonuniform sample timing in the analog demultiplexer when converting a single high-speed signal into several low-speed sampled-and-held signals. The results of the analysis can be used to specify the degree of precision to be achieved in an actual monolithic implementation. >

Position identification system

Abstract: A position identification and navigation system comprising an active transceiver unit for transmitting a request signal, and a network of passive units for transmitting digital location information back to the active unit in response to the request signal. The active unit receives the information signals and displays the location information to assist in position identification, navigation and tracking.

Contactless, inductive data transmission system

Abstract: A contactless inductive data transmission system provides bidirectional signal transfer between a sending-and-receiving station and one or more batteryless transponders. A high-frequency signal from the sending-and-receiving station is pulse width modulated for data transmission to a transponder and provides a system clock, which is extracted in both the sending-and-receiving station and in the transponder for synchronization, and provides the electrical power for operation of the transponder. The pulse width modulated signal is demodulated in the transponder for triggering a response wherein a modulating signal is applied by load modulation to the pulse width modulated high-frequency signal to form an information-carrying load modulated high-frequency signal, which is demodulated in the sending-and-receiving station.

Embedded servo banded format for magnetic disks for use with a data processing system

Abstract: A data processing system records information on magnetic disks in a format in which sector headers, which include embedded servo information, are radially aligned and recorded at a single frequency and data are recorded at various band-related frequencies. The system records sector headers at a frequency which is optimal for the recording of address information in the shortest sector and records the data at frequencies which are optimal for the recording of information in the disk space allocated to the data portion of the various lengths of sectors. The system synchronizes to the headers, using conventional embedded servo synchronization methods, and produces header timing signals. It can then use the same header timing signals to locate and interpret the headers on different tracks, since the header frequency and the location of the headers are the same in every track. The system may record the data portions of the sectors at frequencies which are related to the header frequency by ratios of small integers. The system then uses, in synchronizing to the disk, a phase locked loop which includes a voltage controlled oscillator (VCO) that is driven to a reference frequency which is directly related to the header frequency. The system divides-down the frequency of the VCO output signal to produce the timing signals for the header. Also, it uses a version of the output signal of the VCO, which is divided-down by a band-related value, as a timing signal for the data.

Multiprogram video tape recording and reproducing device

Abstract: A video tape recording and reproducing device and a related method having a recording and a reproducing mode including a plurality of tuners for concomitantly receiving a plurality of television programs and generating a plurality of respective recording signals when in the recording mode, mixing means for producing a mixed recording signal responsive to the plurality of generated recording signals, recording means for recording the mixed recording signal on a video tape, reading means for reading the mixed recording signal from the video tape when in the reproducing mode, separating means for reproducing a selected recording signal from the mixed recording signal, and means for outputting the reproduced selected recording signal to an external device for producing the corresponding television program.

Connectors with ground structure

Abstract: The present invention relates to electrical connectors with a ground structure for impedance and cross talk control between signal carrying conductors.

Synchronous spread-spectrum communications system and method

Abstract: A spread spectrum communications system for use over a communication channel, including a transmitter-generic-chip-code generator (101), a transmitter-message-chip-code generator (102), an EXCLUSIVE-OR gate (103), a combiner (104), a transmitter (107), a receiver-generic-chip-code generator (121), a receiver-generic mixer (123), a generic-bandpass filter (125), a receiver-message-chip-code generator (122), a receiver-message mixer (124), a message-bandpass filter (126), and a synchronous detector (139). The transmitter-generic-chip-code generator (101) generates a generic-chip-code signal and the transmitter-message-chip-code generator (102) generates a message-chip-code signal. The EXCLUSIVE-OR gate (103) spread-spectrum processes message data with the message-chip-code signal to generate a spread-spectrum signal. The combiner (104) combines the generic-chip-code signal with the spread-spectrum signal. The transmitter (107) transmits the combined generic-chip-code signal and spread-spectrum signal, on a carrier signal (108) over the communications channel as a spread-spectrum-communications signal. The receiver-generic-chip-code generator (121) generates a replica of the generic-chip-code signal. The generic mixer (123) recovers the carrier signal from the spread-spectrum-communications signal. The receiver-message-chip-code generator (122) generates a replica of the message-chip-code signal. The receiver-message mixer (124) despreads the spread-spectrum-communications signal as a modulated-data signal. The tracking and acquisition circuit (121) uses the recovered carrier signal for synchronizing the replicas of the generic-chip-code signal to the recovered carrier signal. The synchronous detector (139) synchronously demodulates the modulated-data signal as received data.

Surgical implement detector utilizing a powered marker

Abstract: An apparatus for detecting a surgical implement (16) in human or animal tissue has means for defining a transmitting zone (14) encompassing a surgical wound (12) in the tissue. A battery powered marker (20) is secured to a surgical implement (16) positioned within the wound (12). Field generating means (27) are provided for generating within the transmitting zone (14) an electromagnetic field having a predetermined frequency band. A signal generating (22) means generates a signal having a predetermined frequency band. The signal generating (22) means is operative to cause the field generating (27) means to generate the electromagnetic field, providing the marker (20) with signal identity. A detecting means (30) having an antenna (32) located within the transmitting zone (14) of the marker (20) detects the marker (20) signal irrespective of the marker's orientation therewithin.

Apparatus for the detection of motion transients

Abstract: An apparatus for detecting movement in patients coupled to pulse oximeters and a method for using the signal generated by the apparatus to filter out the effects of motion from the test results generated by the pulse oximeter are disclosed. In a preferred embodiment, a piezoelectric film located in close proximity to the pulse oximeter's sensor provides a voltage signal whenever movement occurs near the sensor. This voltage signal is processed and the resulting signal is used to correct the oximeter's measurements. In addition to piezoelectric film, accelerometers and strain gauges are also usable to provide a signal indicative of motion.

Damping torque analysis of static VAR system controllers

Abstract: The use of a damping torque technique to examine the efficacy of various control signals, for reactive power modulation of a midpoint-located static VAr system (SVS) in enhancing the power transfer capability of long transmission lines is considered. A new auxiliary signal, the computed internal frequency (CIF), is proposed which synthesizes the internal voltage frequency of the remote generator from electrical measurements at the SVS bus. It is demonstrated that this signal is far superior to other conventional auxiliary control signals in that it allows full utilization of the network transmission capacity. The damping torque results are correlated with those obtained from eigenvalue analysis. >

Body temperature thermometer and method fo measuring human body temperature utilizing calibration mapping

Abstract: A body temperature thermometer has a probe head assembly (8) which includes a first sensor (10), such as a thermopile, for generating a first output signal representative of an amount of infrared radiation impinging thereon The probe head assembly further includes a waveguide (16) and a surrounding hollow probe (14) for receiving infrared radiation emitted by a biological surface tissue, such as the external ear canal and tympanic membrane of a patient, and directing the radiation to the first sensor. A second sensor (12) is mounted in the probe head assembly for generating a second output signal representative of a temperature of the first sensor. A third sensor (26) is thermally coupled to the waveguide for providing a third output signal representative to the temperature thereof. A processor (30) is connected to the sensors for processing the output signals to determine a body temperature of the patient utilizing a calibration mapping of a plurality of target temperatures to corresponding output signals taken over a predetermined range of ambient temperatures. A display (34) is driven by the processor for providing a user with a visual indication of the determined body temperature.

Remote tracking system for moving picture cameras and method

Abstract: The system includes a mobile remote unit sensitive to infrared (IR) signals transmitted by a base or stationary unit and an IR transmitter which is placed behind a rotating lens whose position at any time is known with precision resulting in the IR signal being "scanned" across an area. The remote unit detects when the peak strength of the signal occurs and provides this data via an RF signal to the base unit wherein the exact effective angle between the axis of the IR signal and the remote unit creates an error signal used by the base unit to position the camera mounted thereon. Transmitters for TILT and two PAN positions, PAN 1 and PAN 2, are used to include range calculations for ZOOM functions. Command circuitry to override the automatic tracking function is provided in each of the units.

Surgical implement detector utilizing capacitive coupling.

Abstract: An apparatus for detecting a surgical implement in human or animal tissue comprises a battery powered marker. The marker (20) is secured to the surgical implement (16) and positioned within a surgical wound (12). A detection means (30) has an antenna (32) disposed in close proximity of the tissue (2). Means are provided for capacitance coupling of both the marker and the antenna to the tissue. A signal generating means (22) generates a signal having a predetermined frequency band ranging from about 10MHz to 1GHz. The signal generated by the signal generating means causes a field generating means (27) to generate an electromagnetic field providing the marker with signal identity.