Abstract: A compression algorithm for the compression of ECG recordings uses the Karhunen-Loeve Transform (KLT) to transform a set of N sampled ECG beats from a matrix of N.times.M samples into a new form, from which a selected subset can be retained for storage, transmission, or analysis. In order to reduce computation time and storage space, a multirate downsampling operation may be applied, which retains the appropriate spectral information in each block. The downsampled beats are then padded to make them of uniform size, and a Karhunen-Loeve Transform is applied to the sample set. Coefficients from the Karhunen-Loeve Transform of the sample set are retained for reconstruction according to one of two criteria. The average variance of the reconstructed sample set may be controlled, or different numbers of coefficients may be retained for each beat. The KLT compressed data may be reconstituted by reverse KLT transforming the data.

Abstract: A delta sigma modulator of at least second order includes correction means applied to each feedback loop in the modulator, to account for systemic nonlinear output distortions. Since the output distortion is nonlinear, the correction applied to each feedback loop is nontrivially different. Such a corrected delta sigma modulator may be used in a demodulator including an output digital to analog converter (DAC) to account for systemic imperfections in the pulses formed by the DAC. The corrected delta sigma modulator is also useful in correcting output errors associated with high quality multilevel demodulators and class D power amplifiers. The corrected delta sigma modulator may be one bit or multilevel.

Abstract: A spatial enhancement system broadens the sound image of a stereo signal. The system emphasizes dissimilarity between the left and right channels by (i) boosting the level of the dissimilar components, (ii) providing spectral equalization to enhance the perception of breadth, and (iii) injecting an equalized, attenuated and inverted version of the dissimilar component into the opposite channel to broaden the components stereo image. The present invention avoids spectral coloration by providing a generally flat transfer function from input to output. Interchannel dissimilarity is estimated by performing a first order comparison of the left and right input signals. The comparison may be implemented by a peak detector on the L-R signal, a cross-correlation procedure, or some other scheme. As a feature, a feedback mechanism alters the equalization characteristics of the signals in a manner that is responsive to the dissimilarity of the output signals.

Abstract: An improved multiband audio compressor is well behaved for both wide band and narrow band signals, and shows no undesirable artifacts at filter crossover frequencies. The compressor includes a heavily overlapped filter bank, which is the heart of the present invention. The filter bank filters the input signal into a number of heavily overlapping frequency bands. Sufficient overlapping of the frequency bands reduces the ripple in the frequency response, given a slowly swept sine wave input signal, to below about 2 dB, 1 dB, or even 0.5 dB or less with increasing amount of overlap in the bands. Each band is fed into a power estimator, which integrates the power of the band and generates a power signal. Each power signal is passed to a dynamic range compression gain calculation block, which calculates a gain based upon the power signal. Each band is multiplied by its respective gain in order to generate scaled bands. The scaled bands are then summed to generate an output signal.

Abstract: A hair clip includes a low profile clip mechanism which translates linear pressure on the ends of the clip into rotational action for opening the curved comb moldings. Springs cause the clip to close when pressure on the clip ends is removed. The barrel of the clip may comprise sections which are fixed with respect to the clip ends and sections which are attached to the comb moldings, and which are rotated by the clip mechanism. Or, the barrel may comprise alternating sections attached to each comb molding. Removable decorative attachments attach to the fixed portions of the barrel of the clip, via magnets, snap on grips, velcro.TM. or the like.

Abstract: Audio spatial localization is accomplished by utilizing input parameters representing the physical and geometrical aspects of a sound source to modify a monophonic representation of the sound or voice and generate a stereo signal which simulates the acoustical effect of the localized sound. The input parameters include location and velocity, and may also include directivity, reverberation, and other aspects. The input parameters are used to generate control parameters which control voice processing. Thus, each voice is Doppler shifted, separated into left and right channels, equalized, and one channel is delayed, according to the control parameters. In addition, the left and right channels may be separated into front and back channels, which are separately processed to simulate front and back location and motion. The stereo signals may be fed into headphones, or may be fed into a crosstalk cancellation device for use with loudspeakers.

Abstract: Feedback cancellation apparatus uses a cascade of two filters along with a short bulk delay. The first filter is adapted when the hearing aid is turned on in the ear. This filter adapts quickly using a white noise probe signal, and then the filter coefficients are frozen. The first filter models parts of the hearing-aid feedback path that are essentially constant over the course of the day. The second filter adapts while the hearing aid is in use and does not use a separate probe signal. This filter provides a rapid correction to the feedback path model when the hearing aid goes unstable, and more slowly tracks perturbations in the feedback path that occur in daily use. The delay shifts the filter response to make the most effective use of the limited number of filter coefficients.

Abstract: An optical system for providing an in-focus, extended depth of field image on a projection surface includes an encoded mask or light encoder for preceding the light to include object information (or, equivalently, information about the desired image), and an extended depth of field (EDF) mask, for extending the depth of field of the projection system. In addition to including object information, the encoded mask encodes the light from the light source to account for the variations introduced by the EDF mask in extending the depth of field, so that no post processing is required.

Abstract: An integrated parking meter system automates the issuance of parking citations. Each parking meter will be equipped with a sonar range finder, mercury type switch and a two way radio that communicates via N-PCS to a host computer back at the control center. When a meter runs out of money it checks to see if a vehicle is present in the parking space. If it is, the meter notifies the host computer that there is a car illegally parked in the space. The host computer correlates the information to identify the exact location of the violator. The host computer then sends this information via wireless network to the parking meter attendants' personal communicator. The parking attendant proceeds to the violator and issues the citation. Included within this technology is the capability to remotely change the rate structure of any or all electronic parking meters. A meter diagnostic feature alerts repair personnel to specific malfunctioning meters.

Abstract: An anti-aliasing filter for use in an incoherent imaging system reduces the resolution of the optical image to prevent aliasing, without requiring a reduction in the amount of light captured by the system, and without adversely affecting image quality or requiring complex optical systems. The filter modifies the wavefront of light emanating from the object in a curved, non-symmetrical manner, in such a way as to effectively attenuate spatial frequencies in the image to values less than some desired small level for all spatial frequencies beyond a predetermined bandlimit. The filter may be reflective or transmissive.

Abstract: A renewable energy flashlight comprises a housing and a barrel located within the housing. The barrel has a wire coil wrapped around it, between the barrel and the housing. A magnet disposed within the barrel oscillates within the barrel when the barrel is shaken, generating an alternating current in the coil. Two springs at either end of the barrel cause the magnet to recoil when the magnet strikes the springs. An electronics assembly located within the housing includes a capacitor for storing charge, a rectifier connected to the capacitor, and means for conducting current flowing in the coil to the rectifier, to provide rectified current to the capacitor and charge the capacitor. A light emitting diode (LED) is connected to the capacitor by means of a switch, so the LED lights up when the switch is switched on.

Abstract: An in-line roller skate wheel is formed of a polyurethane tire injection molded onto a plastic hub, also formed by injection molding. The hub includes semicircular recesses along the outside rim to prevent the tire from slipping with respect to the hub. The hub also includes sloped surfaces on its outer rim to prevent the tire from slipping sideways with respect to the hub. The hub further includes annular ridges formed on the sloped surfaces, to prevent sideways slippage of the tire with respect to the hub, and also to allow the hub to be removed from the injection mold. The bearing seats of the hub have notches cut out to allow the hub to slide and lock onto the tire injection mold.

Abstract: A disk for throwing or rolling is formed of a central disk shaped core attached to a top and bottom pad assembly. The core includes a slot extending inward from its periphery for the insertion of an accelerator strap. The core includes a plurality of cavities, into which may be inserted plugs of various materials. The disk will possess different characteristics depending upon the composition of the plugs, and where they are placed. Wooden plugs may be used to cause the disk to float, metal plugs may be used to increase the weight of the disk, or porous plugs may be impregnated with scent to train dogs to retrieve. The placement and number of each type of plug affects the performance of the disk.

Abstract: In a delta sigma modulator, generally comprising one or more integrators fed into a multilevel quantizer, the output of which is the output of the delta sigma modulator and is also fed through a digital to analog converter in a feedback loop to the integrators, the quantizer is made sparse, i.e. the levels output by the quantizer are not evenly spaced, but rather are closely spaced for small deviations from 0 V, and broadly spaced for large deviations from 0V. The A/D converter in the feedback is matched to the quantizer. For example, the levels might be -1 V, -1/8 V, 0V, 1/8 V, and 1 V. The digital output signal from the sparse quantizer is fed into a correction RAM, which corrects for nonlinearities in the D/A converter before the digital signal is filtered by a low pass filter and frequency down converted. The contents of the RAM are selected whenever the A/D conversion system is powered on.

Abstract: Apparatus for simultaneously decompressing and interpolating compressed audio data. The compressed audio data is stored in differential log format, meaning that the difference between each two consecutive data points is taken and the log of the difference calculated to form each compressed data point. To efficiently decompress and interpolate the compressed data, advantage is taken of the fact that addition of logs is equivalent to multiplication of linear values. Thus the log of an interpolation factor is added to each compressed data point prior to taking the inverse log of the sum. An integrator block completes the interpolation and decompression of the data.

Abstract: Retrofittable hay bale measuring apparatus measures the size of the hay bale being formed, and indicates the size of the bale being formed to a control and display unit. The baler operator sets the desired hay bale size and monitors the baler operation on the display. A contact wheel, which contacts the hay bale and rotates as the bale is being formed, is rotationally attached to a measuring wheel. Alternatively, the contact wheel may itself comprise the measuring wheel. The rotation of the measuring wheel is monitored by a rotation detector which generates a hay bale measuring signal, and sends it to the control and display unit. The control and display unit generates a signal which indicates to the baler when it is time to tie off a bale of hay, based upon the measuring signal.

Abstract: A preadder for a multiplier integrates a pre-adder and Booth encoder. The integrated pre-adder/Booth encoder comprises multiple stages, each of which adds and encodes multiple bits (usually two) of two numbers x and y. Each stage comprises three blocks, a first carry generation block, a second carry generation block, and an output code generation block. The x input bits and y input bits are input into the first carry block, which generates a first carry out and multibit combination signal, which generally comprises the x input bits and y input bits carried straight through or only slightly modified. The combination signal and a first carry in signal are inputs to the second carry generation block. Generally, the first carry in is the is the first carry out of another stage which is combining less significant bits than the present stage. The second carry generation block generates a second carry out signal and a sum signal.

Abstract: A digital to analog (D/A) converter for hearing aids and the like includes a delta sigma modulator and a duty cycle demodulator. The delta sigma modulator converts medium rate, high resolution data into medium rate, medium resolution data, and the duty cycle demodulator converts the medium rate, medium resolution data into low resolution, high rate data. The duty cycle demodulator utilizes a lookup function to format the output data in a format having lowered transition rates, resulting in lower power use. The delta sigma converter may include a correction factor in at least one of its feedback loops to compensate for the characteristics of the output data from the duty cycle demodulator.