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Showing papers on "Digital signal published in 1997"


Patent
18 Feb 1997
TL;DR: In this article, a system for digital image capture and transmission includes an image fulfillment server, having a transceiver for sending and receiving channel assessment signals and receiving a digital image file and a memory for storing the received digital image files.
Abstract: A system method for digital image capture and transmission includes an image fulfillment server, having a transceiver for sending and receiving channel assessment signals and receiving a digital image file and a memory for storing the received digital image file. The system also includes a digital camera having an electronic image sensor for sensing an image and producing a digital image; a short term memory for storing digital images produced by the image sensor in digital image files; a transceiver for communicating with and transmitting the digital image files to the image fulfillment server; a signal strength detector for monitoring the registration signal from the fulfillment server and producing a transmit enable signal; a long term memory for storing the digital image files; the transmit enable signal for disabling transmission of the digital image data when the channel assessment signal indicates that successful transmission of the digital image data is not possible; and a timer for transferring the digital image file from the short term memory to the long term memory after a predetermined period of time.

254 citations


Patent
20 Nov 1997
TL;DR: In this article, a system for monitoring television viewer behavior, which comprises a signal receiving device, a data latching device, and an event timing device, is presented, which is used to keep a real-time record of event time occurrence and for generating a digital signal representative of event timescales.
Abstract: A system for monitoring television viewer behavior, which comprises a signal receiving device, wherein said signal receiving device further comprises a monitoring device, for monitoring an occurrence of an event, wherein the event comprises a change of at least one of on/off status of said signal receiving device, a channel change, a volume change, a mute/unmute operation and a user interactive or non-interactive event or operation. The monitoring device generates a digital signal representative of at least one of on/off status of the signal receiving device, channel change, volume change, mute/unmute operation, and user interactive or non-interactive one of event and operation. The signal receiving device also comprises an event timing device for keeping a real-time record of event time occurrence and for generating a digital signal representative of event time occurrence. The signal receiving device also comprises a data latching device for one of latching and storing the digital signals generated by said monitoring device and said event timing device. The signal receiving device also comprises a database for storing the data latched or stored by said data latching device.

253 citations


Journal ArticleDOI
TL;DR: A blind approach is proposed that does not use training sets to estimate the transmitted signals and the space-time channel, and takes advantage of spatial and temporal oversampling techniques and the finite alphabet property of digital signals to determine the user symbol sequences.
Abstract: The two key limiting factors facing wireless systems today are multipath interference and multiuser interference. In this context, a challenging signal processing problem is the joint space-time equalization of multiple digital signals transmitted over multipath channels. We propose a blind approach that does not use training sets to estimate the transmitted signals and the space-time channel. Instead, this approach takes advantage of spatial and temporal oversampling techniques and the finite alphabet property of digital signals to determine the user symbol sequences. The problem of channels with largely differing and ill-defined delay spreads is discussed. The proposed approach is tested on actual channel data.

251 citations


Patent
19 Aug 1997
TL;DR: In this paper, a system and method for transmitting digital information through a medium such as atmospheric free-space includes a transmitter which generates a signal based on a basis set of mutually orthogonal, spectrally-shaped, sequences of substantially equal length and having predetermined autocorrelation values.
Abstract: A system and method for transmitting digital information through a medium such as atmospheric free-space includes a transmitter which generates a signal based on a basis set of mutually orthogonal, spectrally-shaped, sequences of substantially equal length and having predetermined autocorrelation values. The sequences may resemble noise in at least some of their characteristics. The orthogonality or cross-correlation characteristics, the autocorrelation characteristics and the resemblance to noise are due to features derived from sequences of pseudo-random numbers which themselves resemble noise in at least some of their characteristics. The waveform set based on the sequences is modulated digitally. The modulated set may be summed together along with a wideband reference signal of reduced amplitude and optionally an FM analog signal to form a composite signal which is broadcast typically through free space to at least one receiver. The receiver separates the analog FM signal from the digital signal and thereafter demodulates the digital data-carrying waveforms and outputs a stream of digital data. It has been determined to be resistant to multipath degradation.

220 citations


Patent
07 Jan 1997
TL;DR: In this article, a dual-mode digital communication system for communicating an information signal during operation in frequency-modulated (FM) and multiple-access modes is described, which includes a dualmode transmitter for transmitting the information signal using an FM communication signal during FM mode operation and a dual mode receiver for receiving the multiple access communications signal during multiple access mode operation.
Abstract: A dual-mode digital communication system for communicating an information signal during operation in frequency-modulated (FM) and multiple-access modes is disclosed herein. The digital communication system includes a dual-mode transmitter for transmitting the information signal using an FM communication signal during FM mode operation, and for transmitting the information signal using a multiple-access communication signal during multiple-access mode operation. The communication system further includes a dual-mode receiver for receiving the FM communication signal during FM mode operation, and for receiving the multiple-access communication signal during multiple-access mode operation. Incorporated within the dual-mode receiver is a digital demodulator for recovering the information signal from the received FM signal during operation in the FM mode, and for recovering the information signal from the received multiple-access signal during multiple-access mode operation. In a preferred implementation the dual-mode transmitter is disposed to convert a first sequence of binary data within the information signal into a sampled modulation waveform, and to provide the FM communication signal by modulating a carrier signal based at least in part on the sampled modulation waveform. The dual-mode transmitter may also be configured to multiplex a second sequence of wideband message data with the sampled modulation waveform so as to form a composite FM modulation waveform.

185 citations


Patent
04 Apr 1997
TL;DR: In this paper, a method and system for the transmission and reception of a composite radio-frequency (RF) signal including a supplemental signal, preferably representing encoded digital information, together with an analog signal which represents monophonic analog audio in the AM-band.
Abstract: A method and system are provided for the transmission and reception of a composite radio-frequency (RF) signal including a supplemental signal, preferably representing encoded digital information, together with an analog signal which represents monophonic analog audio in the AM-band. The analog monophonic component of the composite signal may be received by conventional AM-band audio receivers. In certain embodiments, the analog signal is a single-sideband large-carrier or vestigial-sideband large-carrier signal, and the composite RF signal includes a digital signal whose spectrum is substantially confined in one inner sideband. In other embodiments, a baseband digital signal is combined with an analog monophonic audio signal and transmitted in upper inner and lower inner sidebands using nonlinear compatible quadrature amplitude modulation (NC-QAM). Additional digital signals' spectrum occupies the lower outer and upper outer sidebands. In certain embodiments, for each transmitted codeword, part of the codeword information is replicated by modulated signals in both the upper outer and lower outer sidebands, preferably with diversity delay between the outer sideband signals.

180 citations


Patent
23 Dec 1997
TL;DR: In this article, a system for providing an interactive look-and-feel in a digital video broadcast via an X-Y protocol is provided, where the user is provided with a remote control or selection of a desired indicia, the user may excersize the predetermined link associated with the selected indicia in order to obtain the desired playable signal.
Abstract: A system for providing an interactive look-and-feel in a digital video broadcast via an X-Y protocol is provided. At a head-end (106), video information is digitized and associated with private data, such as event identifications, X-Y coordinates, link event identification and synchronization data. This information is then transmitted to a receiving end (104) and is input into a set-top box (112). Set-top box (112) receives the broadcast digital signal and includes a member for receiving the broadcast digital signal and generating a playable signal including indicia of the link data. The playable signal is then played on a playing device. The user is provided with a remote control or selection of a desired indicia, the user may excersize the predetermined link associated with the selected indicia in order to obtain the desired playable signal.

175 citations


Journal ArticleDOI
TL;DR: The simulations and practical implementation results affirm that the presented method assures a high fault coverage and implies that the oscillation-test strategy is very attractive for wafer-probe testing as well as final production testing.
Abstract: A new low-cost test method for analog integrated circuits, called the oscillation test, is presented. During the test mode, the circuit under test (CUT) is converted to a circuit that oscillates. Faults in the CUT which deviate the oscillation frequency from its tolerance band can be detected. Using this test method, no test vector is required to be applied. Therefore, the test vector generation problem is eliminated, and the test time is very small because only a single output frequency is evaluated for each CUT. The oscillation frequency may be considered as a digital signal and therefore can be evaluated using pure digital circuitry. These characteristics imply that the oscillation-test strategy is very attractive for wafer-probe testing as well as final production testing. In this note, the validity of the proposed test method has been verified throughout various examples such as operational amplifiers, amplifiers, filters, and analog-to-digital converters (ADCs). The simulations and practical implementation results affirm that the presented method assures a high fault coverage.

154 citations


Patent
28 Mar 1997
TL;DR: In this article, the authors proposed a method for the joint detection of multiple coded digital signals that share the same transmission medium in a manner that causes mutual interference, consisting of two steps that are applied to preliminary estimates of each digital signal, one or more times.
Abstract: A method for the joint detection of multiple coded digital signals that share the same transmission medium in a manner that causes mutual interference. The method is comprised of two steps that are applied to preliminary estimates of each digital signal, one or more times. The first step is to obtain reliability estimates for each data element of each digital signal by combining the preliminary estimates, a statistical model for the interference, and any a priori information regarding the data elements. The second step is to revise these reliability estimates for each digital signal based on the forward error correction code used for that digital signal. When the steps are repeated, the revised reliability estimates from the second step are used as a priori information for the first step.

153 citations


Patent
27 Nov 1997
TL;DR: In this paper, a digital camera for embedding authentication information to detect the identity of a photographed image into an image is presented, where authentication information is generated from data in the first region, which information is then encrypted.
Abstract: A digital camera for embedding authentication information to detect the identity of a photographed image into an image. By supplying the authentication information integrally with image data, the verifier is enabled to verify the image data without saving the authentication information. Particularly, by converting the light inputted through an optical system to an electric signal, a CCD outputs an analog signal of an image which is converted to a digital signal. In response to the digital signal of the image, a digital camera having a region dividing unit divides the digital image into first and second regions. Authentication information is generated from data in the first region, which information is then encrypted. The encrypted authentication information is embedded into the second image region. The first and second image regions are then combined.

143 citations


Patent
25 Apr 1997
TL;DR: In this article, the authors describe a control device that can actuate at least one vehicular safety device such as a seat belt pretensioning mechanism, an airbag, an automatic roll-over bar, a door lock, and a safety device actuator.
Abstract: A control device (10) actuates at least one vehicular safety device such as a seat belt pretensioning mechanism (12), an airbag (14), an automatic roll-over bar, a door lock (16) or a cellular phone comprising a sensor stage (20) to sense a plurality of parameters including acceleration, pitch angle and roll angle of a vehicle. A corresponding plurality of digital signals representing each such parameter are generated. A control stage (22) includes circuitry to receive the plurality of digital signals and to generate a control signal corresponding to each such parameter when the corresponding digital signal exceeds a predetermined value. A safety device actuator includes circuitry to receive the control signals and to generate a corresponding actuator signal to actuate the corresponding vehicular safety device.

Patent
03 Jul 1997
TL;DR: In this article, a pair of digital signal segments is measured by apparatus including a pluraltiy of multipliers (1200), each of the multipliers produces the product of a respective sample of each one of the signal segments.
Abstract: Correlation between a pair of digital signal segments is measured by apparatus including a pluraltiy of multipliers (1200). Each of the multipliers produces the product of a respective sample of each one of the signal segments. The outputs of a plurality of digital-to-analog (D/A) converters (1300) are coupled to a summer (80), while each respective one of the multipliers (1200) is coupled to the input of a respective one of the D/A converters (1300). The summer (80) produces an analog output signal equal to the sum of the analog output signals produced by the plurality of D/A converter.

Patent
19 Dec 1997
TL;DR: In this paper, a multi-mode, multi-band and multi-user radio system architecture is presented. But the architecture is not suitable for the use of a single-input single-output (SIMO) channel.
Abstract: A multi-mode, multi-band, multi-user radio system architecture includes four channels of exciter circuits and receiver circuits coupled to a digital signal processing array. Each of the exciter and receiver circuits includes three separate signal paths for three separate frequency ranges of analog signals. Each path includes an analog-to-digital converter or a digital-to-analog converter for converting both modulated analog signals to modulated digital signals and modulated digital signals to modulated analog signals. The digital signal processing array performs modulation and demodulation functions for the radio system.

Patent
T. Ono1, Yutaka Yano1
18 Aug 1997
TL;DR: In this article, a method for generating a duobinary signal which has the step of modulating individually an intensity and a phase of a carrier wave was presented, where a laser device outputs signal light; an optical intensity modulator which intensity-modulates the signal light according to a first data signal generated by dividing a data signal into two signals; a precoder which inputs a second data signal created by dividing the data signal between two signals.
Abstract: Disclosed is a method for generating a duobinary signal which has the step of: modulating individually an intensity and a phase of a carrier wave. Also disclosed is a duobinary-manner optical transmitter which has: a laser device which outputs signal light; an optical intensity modulator which intensity-modulates the signal light according to a first data signal generated by dividing a data signal into two signals; a precoder which inputs a second data signal generated by dividing the data signal into two signals; and an optical phase modulator which phase-modulates the intensity-modulated signal light according to a signal which is obtained delaying 0.5 bit an output signal of the precoder.

Patent
30 Jul 1997
TL;DR: In this article, a system for determining the operating characteristics of an energy source is presented, which consists of controller means for generating and shaping a time-varying voltage signal for application to the energy source; conversion means for receiving from the source a timevaryed return voltage signal and for converting the time-variating return signal into a digital signal.
Abstract: A system for determining the operating characteristics of an energy source. The system comprises controller means for generating and shaping a time-varying voltage signal for application to the energy source; conversion means for receiving from the energy source a time-varying return voltage signal and for converting the time-varying return voltage signal into a digital signal. The amplitude of the time-varying return signal contains information representative of the operating characteristics of the energy source. The time-varying return voltage signal is produced in response to the time-varying voltage signal. The controller means is responsive to the digital signal and determines the operating characteristics of the energy source. The controller means generates display signals, and the display signals are representative of the operating characteristics of the energy source. The system also comprises display means for displaying the display signals.

01 Jan 1997
TL;DR: The FPGA approach to digital filter implementation includes higher sampling rates than are available from traditional DSP chips, lower costs than an ASIC for moderate volume applications, and more flexibility than the alternate approaches.
Abstract: Digital filtering algorithms are most commonly implemented using general purpose digital signal processing chips for audio applications, or special purpose digital filtering chips and application-specific integrated circuits (ASICs) for higher rates. This paper describes an approach to the implementation of digital filter algorithms based on field programmable gate arrays (FPGAs). The advantages of the FPGA approach to digital filter implementation include higher sampling rates than are available from traditional DSP chips, lower costs than an ASIC for moderate volume applications, and more flexibility than the alternate approaches. Since many current FPGA architectures are in-system programmable, the configuration of the device may be changed to implement different functionality if required. Our examples illustrate that the FPGA approach is both flexible and provides performance comparable or superior to traditional approaches.

Patent
25 Jun 1997
TL;DR: In this article, an image signal is temporarily stored in a shift register (502) by a latch circuit, and a voltage converter (111) boosts a voltage representing the ON state of the signal, and applies the boosted voltage to the power transistor (410).
Abstract: Upon executing printing by latching an input digital image signal temporarily stored in a shift register (502) by a latch circuit (501), and energizing and driving a heater (401) using a power transistor (410) using an nMOSFET on the basis of the latched image signal, a voltage converter (111) boosts a voltage representing the ON state of the latched digital signal, and applies the boosted voltage to the power transistor (410).

Patent
20 Mar 1997
TL;DR: In this paper, a predistortion table is updated on the basis of mean values calculated from blocks of samples of the input complex signal and of the demodulated complex signal, which are stored in the adaptation period.
Abstract: In order to correct nonlinearities of an amplifier (20) which receives a radio signal (d') and produces an amplified radio signal representing an input complex digital signal (m), a predistortion table, associating a value of a predistorted complex digital signal with each value of the input complex digital signal, is stored, and the predistorted complex signal (d) is modulated in order to obtain the radio signal addressed to the amplifier. In an adaptation period, a fraction (r') of the amplified radio signal is demodulated in order to obtain a demodulated complex signal (r) which is compared with the input complex signal, with which the predistorted complex signal modulated in said adaptation period is associated, in order to update the predistortion table. The predistortion table is updated on the basis of mean values calculated from blocks of samples of the input complex signal and of the demodulated complex signal, which are stored in the adaptation period.

Patent
06 Aug 1997
TL;DR: In this paper, a method and circuit for dynamically adjusting the supply voltage (Vdd) in a digital circuit (204, 404) determines the propagation delay (tpd) of a signal along a signal path (222, 310) in the digital circuit.
Abstract: A method and circuit (200, 300) for dynamically adjusting the supply voltage (Vdd) in a digital circuit (204, 404) determines the propagation delay (tpd) of a signal along a signal path (222, 310) in the digital circuit and adjusts the supply voltage so that the determined propagation delay equals a predetermined period, such as the clock period of the clock signal (CLK) which clocks the digital circuit. When the determined propagation delay equals the predetermined period, the adjusted supply voltage is applied to the digital circuit (204, 404). This technique can be used to optimise power consumption and processing capability.

Patent
02 Apr 1997
TL;DR: In this article, a digital VCR is used as a terminal unit for an IC card application system for home banking, home shopping, and so on, where a host interface is connected to a modem and the modem connected to the host computer of a bank, a department store, or the like through the public phone network.
Abstract: A digital VCR incorporates an IC card reader/writer that cooperates with an IC card that stores therein control data corresponding to the transmission format of video signals to be recorded. The signal processing circuits with the digital VCR are controlled by the control data and are structured of digital signal processors and the operations of the circuits are controlled such that the sync block length and the like of the record data are controllable. A host interface is connected to a modem is and the modem connected to a host computer of a bank, a department store, or the like through the public phone network, so that the digital VCR can be utilized as a terminal unit for an IC card application system for home banking, home shopping, and so on.

Patent
14 Feb 1997
TL;DR: In this article, a rotary encoder is mounted at each joint for measuring the rotation angle of one arm relative to the other; each encoder sends an analog sinusoidal signal to an associated micro-controller which comprises an analogic to digital converter and a processing unit to generate a digital signal indicative of an instantaneous rotation angle.
Abstract: This apparatus measures the XYZ coordinates of a point on a part to determine its position in space. The apparatus comprises a movable measuring assembly and a remote processing station. The assembly includes serially arranged rigid arm members pivoted by rotary joints to a wheeled base and to a probe for engaging the part. A rotary encoder is mounted at each joint for measuring the rotation angle of one arm member relative to the other; each encoder sends an analog sinusoidal signal to an associated micro-controller which comprises an analogic to digital converter and a processing unit to generate a digital signal indicative of an instantaneous rotation angle. All the controllers are connected in a network and the resultant of the simultaneous readings of all of the encoders is sent by a radio frequency transmitter mounted on the base to the remove processing station equipped with a radio receiver and a computer which processes the transmitted data into measurement coordinates. To increase the measuring precision, each micro-controlller is capable of taking several instantaneous readings of the sinusoidal pulse emitted by the encoder and to calculate an average of said readings. The base has an automatic levelling device; each arm has a temperature sensor for effecting temperature compensation. Data recording is automatically stopped if the machine is subjected to excessive vibration or shocks.

Patent
Christopher F. Lane1
07 Jan 1997
TL;DR: In this paper, a digital delay lock loop for generating frequency multiples of an input clock signal includes a programmable digital oscillator, a phase comparator, programmable counter and delay control logic.
Abstract: A digital delay lock loop for generating frequency multiples of an input clock signal includes a programmable digital oscillator, a phase comparator, a programmable counter and delay control logic. The programmable digital oscillator is a ring connected programmable delay line and inverter which together generate an output clock signal having a frequency which depends upon the time delay of the programmable delay line. The phase comparator compares the phase of the output clock signal to that of a reference clock signal and generates a phase error signal which represents the phase difference between such signals. The programmable counter, programmed and reprogrammed with the arrival of every reference clock signal pulse, counts the output clock signal pulses to generate a count signal. The delay control logic, in response to the phase error signal and count signal, programs the time delay of the programmable delay line, thereby causing the output clock signal frequency to be the desired multiple of the reference clock frequency.

Patent
26 Sep 1997
TL;DR: In this article, a dynamic volume control system in an audio processor uses gain and delay signals from a digital signal processor to dynamically control the user-selected volume of the audio processor.
Abstract: A dynamic volume control system in an audio processor uses gain and delay signals from a digital signal processor to dynamically control the user-selected volume of the audio processor. The digital signal processor executes audio signal processing operations that affect the gain applied to the audio signal so that the signal gain inherent in the signal processing path is known. The digital signal processor transfers the known gain and a predicted group delay signal to the dynamic volume control system to dynamically adjust the user-selected volume of the system. The digital signal processor is integrated with a digital-to-analog converter (DAC) in a dynamic volume control system that exploits the known gain and group delay to perform DAC volume control.

Patent
16 May 1997
TL;DR: In this article, the authors proposed a method for securely storing analog or digital data on a data storage medium. But this method requires the storage medium data is read, decompressed, and decrypted using a decryption key derived from the stored encrypted key.
Abstract: A method for securely storing analog or digital data on a data storage medium. An analog information signal is combined with a noise signal. The composite noise and information signal is encrypted with a key which is derived from the noise signal. The encrypted composite signal is compressed and then recorded on the data storage medium along with an encrypted value of the key. The storage medium data is read, decompressed, and decrypted using a decryption key derived from the stored encrypted key. The data is then converted to an analog signal and combined with a noise correction signal derived from said key to eliminate the noise signal added to the analog information signal before storing the signal on the data storage medium.

Patent
10 Jan 1997
TL;DR: In this paper, a plurality of twisted pair subscriber lines are split into twisted pair data lines (54) and twisted pair phone lines (52), and an XDSL modems (620) is selected in response to detecting the need for data service.
Abstract: A communication server (58) using digital signal switching is provided. A plurality of twisted pair subscriber lines are split into twisted pair data lines (54) and twisted pair phone lines (52). Analog signals received on the twisted pair data lines (54) are converted into incoming parallel digital words and outgoing parallel digital words are converted into analog signals for transmission on the twisted pair data lines (54) using first converters (614) coupled to each twisted pair data line (54). The incoming parallel digital words are converted into incoming serial bit streams and outgoing serial bit streams are converted into the outgoing parallel digital words using second converters (616) coupled to the first converters (614). A need for data service is detected on a selected twisted pair data line (54), and one of the XDSL modems (620) is selected in response to detecting the need for data service. The selected XDSL modem (620) is then coupled to a second converter (616) associated with the selected twisted pair data line (54) where the selected XDSL modem (620) receives the incoming serial bit stream from and provides the outgoing serial bit stream to the associated second converter (616).

Patent
01 May 1997
TL;DR: In this article, a method and apparatus for decoding a multi-channel digital serial encoded signal and converting it into a synchronized set of binary characters is described, which includes an oversampler, a digital phase-locked loop and a byte synchronizer.
Abstract: A method and apparatus is disclosed that receives a multi-channel digital serial encoded signal and converting it into a synchronized set of binary characters. A charge pump phase-locked loop receives a transmitted reference clock and derives a multi-phase clock from the reference clock. The multi-phase clock is used to control a plurality of multi-bit block assembly circuits. Each assembly circuit receives one channel of the digital signal and produces a multi-bit block or character. The multi-bit block assembly circuit includes an oversampler, a digital phase-locked loop and a byte synchronizer. The oversampler ovesamples the received digital signal under control of the multiphase clock and produces a sequence of oversampled binary data. The digital phase-locked loop receives the oversampled data and selects samples from it depending on the skew characteristics of the sample. The byte synchronizer assembles a sequence of selected bits into a bit block, or character. An interchannel synchronizer receives as input the characters produced by each of the multi-bit block assembly circuits, and selectively delays output of the received characters in order to synchronize the characters of each channel with one another.

Patent
16 Jan 1997
TL;DR: In this article, the data having a plurality of programs at the same time are transmitted on the data bus 5 in a multiplexed state, and then a data bus interface circuit 6 restores the data from the bus 5 into the original data and supplies it to the storage medium 7.
Abstract: Digital signal receiver for recording a plurality of program streams at the same time period with a single storage medium. The transport streams from the tuners T11 through T1n are converted into the program streams at the format conversion circuits F11 through F1n, then converted into the data forms corresponding to the data bus 5 in the data bus interfaces IF11 through IF1n, so as to output them to the data bus 5. Therefore, the data having a plurality of programs at the same time are transmitted on the data bus 5 in a multiplexed state. The data bus interface circuit 6 restores the data from the data bus 5 into the original data and supplies it to the storage medium 7. Accordingly, the storage medium 7 is able to record the program streams of a plurality of programs at the same time period.

Patent
04 Nov 1997
TL;DR: In this paper, high-speed digital transmission is achieved with existing phone lines and HDSL chipsets while retaining plain old telephone service (POTS) with full failsafe capability.
Abstract: High-speed digital transmission is achieved with existing phone lines and HDSL chipsets while retaining plain old telephone service (POTS) with full failsafe capability One original digital data signal (4) at a rate of at least 352 kbps and one POTS channel (10) digitized at 64 kbps are multiplexed by a HPCS card (6) of a signal provider (1) The resulting digital signal is transported over a twisted cable pair (2) which is approximately 16 kft based on the current technology At a receiving end, the signal is demultiplexed and regenerated by a subscriber's HPCS card (7) The subscriber's HPCS card is line-powered via the cable (2) to avoid dependence upon local power The regenerated signals are transmitted over one POTS line (42) and one data line (8) to or within a remote premise Both HPCS cards have bypass relays for the POTS line to ensure the subscriber's POTS access in the event of a local power outage or electronic failure

Patent
10 Oct 1997
TL;DR: In this paper, a clock signal reproducing device has the clock signal generating device 24 having: a frequency setting device 12 for setting a desired frequency on the basis of the predetermined linear velocity and a radius position of a pickup 1; a first frequency difference signal generator device 242 for generating a binary signal E corresponding to a difference between the desired frequency fsd and the frequency fs of the sample clock signal A to be used for reproducing a reproduction digital signal.
Abstract: A digital signal reproducing apparatus has the clock signal generating device 24 having: a frequency setting device 12 for setting a desired frequency on the basis of the predetermined linear velocity and a radius position of a pickup 1; a first frequency difference signal generating device 242 for generating a binary signal E corresponding to a difference between the desired frequency fsd and the frequency fs of the sample clock signal A to be used for reproducing a reproduction digital signal; a second frequency difference signal generating device 243 for generating a pulse signal L corresponding to a difference between the frequency based on the reproduction digital signal and the frequency fs of the sample clock signal A; a phase difference signal generating device 244 for generating a pulse signal Y corresponding to a difference between the phase based on the reading signal read from the disc and the phase of the sample clock signal A; and a synchronizing device 24 for synchronizing the frequency fs and phase of the sample clock signal A with the frequency of the reading signal on the basis of the binary signal E, the pulse signal L and the pulse signal Y.

Patent
08 Oct 1997
TL;DR: In this article, a digital demodulator which demodulates an analog signal obtained through a quadrature amplitude modulation (QAM) to produce a digital signal includes a converter to convert the analog signal into digital signal and a signal processor to quadratures-demodulating the digital signal from the converter.
Abstract: A digital demodulator which demodulates an analog signal obtained through a quadrature amplitude modulation to produce a digital demodulated signal includes a converter to convert the analog signal into a digital signal and a signal processor to quadrature-demodulating the digital signal from the converter. Assuming that the analog signal has a carrier frequency of f IF and the signal conversion is accomplished with the sampling frequency fs, the demodulator is set to satisfy fs=4·f IF /(2n+1), where n denotes a positive integer. The signal processing section conducts the quadrature demodulation according to a quadrature local oscillation signal having a frequency fc satisfying fc=fs/4.