Abstract: A physical layer device (PHY) device in a home LAN employs discrete multitone technology (DMT). The DMT system enables usage of existing residential wiring, which typically is telephone system grade twisted copper pair. The PHY device comprises an analog front end (AFE) circuit that frequency shifts the spectral images by using a clock signal. The multiplication of the clock signal is accomplished using a digital mixer or, in the alternative, an analog switch.

Abstract: A demodulation circuit for recovering frequency redundant quadrature amplitude modulated data comprises an A/D converter generating digitized carrier signal. A mixer receives the digitized carrier and generates a frequency shifted I-signal and a frequency shifted Q-signal. A bank of filters includes a narrow band filter centered at each one of a plurality frequency shifted sub-spectra to generate a digital data signal for each sub-spectrum. A selection circuit determines which one of the sub-spectrum data signals is the strongest and a receiver circuit recovers the transmitted data in response to the strongest sub spectrum data signal.

Abstract: A random access data network in accord with the invention will utilize discrete multi-tone (DMT) transmission over a link within a home or other premises, such as over existing in-house telephone wiring. Discrete multi-tone communication in a random access implementation raises a number of timing issues. To address these issues, all packet transmissions through the network will begin with one or more cycles of a defined periodic signal, typically a sinusoid at a specified frequency. All timing of decoding of subsequent signals, such as ID signals and DMT symbols, is based on counting signal sampling intervals following the detected timing mark. The preferred embodiment utilizes differential modulation of the tones within the DMT symbol. Each packet may include a reference symbol to enable demodulation of the first DMT data symbol. Also, the preferred embodiment of the DMT symbol includes a prefix code followed by the actual DMT waveform carrying the modulated information.

Abstract: A random-access local network having multiple nodes provides data communication across residential wiring such as telephone line as a network medium, where each node accesses the network medium using discrete multi-tone (DMT) modulated symbols. The effects of amplitude and phase distortion of transmitted DMT symbols are overcome, without the necessity of complex equalizers, by differentially encoding data prior to transmission, and recovering the transmitted data by comparing phase differentials between consecutive symbol tones. Each transmitted symbol is composed of a plurality of tone signals, each tone signal modulated according to a constellation point in a complex domain. A transmitter modulates data, such as a bit-pair, to a new constellation point based on the value of the bit-pair and a prior position of a consecutively-preceding constellation point, such that the data is represented by the difference in positions between the consecutively-preceding constellation point and the new constellation point.

Abstract: An apparatus and a method a method for testing, configuring, and evaluating a transmission line. The method receives a set of command and data signals through an input/output interface and processes the command and data signals from the input/output interface for controlling at least one relay. The method also activates at least one switch for testing and improving a transmission signal line using the relay and testing and emulating the transmission signal line based upon the activated switch. The method also configures the transmission signal line based upon the testing and emulating.

Abstract: A demodulation circuit for recovering frequency redundant quadrature amplitude modulated data comprises an A/D converter generating digitized carrier signal. A mixer receives the digitized carrier and generates a frequency shifted I-signal and a frequency shifted Q-signal. A bank of filters includes a narrow band filter centered at each one of a plurality frequency shifted sub-spectra to generate a digital data signal for each sub-spectrum. A selection circuit determines which one of the sub-spectrum data signals is the strongest and a receiver circuit recovers the transmitted data in response to the strongest sub spectrum data signal.

Abstract: A novel collision detecting method at the physical layer is provided for use in a multi-point DMT communication system. A time mark transmitted at the beginning of a portion of a random access data communication is followed by an ID signal for identifying the communication station. The ID signal produced based on the time mark may be transmitted between the time mark and a data portion of the random access data communication. The time mark distorted by a communication channel is received by a receiver of the station that transmitted it. An additional ID signal representing the same ID data as the ID signal is produced based on the received time mark. The additional ID signal is compared with the ID signal received from the communication channel. A collision event is detected if the incoming ID signal does not match the additional ID signal. In response to the detection of the collision event, the transmission of the data portion is terminated.

Abstract: The present invention provides for an apparatus and a method for testing, configuring, and evaluating a transmission line. The apparatus of the present invention comprises a Universal Telephone Equipment Terminator (UTET) capable of implementing at least one of a test, configuration, and emulation on the transmission line.

Abstract: A method and apparatus for detecting a sinusoidal signal samples a received signal. An error signal generator receives at its inputs two previous samples of the signal and a current sample of the signal and generates an error signal based on these previous and current samples. A comparison circuit compares the generated error signal for the current sample to an error threshold value and generates a threshold comparison signal that indicates whether the generated error signal is below the error threshold value. A determination circuit then determines whether the received signal is a sinusoidal signal based on the threshold comparison signals that are generated for a plurality of samples.

Abstract: A method and apparatus for detecting a sinusoidal signal samples a received signal. An error signal generator receives at its inputs a previous sample of the received signal and a current sample of the received signal and generates an error signal based on these previous and current samples. A comparison circuit compares the generated error signal for the current sample to an error threshold value and generates a threshold comparison signal with a first value that indicates the generated error signal is below the error threshold value for a second value that indicates a generated error signal is above the error threshold value. A determination circuit then determines whether the received signal is a sinusoidal signal based on a threshold comparison signal generated for a plurality of samples. The determination circuit includes a counter that maintains a count of the number of threshold comparison signals having the first value within a sampling period.

Abstract: A demodulation system is provided with input variable gain amplifiers controlled by a digital amplitude processing unit to adjust the level of a received amplitude and phase modulated line signal. An amplitude decoder determines a digital amplitude value corresponding to the amplitude of the received signal. A phase matching circuit compares the received signal with a set of reference phase values to determine the phase of the received signal. The reference phase values are produced by delay cells connected in series in a receive digital delay line. A reference digital delay line supplied by a reference clock signal from a local crystal oscillator is used as a timing reference for the adjustment of the receive delay line. Based on the detected amplitude and phase values of the received signal, a symbol decoder identifies the transmitted digital data.

Abstract: A discrete multi-tone communication system employing bin-to-bin differential encoding of data frames to be transmitted within the communication system. The bin-to-bin differential encoding utilizes the phase angle of previously encoded data to encode the current data relative to that phase angle. Hence, only a single reference tone is required to encode a first portion of the data frame into a discrete tone, and then the remaining data portions of the data frame are each subsequently encoded into discrete tones with reference to the phase angle of data already encoded into a discrete tone. Thus, to achieve decoding, a decoding device only requires the reference tone to begin decoding the discrete tones to the correct phase angle for an accurate reproduction of the original data frame.

Abstract: A system for amplitude and phase modulation combines digital and analog circuitry for converting digital data into a line signal. Amplitude and phase decoders decode the digital data to determine the amplitude and phase required to represent the current symbol of the digital data. A reference oscillator produces a carrier signal supplied to a digital delay line composed of a sequence of delay cells. Outputs of the delay cells are supplied to a phase selector controlled by the phase decoder to select the required phase of the carrier signal. The carrier signal having the selected phase is fed to a variable gain amplifier controlled by the amplitude decoder to produce the carrier signal with the required amplitude.

Abstract: A novel collision detecting method is provided at the physical layer for use in a multi-point DMT communication network having stations transmitting over common media. The method includes generating a collision code corresponding to ID information of a station. A collision symbol representing the collision code is transmitted at the beginning of a portion of a random access data communication. A station in the network receives the collision symbol and decodes a collision signal carried by the collision symbol. A collision event is detected if the collision signal does not satisfy pre-set requirements. For example, energy of each component of the collision signal may be compared with a predetermined minimum energy level to generate a code element for each component having energy exceeding the predetermined minimum energy level. Validity of the code having the generated code elements is determined based on a predetermined validity criterion.

Abstract: A circuit is provided to convert an analog signal into a pulse signal, and simultaneously compress the analog signal. The input analog signal buffered by a sample-and-hold circuit is supplied to a chain of amplifier stages having equal gains greater than 1. A set of comparators compares the output signal of each amplifier stage with a reference value. As soon as the output of any amplifier stage exceeds the reference value, a logical summing device coupled to the comparators causes a pulse signal produced by the conversion circuit to become active. A clock signal controls the sample-and-hold circuit to produce a zero level sample-and-hold signal that causes the pulse signal to become inactive. As the amplifier chain is arranged so as to increase its total gain for a lower level of the input analog signal with respect to its total gain for a higher level of the input analog signal, the conversion circuit compresses the input analog signal simultaneously with its conversion into the pulse signal.

Abstract: A method and arrangement for transferring data between nodes over a telephone cable that couples the nodes provides a dual configuration node transmitter, and a dual configuration node receiver. The dual configuration transmitter has a first transmitter circuit that transmits data over a first configuration of the telephone cable and a second transmitter that simultaneously transmits other data over a second configuration of the telephone cable. The dual configuration receiver is coupled to the telephone cable and has a first receiver circuit that selects the data transmitted by the first transmitter circuit and rejects the data transmitted by the second transmitter circuit, and a second receiver circuit that selects the data transmitted by the second transmitter circuit and rejects the data transmitted by the first transmitter circuit.

Abstract: A circuit is provided to carry out conversion and an analog signal into a digital signal, simultaneously with compression of the analog signal. An input analog signal buffered by a sample-and-hold circuit is supplied to a chain of amplifier stages having equal gains greater than 1. A set of comparators compares the output signal of each amplifier stage with a reference value. As soon as the output of any amplifier stage exceeds the reference value, an output of the corresponding comparator becomes active indicating the number of amplifier stages that were required to make the input signal higher than the reference value. A digital output device uses the comparator output signals to produce a digital signal proportional to the input signal level.

Abstract: Disclosed herein is a cascode operational amplifier design with multiple input stages, and methods of operating the same, resulting in enhanced output gain and unity gain bandwidth operational amplifiers. The cascode operational amplifier comprises a differential input block which receives a differential input having a first differential input stage and a second differential input stage. A cascode block is coupled to the differential input block and provides a differential output for the operational amplifier. A common mode feedback block coupled to the second differential input stage of the differential input block and the differential output of the cascode block stabilizes a DC output level for the differential output. A load block is coupled to the differential output of the cascode block and applies a resistive load to the differential output in response to a differential input signal applied to the differential input block.

Abstract: An on-chip digital servo scheme for providing continuous calibration of integrated circuit on-chip time delay devices to provide real-time regulation against various parameter or environmental changes, such as processing, temperature and power supply variations. The techniques are particularly useful for semiconductor delay lines comprised of a selectable number of identical unit delay circuits having the same propagation time. This scheme constantly monitors the delay changes in the unit delay elements and calibrates the delay line by comparing the delay against a stable, crystal controlled reference clock period to determine, in each instance, how many unit delay elements in the delay line is needed to effectively delay the amount of time to equal the reference clock period. A real time digital pointer number is generated and updated while the device is in operation.

Abstract: There is disclosed a sample and hold circuit using a four diode bridge using a voltage source and a bridge and a storage capacitor and the voltage source to be sampled coupled to the other two opposite nodes of the bridge. Switches in the lines coupling the voltage and current sources to the bridge control whether the sample and hold circuit is sampling data or holding the sampled voltage. This arrangement is characterized by extremely low sample voltage acquisition time.