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| Number | Title | Issue Date |
| 6091808 | Methods of and apparatus for providing telephone call control and information Telephone call management is provided via a computer network (web) facility which can be remotely accessed by subscribers using web browsers. The web facility includes an information database for storing personal telephone directories and call logs, and a... | 07/18/2000 |
| 6023122 | Surface wave devices with tapered transducers A SAW device has tapered trasnsducers each of which is divided into two or more tapered transducer parts, which are arranged in line with one another in one or more SAW tracks with the tapers of adjacent tapered transducer parts complementary to one anoth... | 02/08/2000 |
| 6016258 | Full bridge DC-DC converters A full bridge DC-DC converter has four switching devices in two switching legs each of two devices connected in series between two supply voltage terminals, junction points of the legs being connected to a primary winding of a transformer, from a secondar... | 01/18/2000 |
| 6005782 | Flyback converter with soft switching using auxiliary switch and resonant circuit A flyback converter has a main switch coupling a primary winding of a transformer between supply terminals, a duty cycle of the main switch controlling an output of the converter derived from a secondary winding of the transformer. Soft (zero voltage) swi... | 12/21/1999 |
| 6006083 | Tone detection AMPS (Advanced Mobile Phone System) ST (signalling tone) is detected by a tone detector in which samples of a demodulated signal are amplitude limited to remove click energy, and the limited signal is bandpass filtered, using a notch filter and summer, to... | 12/21/1999 |
| 5991273 | Determining SINR in a communications system Diversity path signals, each comprising time division multiplexed symbols in a time slot including known symbols constituting a reference signal, are combined with respective weights to reduce co-channel interference. The weights are determined, from a co... | 11/23/1999 |
| 5977759 | Current mirror circuits for variable supply voltages A current mirror circuit comprises first and second resistors for conducting first and second reference currents dependent upon a supply voltage, and first and second current mirrors coupled to the first and second resistors, the second resistor being in ... | 11/02/1999 |
| 5972568 | Method of making surface wave devices A surface wave device is made by forming conductors on a surface of a piezoelectric material in a conductor pattern defined by exposing photoresist via a reticle. The conductor pattern is provided on the reticle in two parts each defining a set of substan... | 10/26/1999 |
| 5960075 | Switchmode power converters for telephone subscriber line interface circuits A power converter forming part of a telephone subscriber line interface circuit selectively generates a ringing signal waveform, for supply to the line, or a supply voltage for a driver circuit for providing loop current on the line. First and second fixe... | 09/28/1999 |
| 5937017 | Complex signal limiting Each complex signal sample a(k)+jb(k) of a frequency modulated signal is limited in order to reduce co-channel interference. The limiting is performed efficiently in a digital signal processor by determining a ratio r with a magnitude less than one, equal... | 08/10/1999 |
| 5930305 | Signal demodulation and diversity combining in a communications system using orthogonal modulation For combining diversity path signals comprising symbols each modulated in accordance with one of a plurality of orthogonal (e.g. Walsh) functions, a diversity combiner includes, for each path, a demodulator to demodulate each modulated signal symbol in ac... | 07/27/1999 |
| 5896071 | Surface wave device balun resonator filters A surface wave device comprises first and second SPUDT (single phase unidirectional transducer) resonator filters each comprising first and second transducers, which are preferably RSPUDTs (resonant SPUDTs), the resonator filters being the same except tha... | 04/20/1999 |
| 5870475 | Facilitating secure communications in a distribution network In a hybrid fiber-coax distribution network, communications between a central station and particular end stations are encrypted using a working key (WK) of a symmetric encryption scheme. The central station has a public and private key (PPK) of a PPK encr... | 02/09/1999 |
| 5848108 | Selective filtering for co-channel interference reduction Complex signal samples of an input signal are supplied to via a frequency down-shifter to a digital filter, and to a time-frequency transform unit which produces a plurality of frequency components each associated with a respective frequency band within a... | 12/08/1998 |
| 5838742 | Diversity path co-channel interference reduction Diversity path signals, each comprising time division multiplexed symbols in a time slot including known symbols, are combined with respective weights to reduce co-channel interference. Initial weights are determined, using a window on the known symbols, ... | 11/17/1998 |
| 5838788 | Telephone ringing signal generator A telephone ringing signal generator includes a DC converter for producing high positive and negative voltages that define peak amplitudes of the ringing signal, which is produced by low pass filtering a generally trapezoidal waveform having these peak am... | 11/17/1998 |
| 5835990 | Longitudinally coupled double mode surface wave resonators A longitudinally coupled double mode surface wave resonator comprises two reflectors, two lateral IDTs (inter-digital transducers), and a centre IDT arranged on a surface of a piezoelectric substrate, for coupling surface waves longitudinally between the ... | 11/10/1998 |
| 5821834 | Surface wave device with capacitance A surface wave device filter comprises two 2-pole waveguide coupled double mode resonators (WCRs) electrically connected together in cascade. To permit narrowing of the filter passband for improved out-of-band rejection, e.g. for use of the filter as an i... | 10/13/1998 |
| 5790000 | Cascaded surface wave device filters providing balanced and unbalanced signal connections A cascaded surface wave device filter comprises two 2-pole surface wave device filters connected in cascade. The 2-pole filters each provide a balun function between balanced and unbalanced signal connections, and have either their unbalanced or their bal... | 08/04/1998 |
| 5787089 | Digital signal broadcasting A distribution network groups television program signals into service tiers. To provide these from unsynchronized MPEG streams without resynchronization, each stream, representing a single program signal is encapsulated into ATM cells with a virtual path ... | 07/28/1998 |
| 5778310 | Co-channel interference reduction Co-channel interference of a frequency modulated signal represented by complex signal samples is reduced by amplitude limiting each sample and non-linearly filtering the limited samples. The non-linear filter low pass filters the limited samples, multipli... | 07/07/1998 |
| 5761197 | Communications in a distribution network A central station of a cable television distribution network transmits TDM frames comprising distribution information and overhead information downstream to customer terminals, and determines corresponding upstream TDMA frames by including an upstream fra... | 06/02/1998 |
| 5757683 | Digital receive filter for communications systems A digital receive filter comprises first and second filter parts with a down sampler between them. Each filter part is formed by a plurality of cascaded filter stages each comprising a second order finite impulse response digital filter having symmetrical... | 05/26/1998 |
| 5754945 | Fuzzy logic control of cellular handoff In a cellular radio communications system, handoff of a mobile terminal from a serving base station to an adjacent base station is performed using two separate fuzzy logic procedures for handoff triggering and handoff targeting. For triggering, inputs to ... | 05/19/1998 |
| 5745564 | Echo cancelling arrangement In an echo canceller, an estimated echo signal is produced by an adaptive filter from a receive path signal and is subtracted from an incoming transmit path signal to produce an outgoing transmit path signal. Averages of signal levels on the receive path ... | 04/28/1998 |
| 5740207 | Complex signal limiting Each complex signal sample a(k)+jb(k) of a frequency modulated signal is limited in order to reduce co-channel interference. The limiting is performed efficiently in a digital signal processor by determining a ratio r with a magnitude less than one, equal... | 04/14/1998 |
| 5668431 | Surface wave devices for differential coherent detectors A surface wave device, for use in differential coherent detection in a commutation signaling communications system using N predetermined M-bit codewords, propagates surface waves for each codeword to a first coded output IDT (inter-digital transducer) com... | 09/16/1997 |
| 5666406 | Hazard prevention for telephone line interface circuits A telephone line interface circuit comprises a controlled voltage generator for selectively generating a ringing voltage waveform for a telephone line or a supply voltage for a drive circuit for the telephone line, and a switching circuit interconnecting ... | 09/09/1997 |
| 5661794 | Telephone line interface circuit with voltage control An active impedance line interface circuit for connection to a two-wire telephone line comprises tip and ring unity gain d.c. amplifiers having outputs d.c. coupled via feed resistors to tip and ring wires respectively. Loop current and common mode curren... | 08/26/1997 |
| 5646678 | Digital video network with continuous audio presence at network sites A digital video network comprises a controller and network sites each coupled to the controller via communication paths. The network sites and controller include codecs for converting between encoded signals on the communications paths and video and audio... | 07/08/1997 |
| 5577097 | Determining echo return loss in echo cancelling arrangements In an echo cancelling arrangement, an estimated echo signal is produced by an adaptive filter from a receive path signal and is subtracted from an incoming transmit path signal to produce an outgoing transmit path signal, to compensate for ERL (echo retur... | 11/19/1996 |
| 5559423 | Voltage regulator including a linear transconductance amplifier A voltage regulator for an electronic circuit card includes a FET with a source supplied via an input LC filter with a voltage to be regulated, a drain for delivering a regulated output voltage via a current-sensing resistor and an output LC circuit, and ... | 09/24/1996 |
| 5539820 | Protection of active telephone line interface circuits A telephone line interface circuit with d.c. amplifiers coupled to tip and ring paths is protected against transient voltages by a crowbar-type protection device coupled via a diode bridge to the tip and ring paths, positive and negative terminals of the ... | 07/23/1996 |
| 5532637 | Linear low-noise mixer A tree mixer includes a first differential pair of transistors which divide current from a first current source between the transistors in dependence upon a first differential input signal supplied to first input terminals. Two second differential pairs o... | 07/02/1996 |
| 5511118 | Method of providing d.c. feed to a telephone line A two-wire telephone line is supplied with d.c. feed from a drive circuit including two amplifiers via which a transmission signal is supplied to the line. Output potentials of the two amplifiers determine a loop current on the line, which is monitored an... | 04/23/1996 |
| 5506747 | Provision of FIFO buffer in RAM FIFOs having various depths are provided in a RAM in a plurality of groups. For each group, stored numbers B and D determine a base address 2B in the RAM for the group and a depth 2D of each FIFO in the group. Each FIFO is identified... | 04/09/1996 |
| 5499047 | Distribution network comprising coax and optical fiber paths for transmission of television and additional signals A cable television network is supplemented with optical fibers and fiber termination units to communicate additional downstream digital signals and upstream signals. A drop unit for each customer premises is provided in the drop cable. The drop unit demod... | 03/12/1996 |
| 5436938 | Phase error detector for a phase locked loop A phase lock loop (PLL) arrangement includes a voltage controlled ring oscillator (VCRO) including delay elements whose delay is controlled by a control voltage produced by the PLL. A phase error detector is provided which compares pulses of a PLL feedbac... | 07/25/1995 |
| 5408259 | Data modulation arrangement for selectively distributing data A cable television distribution arrangement is supplied via optical fibers with additional digital signals which are delivered to customers via coaxial drop cables modulated at frequencies above those of the conventional analog television channels. A redu... | 04/18/1995 |
| 5408260 | Customer premises ADSL signal distribution arrangement A plurality of ADSL (asymmetric digital subscriber line) terminals are coupled to the coaxial cable of a cable television distribution arrangement. Each ADSL terminal is coupled to a respective ADSL path and a respective customer premises telephone line f... | 04/18/1995 |
