Our Engineers' Patent Portfolio - Signal Integrity
Passive distributed filter system and method including caller ID
Patent Number 6,028,919
A plurality of distributed POTS filters (DPF) are associated with a respective plurality of POTS communications devices and decouple a POTS channel from a telephone connection, while permitting and not interfering with a second communications channel (e.g., DSL, ADSL, SDSL, RADSL, VADSL, etc.) on the telephone connection that is utilized by a modem, and permit the passage of additional signals, such as caller ID signals, to the plurality POTS communications devices. In architecture, the DPF system includes a plurality of POTS communications devices, such as telephones, and a plurality of the DPFs corresponding respectively with and connecting each of the POTS communications devices to the telephone connection. Each of the DPFs comprise an automatic control mechanism, which includes circuitry configured to allow the passage of additional signals, such as caller ID signals, to the plurality of POTS communications devices and a POTS filter. The automatic control mechanism is configured to isolate the POTS filter when a respective POTS communications device is on-hook. Each DPF is configured to permit POTS communications over a POTS channel on the telephone connection with the respective POTS communications device when the POTS communications device is off-hook. Furthermore, a second communications device, such as a DSL (e.g., ADSL, SDSL, RADSL, VADSL, etc.) communications device, is connected to the telephone connection and communicates signals over a second channel. The POTS and second channel are communicated over the telephone connection concurrently without appreciable interference.
Method and apparatus for reducing interference in a twisted wire pair transmission system
Patent Number 6,173,021
The present invention provides a method and apparatus for eliminating or reducing local area and broad area interference in a twisted pair transmission system. The apparatus of the present invention comprises a detection device, such as an antenna, for example, for detecting electromagnetic interference coupled into a twisted pair line, a sampling/scaling device which samples and scales the detected signal, and a combiner device which combines a signal correction component with the signal received over the twisted pair by a differential receiver. The sampling/scaling device preferably comprises an analog-to-digital converter (ADC) which converts the detected analog signal into a digital signal and a digital signal processor which receives the digital signal from the ADC and processes the signal to generate a correction signal. The correction signal is then subtracted from the signal received by the differential receiver. The sampling/scaling device may be fixed or adaptive. If the interference is stationary in time, a fixed sampling/scaling device is suitable for use with the present invention. If the interference is non-stationary, preferably the sampling/scaling device will be adaptive such that the amount of scaling performed can be altered in accordance with changes in the interference signal detected by the detector.
Method and apparatus for reducing interference in a twisted wire pair transmission system
Patent Number 6,477,212
The present invention provides a method and apparatus for eliminating or reducing local area and broad area interference in a twisted pair transmission system. The apparatus of the present invention includes a detection device, such as an antenna, for example, for detecting electromagnetic interference coupled into a twisted pair line, a sampling/scaling device which samples and scales the detected signal, and a combiner device which combines a signal correction component with the signal received over the twisted pair by a differential receiver. The sampling/scaling device preferably includes an analog-to-digital converter (ADC) which converts the detected analog signal into a digital signal and a digital signal processor, which receives the digital signal from the ADC and processes the signal to generate a correction signal. The correction signal is then subtracted from the signal received by the differential receiver. The sampling/scaling device may be fixed or adaptive.
Line sharing multipoint POTS splitter with intelligent termination
Patent Number 7,035,380
The present invention provides for a system and method for blocking leakage signals and uncoupling connections in a communication system. A leakage signal (LS) blocking splitter employs a high-pass filter which effectively blocks the lower frequency leakage signal. The high-pass filter (an LS filter) has a cut-off frequency selected to fall between the upper range of the leakage signal (which is approximately 4 KHz in the preferred embodiment) and the low-end frequency of a data signal. A detect and terminate function detects service on the communication connection to which each one of the leakage signal (LS) filters are coupled to. The detect and terminate function detects service on the communication connection to ensure that each LS blocking splitter is coupled to an in-service communication connection. If the communication connection becomes out-of-service, such as when a customer discontinues service with the service provider, the detect and terminate functions automatically uncouple the respective LS filter from the communication connections so that the LS filter cannot introduce undesirable harmonics into the communication system. In an alternative embodiment, the detect and terminate function may insert an impedance matching element in addition to uncoupling the LS filter.
Synthetic termination
Patent Number 5,999,619
A method and apparatus for actively simulating an apparent termination input impedance to a current driven data communication equipment (DCE) device is disclosed. The DCE device utilizes several components to implement the apparent termination impedance. A first component is a current driver for providing a source of current within the DCE device. The current source is configured to actively drive an input-output signal line within a communication link. The current driven DCE also includes a mechanism for sensing an input-output signal line voltage, a mechanism for converting the sensed voltage to a feed back current and an active termination for simulating an apparent termination impedance. The converting mechanism is coupled to a summation node which sums current provided from the current driver and current from the converting mechanism to force the desired termination impedance in the DCE device, whilst performing DCE current drive function.
System and method for bridging multiple communication devices to a single communication connection
Patent Number 6,078,613
A transceiver capable of transmitting and receiving current-driven communication signals is implemented within a communication system, for example a subscriber loop associated with the public-switched-telephone-network (PSTN). By utilizing current drivers having high source impedance the load across a communication connection servicing the transceiver is significantly reduced such that additional transceivers may be bridged to the communication connection without substantially affecting the quality of the communication signals.