Abstract: Apparatus for synchronizing a local clock to a master clock, the apparatus comprising: at least one port for receiving and transmitting packets; a local clock; and a packet inspector that uses time from the local clock to timestamp packets received at a port of the at least one port, copies timing information from the received packets if the packets are timing distribution packets that are transmitted between a master clock and a slave clock in order to synchronize the slave clock to the master clock, and forwards the received packets for transmission from a port of the at least one port towards a packet destination that is not a packet source from where the packets originate, wherein the local clock uses the copied timing information and timestamps to synchronize the local clock to the master clock.

Abstract: Apparatus for monitoring a packet switched network, the apparatus comprising: at least one port for receiving and transmitting packets; a local clock; and a packet inspector that uses time from the local clock to timestamp packets received at a port of the at least one port, and additionally copies timing information from received timing distribution packets, which are transmitted from a master clock to a slave clock in order to discipline the slave clock, and forwards the received packets for transmission from a port of the at least one port; wherein the apparatus uses the timestamp of a received timing distribution packet and the copied timing information to monitor timing distribution performance of the network.

Abstract: A method of characterizing a communications channel between two communications nodes, the method comprising: determining at least one feature of a communications path between a first communications node and a second communications node; determining at least one feature of a communications path between the first communications node and a third communications node; transmitting at least one packet from the first node to propagate through the second and third nodes and return to the first node; and determining at least one feature of the communications channel between the second and third nodes responsive to receiving the packet at the first node, the at least one determined feature of the first node and the second node, and/or information comprised in the packet.

Abstract: Apparatus for providing timing information, the apparatus comprising: a primary reference time clock (PRTC) that provides a reference time of day (ToD) and a reference frequency; a packet master clock that receives the ToD and reference frequency and is configured to distribute timing to a slave clock in accordance with a timing over packet procedure responsive to the ToD and the reference frequency; and a housing that houses the PRTC and packet master clock which may be plugged into a conventional small form factor (SFP) compliant cage to connect the packet master clock to a packet switched network (PSN).

Abstract: A method and system in which a Digital Subscriber Line Access Multiplexer (DSLAM) that is part of a DSL (Digital Subscriber Line) system is able to provide synchronous services to end user equipment connected to the DSLAM via a DSL link and Customer Premises Equipment (CPE). A sniffer device having direct or indirect access to a Primary Reference Clock (PRC) of the DSL system calculates the phase difference between the PRC and the DSLAM's Local Timing Reference (LTR). The phase difference is sent to the CPEs requiring accurate reference clock frequency. The CPEs are able to derive the PRC from the phase difference information transmitted by the sniffer device thus enabling synchronous end user equipment operation.

Abstract: Apparatus for monitoring a packet switched network, the apparatus comprising: at least one port for receiving and transmitting packets; a local clock; and a packet inspector that uses time from the local clock to timestamp packets received at a port of the at least one port, and additionally copies timing information from received timing distribution packets, which are transmitted from a master clock to a slave clock in order to discipline the slave clock, and forwards the received packets for transmission from a port of the at least one port; wherein the apparatus uses the timestamp of a received timing distribution packet and the copied timing information to monitor timing distribution performance of the network .

Abstract: A method and system in which a Digital Subscriber Line Access Multiplexer (DSLAM) that is part of a DSL (Digital Subscriber Line) system is able to provide synchronous services to end user equipment connected to the DSLAM via a DSL link and Customer Premises Equipment (CPE). A sniffer device having direct or indirect access to a Primary Reference Clock (PRC) of the DSL system calculates the phase difference between the PRC and the DSLAM's Local Timing Reference (LTR). The phase difference is sent to the CPEs requiring accurate reference clock frequency. The CPEs are able to derive the PRC from the phase difference information transmitted by the sniffer device thus enabling synchronous end user equipment operation.

Abstract: A method and system in which a Digital Subscriber Line Access Multiplexer (DSLAM) that is part of a DSL (Digital Subscriber Line) system is able to provide synchronous services to end user equipment connected to the DSLAM via a DSL link and Customer Premises Equipment (CPE). A sniffer device having direct or indirect access to a Primary Reference Clock (PRC) of the DSL system calculates the phase difference between the PRC and the DSLAM's Local Timing Reference (LTR). The phase difference is sent to the CPEs requiring accurate reference clock frequency. The CPEs are able to derive the PRC from the phase difference information transmitted by the sniffer device thus enabling synchronous end user equipment operation.

Abstract: A frequency reference, comprising: an optical waveguide closed on itself so that a light pulse inserted into the waveguide circulates therein; a light source coupled to the waveguide and controllable to generate a light pulse that circulates in the waveguide; and a detector coupled to a region of the waveguide that generates an output pulse each time the circulating light pulse passes the region.

Abstract: A method and system in which a Digital Subscriber Line Access Multiplexer (DSLAM) that is part of a DSL (Digital Subscriber Line) system is able to provide synchronous services to end user equipment connected to the DSLAM via a DSL link and Customer Premises Equipment (CPE). A sniffer device having direct or indirect access to a Primary Reference Clock (PRC) of the DSL system calculates the phase difference between the PRC and the DSLAM's Local Timing Reference (LTR). The phase difference is sent to the CPEs requiring accurate reference clock frequency. The CPEs are able to derive the PRC from the phase difference information transmitted by the sniffer device thus enabling synchronous end user equipment operation.

Abstract: A method for encoding data, including processing the data one data window at a time, as follows: computing spectral components of data of a first frame of data using data from the one data window, selecting prominent spectral components of the data using a selection method appropriate for the data, and quantizing the prominent spectral components, thereby producing a frame of encoded data. A method for decoding data including frames of encoded data, by performing, for each frame, de-quantizing the frame of encoded data, thereby producing a frame of de-quantized encoded data, smoothing continuity of the de-quantized encoded data based, at least in part, on comparing values of the de-quantized encoded data with values of de-quantized encoded data of a prior frame, thereby producing a frame of smoothed data, and transforming the frame of smoothed data to a frame of time domain data. Related apparatus and methods are also described.

Abstract: A small form-factor transceiver module performs protocol translation, in addition to the conventional electrical and/or optical transmission media conversion. Such protocol conversion may enable transport of traffic from limited-range primary networks over long-range secondary networks, such as extension of Ethernet networks over low-rate TDM links. Additionally, such protocol conversion may enable interworking between different networks of differing technologies, such as transport of ATM traffic over Ethernet networks. The transceiver module may be a Small Form Factor transceiver (SFF), Small Form Factor pluggable module (SFP), Gigabit Interface Converter (GBIC) or any similar small form-factor module consisting of a housing, internal electronic circuitry and optionally optical components, and associated electrical or optical connectors.

Abstract: A system and method of compressing audio signals (110, 116, 130, 136, 140, 146) which simultaneously contain speech (110, 116), music (130, 136, 140, 146) and possibly other audio in such fashion as to reduce the required bandwidth or storage capacity. Audio (110, 116, 130, 136, 140, 146) is transmitted as simultaneous but separate streams of speech audio (110, 116) and music (or other non-speech) audio (130, 136, 140, 146), as well as other streams such as video (210, text (120, 220), computer graphics (230), etc. By keeping the music (130, 136, 140, 146) separate from the speech (110, 116), each can be maximally compressed. By synchronizing these streams (110, 116, 130, 136, 140, 146, 210, 216, 220, 230), the desired combination can be recreated at the receiver with the user being unaware of the separation.

Abstract: A system and method for extending the distance that xDSL services are able to be provided to subscribers. A DSLAM located at a Central Office is connected to a general-purpose network, such as the Internet. The DSLAM is additionally connected to a first fiber optic transceiver. The first fiber optic transceiver is connected via a fiber optic link to a second fiber optic transceiver located proximate to the subscribers' premises, preferably in a street cabinet. Each subscriber premise's equipment is connected to the broadband transceiver via subscriber lines. Electrical signals to be transmitted between the Central Office and the subscribers' premises are utilized to form a frequency division multiplexed signal. The frequency division multiplexed signal is used to modulate a light subcarrier for transmission across the fiber optic link.