Abstract: The present invention discloses a method of detecting and correcting skew across a plurality of transmitting lanes. Through the use of an N framer system, including a frame start signal and a frame synchronization signal, skew can be detected and corrected by writing data from a plurality of framers into offsetting bit locations of a plurality of buffers. The present invention also provides a method of transmitting data in a multiple lane distribution (MLD) transmission system.

Abstract: Extending wired networks by aggregating multiple wireless links. Multiple wireless links are used to bridge wired networks, such as wired Ethernet networks. Each wireless link applies a hash function to the destination MAC address of presented traffic and uses the result of the hash function to determine if the traffic is passed by that wireless link or is dropped. For broadcast and multicast frames, the hash function is calculated on the source MAC address. Dynamic source MAC rewriting may be performed to prevent port flapping or out-of-order arrival of frames. Establishing one link as a master and communicating among links allows for load balancing and link failure detection.

Abstract: A communication method in a mobile communication system that transmits different data to which transmission sequence numbers have been attached, over each of a plurality of paths from a mobile station to a radio network controller via a plurality of base stations; where the radio network controller monitors the communication state of each path, determines to transmit the data over all of a plurality of paths, transmit the data over two or more specified paths, or transmit the data over only one specified path, based on the communication state of each path, and notifies the mobile station of the determined path/paths; and where the mobile station transmits different data to which different transmission sequence numbers have been attached, over said notified path/paths, and the radio network controller rearranges the data received from each path by reference to the transmission sequence numbers and transmits the rearranged data to a core network.

Abstract: Systems and methods for communication of scaleable-coded audiovisual signals over multiple TCP/IP connections are provided. The sender schedules and prioritizes transmission of individual scalable-coded data packets over the plurality of TCP connections according to their relative importance in the scalable coding structure for signal reconstruction quality and according to receiver feedback. Low-latency packet delivery over the multiple TCP/IP connections is maintained by avoiding transmission or retransmission of packets that are less important for reconstructed media quality.

Abstract: A multi-chip module (MCM) may include a substrate, and first and second physical-layer (PHY) chips mounted on the substrate. In some implementations, the first PHY chip includes a multiplexer and a PHY circuit. The multiplexer is configured to receive a multiplexed data stream from a media access control (MAC) device, to demultiplex the multiplexed data stream into first and second data streams, to output the first data stream to the PHY circuit, and to output the second data stream to the second PHY chip. In some implementations, the first PHY includes a router and a PHY circuit. The router is configured to receive a plurality of data packets from a MAC device, to route one or more of the data packets having a first address to the PHY circuit, and to route one or more of the data packets having a second address to the second PHY chip.

Abstract: An apparatus and media are provided for more effectively utilizing modems in a WiMAX environment. The apparatus connects a computing device to a network-based information system through at least a first WiMAX modem that is located within the apparatus. A second WiMAX modem can be removably coupled to the apparatus so as to connect the first computing device to the network in combination with the first WiMAX modem. In the event the second WiMAX modem is removed, network connectivity provided by the first WiMAX modem is maintained.

Abstract: An optical system includes a transmitter module and/or a receiver module. The transmitter module is configured to receive input data, map the input data to a set of subcarriers associated with an optical communication channel, independently apply spectral shaping to each of the subcarriers, generate input values based on the spectral shaping of each of the subcarriers, generate voltage signals based on the input values, modulate light based on the voltage signals to generate an output optical signal that includes the subcarriers, and output the output optical signal. The receiver module is configured to receive the output optical signal, convert the output optical signal to a set of voltage signals, generate digital samples based on the set of voltage signals, independently process the digital samples for each of the subcarriers, map the processed digital samples to produce output data, and output the output data.

Abstract: A frame generating apparatus includes an optical-transport-network frame generator configured to generate an optical transport network frame from a client signal; and a frame decomposer configured to perform serial-parallel conversion on the optical transport network frame to generate a plurality of virtual lanes, where the optical-transport-network frame generator arranges frame synchronization bytes and virtual lane identifiers in an overhead area and/or a fixed stuff part so that a frame synchronization byte and a virtual lane identifier are arranged in each virtual lane.

Abstract: An interconnection between fully synchronous networks and next-generation frame communications networks is disclosed. A means of bidirectional frame format conversion between a synchronous multiplexing system and a logical multiplexing system is provided, along with a method of transmitting data between different networks on a path as if it were being transmitted in the same network. Further, when converting network control information in an STM network into data suitable for a packet network, even across the boundary of a synchronous multiplexing system and a logical multiplexing system, a unified communication management means is provided over the whole path.

Abstract: A packet network interface apparatus includes a media access control (MAC) module for constructing a packet for transmission over a packet network and a physical coding sublayer (PCS) module for encoding the packet for transmission over a physical interface. An inter packet gap module located between the MAC module and the PCS module directly transfers data to the PCS module while maintaining a certain inter packet gap by deleting or inserting idle characters. The inter packet gap module has at least one memory module for temporary storage of packet data. The modules preferably operate in a common time domain.

Abstract: Techniques are described that can be used to extend the data transmission rate specified by 10GBASE-KR of IEEE 802.3ap (2007) to more than 10 Gb/s using a multiple lane backplane. A signal for transmission over 10 Gb/s can be divided into multiple streams for transmission over multiple lanes. Multiple transceiver pairs can be used for transmission and receipt of the multiple streams. Each transceiver pair may comply with 10GBASE-KR of IEEE 802.3ap (2007).

Abstract: Under one aspect of the present invention, a system for processing a group of signals and interference includes (a) an analog-to-digital (A/D) converter for digitizing the group of signals and the interference; (b) a Fourier transform circuit for obtaining a Fourier transform of the digitized group of signals and the interference and to provide as output spectral bins, at least one of which contains the interference; (c) a power analysis circuit for comparing the collective power level of the spectral bins to a predetermined threshold, and if the collective power level exceeds the predetermined threshold, and for excising at least one bin that contains the interference; and (d) an inverse Fourier transform circuit for obtaining an inverse Fourier transform of the remaining spectral bins and outputting a digitized group of signals less the interference in any excised spectral bin.

Abstract: An interface circuit includes a deserializer and a frame detection circuit. The deserializer includes a serial input terminal for receiving a serial signal, the serial signal including a frame start code; and a plurality of first output terminals for outputting a plurality of parallel signals based on the received serial signal, one of the plurality of parallel signals being a frame signal including the frame start code.

Abstract: A broadband receiving apparatus includes an antenna to receive a radio signal having a plurality of modulation frequencies. An amplifier drives a laser source from the broadband radio signal to produce an optical signal having a plurality of spectral components. A diffraction grating transforms the optical signal into its spectral components. An array of photo-detectors converts the spectral components into electronic signals corresponding to the plurality of modulation frequencies. A transmitting apparatus includes an array of coherent laser emitters driven by electronic signals corresponding to a plurality of modulation frequencies to produce optical signals corresponding to a plurality of spectral components. A diffraction grating inverse transforms the spectral components into a composite optical signal. A photo-detector converts the composite optical signal into a composite electronic signal including the plurality of modulation frequencies.

Abstract: A technique for reducing a necessary bandwidth of an optical receiver in an optical OFDM communication system is disclosed. Optical OFDM signals of different spectra are alternately transmitted for each OFDM symbol time, and; after this light is transmitted via an optical fiber, the light undergoes photoelectric conversion by a delay interferometer having a delay time equal to one symbol time and a balanced direct detection receiver and is received.

Abstract: An optical device, suitable for use either as a coherent receiver or analog-to-digital converter, of optical phase modulated signals borne on a carrier. The signal is four-wave mixed with a pump to generate a non-linear comb of a series of harmonic components of the signal. The modulation-free carrier is also combined with the pump to generate an equivalent linear comb matched in frequency to the components of the non-linear comb. The harmonic and modulation-free components are linearly combined so they interfere in a pairwise manner, and then the interfered frequency components are separated out in an optical wavelength division demultiplexer into a plurality of frequency-specific optical output channels. A plurality of photodetectors connected to respective ones of the optical output channels then converts the analog values in each channel to respective electronic signals which are then digitized using a processor into binary digits using a thresholding process.

Abstract: A method for processing network traffic in a modular switching device that includes a source device, a target device, and a plurality of connecting devices, includes generating a communication unit at the source device, where the communication unit is associated with a unique communication unit identifier, and where the communication unit is to be transmitted to the target device; dividing the communication unit into a plurality of transmission units, including assigning a respective position identifier to each of the plurality of transmission units, where the position identifier is indicative of a position of the transmission unit within the communication unit, and assigning the communication unit identifier to each of the plurality of transmission units; the method further comprising causing the plurality of transmission units to be transmitted in parallel to respective ones of the plurality of connecting devices, where each of the plurality of connecting devices connects the source device to the target dev

Abstract: Methods and systems for injecting information into a power signal, and techniques to capture the injected information are disclosed. Various processes for using the information are also presented, which may relate to the type of device receiving the information. Moreover, techniques for determining the distance of a consumer device are disclosed, as have a specific implementation which relates to mobile consumer devices. Also various ways of encrypting both in-band and out-of-band transmission are disclosed.

Abstract: An Orthogonal Frequency Division Multiplex (OFDM) communication system comprises OFDM transmitters and an OFDM receiver. The system comprises a subcarrier status data controller for transmitting subcarrier status data to the OFDM receiver. The subcarrier status data indicates the active subcarriers of the OFDM transmitters. The OFDM receiver comprises a receiver which receives a signal comprising a desired signal component from a first OFDM transmitter and interference from at least one interfering OFDM transmitter. The OFDM receiver further comprises a subcarrier status processor which receives the subcarrier status data and a channel estimator which determines channel estimates for at least an air interface communication channel from the first OFDM transmitter and an air interface communication channel from the interfering OFDM transmitter. An interference mitigation processor performs interference mitigation of the interference in response to the subcarrier status data and the channel estimates.

Abstract: A method and a device for mapping Ethernet code blocks to an optical transport network (OTN) for transmission is provided. According to a preset mapping manner, four groups of 10 Gigabit (10G) Ethernet code blocks are uniformly mapped to a payload area of a general frame provision (GFP) frame, or each group of 10G Ethernet code blocks is interleaved into the payload area of each row of the OTN frame. Thus, specific solutions for mapping four groups of 10G Ethernet code blocks having an encoding rate smaller than the minimum payload bandwidth of the OPU3 to the OTN for transmission are provided, thereby achieving transparent transmission without changing the mature OTN architecture.

Abstract: Time-varying and frequency-selective channels in an orthogonal frequency division multiplexing (OFDM) network are estimated by first storing, in a buffer at a receiver, a received signal corresponding to a set of pilot tones of a set of OFDM symbols. The pilot tones are predetermined and inserted in frequency subcarriers and time slots of the OFDM symbol. A covariance matrix of the received signal is estimated. A diagonal matrix is estimated based on the covariance matrix and a variance of noise in the received signal. The diagonal matrix indicates delays of non-zero paths in a time domain. A channel impulse response (CIR) for each OFDM symbol is estimated using the diagonal matrix, and the received signal. Then, the CIR is transformed to the frequency domain to obtain the channel frequency response (CFR).

Abstract: The present invention discloses an apparatus to implement a m=n Non-Blocking Minimal Spanning Switch, where n=the total number of data input signals and m=the total number of data output signals and m=the number of crossbar connections in each switch. Data is input to the switch as a plurality of frames, whereby each crossbar connection contains a framer which detects framing patterns in the data. Skewed data is re-aligned and buffered so that the data output by each crossbar connection is equal and identical, thus any crossbar connection may be used to ensure a connection, eliminating the possibility of data interrupts.

Abstract: The invention is directed toward techniques for Multi-Protocol Label Switching (MPLS) upstream label assignment for the Resource Reservation Protocol with Traffic Engineering (RSVP-TE). The techniques include extensions to the RSVP-TE that enable distribution of upstream assigned labels in Path messages from an upstream router to two or more downstream routers of tunnel established over a network. The tunnel may comprise a RSVP-TE P2MP Label Switched Path (LSP) or an Internet Protocol (IP) multicast tunnel. The techniques also include extensions to the RSVP-TE that enable a router to advertise upstream label assignment capability to neighboring routers in the network. The MPLS upstream label assignment using RSVP-TE described herein enables a branch router to avoid traffic replication on a Local Area Network (LAN) for RSVP-TE P2MP LSPs.

Abstract: A network element aggregates a number of its ports together to form a link aggregation group. To move communications from one of the aggregated ports in case that port fails or otherwise becomes inactive, the network element may use exchange a special marker message and response with a remote network element coupled to the failed port. The network elements use proprietary signaling within the special marker message and response to enable the exchange of these messages on an active one of the aggregated ports while identifying the failed one of the ports.

Abstract: A method and apparatus of automatically identifying IMA links of an asynchronous transfer mode network and automatically configuring a distributed network analyzer to monitor the identified IMA links. Information is selectively extracted from streams of cell data exchanged across an asynchronous transfer mode network to automatically identify IMA links of the asynchronous transfer mode network, and automatically configuring a distributed network analyzer to monitor the identified IMA links. A graphical user interface is provided to display status information of the automatically identified IMA links of an asynchronous transfer mode network based on monitoring of the identified IMA links using a distributed network analyzer automatically configured to monitor the identified IMA links.

Abstract: Systems and methods for de-combining a single combined data stream into a plurality of original data streams, where each original data stream has its own timing information, and passing respective original data steams to, e.g., one or more DVB-T modulators for broadcast into, e.g., a single frequency network. The original data streams and the single combined data stream may be, e.g., MPEG-compliant data streams.

Abstract: An apparatus and method for beamforming in a wireless communication system are provided. The base station apparatus includes a calculator, a plurality of formers, and a plurality of adders. The calculator calculates a beam coefficient considering interference to a neighbor sector to be applied to transmission signals to mobile stations. The plurality of formers performs beamforming for a transmission signal to each mobile station within a corresponding sector using the beam coefficient. The plurality of adders adds the sector-based beamformed signals each provided from the plurality of formers, on a per-transmission-antenna basis.

Abstract: In a data transfer interface, at least one deserializer receives a serial data stream at a first clock speed and outputs a first parallel data stream at a second clock speed. The first parallel data stream includes data symbols representing data and alignment symbols for aligning the data symbols at a downstream location. A demultiplexer demultiplexes the first parallel data stream into a plurality of second parallel data streams based on the alignment symbols.

Abstract: The invention discloses a network aggregation system, apparatus and method for creating aggregated network connections to provide high availability and increased throughput where the plurality of network connections may possess diverse physical and logical characteristics. Increased throughput on the aggregated network connection equals the sum of the available throughput on the aggregated network connections. Aggregation is performed in a transparent fashion, independent of any physical or logical characteristics of the individual connections. Network connectivity over the aggregated connection is managed such that the loss or gain of connectivity in an individual connection among the aggregated group does not result in the loss of data from the data stream aggregation device.

Abstract: Methods and systems for processing signals in a receiver are disclosed herein and may comprise receiving spatially multiplexed signals via M receive antennas. A plurality of multiple data streams may be separated in the received spatially multiplexed signals to detect MIMO data streams. Each of the MIMO data streams may correspond to a spatially multiplexed input signal. Complex phase and/or amplitude may be estimated for each detected MIMO data streams utilizing (M-1) phase shifters. Complex waveforms, comprising in-phase (I) and quadrature (Q) components for the MIMO data streams within the received spatially multiplexed signals may be processed and the processed complex waveforms may be filtered to generate baseband bandwidth limited signals. Phase and/or amplitude for one or more received spatially multiplexed signals may be adjusted utilizing the estimated complex phase and amplitude. Phase and/or amplitude may be adjusted continuously and/or at discrete intervals.

Abstract: According to one example of the present invention, there is provided a method of routing data packets to a plurality of packet processors in a computer network. The method comprising obtaining workload data from the packet processors, determining a workload distribution across the packet processors, and updating a balancing table used by a switching element in the network based on the determined workload.

Abstract: A communication system including first, second, and third nodes interconnected via interconnect links, a primary path composed of an interconnect link between the first node and the third node, and a secondary path composed of an interconnect link between the first and second nodes and an interconnect link between the second and third nodes, wherein when the first node and the third node function as a transmitting node and a receiving node respectively, having a path multiplexing function to communicate with each other using bandwidths of a plurality of paths simultaneously, the first node transmits, to the second node, a path multiplexing request message for requesting communication with the third node, and when receiving the path multiplexing request message, the second node functions as a relay node and determines whether the primary path and the secondary path can be logically multiplexed by providing, to the first node, the bandwidth of the interconnect link between the second and third nodes, and if

Abstract: The present invention discloses a method of detecting and correcting skew across a plurality of transmitting lanes. Through the use of an N framer system, including a frame start signal and a frame synchronization signal, skew can be detected and corrected by writing data from a plurality of framers into offsetting bit locations of a plurality of buffers. The present invention also provides a method of transmitting data in a multiple lane distribution (MLD) transmission system.

Abstract: An indicator apparatus, having a pulse width modulation circuit (1), a demultiplexer (2) which has at least one signal input (21) and at least two signal outputs (22), wherein the signal input (21) is connected to the pulse width modulation circuit (1), and at least two light-emitting diodes (3) which are each connected to a signal output (22) of the demultiplexer.

Abstract: A device for bit-demultiplexing in a multicarrier MIMO communication system (e.g. precoded spatial multiplexing MIMO communication systems using adaptive OFDM), including a multicarrier MIMO transmitter and a multicarrier MIMO receiver. The multicarrier MIMO transmitter includes a demultiplexer and symbol mapper unit receiving an input bit stream and generating a plurality of symbol streams, each symbol stream being associated with a different transmission channel and including a plurality of data symbols, each data symbol being attributed to a different carrier; one or more multicarrier modulators generating at least two multicarrier modulated signals based on the symbol streams; and at least two transmit ports respectively transmitting the at least two multicarrier modulated signals, wherein a data throughput rate of each transmission channel is separately variable.

Abstract: A device demultiplexes an optical signal to produce a number of client streams for client devices. The device produces overhead packets for the client devices. The overhead packets are sent using a packet interface on the device. The overhead packets are sent to the client devices with a Virtual Local Area Network Identification (VLAN ID) portion of the overhead packets identify a client device of the client devices.

Abstract: In wireless systems, method and system for weight determination in a single channel (SC) multiple-input multiple-output (MIMO) system for WCDMA/HSDPA are provided. Models of signals received in multiple receive antennas may be determined in a single weight baseband generator (SWBBG) from propagation channel estimates and noise statistics. The models may be utilized to determine combined signal and noise components. The combined signal and noise components may be utilized to determine a plurality of signal-to-noise ratio (SNR) or signal-to-interference-and-noise ratio (SINR) values for various phase and/or amplitude factors. The SINR may be utilized when either single or multiple interfering signals are present. A highest of the SINR or SNR values may be selected to determine a channel weight to apply to the additional receive antennas.

Abstract: A digital broadcast transmitting/receiving system and a method for processing data are disclosed. The method for processing data may enhance the receiving performance of the receiving system by performing additional coding and multiplexing processes on the traffic information data and transmitting the processed data. Thus, robustness is provided to the traffic information data, thereby enabling the data to respond strongly against the channel environment which is always under constant and vast change.

Abstract: Polarization multiplexing by encoding data using a return-to-zero format, and by interleaving the constituent orthogonal polarization components such that the data-carrying portion of the bit window from one orthogonal polarization component occupies the zero portion of the bit window for the other orthogonal polarization component.

Abstract: Techniques are described that can be used to extend the data transmission rate specified by 10GBASE-KR of IEEE 802.3ap (2007) to more than 10 Gb/s using a multiple lane backplane. A signal for transmission over 10 Gb/s can be divided into multiple streams for transmission over multiple lanes. Multiple transceiver pairs can be used for transmission and receipt of the multiple streams. Each transceiver pair may comply with 10GBASE-KR of IEEE 802.3ap (2007).

Abstract: To improve transmission of digital broadcast information, there is proposed a method of transmitting digital broadcast information from a main transmitter (12) to at least one repeater (14). There is generated a composite digital broadcast signal carrying first digital broadcast information according to a first digital broadcast specification (DVB-T) and second digital broadcast information according to a second digital broadcast specification (DVB-H). The composite digital broadcast is then broadcasted such that the second digital broadcast information (DVB-H) is sent in a transmission mode used for transmission of the first digital broadcast information (DVB-T).

Abstract: A method for transferring control signals and data signals, particularly in a motor vehicle. The control signals and the data signals are transferred by a physical medium. The control signals or the data signals are modulated prior to transferring. The modulated signals and the non-modulated signals are sent by the physical medium.

Abstract: A demultiplexer circuit is disclosed which can be used with a conventional neural stimulator to extend the number of electrodes which can be activated. The demultiplexer circuit, which is formed on a semiconductor substrate containing a power supply that provides all the dc electrical power for operation of the circuit, includes digital latches that receive and store addressing information from the neural stimulator one bit at a time. This addressing information is used to program one or more 1:2N demultiplexers in the demultiplexer circuit which then route neural stimulation signals from the neural stimulator to an electrode array which is connected to the outputs of the 1:2N demultiplexer. The demultiplexer circuit allows the number of individual electrodes in the electrode array to be increased by a factor of 2N with N generally being in a range of 2-4.

Abstract: Embodiments of the present invention disclose a method for binding transmission lines and the method includes the following steps: first decide a transmission speed supported by all the transmission lines to be bound, activate all the transmission lines to be bound at the transmission speed supported by all the transmission lines and then bind all the transmission lines. Apparatus for binding transmission lines is also disclosed in the embodiments, which includes a speed reselecting module, a reactivating module and a binding module. According to the embodiments of the present invention, transmission lines with different transmission speeds are bound together in such a way that transmission lines with different transmission speeds could be activated at one transmission speed. Therefore, the bound transmission line may provide wider bandwidth for the user because all the bound transmission lines have the same transmission speed.

Abstract: A system and method are provided for more effectively utilizing modems in a WiMAX environment, so as to improve network connectivity while providing access for both fixed as well as portable computing devices. The apparatus connects one or more computing devices to a network-based information system through at least a first WiMAX modem that is located within the apparatus. A second WiMAX modem can be removably coupled to the apparatus so as to improve network connectivity and operability. In the event, the second WiMAX modem is removed and coupled to a portable computing device, network connectivity provided by the first WiMAX modem is maintained.

Abstract: According to the invention, there is provided an audio signal receiving apparatus which receives audio signals transmitted from external connection apparatuses through a plurality of channels, including an audio signal transmitting scheme determining unit which determines a transmitting scheme of the audio signal in the external connection apparatus on the basis of channel mapping information representing types of the audio signals transmitted by the external connection apparatuses. When the audio signal to be received is changed, a process to be executed is changed depending on the transmitting scheme of the audio signal.

Abstract: Systems and methods consistent with the present invention provide a better fragment drop heuristic that determines a per-fragment determined “remainder time” value to trigger potential drops on the whole bundle. A per-bundle drop timeout value is assumed. This value is to be configured based on differential delay considerations of the various links that constitute the bundle. The arrival time of a fragment to a reassembly algorithm triggers a remainder timer. When the reassembly algorithm instance actually processes the fragment, the “remainder time,” which is difference of a bundle drop timeout and time elapsed on the remainder timer, is used to determine whether the fragment and the other fragments of the packet should be dropped.

Abstract: A method and system for providing Layer 1 time division multiplexing (TDM) framing, multiplexing, and mapping as well as Layer 2 data and protocol processing. One embodiment of the invention provides an integrated Layer1/Layer2 service aggregator within a single-device. Such an embodiment provides a complete System-on-Chip implementation for clear channel and deeply channelized OC-48 (STM-16), 4×OC12/3 (STM4/1) application of 2,000 channels or more. One embodiment implements functionality of Layer2 data and protocol processing as well as Layer1 TDM framing, multiplexing and mapping. For one embodiment, target applications include packet-based transport systems, multi-service access and metro systems, switches and routers and ADM/MSPP systems.

Abstract: A digital broadcasting system and a data processing method thereof are provided. An apparatus for generating a transport stream includes a packet generator for generating a plurality of packets by compressing video and audio signals; a counter for counting the number of the generated packets and outputting the count result; and an information controller for determining whether the count result of counting reaches a predetermined number of packets, inserting packet start information into the packets according to the count result, and transmitting the packets with the packet start information inserted therein. The packet start information is added to a packet to be transmitted in a transmitter, and the packet start information is extracted from the received packet in a receiver, so that the waste of frequency resources can be reduced.

Abstract: A broadband receiving apparatus includes an antenna to receive a radio signal having a plurality of modulation frequencies. An amplifier drives a laser source from the broadband radio signal to produce an optical signal having a plurality of spectral components. A diffraction grating transforms the optical signal into its spectral components. An array of photo-detectors converts the spectral components into electronic signals corresponding to the plurality of modulation frequencies. A transmitting apparatus includes an array of coherent laser emitters driven by electronic signals corresponding to a plurality of modulation frequencies to produce optical signals corresponding to a plurality of spectral components. A diffraction grating inverse transforms the spectral components into a composite optical signal. A photo-detector converts the composite optical signal into a composite electronic signal including the plurality of modulation frequencies.