Abstract: An example method of receiving a data packet includes receiving a data packet at a channel receiver of at least one channel receiver each associated with a channel, providing the data packet to a data packet identification block that corresponds to the channel receiver, validating the data packet at the data packet identification block, and providing the validated data packet to an available decoder block of at least one decoder block capable of performing one or more decoding functions, where a quantity of the decoder blocks is less than a quantity of the data packet identification blocks and optimized according to one or more goals. If no decoder block is available and the validated data packet is a higher priority data packet, a decoder block processing a lower priority data packet may be forced to stop processing the lower priority data packet and process the higher priority data packet.

Abstract: A post-encoding bitrate reduction system and method for generating one more scaled compressed bitstreams from a single encoded plenary file. The plenary file contains multiple audio object files that were encoded separately using a scalable encoding process having fine-grained scalability. Activity in the data frames of the encoded audio object files at a time period are compared with each other to obtain a data frame activity comparison. Bits from an available bitpool are assigned to all of the data frames based on the data frame activity comparison and corresponding hierarchical metadata. The plenary file is scaled down by truncating bits in the data frames to conform to the bit allocation. In some embodiments frame activity is compared to a silence threshold and the data frame contains silence if the frame activity is less than or equal to the threshold and minimal bits are used to represent the silent frame.

Abstract: An aircraft communication system for performing communication between each of a plurality of devices installed in an aircraft, wherein the communication system is provided with a plurality of communication processing units provided corresponding to the plurality of devices and a plurality of communication lines for connecting between the communication processing units, the plurality of communication processing units being capable of bidirectional communication via the plurality of communication lines. Upon receiving a plurality of communication data from the plurality of communication lines, one of the communication processing units determines, on the basis of identification information included in the received plurality of communication data, whether the received plurality of communication data needs to be acquired and acquires the communication data determined to need to be acquired.

Abstract: Technologies are generally described for reducing spectral allocation conflicts in wireless networks. In some examples, two (or more) wireless devices with intersecting spectral allocation may be identified, followed by determination of one or more time-frequency vectors of the spectral allocation for one of the wireless devices that have a first overlap with one or more time-frequency vectors of the spectral allocation of the other wireless device. For each determined time-frequency vector, an alternate time-frequency vector may be determined such that a second overlap between the alternate time-frequency vector and the time-frequency vectors of the other wireless device is lower than the first overlap. The alternate time-frequency vector may be transmitted to the wireless device to enable that device shift its communication to the alternate time-frequency vector for enhanced communication performance.

Abstract: A system is provided for intercepting signals transmitted between a target served by a fiber optic network and a subscriber. A network is described having a phone switch at a central office configured to receive signals for transmission to and from a target, such as the target of a criminal investigation. A signal received at the central office is assigned to an analog circuit, and a monitoring device configured to intercept and monitor the signal is installed along the analog circuit at a location that allows the monitoring of communications without notifying the target that he is under surveillance. After the signal has been monitored, it is converted to a digital signal for transmission. A method is also provided for intercepting a signal transmitted between the target served by a fiber optic network and a subscriber, such that a monitoring device may be installed without alerting the target.

Abstract: A radio equipment in a radio base station is configured to measure received signal strength of an uplink signal transmitted by a mobile station and includes a TRX function unit configured to transmit IQ data and control information to a radio equipment controller by using a frame including an IQ data region for mapping the IQ data and a control region for mapping the control information, the IQ data being obtained by subjecting the uplink signal to demodulation processing (orthogonal demodulation processing), and the TRX function unit is configured to map information indicating the received signal strength (RSSI) measured by the measurement unit to a fixed region in the control region.

Abstract: A system for assessing a voice communication quality of a communication path between first and second nodes over a network, wherein coded data of voice communication signals are transferred in a stream of packets via the communication path, including: a capturing unit for capturing at the first node at least one packet containing coded data representing non voice signals among the packets of the coded data to be transferred from the first node to the second node; a replacing unit for replacing a part of the coded data representing non voice signals in the captured packet with a predetermined code before the captured packet is transferred from the first node; a retrieval unit for retrieving at the second node said at least one packet containing coded data representing non voice signals; and an assessment unit for assessing the voice communication quality of the communication path.

Abstract: A transmitting device encrypts DMR voice superframes using encryption parameters and sends the encryption parameters in at least one of the voice superframes by: identifying a selected number of bits from a plurality of vocoder frames the voice superframe; replacing each of the identified bits with a corresponding bit of a first encryption parameter; placing at least one encryption parameter in an embedded signaling field of the voice superframe; and transmitting the voice superframe with the encryption parameters to a receiving device. The receiving device extracts the encryption parameters, which can be a key identifier, an algorithm identifier, and an initialization vector for use in decrypting messages from the transmitting device.

Abstract: Packet switch operating methods and packet switches use a first port of forwarding circuitry of the packet switch to receive first packets and transmit second packets. The methods and packet switches mirror the first and second packets on a second port of the forwarding circuitry, encapsulate the mirrored packets with a transport identifier, and transmit the encapsulated packets using a third port of the forwarding circuitry.

Abstract: Embodiments related to echo compensation have been described and depicted.

Abstract: An apparatus and method for transmitting and receiving wireless packet data are provided. In a wireless packet data transmitter for transmitting to a wireless packet data receiver data packet on a transport channel and control information for supporting the transport channel on a control channel in a wireless packet data communications system, a padding bit eliminator eliminates optional padding bits of a variable size from a transport block for data packet transmission. A transport channel encoder for transport channel-encodes the transport block without the padding bits and transmits the encoded transport block on the transport channel. A control channel encoder control channel-encodes the control information including a padding bit number indicator indicating the number of the eliminated padding bits and transmits the encoded control information on the control channel.

Abstract: An apparatus comprising a first circuit and a second circuit. The first circuit may be configured to analyze an audio-video data stream to determine watermark appropriate information for the audio-video data stream. The second circuit may be configured to communicate the watermark appropriate information either in-band with or out-of-band from a bit stream communicating the audio-video data.

Abstract: An apparatus and method for transmitting and receiving wireless packet data are provided. In a wireless packet data transmitter for transmitting to a wireless packet data receiver data packet on a transport channel and control information for supporting the transport channel on a control channel in a wireless packet data communications system, a padding bit eliminator eliminates optional padding bits of a variable size from a transport block for data packet transmission. A transport channel encoder for transport channel-encodes the transport block without the padding bits and transmits the encoded transport block on the transport channel. A control channel encoder control channel-encodes the control information including a padding bit number indicator indicating the number of the eliminated padding bits and transmits the encoded control information on the control channel.

Abstract: The invention relates to a method for ensuring the adequacy of transmission capacity in a digital packet-switched cellular network where both voice sample packets and associated header fields are transmitted in real time in one and the same transmission channel. The invention also relates to a terminal employing the method. In the method, the contents of voice sample packets at the beginning of a speech spurt are partly replaced by packet header field data in situations where the combined bit count of voice sample data and packet header data exceeds the transmission capacity of the transmission channel.

Abstract: A system and method for controlling the quantity of training symbols in a transmission sequence sent by a terminal (102, 106, 107) in a wireless network (100). The transmission sequence include training symbols and data symbols. The system and method determine the number of data symbol errors which are close to training symbols in the transmission sequence, determine the number of symbol data errors which are far from training symbols in the transmission sequence, and adjust the quantity of training symbols in the transmission sequence based on a result of a comparison of the ratio of the number of data symbol errors which are close to training symbols to the number of data symbol errors which are far from training symbols.

Abstract: A circuit and method are presented for signal processing and routing of digital voice telephony signals, using a specialized high-density integrated circuit voice processor. The voice processor performs several essential functions required for telephony processing, including echo cancellation, protocol conversion, and dynamic range compression/expansion. These functions are traditionally performed by multiple circuits or modules. By combining these capabilities in a single device, power and circuit board area requirements are reduced. The embodiment of the circuit and method disclosed herein include novel implementations of a time-slot interchange circuit and a telephony signaling circuit. Both of these circuits are designed to minimize demands on the signal processing engines incorporated within the voice processor, and account for very little of the on-chip circuitry.

Abstract: A system for transmitting and receiving control data in a TDM communications network includes a single master TDM multiplexor and one or more slave TDM muliplexors. The master station stimulates the one or more slave stations, and only one station can transmit control data at any given time. Both slave and master TDM multiplexors include (i) a receiver component for extracting control data from the TDM signal and passing this control data to a control processor; (ii) a transmitter component for inserting control data from a control processor into the TDM signal; and (iii) a bridging component for passing control data along to the next TDM multiplexor without the need for control processor intervention. The system allows a single node in the network to communicate with and control all the nodes in the network. The system can control other TDM sub-networks using secondary communication links.

Abstract: The method and system provide for transporting a secondary communication signal from a secondary carrier network with a primary communication signal from a primary carrier network. The method and system load the overhead from the secondary communication signal into unused bytes of the primary communication signal, thereby creating a transport overhead. The payload from each of the secondary communication signal and the primary communication signal are combined, thereby creating a transport payload. The transport payload is combined with the transport overhead to form a transport communication signal. The transport communication signal is sent to a destination where the transport communication signal is disassembled. The secondary communication signal's overhead and payload are removed from the transport communication signal and transmitted in a secondary communication signal to the secondary carrier network.

Abstract: Control signal transmitting and receiving methods for video/audio processing integrated circuit (IC), the method applied to a video player, and an apparatus therefor are provided. The control signal transmitting method, in a video player having an integrated circuit (IC) for processing video/audio signals and a microprocessor generating control signals to control the IC, has the steps of mapping serial data corresponding to possible control states of the video/audio signal processing IC, and storing the mapped data in a lookup table, reading serial data corresponding to a control state of the video/audio signal processing IC requested by the microprocessor, from the lookup table; and transmitting the serial data to the video/audio signal processing IC, being synchronized to a clock signal.

Abstract: A method for training a receiving modem connected through a telephone network to correct for differences between a transmitted and a received symbol occasioned by network impairments including robbed bit signaling which preempts a least significant bit of a customer's data depending on the frame assigned by the network for such connection.

Abstract: A system and method for reducing the unused capacity of a wireless communication channel utilize the data fields of an special burst (SB) in order to signal physical layer control signaling for coordination between a Node B and a user equipment (UE). The control signaling may include improved reception of SBs, enclose transmit power control commands or any physical layer control signaling for coordination between the UE and the Node B for synchronization timing advance or reconfiguration of the physical channel. This system and method may be applied independently to the uplink and the downlink.

Abstract: The apparatus for symbol boundary synchronization in one embodiment includes on the receive path of a multi-tone modem a window synchronizer, a converter and a symbol boundary component. The window synchronizer obtains windowed portions of the received datastream which includes symbols each expressed with a corresponding set of tones in a time domain. The windowed portions obtained in the training phase exhibit varying degrees of misalignment with the corresponding symbol boundaries. The window synchronizer is responsive to an alignment signal to obtain succeeding windowed portions of the incoming datastream aligned with the corresponding symbol boundaries therein. The converter couples to the window synchronizer to convert the set of tones from each windowed portion from the time domain to a frequency domain.

Abstract: The invention generally relates to a modem connected via a digital interface to a switched public telephone network and to a method for probing the line properties. The modem communicates with a second modem also connected via a digital interface to the same switched public telephone network. The public telephone network may incorporate voice compression devices (ADPCM G.726, G.723 etc.), digital pads (digital attenuators), robbed bit signalling and echo cancelling devices. The probing sequence of the invention uses large amplitude changes in a symbol sequence (each symbol having a duration of 125 ?s). After that single amplitude change, the signal may return to the previous value or continue with the new amplitude value for a number of symbols. The number of symbols is selected to be larger than any expected impulse response of a digital impairment of the channel.

Abstract: A method and apparatus for detecting the location of robbed bits by a digital communications network. A complete echo cancellation circuit also is disclosed employing the robbed bit detection method and apparatus in which the coefficients of the echo cancellation FIR filter are trained simultaneously during the detection of the position of the robbed bit or bits.

Abstract: A data reproducing apparatus and method for improving data detection performance by adjusting decision levels used in a data detector. The data reproducing apparatus includes an equalizer which equalizes an input digital signal, a data detector which detects data from the output of the equalizer based on decision levels, and a level decision unit which detects levels corresponding to the decision levels used in the data detector from the output of the equalizer and feeds back corrected decision levels, which adaptively vary with the output level of the equalizer, to the data detector. Accordingly, the detection performance of the data detector is improved.

Abstract: A method and apparatus are described for transmitting data in a network between first and second single-line digital subscriber line (SDSL) modems using a standard high data rate digital subscriber line (HDSL) frame format. The frame format includes at least one field in each data payload block, e.g., the F/Z bit field, for implementing a feature relating to one of the T1 and E1 transmission protocols. According to the invention, the at least one field is employed for transmission of selected payload data.

Abstract: A CAS data processing apparatus of an STM-1 interface block which is capable of processing CAS signaling data in real time is disclosed. The CAS data processing apparatus of the STM-1 interface block preferably includes a plurality of framers, which separately read signaling data streams from 21 E1 links, a CPU, which outputs a start signal in the CAS signaling data processing, a CAS signaling processing unit, which reformats the signaling data streams inputted from the plurality of the framers into report data in order of the each link, and a Common Memory, which stores the report data outputted from the CAS signaling processing unit.

Abstract: A data optimization engine disposed inline with a first communication channel and a second communication channel. The data optimization engine comprises a transmit interface circuit configured to receive a first data stream from the first communication channel and to obtain a first data file from the first data stream. The data optimization engine further includes an optimization processor coupled to the transmit interface circuit for receiving a second data file from the transmit interface circuit. The second data file represents the first data file after the first data file has been processed by the transmit interface circuit into a format suitable for optimization by the optimization processor. The optimization processor performs one of a compression and an encryption on the second data file, thereby obtaining all optimized data file. In one embodiment, the first data file is a Fiber Channel data frame.

Abstract: A frame of digital data with L symbols is matched to a frame with N symbols by making that number of copies of the original L symbols that results in N symbols. In particular, M=floor(N/L) is computed. L2=N?ML is computed. (L1=L?L2 where L1 and L2 solve the simultaneous equations L1+L2=L and L1*M+L2*(M+1)=N). The frame is effectively divided into two mutually exclusive groups of symbols; one group (consisting of L1 symbols) is copied M times and the other group (consisting of L2 symbols) is copied M+1 times.

Abstract: The present invention pertains to a frame matching method for digital systems. Excess bits are deleted from a frame of data in a single iteration through the data, thereby creating a reduced length frame, wherein the deleting step is performed such that the distance between any two consecutive deleted bits within any group within first subset of the frame is A bits, and the distance between any two consecutive deleted bits within any group within a second subset of the frame is B bits, where A is an integer greater than 0 and B is an integer greater than A, and where the first subset and the second subset together form a plurality of consecutive bits.

Abstract: The invention provides method and apparatus for transporting tone signalling information through a GCME link in a GSM network supporting TFO and speech compression modes for the passage of signals through the link, respectively using TFO frames and TRAU-like In a data stream to the local entrance to the GCME link, a tone signal to be transported is detected. The detected tone signal is coded into bits of a TFO or TRAU-like frame for sending through the GCME link, including setting bits to mark the frame as a containing tone signalling information and setting bits to identify the detected tone signal, whereby the tone signalling information is transported in-band through the GCME link as a marked TFO or TRAU-like frame. At the remote exit from the GCME link, the marked frame is detected and the tone signal regenerated in dependence upon the bits of the marked frame.

Abstract: Transcoder apparatus is designed to transcode a receive signal (UR) into a transmit signal (UE). For this purpose, it includes a signaling transmitting member (14) for producing a signaling message and for introducing it into the transmit signal by stealing bits from said signal. According to the invention, the signaling transmitter member (14) also comprises a tone generator (15) to add a tone signal (UTS) to the transmit signal (UE) prior to applying the signaling message to said transmit signal.

Abstract: A system and method for reducing the unused capacity of a wireless communication channel utilize the data fields of an SB in order to signal physical layer control signaling for coordination between a Node B and a UE. The control signaling may include improved reception of SBs, enclose transmit power control commands or any physical layer control signaling for coordination between the UE and the Node B for synchronization timing advance or reconfiguration of the physical channel. This system and method may be applied independently to the uplink and the downlink.

Abstract: Methods, systems and computer program products for averaging measured levels from differing intervals and differing code points based on their proximity with other measured levels are provided. Such proximity averaging may be provided by methods, systems and computer program products for averaging measured levels of code point sequences from a plurality of frame intervals in the presence of robbed-bit signaling by comparing a first measured level of a first code point from a first of the plurality of frame intervals and a measured level of a second code point from the plurality of frame intervals so as to provide a first comparison result. The measured level of the second code point is incorporated into an average of the measured levels for the first code point from the plurality of frame intervals based on the first comparison result and a threshold value.

Abstract: In accordance with the invention, an interface between an incumbent local exchange carrier's central office terminal and a competitive local exchange carrier's remote terminal is provided by an Integrated Services Digital Network interconnection. Such a connection provides two basic data channels of 64 Kbps each and at least one utility channel. The ISDN signal can be carried over a single wire pair. The interface may be used to interconnect one or two digital channels. The channel units may be designed to remove the robbed bits from the data channels and place them in the utility channels. Further, the utility channel may be employed to transmit frame phasing information so that the networks can synchronize their robbed bit signaling so that both networks use the same bit positions for robbed bit signaling thus minimizing data bandwidth reduction due to robbed bit signaling.

Abstract: The data stream between the transcoders (TCE1, TCE2) of a mobile wireless system is subdivided into a first data stream with samples for transmission and a second data stream with signal parameters for reconstruction of user data and/or for signaling. Both data streams are transmitted at the same time in particular in a handshake phase. The invention permits an improvement in the quality of transmitted data, e.g., speech data in a GSM network in tandem operation between mobile subscribers, in particular during a handshake phase.

Abstract: A method and system for detecting frame slips due to loss of synchronization in a digital communication channel is described. In an illustrative embodiment, a synchronization bit pattern is periodically embedded in the digital data stream. In a described embodiment, the sign bits of the octets of every N frame of data is robbed to form a periodic control channel carrying the synchronization bit pattern. The control channel can be monitored at the appropriate intervals to detect the appropriate synchronization bit pattern. Failure to detect the synchronization bit pattern at the appropriate interval indicates a loss of synchronization such as a frame slip.

Abstract: A method for determining the encoding law of an incoming signal in a network which possibly contains an A-&mgr; or &mgr;-A conversion includes obtaining digital impairment learning (DIL) probing data, generating an ordered table of levels therefrom, using the table to find two functions, and using a logical analysis of the functions to determine the encoding law of the signal. A first function is a maximum from the values DL(i) and the threshold Th1 which are less than T(i), with T(i)=a +bi, and DL(i)=L(i+16)−2L(i) with L(i) being the DIL signal corresponding to the transmitted Ucode=i.

Abstract: A communications device is presented that allows dynamic bandwidth allocation of an unswitched data path based upon the current utilization of one or more switched data channels. The device operates over the local loop of a digital communications carrier, such as a T1 line, that has a variety of time division multiplexed channels. Each data channel can be configured to operate as a channel dedicated to carrying unswitched data on the unswitched data path, or as a switched channel. Switched channels maintain status information about their current status, allowing switched data communication when the channel's status is active, and permitting the unswitched data path to utilize the channel when the channel's status is idle. In one embodiment, channel status information is passed to a remote unit by altering a redundant robbed-bit signaling bit in a multiframe. In a second embodiment, channel status is determined by monitoring switching information that is already transmitted about the channel.

Abstract: A shared T1/E1 signaling bit processor interfaces with either T1 or E1 traffic, and controllably performs robbed bit signal extraction and insertion for T1/E1 signaling protocol using a common set of input/output circuitry and associated decode/control logic therefor. A receiver subsystem controllably samples and extracts signaling bits from selected time slots within serial frames of data incoming from the network to the DTE for delivery to the control processor; a transmitter subsystem controllably inserts signaling bits into selected signaling channels of serial frames of data outgoing from the DTE to the network.

Abstract: A first transceiver transmits a set of test levels to a second transceiver as a signal through a communication channel as encoded samples and subjected to one or more of a plurality of line encoding algorithms. An information channel is superimposed in the signal transmitted through the communication channel. The second transceiver determines line encoding with, and conversion between, the companding laws present in the communication channel based on the received set of test signals. The set of test levels are signals having levels determined based on the difference between the normalized amplitude, vertex, or energy curves for the types of companding laws, with or without accounting for other sources of network distortion. Encoded samples representing the transmitted test levels are reconstructed by the second transceiver in accordance with the one or more detected line encoding algorithms, the encoded samples for each of the set of test levels packed into a corresponding sample cell.

Abstract: The present invention provides a method for conveying information over a communication network such as a Digital Loop Carrier (DLC) network free of in-band signaling information for at least a portion of an established communication between at least two users so as to reduce the information error rate associated with the established communication. For communication links that support robbed-bit signaling (RBS), the RBS signaling is disabled to allow the communication link to be operated in a clear channel mode. When appropriate, operations can be switch from the clear channel mode back to the RBS mode. Embodiments are described for one-stage DLC systems having a local digital switch (LDS) connected to a remote terminal (RT) by a communication link conforming to either the TR-303 protocol or the TR-008 protocol. In addition, embodiments are described for two-stage DLC systems that also have a distance terminal (DT) connected to the RT by a second communication link.

Abstract: Systems compensate for the presence of digital impairments using adaptive constellation techniques. Sample magnitudes are estimated from received samples transmitted during a training period using an algorithm based on minimizing the sum of squares of the estimated errors, after which a suitable constellation is derived. In one embodiment, an optimum least-squares algorithm is employed. In an alternate embodiment, a least mean squares (LMS) or normalized LMS algorithm is performed.

Abstract: A pulse code modulation modem having a far echo canceller that compensates for robbed bit echo noise by polling the receiving modem for robbed bit position information and incorporating that information into its far echo cancellation circuitry.

Abstract: Robbed Bit Signaling (RBS) and PAD digital impairments in sets of Digital Impairment Learning (DIL) signals that are repeatedly transmitted from a server modem to a client modem during DIL intervals are identified by identifying a PAD level for the sets of DIL signals in the DIL intervals and then identifying an RBS type for individual sets of DIL signals based upon the PAD levels so identified. The PAD level may be identified using model DIL signals that correspond to PAD levels that are not subject to RBS. The RBS type may be identified using model DIL signals that correspond to multiple RBS types that are subject to the identified PAD level. More specifically, one of the DIL intervals that contains DIL signals that are not subject to RBS is identified. A PAD level for the DIL signals in the one of the DIL intervals so identified then is determined.

Abstract: Methods of determining systemic impairments in a telecommunications network comprise sending a candidate set of digital symbols from a digital modem to an analog modem. The symbols are affected by systemic impairments in the network. Data information symbols or mapping tables are derived in the analog modem. The data information symbols or mapping tables are then provided to the digital modem. The digital modem may use the data information symbols or mapping tables in a variety of manners, such as for data transmission, spectral shaping, echo cancellation, or adaptation to robbed bit signaling.

Abstract: Signal points from a PCM-derived constellation are selected for transmission via a modulation technique which employs different levels of redundancy coding—including the possibility of no redundancy coding—for respective different sub-constellations of the overall PCM-derived constellation. The coding that is employed for at least one of the sub-constellations is carried out independently from any coding that is employed for any of the other sub-constellations. The PCM-derived constellation and the overall modulation technique are designed so as to accommodate the possibility that the telecommunications system in which the modulation technique is implemented may include so-called bit robbing and so-called digital attenuation.

Abstract: Digital code words are transmitted via a digital communication network, e.g. from a digital modem (1) to an analog modem (5). Whenever an RBS technique is used for an RBS channel, a given bit, as a rule the LSB, of a corresponding code word is changed. In order to recognize and correct such RBS channels, training code words transmitted during a training phase are evaluated. If an RBS channel is detected, the given bit of the corresponding code word is set to a fixed value.

Abstract: A method and system for robbing bits in an ATM channel for forming a robbed bit stream. Unused portions of the header in an ATM cell stream are robbed to form a new robbed bit stream. Information is inserted into the new robbed bit stream and sent to a service area. The information in the robbed bit stream is then extracted and input into information appliances in, for example, homes. The information in the robbed bit stream can include an additional video channel, a program guide or other information.

Abstract: A pulse code modulation modem system is configured to transmit data from a first modem to a second modem over the public switched telephone network (PSTN). The PSTN employs robbed bit signaling (RBS) such that symbols affected by RBS arrive at the second modem in a periodic manner based on a period of six symbols. The modem system is configured such that signal segments are formatted and transmitted with six symbols per segment. After obtaining symbol synchronization, the second modem initializes a modulo-6 symbol counter such that the zero count corresponds to the first symbol of each received signal segment. Those symbols affected by RBS are identified and analyzed to determine optimized signal point constellations that may be used to compensate for the RBS on a symbol-by-symbol basis during subsequent encoding and decoding. Upon a loss of synchronization, the second modem resets its modulo-6 counter in response to the detection of the first symbol in a subsequent signal segment.