Abstract: An integrated circuit includes a plurality of processing stages each including processing logic 1014, a non-delayed signal-capture element 1016, a delayed signal-capture element 1018 and a comparator 1024. The non-delayed signal-capture element 1016 captures an output from the processing logic 1014 at a non-delayed capture time. At a later delayed capture time, the delayed signal-capture element 1018 also captures a value from the processing logic 1014. An error detection circuit 1026 and error correction circuit 1028 detect and correct random errors in the delayed value and supplies an error-checked delayed value to the comparator 1024. The comparator 1024 compares the error-checked delayed value and the non-delayed value and if they are not equal this indicates that the non-delayed value was captured too soon and should be replaced by the error-checked delayed value.

Abstract: A method for selecting members in a hierarchy includes determining a sequence of one or more actions associated with a member selection tree. The actions collectively selecting one or more members from a hierarchy of members. The hierarchy of members is associated with a particular dimension of an organization of data. The method further includes recording the sequence of actions in a member selection script. In addition, the method includes executing the member selection script to select one or more members after the hierarchy of members has been modified.

Abstract: An integrated circuit includes a plurality of processing stages each including processing logic 1014, a non-delayed signal-capture element 1016, a delayed signal-capture element 1018 and a comparator 1024. The non-delayed signal-capture element 1016 captures an output from the processing logic 1014 at a non-delayed capture time. At a later delayed capture time, the delayed signal-capture element 1018 also captures a value from the processing logic 1014. An error detection circuit 1026 and error correction circuit 1028 detect and correct random errors in the delayed value and supplies an error-checked delayed value to the comparator 1024. The comparator 1024 compares the error-checked delayed value and the non-delayed value and if they are not equal this indicates that the non-delayed value was captured too soon and should be replaced by the error-checked delayed value.

Abstract: A method a system for automatically controlling an adaptive interleaver involves monitoring performance parameters of a transmission system and controlling the adaptive interleaver in response to the performance parameters. The SNR and the data rate of the transmission system are preferably determined. The data rate is analyzed and the adaptive interleaver is adjusted in response to the data rate and the SNR. Alternatively, the BER and the data rate of the transmission system are determined. The data rate is analyzed and the adaptive interleaver is adjusted in response to the data rate and the BER. Alternatively, any one of the SNR, BER or data rate can alone be monitored and used to the adaptive interleaver. The system provides a effective system for adjusting an adaptive interleaver in response to performance parameters of a transmission system.

Abstract: A process for automatically monitoring the packet error rate of a logical channel in a cable television DOCSIS data transmission system and automatically altering the bit rate on the channel or sending a message to a cable operator recommending a change in burst profile and bit rate. The preferred embodiment of the process comprises determining the dominant noise type and SNR of the channel and selecting a set of burst profiles best adapted for the dominant noise type and selecting an initial burst profile based upon the SNR. Then the packet error rate of the channel is monitored and compared to one or more thresholds to decide whether a change in bit rate is required to bring the packet error rate within limits. If a change is bit rate is indicated, automatically selecting a new burst profile with an appropriately changed bit rate and automatically generating and sending a UCD message defining the channel's new burst profile.

Abstract: A serial link system is provided for determining a worst-case cumulative data eye. The system includes a transmitter, a receiver, and a channel between the transmitter and receiver such that data sent by the transmitter is received by the receiver through the channel. The channel includes a plurality of connections including a victim and at least first and second aggressors, with the victim being disposed between the first and second aggressors. The system also includes a controller constructed and arranged to determine a worst case cumulative data eye based on a data pattern of the victim, jitter on the victim, an effect a data and jitter pattern on the first aggressor has on the victim and an effect a data and jitter pattern of the second aggressor has on the victim and to combine the effects of the data pattern of the victim, the jitter on the victim and the effects of the first and second aggressors on the victim into a single pattern to determine cumulative data eye for use in a simulator.

Abstract: A method for preparing electronic data for transmission includes calculating a duration for compressing the electronic data, calculating a duration for transmitting the electronic data if not compressed, and compressing the electronic data only if the duration for compressing does not exceed the duration for transmitting.

Abstract: A method of generating a CRC code to determine a variable field value for equalizing a CRC value, which is calculated based on data including the variable field value of a variable field included in a data field according to a generator polynomial, to a desired CRC value, comprises the steps of establishing a temporary variable field value, reading all corrective values which correspond to a bit number where a bit value of said temporary variable field value is “1”, from a conversion table which stores therein corrective values for indicating a bit to be inverted in the variable field value as “1” corresponding to a predetermined bit number, and exclusive-ORing the read corrective values to calculate a first calculated value, and, determining whether the first calculated value corresponds to the desired CRC value or not.

Abstract: Apparatus for passively tracking expired data in a dynamic memory includes an error encoding circuit operative to receive an input data word and to generate an encoded data word which is stored in the dynamic memory. The apparatus further includes a decoding circuit operative to receive an encoded data word from the dynamic memory, to detect at least one or more unidirectional errors in the input data word read from the dynamic memory, and to generate an error signal when at least one error is detected, the error signal indicating that the input data word contains expired data. Control circuitry included in the apparatus is configured for initiating one or more actions in response to the error signal.

Abstract: A readout controlling apparatus for controlling reading conditions at the time of reading data coded in units of predetermined code blocks from a recording medium capable of performing error correction at a high reliability even when the playback conditions are poor by calculating an error rate using the number of bytes for which outer code error correction has been completed etc. in the error correction in an error corrector and controlling the reading conditions so that the error rate becomes small.

Abstract: The invention relates to a receiving circuit for receiving message signals, having a sampler for converting the message signal into a sampled signal, an analyzing unit for decoding the sampled signal and checking it for errors, and a control unit for controlling the sampling method as a function of the error-check on the sampled signal.

Abstract: In the absence of a continuous channel from the mobile terminal that incorporates a CRC in each transmitted frame from which the base station can derive a power control signal for feedback to the mobile station for maintaining the mobile station's pilot Eb/N0 level at a desired target that corresponds to a particular frame error rate, the pilot signal received by the base station from the mobile terminal itself is arranged in a frame format. Each pilot frame is compared with an a prioi known transmitted pilot signal bit pattern to determine whether it has been received in error. In response to a comparison of a received pilot frame with the expected known bit pattern of the pilot frame, an error signal is derived, which in the described embodiment is either a step-up or step-down signal that is fed back to the mobile terminal to increase or decrease its transmitted pilot Eb/N0 level, respectively.

Abstract: In a receiver operable in response to a data signal, an eye aperture size is detected along a time axis by an eye aperture detection circuit and is controlled by a control circuit so that it becomes a maximum. The eye aperture detection circuit determines different decision time points of the same level arranged along a time axis and judges whether or not an error is caused to occur at each of the decision time points, so as to detect the eye aperture size and to produce detection results. The control circuit processes the detection results in accordance with a predetermined algorithm to successively vary the eye aperture size and to keep the data signal at an optimum amplitude.

Abstract: A method and apparatus for characterizing whether a head of a data storage device exhibits excessive performance degradation. The device includes a data transducing head adjacent a recording medium, and read channel circuitry with a variable gain amplifier (VGA) and gain control block. The gain control block supplies VGA gain control values to the VGA to nominally maintain amplitudes of readback signals obtained from the head within a selected range suitable for remaining portions of the read channel circuitry. A baseline VGA gain control value is first obtained, after which the read channel is parametrically adapted to optimize read error performance. An adaptive VGA gain control value is thereafter obtained, and head degradation is determined in relation to the magnitude of the adaptive VGA gain control value as well as in relation to a difference between the VGA gain control value and the baseline value.

Abstract: A device for estimating a likelihood of a wireless link outage includes a memory, a variability calculator, and an outage predictor. The memory maintains a history of signal quality for a signal received from a transmitter. The variability calculator is coupled to the memory. The variability calculator computes a variability statistic for the history of signal quality maintained in the memory. The outage predictor is coupled to the variability calculator. The outage predictor estimates the likelihood of the wireless link outage in direct proportion to the variability statistic.

Abstract: A system for configuring solid-state storage devices comprises a solid-state storage device and an error correction code (ECC) selection system. The ECC selection system is configured to automatically select a set of error correction code based on an error rate of the storage device. The ECC selection system is further configured to install the selected set of error correction code in the solid-state storage device.

Abstract: A communication system, network interface, and communication port is provided for interconnecting a network of multimedia devices. The multimedia devices can send streaming and/or non-streaming data across the network. The network accommodates all such types of data and assigns data types to time slots or frame segments within each frame to ensure streaming data maintains its temporal relationship at the receiver consistent with the transmitter. A coding violation within a frame segment of one or more frames is used to indicate the absence of isochronous streaming data within the byte locations containing the coding violations. Coding violations can, therefore, be interspersed between isochronous data messages or data transfers to note that a particular portion of a frame segment does not contain isochronous data.

Abstract: An information processing method is provided which allows each shop in a cyber shopping site to continue its operation even if some errors of merchandise data are found in each of a plurality of data processes. More specifically, an error rate of input merchandise data is calculated at each process, and if the error rate is equal to or larger than a data error allowable threshold value, the next process is performed in order to continue the operation of the shop.

Abstract: A method and apparatus determines an uncoded bit error rate pb based on a target symbol error rate ?s. The uncoded bit error rate pb is determined based on a weighted series expansion of the target symbol error rate ?s, comprising weights W that are a function of a maximum number of symbol errors that can be corrected t and a number of symbols in an information field K. The maximum number of symbol errors t and the number of symbols in the information field K is selected such that the uncoded bit error rate pb that produces a symbol error rate that is less than or equal to the target symbol error rate ?s is largest.

Abstract: A state machine method and system are provided for determining non-causal channel equalization thresholds. The method comprises: receiving a non-return to zero (NRZ) data stream encoded with forward error correction (FEC); setting x=0; in State 0, adjusting a third threshold (Vopt) in response to corrected bit errors; if x=0, setting a first and second threshold equal to the third threshold; in State 1, if x=0, simultaneously adjusting the first threshold and the second threshold, to minimize the total number of corrected bit errors; in State 2, following State 0, adjusting the first threshold, independent of the second threshold, to minimize the total number of errors; in State 3, following State 0, adjusting the second threshold, independent of the first threshold, to minimize the total number of errors; and, adding 1 to x and returning to State 0.

Abstract: Disclosed are a method and system for detecting point. The method of this invention comprises the steps of providing a set of points representing measured time delays between two clocks, providing a turning indicator to measure a magnitude of turns per measurement interval, and identifying a turn at a given point when the turn indicator at said given point is above a given value. With the preferred embodiment of the invention, the turn indicator is given by the equation: turn_indicator=(rtt_min?rtt_estimate)/number_of_points; where rtt_min is the minimum round trip delay in all the measurement points, and rtt_estimate is estimated round trip delay by using the symmetric convex hull algorithm.

Abstract: Apparatus and method for transmitting data messages between a plurality of stations interconnected by a bus line is disclosed, in which each message includes a frame portion and a data portion. The frame portion represents content and priority information of the data message, and the data portion represents data to be transmitted. At least one station transmits a data message having the frame portion transmitted at a first data transmission rate, and the data portion transmitted at a second data transmission rate which is not less than the first data transmission rate. The first and/or second data transmission rate is adjustable in dependence on a signal quality determined for transmission of a data message.

Abstract: A system and method for detecting a correct transmission format upon encountering a decoding error in a variable-format transmission scheme, wherein the decoding error results from an unsuccessful decoding of a frame. The invention provides for prioritizing the permissible formats, resulting in a prioritized order. The frame data is then decoded according to one or more of the permissible formats in the prioritized order, and if the decoding is successful in accordance with one of the formats, that format is selected as the correct transmission format.

Abstract: Sample values of an input information signal are obtained at sampling instants. For each of a plurality of states at a sampling instant, an optimum path metric value is determined. For each of the plurality of states a best predecessor state at he directly preceding sampling instant is determined. A state at the sampling instant identifies a sequence of n subsequent bits, where n is larger than 3, and sequences of n subsequent bits having n?1 directly successive bits of the same binary value ar allocated to the same state. The best path is established from the state at the sampling instant having the lowest optimum path metric value, back in time towards a previous sampling instant via best predecessor states, established earlier for earlier sampling instants, to establish an optimum state at the previous sampling instant. Then at least one bit of the n bits of the sequence of bits corresponding to the established optimum state at the previous sampling instant is output.

Abstract: A method and apparatus is provided for routing workpieces based upon detecting a fault. The method comprises routing a workpiece to a first processing tool identified by a dispatch system, detecting a fault condition associated with the first processing tool and notifying the dispatch system of the detected fault condition. The method further comprises routing a second workpiece to a second processing tool in response to the dispatch system being notified of the fault condition.

Abstract: A method is disclosed for providing data for automatically estimating channel performance if different parameters of a Reed-Solomon (RS) code are used in a communication system while transmission is occurring in the communication system without changing the current Reed-Solomon (RS) code parameters.

Abstract: System and methods for propagating error status over an error checking and correcting (ECC) protected channel. A first device receives data and an error status associated with the data. The first device generates check bits for the data based on a first ECC code and combines the check bits with the data to form one or more code words. The first device sends the code words across the channel where the first device inserts a triple error into a nibble of at least one codeword sent if the error status indicated an uncorrectable error. A second device connected to the channel receives the code words sent across the channel. The second device detects triple errors within a nibble of any code word and any other single error in the code word using a second ECC code, where the second ECC code is the first ECC code with columns for check bits inserted.

Abstract: A system and method for efficiently correcting block errors in packet-based digital communications are provided whereby the ratio of redundant symbols/message symbols over the length of a data packet decreases in order to more efficiently use available bandwidth. The reduction of this ratio, and subsequently the change in a corresponding framing schedule, may be determined through negotiations between the transmitting device and the receiving devices. Each receiving device calculates a redundancy requirement based on signal-to-noise ratio samples. This requirement is returned to the transmitting device in the form of a schedule request. The transmitting device determines if a new framing schedule is needed based on the schedule request, and communicates this new framing schedule to the receiving device. Once the receiving device acknowledges receipt of the new schedule, the transmitting device switches to the new framing schedule for future data packet transmissions.

Abstract: A method and system are disclosed for counting error rates occurring within an optical compact disk system as data is read from an optically encoded compact disk. In a preferred embodiment error flag data are generated as errors occur within the optical compact disk system. From the error flag data, error flag bits corresponding to errors in reading information from an optically encoded disk are identified for further processing. Further processing includes, among other things, generating an error rate over a predetermined time period. The operation of some or all of the functions within the optical compact disk system may be interrupted upon the exceeding of a predetermined threshold error rate. From the error rate information, the hardware, software and firmware within the optical compact disk system may be optimized for increased performance.

Abstract: A system that adapts wireless link parameters for a wireless communication link. A measure is determined of errors occurring in communication over a wireless link. In a case that the measure of errors corresponds to more errors than a first predetermined threshold, communication changes from a first set of wireless link parameters to a second set of wireless link parameters. The second set of wireless link parameters corresponds to higher error tolerance than the first set of wireless link parameters. In a case that the measure of errors corresponds to fewer errors than a second predetermined threshold, communication changes from the first set of wireless link parameters to a third set of wireless link parameters. The third set of wireless link parameters corresponds to lower error tolerance than the first set of wireless link parameters. Preferably, the measure of errors is determined by monitoring a number of NACK messages and a number of ACK messages that occur.

Abstract: A method of assembling a plurality of frames including cell/packet-formatted data according to a predetermined frame format for transmission in a communication signal in a wireless or satellite environment. The method begins by assembling a data payload for each frame having a first variable size, including at least one of a partial data cell/packet and a complete data cell/packet. Then, for each frame a block code having a second variable size is generated for use in error correction. Each frame is provided with a frame header which defines aspects of said frame. Finally, the data payload, the block code and the format header are combined to form a frame corresponding to the plurality of frames, the format header defining a first portion of the frame, the data payload defining a second portion of the frame and the block code defining a third portion of the frame.

Abstract: A network element (NE) in a communications network decodes a data stream received over a communication link. Upon synchronization with the data stream, the NE determines a performance metric for the link based on a number of transmission code violations. In response to the performance metric exceeding a predetermined threshold, the NE commands the selection of a different link to carry the data stream via a switch signal. The switching or rerouting of signals may occur between a single pair of NEs (e.g., point-to-point span) or in a more complex topology having a plurality of interconnected NEs.

Abstract: An optical receiver threshold may be optimized in real time based on a forward error correction (FEC) error statistics. A relative number of corrected ones as compared to corrected zeros is tracked. The threshold is shifted in response to an imbalance between the two types of errors.

Abstract: Methods and network nodes are provided which are adapted to perform protection switching on the basis of raw signal quality information, such as raw BER information, in a manner which instigates the protection switching before an actual failure has occurred. In some embodiments, these methods leverage forward error correction and uncorrected BER to effect traffic redirection before faults are observed at layer 2 and above. This is as opposed to the method of switching layer 2 traffic in response to bitstream characteristics observed at that layer.

Abstract: A mobile station adapted to be used in a radio communications system includes a receiver apparatus adapted to receive blocks of distorted information bits at a first rate from a transmitter via a communications link, and a first detecting apparatus adapted to detect information bits from the distorted information bits. The mobile station also includes a second detecting apparatus adapted, when the quality of the received blocks of information bits is above a given level, to detect information bits from the distorted information bits using fewer computation resources than the first detecting apparatus.

Abstract: A method and an apparatus encodes and decodes blocks having a predetermined number of sectors of data bytes to detect and correct data bytes in error in each sector of a block. The method and the apparatus generates sector level check bytes for each sector in the block responsive to the data bytes in each sector according to a first level of an error correction code, and generates block level check bytes for a predetermined sector in the block responsive to the sector level check bytes of various sectors, including the predetermined sector, according to at least a second level of the error correction code.

Abstract: An increase in the code error rate in a received signal is detected in a light receiver. An loss of signal detector circuit for a light receiver 20 comprises a main discrimination circuit 8a for comparing the intensity of an electric signal obtained by converting a light signal by photoelectric conversion using a photoelectric conversion element 1 with a predetermined discrimination threshold; a reference discrimination circuit (8b, 8c, . . . ) for comparing the intensity of the electric signal with regard to a reference threshold which differs from the discrimination threshold; and an operation circuit 9 for detecting loss of the signal based on the results of the comparisons performed by the main discrimination circuit 8a and the reference discrimination circuit (8b, 8c, . . . ).

Abstract: A method for providing error compensation to a signal includes providing error adjustment to a signal at a transmitter and communicating the signal over a channel at a channel speed. The method includes receiving the signal from the channel at the channel speed and sampling the signal at a speed less than the channel speed to yield a sampled signal. The method includes determining an error associated with the signal and determining compensation information for providing the error adjustment. The compensation information is based on the error and is determined at a compensation speed. The compensation speed is less than the channel speed. The method also includes communicating information to the transmitter for providing error adjustment. The information communicated to the transmitter may comprise the compensation information. The information communicated to the transmitter may also comprise intermediate information from which the compensation information is determined.

Abstract: A data processor includes first and second devices that are coupled together via a signal path. The first device includes a first arithmetic unit. The first arithmetic unit performs an arithmetic operation on data to obtain a first result during an operation cycle, in which the first device transfers the data to the second device through the signal path. The first arithmetic unit outputs the first result onto the signal path during an idle cycle in which no data is transferred through the signal path. The second device includes second arithmetic unit and comparator. The second arithmetic unit performs the same type of arithmetic operation on the data, transferred through the signal path in the operation cycle, to obtain a second result. The comparator compares the first result, transferred through the signal path in the idle cycle, to the second result and outputs a comparison result.

Abstract: Alternate methods, devices and systems are presented for providing service providers and/or end users of mobile stations to monitor and/or report regions with high error rates and/or dead zones. A protocol is provided such as to yield the error occurrence, error rate and/or the address of the end user. In some embodiments it also contains location information and time of day information. This information may be collected from the G.P.S., and/or all or a portion of users when there is a significant transmission difficulty and/or an abundance of errors. The collected data forms a database which is analyzed to generate coverage maps. This may include the dynamic aspects of the mobile network. In another aspect of this invention, each mobile station periodically compares its current location with the data base. The results of this comparison enables the mobile unit to anticipate connection problems.

Abstract: There is provided an error rate select circuit activated in an information sustaining mode, wherein data is read out from a memory circuit comprising dynamic memory cells and inspection bits for detection and correction of an error. If no error is detected, a first detection signal is accumulated in a first direction, that is, the first detection signal is added to a sum. If an error is detected, a second detection signal is accumulated in a second direction, that is, the second direction signal is multiplied by a weight to produce a product before subtracting the product from the sum. If the sum increases in the first direction, exceeding a predetermined value, the refresh period is lengthened by a predetermined incremental time. If the sum decreases in the second direction, becoming smaller than another predetermined value, the refresh period is shortened by a predetermined decremental time.

Abstract: A system and method are provided for using an analysis of forward error corrections (FEC) in a digital communications signal as feedback information to improve the performance of an analog receiver system. The FEC decoder supplies the number of “1” bit and “0” bit corrections made to a control unit. In response to the FEC corrections, the control unit changes receiver control parameters. The control signal modifies processing in the receiver front end to achieve the fewest number of FEC corrections.

Abstract: The present invention addresses the need for optical transmission systems, apparatuses, and methods having increased flexibility and reliability. Optical systems of the present invention are configured to provide alarms, provision, and/or perform protection switching, if the number of corrected errors exceeds a threshold criteria. Various system parameters, in addition to protection thresholds, can be adjusted based on the relationship between the number of one errors, zero errors, and/or total errors being corrected in the system.

Abstract: A method for synchronizing multi-carrier signals in an orthogonal frequency division modulation (OFDM) data transmission system is disclosed which provides maximum likelihood estimation of timing offset and frequency offset. The estimates are able to compensate the estimation error over an entire span of observed data samples. The method requires no training sequence thus enabling blind frequency compensation. The method provides a joint probability density function for the estimates which consists of two terms; one generated from observed data received during a first interval and one generated from observed data received during a second, following, interval. The estimates provided by the method are therefore maximal likelihood over the entire span of observed signals and are a significant improvement over estimates provided by methods based only observations during the first interval. The method is mathematically robust and computationally and statistically efficient.

Abstract: Error rate control systems, methods, and computer program products request a data rate slow-down based on the status of the error rate. A linear penalty is generated if a data rate slow-down is requested, which is then used to determine a minimum distance between constellation points in a signaling constellation or alphabet. Because the minimum distance between constellation points may be directly related to the error probability, the error rate may be controlled through the linear penalty.

Abstract: A system that adapts wireless link parameters for a wireless communication link. A measure is determined of errors occurring in communication over a wireless link. In a case that the measure of errors corresponds to more errors than a first predetermined threshold, communication changes from a first set of wireless link parameters to a second set of wireless link parameters. The second set of wireless link parameters corresponds to higher error tolerance than the first set of wireless link parameters. In a case that the measure of errors corresponds to fewer errors than a second predetermined threshold, communication changes from the first set of wireless link parameters to a third set of wireless link parameters. The third set of wireless link parameters corresponds to lower error tolerance than the first set of wireless link parameters. Preferably, the measure of errors is determined by monitoring a number of NACK messages and a number of ACK messages that occur.

Abstract: A method of determining the actual transmission rate in a variable transmission rate communication system is provided, using error detection metrics. The received symbols are decoded assuming each possible rate, and then re-encoded to determine a symbol error rate for each possible rate. The possible transmission rates are then narrowed down using a simple measure of the likelihood of error, such as the CRC status determined for each rate. The symbol error rates are compared to either make a confident decision as to the actual transmission rate or to erase the frame. Rather than compare the values of the symbol error rates with predetermined thresholds, the method compares the differences between the symbol error rates for each possible rate with predetermined thresholds. This results in fewer erasures, even if the symbol error rates are low due to high signal to noise ratios.

Abstract: Methods and network nodes are provided which are adapted to perform protection switching on the basis of raw signal quality information, such as raw BER information, in a manner which instigates the protection switching before an actual failure has occurred. In some embodiments, these methods leverage forward error correction and uncorrected BER to effect traffic redirection before faults are observed at layer 2 and above. This is as opposed to the method of switching layer 2 traffic in response to bitstream characteristics observed at that layer.

Abstract: A partial response maximum likelihood (PRML) bit detection apparatus derives a bit sequence from an input information signal. The apparatus includes: input apparatus for receiving the input information signal; sampling apparatus for sampling the input information signal at sampling instants so as to obtain samples of the input information signal at the sampling instants; conversion apparatus for converting an array of the samples into an array of bits of a first or a second binary value, detection apparatus for repeatedly detecting a state for subsequent sequences of n subsequent bits of the array of bits, the subsequent sequences being obtained by shifting a time window of n subsequent bits each time over one bit in time; apparatus for establishing the best path through the states; and deriving apparatus for deriving a sequence of bits in accordance with the best path through the states.

Abstract: A method and apparatus for reducing the audible “clicks” or “pops” which occur when an ADPCM encoding and decoding system is employed in a communications system in which communication occurs over a dispersive channel. A novel technique is employed in which ADPCM-encoded silence is substituted for error-containing frames, and post-processing is performed on decoded frames while a muting window is open.