Abstract: The invention provides an apparatus for decoding a coded digital data sequence. The apparatus includes a first Viterbi decoder of a first response type, a first filter and a second filter. The first and second filters are coupled to receive decoded sequences from the first Viterbi decoder. The first Viterbi decoder generates a first decoded sequence from the coded digital data sequence. The first and second filters generate respective first and second error signals in response to receiving the first decoded sequence. The first and second error sequences indicate differences between the first decoded sequence and second and third decoded sequences, respectively. The second and third decoded sequences are probable sequences produced by Viterbi decoders of respective second and third response types in response to receiving the coded digital data sequence.

Abstract: A disk drive system corrects run-out errors without substantial PES transients and without significant response time. The disk drive system includes a servo compensation system coupled to a read/write head. The servo compensation system is adapted to generate a run-out correction waveform for a track in a disk. The run-out correction waveform includes one or more sinusoidal component waveforms, each of which is defined by a phase and an amplitude. The method includes measuring an amplitude and a phase of one or more sinusoidal component waveforms for a set of specified tracks in a disk. The method also includes determining a phase and an amplitude of one or more sinusoidal component waveforms for a destination track based on a measured amplitude and a measured phase of the one or more measured sinusoidal component waveforms. The sinusoidal component waveforms for the destination track are adapted to substantially correct a run-out error in the destination track.

Abstract: A multi-carrier transmission system using orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol. Such systems place high demands on the synchronization of the receiver with the transmitter. The maximum permitted deviation from exact synchronization is usually a small fraction of a sampling interval. A reserve carrier, the pilot carrier, which is given a fixed phase, is usually used as the reference to achieve this high accuracy. The receiver sampling clock oscillator is phase locked to the pilot carrier. It is therefore necessary to estimate the phase of the pilot carrier. Using a bandpass filter to recover the pilot carrier, regardless of the frame structure of the DMT signal, does not eliminate the influence of neighboring carriers on the pilot carrier.

Abstract: The transmission power of a cellular mobile telephone is adjusted as a function of received power information. The celluar mobile telephone is equipped with a variable-gain amplifier that covers the transmission power range, and the gain and supply voltage of the amplifier are tuned as a function of the received power information.

Abstract: A baud rate digital timing recovery circuit for use in the read channel of a storage device controller is able to operate nominally at the baud rate by recognizing and compensating for oversampling and undersampling conditions. The read channel includes a sample rate converter for interpolating between digitally sampled values and a digital timing recovery loop that detects a phase error in the interpolated signal and adjusts the interpolation interval accordingly. An accumulator circuit generates a modulo-TS interpolation interval value, where TS is the sampling period. Detection circuitry detects when the interpolation interval value has wrapped through its maximum value or minimum value and generates an oversampling or undersampling signal in response. The oversampling and underampling signals are received by an elastic buffer.

Abstract: A method and system for laying out and accessing data in a disk drive system. The layout resides in a table in firmware of the disk drive system. The table includes multiple entries or rows, one corresponding to each different area in the disk media. The entry provides information about the range of block addresses in that area including the starting and end block address in the area, and information about the range of physical addresses including the head and the starting and ending cylinder number. A firmware routine finds the appropriate entry in the table and converts the block address to the physical address, or vice versa.

Abstract: A multi-carrier transmission system. A received multi-carrier signal is sampled and digitized before FFT processing. Multi-carrier signals consist of many narrow band carrier waves which convey data via a wide band channel. The amplitude distribution of the sum of all the individual carriers is Gaussian. This means that high amplitudes occur with low probability. At the present time, analog to digital converters have a limited dynamic range. It is therefore normal practice to provide a compromise between cutting and quantization noise. The adverse affects of a course quantization have to be balanced between signal distortions caused by the loss of the low probability high amplitude signals.

Abstract: A remote terminal includes a receiver stage for receiving a transmitted signal and for delivering an analog signal. The remote terminal further includes an analog/digital converter for converting the analog signal to a digital signal, and a processing stage for processing the digital signal. The analog/digital converter is a delta-sigma converter having adjustable parameters, and the processing stage includes a tuning circuit for adjusting these parameters on the fly as a function of the transmission standard, of the actual rate of transmission of the useful data, and of the actual conditions of reception.

Abstract: A multi-carrier transmission system such as a DMT system. Channel information is transmitted between two transceivers using a plurality of sub-carriers modulated with symbols, each of which represents a multiplicity of bits. Each of the transceivers includes a receiver and a transmitter in which a fixed maximum value was determined for the number of bits for each symbol and in which the system is adapted to determine the bit capacity per symbol of each of the plurality of sub-carriers and to increase the number of bits represented by a symbol transmitted over those sub-carriers having a capacity less than a fixed maximum value to the maximum value by the addition of channel coding bits. The fixed maximum value for the number of bits for each symbol may be determined on the basis of the bit capacity of that one of the sub-carriers having the highest theoretical bit capacity may be at least as large as the theoretical bit capacity.

Abstract: The successive values of the digital symbols which can each take M different possible values are estimated on the basis of the successive values of digital samples each of which results from the combination of at most L successive symbols. This estimation includes a stage by stage progression through a trellis of the Viterbi type with Mk states, with k being less than or equal to L−1. All the states of all the stages are respectively provided with aggregate metrics. When taking into account the sample of rank n, all the transitions arriving at the various states of the current stage of the trellis are partitioned into M groups, each group containing all the transitions arising from the states of the preceding stage which are associated with one of the M possible values of the symbol of rank n−k. The various aggregate metrics are calculated for these various states of the current stage of the trellis.

Abstract: A method for estimating the impulse response of an information transmission channel includes evaluating a useful number of coefficients of an impulse response of the information transmission channel as a function of actual characteristics of the information transmission channel. This evaluation is carried out, for example, by using a time domain spreading parameter of the channel.

Abstract: The invention includes a drive control integrated circuit with an intelligent and efficient tracing capability. The drive control integrated circuit executes operating instructions grouped into modules. The drive control integrated circuit stores the module numbers for executed modules in a memory. System designers can then retrieve the module numbers from the memory to assess the operation of the drive control integrated circuit. Some typical modules are read, write, seek, error, and servo modules. The drive control integrated circuit also stores operating parameters associated with the executed modules in the memory. Some typical operating parameters are instruction codes, head numbers, cylinder numbers, and error codes. The invention allows system designers to specify a particular trace operation and wait for the drive control integrated circuit to load the module numbers and operational parameters of interest into the memory.

Abstract: A multi-carrier transmission system such as a DMT based VDSL system. The system uses orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol. This estimate includes digital receiver and transmitter units with the receiver unit including a symbol detection unit. This system is adapted to determine a parameter for each single carrier with the parameter being indicative of a deviation of a received signal from a corresponding constellation point. It compares the parameter with an upper lower limit and if the parameter is outside the limits, changes the constellation used to modulate the carrier to a neighboring constellation. The symbol detection unit may be used to determine a parameter such as the ratio d2/&sgr;2, where d is the shortest distance between neighboring constellations, &sgr; is a standard deviation and &sgr;2 is the variance of the deviations of the input and output signal values of the symbol detection unit.

Abstract: A method for maximizing buffer usage in a disk drive system. Control circuitry within the disk drive system tansfers the defective sector list for the disk to a buffer, and places the list in a reserved list area. The size of the defective sector list is then determined and the reserved list area is reduced to a size equal to the size of the defective sector list plus some spare room. If the newly sized reserved list area is not at one end of the buffer, it is then moved to one end of the buffer to leave the remainder of the buffer as a contiguous and expanded reserved user area for use data. The expanded reserved user area reduces the time of read or write operations in a disk drive.

Abstract: A cellular telephone includes a plurality of power amplifiers having a common operating region. If one of the amplifiers has to be deselected, a desired moment for the switching to another amplifier is defined based upon a predetermined transmission interrupt criterion. The power continues to be adjusted with the currently selected amplifier until the instant of switch over. Switching to the other amplifier may then be performed after the transmission has been interrupted.

Abstract: Disclosed is a disc drive system that includes a digital signal processor for processing information sectors read from a CD media. The digital signal processor is configured to parse the information sectors into data frames and subcode frames. A data auto-start unit for triggering a data transfer to a buffer memory when a desired data frame is detected. A subcode auto-start unit for triggering a subcode transfer to the buffer memory when a desired subcode frame is detected. Preferably, the desired data frame and the desired subcode frame have a same MSF. The disc drive system further includes a buffer manager having a plurality of counters that are configured to track the number of data frames and the number of subcode frames being transferred to the buffer memory, and releasing a block including one of the data frames and one of the subcode frames when the counters indicate that the block is complete.

Abstract: A device includes a receiver including an estimation block for estimating the impulse response of the transmission channel and a transformation block. The transformation block may include a preprocessing block for determining a phase minimum transformed impulse response corresponding to a transformed channel based upon the estimated impulse response of the transmission channel, and a filter for filtering the signal received. This makes it possible to retain equality between the autocorrelation of the signal received and the autocorrelation of the filtered signal. Further, the receiver may include an equalizer for applying an equalization processing operation to the filtered signal while taking account of the transformed impulse response.

Abstract: A multi-carrier transmission system, for example a DMT system. Channel information is transmitted between two transceivers using a plurality of subcarriers. Each subcarrier, or symbol, has a parameter associated with it. The transceivers are adapted to transmit the channel information as a sequence of n groups in which each of the n groups contains information concerning the number of adjacent subcarriers which have the same value as the parameter, together with the actual value of the parameter. The parameter which may have a plurality of discrete values, may be a bit-loading value, or a QAM constellation identifier.

Abstract: A device for detecting and correcting errors in error correction coded (ECC) data blocks that are read sequentially from a DVD medium is disclosed. Each ECC data block is defined as a two dimensional block of a plurality of columns and rows. Each of the ECC data blocks is read from the DVD medium sequentially in rows. The device includes row correction circuitry, a buffer, column correction circuitry, and repeat correction circuitry. The row correction circuitry is configured to sequentially receive the rows of an ECC data block for detecting and correcting up to a first predetermined number of errors in each of the received rows. The buffer is coupled to the row correction circuitry for receiving the error corrected rows of the ECC data block as a receiving buffer. The buffer also stores the ECC data block as a correction buffer when all the rows of the ECC data block have received.

Abstract: A multi-carrier transmission system, such as a DMT system. A receiver must be able to recover a sampling clock that is very accurately synchronized to a transmitter sampling clock. Typically, synchronization is achieved by using a reserved carrier, the pilot carrier, which is transmitted with a fixed phase. The receiver sampling clock is then phase locked to the pilot carrier. Frame timing can be recovered by using a correlation technique. Thus an improved method of recovering a sample clock and phase locking the sampling clock to a pilot carrier is provided.