Abstract: A few high power tones used for synchronization and/or other purposes are transmitted in a FDM system during a period of time into a region, e.g., sector of a cell, e.g., a symbol transmission time period. During normal data transmission symbol periods signals are transmitted using at least 10 tones, e.g., per symbol time. Less than 5 high power signals are transmitted in a symbol time with at least 80% the maximum total transmitter power used for transmitting into said region being allocated to the high power signals where the maximum total transmitter power is determined from a period of time which may includes one or more data and/or high power tone transmission periods. When the high power tones are transmitted at most 20% of transmitter power used for transmitting into the region is available for transmitting other tones with the power normally being distributed among multiple tones. Often some tones which would be transmitted in a symbol time go unused during transmission of the high power signals.

Abstract: Power control methods and apparatus for use in a sectorized cell of an OFDM communications system are described. Each sector of a cell uses the same frequencies and transmission times and is synchronized with the other sectors in the cell in terms of tone frequencies used at any given time and symbol transmission times. Tones are allocated to channels in each cell in the same manner so that each channel in a sector has a corresponding channel in another sector. Power differences between channels in different sectors are maintained to be within a pre-selected power difference. Different channels in a cell are assigned different power levels. Wireless terminals are assigned to channels based on channel feedback information. Wireless terminals with poor channel conditions are allocated to higher power channels than wireless terminals with good channel conditions. Lower power channels often include more tones per symbol time than high power channels.

Abstract: A few high power tones used for synchronization and/or other purposes are transmitted in a FDM system during a period of time, e.g., a symbol transmission time period. During normal data transmission symbol periods signals are transmitted using at least 10 tones, e.g., per symbol time. Less than 5 high power signals are transmitted in a symbol time with at least 80% the maximum total transmitter power transmitted being allocated to the high power signals where the maximum total transmitter power is determined from a period of time which may includes one or more data and/or high power tone transmission periods. When the high power tones are transmitted at most 20% of transmitter power is available for transmitting other tones with the power normally being distributed among multiple tones. Normally some tones which would be transmitted in a symbol time go unused during transmission of the high power signals.

Abstract: Power control methods and apparatus for use in a sectorized cell of an OFDM communications system are described. Each sector of a cell uses the same frequencies and transmission times and is synchronized with the other sectors in the cell in terms of tone frequencies used at any given time and symbol transmission times. Tones are allocated to channels in each cell in the same manner so that each channel in a sector has a corresponding channel in another sector. Power differences between channels in different sectors are maintained to be within a pre-selected power difference. Different channels in a cell are assigned different power levels. Wireless terminals are assigned to channels based on channel feedback information. Wireless terminals with poor channel conditions are allocated to higher power channels than wireless terminals with good channel conditions. Lower power channels often include more tones per symbol time than high power channels.

Abstract: A novel composition of a materials that can be extruded into sheets to form panels to create a roofing system wherein the panels are formed to interlock with like panels in order to provide a substantially weatherproof covering on a roof. The sheet member has a top layer made of ASA (Acrylonitrile/Styrene/Acrylate polymer) and a bottom layer made of PVC (Polyvinylchloride). The two layers are extruded and bonded or preferably coextruded. Then the bonded materials are thermoformed to resemble more popular types of roof coverings such as shake or shingles or tiles.

Abstract: Methods and apparatus for simulating, in reduced resolution video decoders, the biasing effect associated with MPEG's specified rounding of pixel values including a fractional component of 0.5 to the next highest integer value are described. In one embodiment, the biasing effect is simulated by generating luminance and chrominance DC DCT coefficient bias values from, e.g., motion vector offset data. The DC DCT bias values are then added to the DC DCT coefficients of the luminance and chrominance blocks, respectively, which correspond to the same image block to which the motion vector data used to generate the bias values corresponds. In another embodiment, pixel values are directly adjusted to simulate the biasing effect associated with MPEG compliant rounding. In such an embodiment, luminance and chrominance pixel biasing values are generated as a function of, e.g., motion vector offset information. The bias values are added to the pixel values generated through the use of motion compensated prediction.

Abstract: Digital video tape recorder ("VTR") and servo circuit for supporting the display of images during trick play VTR operation. The digital VTR, in one embodiment, having a single pair of heads of alternating azimuths located on a head cylinder one track width apart. The digital VTR records data that can be used to generate images during trick play tape speeds and directions of operation in fast scan tracks defined by the paths the single pair of heads trace over the tape during trick play operation. Each fast scan track crosses multiple normal play tracks. Sync blocks and track identification information are recorded on the tape along with video data. To align the heads with the appropriate fast scan track during trick play operation, a lookup table containing information on the pattern of fast scan tracks recorded on the tape is used.

Abstract: Methods and apparatus for converting a relatively low frequency signal, e.g., a 1.5 MHz signal, to a high frequency signal, e.g., a 30-100 MHz signal, in the digital domain without the need for a digital mixer operating at the high frequency are described. The high frequency represents, e.g., the ultimate digital to analog conversion frequency. In accordance with the present invention an interpolation technique is used to convert the low rate digital signal to a high rate signal and to shift the carrier to a desired frequency. This is accomplished, by first positioning the information signal, e.g., the digital waveform to be modulated on a carrier at a relatively low rate using a digital mixer operating at a fraction of the ultimate digital to analog conversion frequency. The relatively low rate signal generated by the mixing operation is then converted to a high rate signal by one or more interpolator stages. An adjustable passband filter circuit is included in each interpolation stage.

Abstract: Methods and apparatus for insuring that a trick play data stream, e.g., a stream of data used for fast forward or reverse playback operation, complies with preselected data standards and in particular the MPEG-2 standard are disclosed. Various methods are described for generating PCR, PTS and DTS values for a trick play data stream, which is generated from a normal play data steam, and is intended for recording in trick play segments of a tape. The described methods include generating new PCR, PTS and DTS values as a function of the trick play speed at which the data is intended to be read back. Methods and apparatus for correcting PCR, PTS and DTS values read from a tape during trick playback operation are also disclosed. The disclosed methods are directed to generating new PCRs, PTSs and DTSs to provide am MPEG-2 compliant bitstream. The described methods and apparatus are applicable to a plurality of storage and playback devices capable of implementing trick play including compact disks.

Abstract: Methods and apparatus for converting a relatively low frequency signal, e.g., a 1.5 MHz signal, to a high frequency signal, e.g., a 30-100 MHz signal, in the digital domain without the need for a digital mixer operating at the high frequency are described. The high frequency represents, e.g., the ultimate digital to analog conversion frequency. In accordance with the present invention an interpolation technique is used to convert the low rate digital signal to a high rate signal and to shift the carrier to a desired frequency. This is accomplished, by first positioning the information signal, e.g., the digital waveform to be modulated on a carrier at a relatively low rate using a digital mixer operating at a fraction of the ultimate digital to analog conversion frequency. The relatively low rate signal generated by the mixing operation is then converted to a high rate signal by one or more interpolator stages. An adjustable passband filter circuit is included in each interpolation stage.

Abstract: In accordance with the present invention an interpolation technique is used to convert a low rate digital signal to a high rate signal and to shift the carrier to a desired frequency. This is accomplished, by first positioning the information signal, e.g., the digital waveform to be modulated on a carrier at a relatively low rate using a digital mixer operating at a fraction of the ultimate digital to analog conversion frequency. The relatively low rate signal generated by the mixing operation is then converted to a high rate signal by one or more interpolator stages. An adjustable passband filter circuit is included in each interpolation stage. One feature of the present invention is directed to a control circuit which is response to an H bit frequency control word representing a desired output carrier frequency. The control circuit generates individual filter control signals for each adjustable filter circuit from the single H bit frequency control word.

Abstract: Methods and apparatus for performing packet synchronization recovery and error detection operation on packets including a CRC check byte, e.g., MCNS packets, are described. The present invention uses a memory during a sync acquisition mode of operation to serve as a storage device for the output of a first function circuit. The delayed bits are used as the input along with current bits from the packet stream to a second function circuit. The second function circuit generates a syndrome byte of interest. When the received packets are error free and the decoder is properly aligned with the packet structure of the bitstream, the syndrome byte of interest will assume a preselected value, e.g., 47 Hex. Once packet synchronization has been achieved, the relatively few bits output by the first function circuit which are required as delayed inputs to the second function circuit are identified and stored using a delay register which is much smaller than the memory.

Abstract: Improved carrier recovery methods and apparatus suitable for use with QAM, QPSK and a wide variety of other modulation formats is described. In accordance with the invention, the phase error between received symbols, representing a frequency error, is determined using one of a plurality of techniques. The estimated frequency error is used to adjust the phase and/or frequency of a received carrier signal to achieve a frequency lock. The methods and apparatus of the present invention can be easily integrated into existing carrier recovery designs to supplement known frequency In accordance with a first embodiment of the present invention, the receipt of pairs of consecutive outer symbols is detected, a frequency error associated with each pair of consecutive symbols is generated, and the frequency error is compared to a selected threshold value to determine if it is a non-ambiguous estimate of the frequency error.

Abstract: Digital video tape recorder ("VTR") and servo circuit for supporting the display of images during trick play VTR operation. The digital VTR, in one embodiment, having a single pair of heads of alternating azimuths located on a head cylinder one track width apart. The digital VTR records data that can be used to generate images during trick play tape speeds and directions of operation in fast scan tracks defined by the paths the single pair of heads trace over the tape during trick play operation. Each fast scan track crosses multiple normal play tracks. Sync blocks and track identification information are recorded on the tape along with video data. To align the heads with the appropriate fast scan track during trick play operation, a lookup table containing information on the pattern of fast scan tracks recorded on the tape is used.

Abstract: Methods and apparatus for insuring that a trick play data stream, e.g., a stream of data used for fast forward or reverse playback operation, complies with preselected data standards and in particular the MPEG-2 standard are disclosed. Various methods are described for generating PCR, PTS and DTS values for a trick play data stream, which is generated from a normal play data steam, and is intended for recording in trick play segments of a tape. The described methods include generating new PCR, PTS and DTS values as a function of the trick play speed at which the data is intended to be read back. Methods and apparatus for correcting PCR, PTS and DTS values read from a tape during trick playback operation are also disclosed. The disclosed methods are directed to generating new PCRs, PTSs and DTSs to provide am MPEG-2 compliant bitstream. The described methods and apparatus are applicable to a plurality of storage and playback devices capable of implementing trick play including compact disks.

Abstract: Methods and apparatus for converting a relatively low frequency signal, e.g., a 1.5 MHz signal, to a high frequency signal, e.g., a 30-100 MHz signal, in the digital domain. An interpolation technique is used to convert the low rate digital signal to a high rate signal and to shift the carrier to a desired frequency. This is accomplished, by first positioning the information signal, e.g., the digital wave form to be modulated on a carrier at a relatively low rate using a digital mixer operating at a fraction of the ultimate digital to analog conversion frequency. The relatively low rate signal generated by the mixing operation is then converted to a high rate signal by one or more interpolation stages. An adjustable passband filter circuit is included in each interpolation stage for selectively filtering out the signal or images created as a result of a signal padding operation performed as part of each interpolation stage.

Abstract: Method and apparatus for providing a QAM, a VSB, and a joint QAM/VSB demodulator are described. The describe demodulators are designed to minimize the amount of duplicated circuitry required to implement a joint QAM/VSB demodulator capable of performing the functions of the disclosed individual QAM and VSB demodulators. All digital architectures are used for each of the described demodulators to facilitate their combination into the described joint VSB/QAM demodulator. The described demodulators are suitable for demodulating, e.g, advanced or high definition television signals modulated using QAM or VSB modulation techniques.

Abstract: A Nyquist filter implemented as a FIR filter comprising a series of N filter cells, where N is an integer is disclosed. The Nyquist filter is especially well suited for use in demodulators capable of demodulating both VSB and QAM signals. During VSB mode operation, each filter cell acts as a single tap of an N tap Nyquist filter. During QAM mode operation, an additional unit delay element, not used during VSB mode operation, is inserted into the signal path of each cell of the Nyquist filter. The introduction of this second unit delay element into the signal path of each filter cell effectively serves to convert each filter cell into two filter taps with the coefficient of the second filter tap being zero. Thus, during QAM mode operation, the Nyquist filter of the present invention operates as a 2N-tap FIR filter which has coefficients of zero for half of the 2N taps.

Abstract: A digital video tape recorder ("VTR") that selects data useful for generating images during trick playback operation and records the data in trick play tape segments arranged on a tape to form fast scan tracks and multi-speed playback tracks. Each fast scan track comprises trick play tape segments located on a diagonal, relative to the length of the tape, of the same angle as the angle at which the heads of a VTR are expected to pass over the tape during trick play operation at a specific speed and direction of operation. Each multi-speed playback track comprises a plurality of trick play tape segments arranged parallel to the length of the tape. Data which is used for at least one mode of trick play operation is recorded in each trick play tape segment. Each fast scan track and multi-speed track crosses multiple normal play tracks.

Abstract: Implementation efficient video decoder for decoding multiple bitstreams to provide picture-in-picture capability in a digital video display device is disclosed. The video decoder includes a full resolution video decoder and a reduced resolution video decoder. The reduced resolution decoder decodes and downsamples video images using the same video memory device used by the full resolution decoder. By using a sufficient amount of downsampling, the amount of memory required to implement the video frame memory and decoder buffer required by the reduced resolution video decoder is reduced to a point where the frame memory and decoder buffer can be implemented using excess memory which is left over from the implementation of the full resolution decoder frame memory and decoder buffer. Accordingly, the present invention avoids or reduces the need to provide additional memory for frame storage when implementing picture-in-picture capability in a digital video display device.