Abstract: A receiver for processing a VSB modulated signal containing terrestrial broadcast high definition television information includes an input analog-to-digital converter (19) for producing a digital datastream. A symbol timing recovery and segment sync recovery network (24; FIG. 3, 4) develops a properly timed sampling clock for the digital converter (19). The symbol timing recovery network (310) responds to an output from the segment sync recovery network (328), which in turn responds to an equalized signal from an adaptive channel equalizer (34). A controlled oscillator (336) generates the sampling clock for the digital converter. A control network (340, 344, 348; FIG. 3) shifts the frequency range of the oscillator to maintain desired linear operation to enhance symbol timing acquisition.

Abstract: Program Guide information is formed suitable for incorporation in a video program datastream and for storage on a storage medium or for broadcast in variable broadcast encoding formats. A method of formatting video data to be suitable for output on one of a plurality of output channels and in one of a plurality of encoding formats is employed. The method involves forming program guide information including a channel map associating an output channel with a video program. The program guide information also associates the channel map with an encoding format. The program guide information and the video data are incorporated into a datastream and the datastream is provided to an output channel. The method may also involve generating a parameter indicative of an encoding format and combining the encoding format parameter and the channel map in the program guide.

Abstract: A receiver system automatically adaptively tunes to broadcast signals that are variable in the number of channels that are transmitted, their signal coding type and their modulation format. A system receives a digital bitstream representing video information encoded in one of a plurality of different formats, and transmitted on one of a plurality of transmission channels. The system includes a processor for identifying and capturing program guide information including a plurality of channel maps. A channel map associates a transmission channel with a video channel output and the channel map is also associated with an encoding format. The system also includes an adaptive decoder for decoding the bitstream to provide the video channel output in response to the program guide information.

Abstract: A satellite signal receiver includes an input demodulator followed by a Viterbi decoder and a Reed-Solomon decoder. A received signal is encoded with information including error-representative information, and exhibits an error correction code rate which is a function of the power level of a satellite transmitted signal. The demodulator produces control signals representing the presence or absence of synchronism with the received signal, and signal quality (e.g., signal-to-noise ratio). The Reed-Solomon decoder produces a control signal indicating whether or not error detection and correction is occurring properly. These control signals are sensed by a control network to change the code rate of the Viterbi decoder if necessary.

Abstract: A tuner of for a digital satellite television receiver comprises a single conversion stage which produces an IF signal at a low enough frequency to permit a SAW filter to be used to perform symbol shaping as well as the normal IF filtering function. The local oscillator is controlled by a phase locked loop tuning control IC normally used to control the local oscillator of a tuner of a conventional broadcast or cable television receiver. In an exemplary embodiment for tuning RF signals provided by a block converter in the 950 to 1450 mHz frequency range, the IF has a center frequency of 140 mHz. A lithium tantalate SAW filter is used in order to minimize shift of the IF center frequency with temperature and to provide the required relative IF bandwidth (i.e., the width of the IF passband divided by the IF center frequency).

Abstract: An economical tuning system for a digital satellite television receiver includes a phase locked loop (PLL) tuning control IC of the which is normally used in a tuning system of a conventional terrestrial broadcast or cable television reciever to control the frequency of the local oscillator (LO). Unfortunately, the PLL IC is only capable of changing the frequency of the LO in relatively large steps. As a result, the operation of a carrier recovery loop which demodulates the digitally encoded IF signal produced by the tuner may be interrupted during a fine tuning mode because the carrier recovery loop may not be able to track frequency changes of the LO. To reduce such possibility, the integrator filter associated with the PLL IC is modified to decrease the rate of change of the LO frequency during the fine tuning mode.

Abstract: A memory efficient trellis demapper for demapping 8-PSK and 16, 32, 64 128 and 256-QAM trellis codes contains respective I-channel, Q-channel and remapper random access memory (RAM), an 8-PSK demapper logic network, and a selector switch. Each RAM includes a lookup table selectively programmed for each QAM code. The I-channel RAM and the Q-channel RAM forward their respective outputs through the switch as the trellis demapper output in response to an even power of 2 (i.e., 16, 64 or 256) QAM trellis code being selected. In response to an odd power of 2 (i.e., 32, 128) QAM trellis code being selected, the respective outputs of the I and Q channel RAMs are input to the remapper RAM, and the remapper RAM output is conveyed via the switch as the trellis demapper output. When an 8-PSK trellis code is selected, the output of the 8-PSK demapper logic network is conveyed via the switch as the trellis demapper output.

Abstract: A Digital signal processor selectively demodulates and decodes signals received from multiple types of transmission channels such as satellite, terrestrial and cable transmission channels. A received signal is representative of compressed digital video information such as television picture information, and is encoded in one of a plurality of coding formats (e.g., trellis or punctured codes of selectable code rate). The received signal is also modulated in one of a plurality of modulation formats (e.g., PAM, QAM or PSK). A demodulator selectively demodulates the signal modulated in one of the plurality of modulation formats, and a decoder selectively decodes the demodulated signal coded in one of the plurality of coding formats.

Abstract: An adaptive receiver includes an adaptive demodulator and an adaptive decoder for providing demodulated and decoded output data from a video signal encoded for satellite, terrestrial or cable transmission. The demodulator recovers demodulated output data by using an adaptive timing recovery network and an adaptive carrier recovery network that incorporates a selectable slicer network. In addition, an Automatic Gain Control network within the demodulator provides a gain control output as a function of a difference between signals produced both prior to and following the slicer. The demodulator may also incorporate a signal quality detector that uses carrier recovery network signals to provide an estimate of the error in the demodulated output data. The decoder produces a Viterbi decoded output from the demodulated output data by using a selectable code rate Viterbi decoder.